This distinction recognises his outstanding contributions to modern magnetism, condensed matter physics, spin caloritronics, and magnon-related transport phenomena, as well as his exceptional scientific leadership and service to the international physics community. https://www.eurasc.eu/blaise-pascal-medal/

The scientific programme comprised of 20 invited talks, 50 contributed talks and more than 50 posters, covering a broad range of scientific fields including condensed matter physics, biophysics, spin physics, photonics and quantum technologies. The consistently high quality of the presentations and the intensive discussions during breaks and poster sessions were particularly well received.

The conference offered opportunities to exchange ideas across research fields and career stages. Alongside the scientific programme, participants could attend soft-skill workshops, learn about career paths in industry and connect with representatives from research institutions and more than 20 sponsors from research-intensive industry. These activities highlighted the links between fundamental research, technological innovation and career development.

A special highlight was a video greeting from the conference's patron, Dorothee Bär, Germany's Federal Minister for Research, Technology and Space. She highlighted the importance of the conference topics for attracting skilled professionals and advancing Germany's High-Tech Agenda.

The DPT demonstrated the value of combining scientific exchange with professional development and networking, while providing women in physics with opportunities to present their research, strengthen their scientific visibility and build connections across career stages.

A varied program of exciting workshops, lectures, and personal encounters introduced the participants to the many facets of physics. Particularly valuable was the direct exchange with female physicists from research, academia, and industry, who shared their experiences and career paths.

At the World of Physics Café, participants were able to strike up conversations with inspiring female physicists and gain very personal insights into different career paths. In laser workshops, it also became clear just how versatile physics knowledge can be—for example, in medicine or in forensic investigation to solve crimes.

The GirlsGoPhysics Day impressively demonstrated that physics is diverse, exciting, and offers numerous career opportunities. The participants were not only able to deepen their enthusiasm for scientific questions but also learned that success in physics is not a matter of gender.

Lecture Assistants from Across Germany Visit the Department of Physics in Kaiserslautern

From September 14 to 16, 2026, the Department of Physics at RPTU in Kaiserslautern hosted a workshop for lecture assistants from German universities. Approximately 25 universities were represented. The focus was on professional exchange and the question of how physical phenomena can be conveyed in a clear and engaging way through experiments in university teaching—and what ideas and innovations the RPTU is leading the way with in this area.

To this end, the RPTU lecture series team presented a hand-picked selection of approximately 35 experiments from various fields of physics: The demonstrations ranged from a fire tornado to numerous experiments newly developed by the RPTU and the Kapitsa pendulum, highlighting the high priority given to experiments in physics education at the Kaiserslautern campus. The experiments were presented in detail, discussed, and evaluated in terms of their use in teaching. Another focus was on the technical implementation of modern experimental lectures. The RPTU’s lecture hall technology provides a modern, well-designed, and time-tested foundation for this purpose. The requirements are particularly high when it comes to presenting physics experiments: The experiments must be presented in a way that is visible and understandable even in large lecture halls, while at the same time being able to be integrated directly into the lecture and live streams via cameras, projectors, and other technology. The technical equipment developed at the RPTU for this purpose therefore also generated great interest among the representatives from the other universities.

The program was complemented by guided tours of the extensive lecture collection and selected laboratories, as well as insights into current research.

In his talk, Prof. Dr. Widera provided insight into the latest advances toward a universal quantum computer, thereby demonstrating how closely current research topics are linked to the education of future physicists.

A special highlight of the program was the keynote lecture by Prof. Dr. Beigang, featuring his magic show “Physik mal anders”. Physics topics and phenomena were presented in a magical context and conveyed in an entertaining way. The unusual combination of magic and physics generated a great deal of enthusiasm among the participants.

The numerous positive responses from the participants showed that the conference was very well received, both in terms of its academic content and its supporting program, and left a very positive impression of the RPTU in Kaiserslautern as a center for physics.

We extend our warmest congratulations to Jonas and are delighted that he will continue to be closely connected to the Department of Physics!

We look forward to this collaboration and to making our research more tangible and visible!

The three classical states of matter: solid, liquid, and gas are everyday phenomena. However, additional states exist, including plasma and the Bose-Einstein condensate (BEC). In a BEC, a large number of quantum particles no longer behave independently but instead collectively occupy a single macroscopic quantum state.

BECs were originally observed in ultracold atomic gases near absolute zero temperature. Twenty years ago, however, researchers demonstrated that a comparable phase transition can also occur in magnetic solids—and notably at room temperature. The corresponding study was carried out by the Department of Physics of TU Kaiserslautern (now RPTU Kaiserslautern-Landau), in collaboration with researchers from the Universities of Münster, Oakland, and Kyiv.

Although the existence of magnon BECs has been established for many years, direct experimental evidence for the spontaneous emergence of their macroscopic phase and its independence from external excitation signals had remained elusive. In the BEC state, magnons no longer behave as an incoherent ensemble but instead organize into a single collective quantum system characterized by a well-defined phase and frequency. Such spontaneous coherence is a defining property of all Bose-Einstein condensates. Until now, however, this hallmark feature had not been experimentally demonstrated for magnon BECs.

Direct Observation of Magnon BEC Using Phase-Resolved Microwave Spectroscopy

Researchers at RPTU have now provided this missing evidence using high-precision phase-resolved microwave spectroscopy. The measurements allowed them to directly observe both the emergence of coherence and the random seeding of the condensate phase in repeated experiments. “You can think of it as a noisy audio signal suddenly turning into a pure tone with a single well-defined frequency,” explains Professor Mathias Weiler, head of the working group Applied Spin Phenomena at RPTU. At that moment, the phase transition into a Bose-Einstein condensate takes place.

To observe the coherent state, the researchers needed a material in which magnons can persist for exceptionally long times. They therefore used yttrium iron garnet (YIG), a material known for exhibiting record-long magnon lifetimes. In the experiment, short and intense microwave pulses create a dense magnon gas. Subsequently, the magnons interact, gradually dissipate energy, and relax toward their lowest-energy state. Within only a few tenths of a microsecond, a large number of magnons accumulate in this state, forming a Bose-Einstein condensate.

“Our experiments provide the first direct evidence that magnons exhibit the defining property of a Bose-Einstein condensate,” says Professor Georg von Freymann, former head of the working group Optical Technologies and Photonics at RPTU, who is now based at Leibniz University Hannover. “This confirms a long-standing theoretical prediction.”

New Device Concepts for Signal Processing

From a fundamental perspective, the results represent an important step toward a deeper understanding of collective quantum states in condensed matter systems. At the same time, magnon BECs may ultimately enable new technological functionalities.

Particularly intriguing is the fact that, at room temperature, magnon condensates display phenomena reminiscent of superconductivity. In superconductors, electric charge can flow without resistance. In magnon Bose-Einstein condensates, by contrast, so-called spin supercurrents can emerge. In this case, spin - a fundamental quantum property of electrons – rather than charge is transported without dissipation.

This could pave the way for entirely new device concepts for analog signal processing. Potential applications include highly sensitive detectors for electric and magnetic fields as well as circuit architectures based on physical principles similar to those of Josephson junctions in superconducting systems. Today, Josephson junctions form the basis of numerous precision technologies and constitute a key building block of superconducting quantum computers.

Dr. Oleksandr Serga, co-author of the study and one of the researchers involved in the original discovery of the magnon BEC together with Professor Burkard Hillebrands, head of the working group Magnetism at RPTU, explains: “Compared with superconductivity, research on magnon Bose-Einstein condensates is still in its infancy. Superconductivity was discovered roughly one hundred years before the magnon BEC. While superconductivity experienced a major technological breakthrough with the development of robust high-temperature superconductors beginning in the 1980s, a key challenge for magnon BECs is maintaining the condensate state over sufficiently long timescales. At present, we achieve lifetimes in the order of microseconds, but we already have ideas for extending them significantly.

If this challenge can be overcome, magnon Bose-Einstein condensates could provide a new platform for energy-efficient information processing and ultrasensitive quantum sensing. The present demonstration of spontaneous coherence and the random formation of a macroscopic phase independent of the microwave excitation therefore marks an important milestone on this path.

The current study:

Malte Koster, Matthias R. Schweizer, Timo Noack, Vitaliy I. Vasyuchka, Dmytro A. Bozhko, Burkard Hillebrands, Mathias Weiler, Alexander A. Serga & Georg von Freymann, Emergence of phase coherence in a magnon Bose–Einstein condensate. Nature Physics (2026) https://Article doi.org/10.1038/s41567-026-03373-6

Scientific Contact:

Malte Koster

Optical Technologies and Photonics
Department of Physics
RPTU University Kaiserslautern-Landau
Tel.: +49 631 205 5228

Prof. Dr. Mathias Weiler

Applied Spin Phenomena
Department of Physics
RPTU University Kaiserslautern-Landau
Tel.: +49 631 205 4099

Press contact:

Christine Pauli
University Communications
E-Mail: presse[at]rptu.de

The Department of Physics would like to thank the Physics Alumni Association for its generous support of this event, as well as the Physics Student Council for its active assistance, including in hosting the guests!

You can find more impressions and photos here.

We welcomed female high-school students to discover physics research, visit labs and meet women working in physics. It was wonderful to see their curiosity and enthusiasm—and to give them the opportunity to connect with female researchers and learn about possible career paths in physics.

A big thank you to everyone who helped make the day possible! 

This was celebrated during the barbecue that followed with department members in the amphitheater on campus. The student council took excellent care of the salads, drinks, desserts, and making sure everyone’s grilled food was cooked to perfection. Summery temperatures and a brief refreshing rain shower created the perfect atmosphere for a successful evening among friends and colleagues.

A heartfelt thank you to the student council for organizing the event, the department for covering the costs, the jDPG for supporting the soccer tournament, and everyone who contributed salads, desserts, or a helping hand. We look forward to doing it again next year!

The Department of Physics is pleased to announce that Dr. Philipp Pirro was appointed today as professor of experimental physics with a focus on magnonics.

We extend our heartfelt congratulations on this appointment and wish him much success, joy, and a smooth start in his new role. We look forward to continuing to work with him and shaping the future of our department together.

phdays26.sciencesconf.org

The MINT-EC Camp focuses on modern physics through lectures and hands-on seminars. The opening lecture will cover oscillations, a fundamental concept in physics. Afterward, physicists from RPTU will introduce the students to many other facets of modern physics. Students can expand their knowledge during a lecture on complex numbers. Hands-on participation is encouraged in the workshops on “3D Microprinting with Light,” “Spectroscopy – What Colors Does Life Have?” and “From Silicon Wafer to Chip.” In these sessions, participants will learn about working in a physics lab, particularly the highly sensitive work required in a cleanroom.

Beyond the hands-on learning, students will also receive first-hand information about studying physics at RPTU. At the evening event on Tuesday, there will be an opportunity to enjoy pizza together with students .

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About MINT-EC

MINT-EC is the national network of excellence for high schools with a strong focus on mathematics, computer science, natural sciences, and technology (MINT). It was founded in 2000 by employers and works closely with their regional educational initiatives. MINT-EC offers a wide range of events and support programs for students, as well as professional development and subject-specific exchange opportunities for teachers and school administrators. Since 2009, the network has been under the patronage of the Standing Conference of the Ministers of Education and Cultural Affairs of the Länder (KMK). The main sponsors of MINT-EC are the employers’ association Gesamtmetall as part of the think ING. initiative, as well as the Siemens Foundation and the Bavarian employers’ associations vbm, bayme, and vbw.

About the PfalzMetall Foundation

The PfalzMetall Foundation focuses on four areas: science and research, education and training, art and culture, and support for youth and the elderly. The foundation’s overarching goal is to spark and sustain enthusiasm for STEM subjects—that is, mathematics, computer science, natural sciences, and technology. For more information about the projects, please visit www.stiftung-pfalzmetall.de.

For questions, please contact:

Anett Fleischhauer
Dean’s Office of Physics

Phone: 0631 205-5251
Email: anett.fleischhauer[at]rptu.de

The conference will take place from September 28 to 30, 2026, at RPTU in Kaiserslautern, Germany, under the patronage of the German minister of research, Dorothee Bär. It brings together researchers, students, and professionals from academia and industry, offering a platform for exchange on current developments in physics and related technology fields.

The scientific program covers topics such as spin physics, quantum technologies, photonics, and solid-state physics. The conference is complemented by career events, soft skill workshops, and numerous networking opportunities.

Confirmed keynote speakers include:

• Prof. Dr. Monika Ritsch-Marte, Medical University of Innsbruck
• Prof. Dr. Karin Jacobs, Saarland University
• Prof. Dr. Sibylle Günter, Max Planck Institute for Plasma Physics Greifswald

The full list of invited speakers is available here.

As hotel availability in Kaiserslautern tends to be limited during this period, the organizing committee recommends registering and booking accommodation early.

For further information and registration, please visit: Deutsche Physikerinnentagung 2026 – Registration and Information

The organizing committee looks forward to welcoming participants from across Germany and beyond in Kaiserslautern in September 2026.

Contact: dpt2026(at)rptu.de

Our colleague Sebastian Westrich, together with Aditya Kumar and Xinran Wang from the Kläui group at JGU Mainz, submitted a project proposal for this competition. With their research idea to investigate so-called van der Waals magnets using a diamond chip, they impressed the other PhD students in the Collaborative Research Centre and ultimately took first place.

The prize money of 3,000 euros will now be used to implement the research idea.

https://freundeskreis-rptu.de/aktuelle-news/der-freundeskreis-kuert-local-hero-beim-falling-walls-wettbewerb/

The Falling Walls Lab is part of the international Falling Walls initiative, which promotes scientific exchange, innovative ideas, and socially relevant projects. The format aims to connect early-career researchers, founders, and thought leaders, as well as present their research to an interdisciplinary jury from academia, industry, and the startup community.

Participants received professional pitch training from Katharina Boguslawski in preparation for the competition. She supported the young researchers in developing their presentations and stage presence.

The Department of Physics at the RPTU University Kaiserslautern-Landau in the Rhineland-Palatinate region achieved outstanding results in the competition, securing second and third place.

Emma Herbst, the second-place winner, presented her research on the detection of free radicals using quantum sensors under the theme “Breaking the Wall of Free Radical Detection.” Her presentation focused on developing new approaches to directly visualize and measure highly reactive, short-lived intermediates under realistic conditions. Her research aims to improve our understanding of photocatalytic processes at the molecular level, thereby contributing to the development of more sustainable technologies, such as green hydrogen synthesis.

In addition to her success in the competition, Herbst was honored as a “Local Hero” by Klaas Bergmann and the Friends of the RPTU. This recognition highlights the visibility and societal relevance of her research.

Kawa Noman, who took third place, presented the prototype of his startup, TennaSonic, under the title "Breaking the Wall of 6G Thermal Limits." He presented a novel solution for stabilizing antenna performance in smartphones, vehicles, and IoT systems under extreme thermal conditions. This technology aims to ensure reliable data transmission at high temperatures, reduce temperature-related failures, and increase the sustainable lifespan of modern wireless electronic systems.

The Department of Physics congratulates all participants on their successful presentations and, in particular, Tara Garschik for winning the competition.

From May 11 to 13, approximately 20 students in grades 10 and 11 will gather at the RPTU in Kaiserslautern for a physics seminar and the third round of the state physics competition. Half of them will compete in the competition’s final round. In addition, all the students will attend physics workshops and conduct experiments in the lab. The program includes topics such as wave optics and related measurement techniques, quantum technologies, and working in the physics lab. On Wednesday, May 13, the winner of the state competition will be announced.

To begin with, the 20 students must present a research paper they have prepared in advance and discuss the results of their work in a colloquium. In addition, they are required to independently conduct and evaluate two experiments in the laboratory. Performance in the experiments, the colloquium, and the research paper is weighted equally and ultimately determines who wins the competition. The winner will be invited by the Department of Physics to participate in an internship, where they will gain insight into laboratory work.

In parallel with the competition, there is a physics seminar for all students. Through lectures and experiments, they—along with the competition participants—gain insights into physics research. Topics include a thorough introduction to the world of quantum physics and quantum objects, 3D microprinting with light, and problem-solving strategies for tricky physics questions. In addition, all students will receive information about the “Frühstudium Physik” (FiPS) program and the physics, biophysics, and technophysics degree programs offered by the Department of Physics at RPTU.

The students attend various high schools in Rhineland-Palatinate.

The State Physics Competition was established by the State of Rhineland-Palatinate. It is sponsored by the Rhineland-Palatinate Ministry of Education, the Heraeus Foundation, the German Physical Society (DPG), the State Research Center for Optics and Materials Science (OPTIMAS), the Collaborative Research Centers SFB-TR185 (OSCAR - Open System Control of Atom and Photonic Matter) and SFB-TR173 (SPIN+X – Spin in its collective environment), as well as the Sparkasse Kaiserslautern.
 

For questions, please contact:

Anett Fleischhauer
Dean’s Office of Physics

Phone: 0631 205-5251
Email: anett.fleischhauer(at)rptu.de

In its announcement, the EMA highlights Hillebrands' scientific achievements in particular: through his advancement of Brillouin light scattering spectroscopy and the realization of magnon-based logic devices, he has firmly established magnonics as a key area of contemporary magnetism. The EMA further recognizes his "dedicated leadership and influential and deeply supportive presence" within the magnetism community, which has greatly strengthened magnetism research across Europe.

Prof. Dr. Burkard Hillebrands studied physics at the University of Cologne, where he received his diploma in 1982 and his doctorate in 1986. Following a postdoctoral stay at the Optical Sciences Center in Tucson, Arizona, he completed his habilitation at RWTH Aachen University in 1993. In 1994, he was appointed Associate Professor at the University of Karlsruhe before moving to TU Kaiserslautern (now RPTU) as a full professor in 1995, where he taught until 2025 and continues to work as a senior professor today. As a highly respected member of the scientific community, he has held several key leadership positions, including Scientific Director and member of the Executive Board of the Leibniz Institute for Solid State and Materials Research Dresden from 2016 to 2017, and Vice President for Research, Technology, and Innovation of TU Kaiserslautern from 2006 to 2014. He is a founding member of the EMA and served as its President from 2019 to 2022. Even beyond his active teaching career, he continues to share his experience and remains engaged — in collaboration with external coaches, among others — in the mentoring of researchers in the postdoctoral, tenure-track and appointment phase.

The Dominique Givord Award for Advancing Magnetism in Europe has been presented every three years by the European Magnetism Association since 2020. It honors scientists who have made significant contributions to advancing magnetism research and the magnetism community in Europe. The award commemorates the French physicist Dominique Givord, who passed away in 2019 and was one of the co-founders of the EMA. 

The award will be formally presented during the Joint European Magnetic Symposia (JEMS) 2027, which will take place in Prague, Czech Republic, from August 29 to September 3, 2027. There, Hillebrands will deliver a talk during the plenary session.

New Architecture for “Plasmonic Neurons” Unveiled
An international research team involving the RPTU University Kaiserslautern-Landau has taken an important step toward ultrafast, light-based computers. In a recently published paper, the scientists present a novel concept for so-called plasmonic neural architectures—tiny building blocks that function like artificial nerve cells but operate using light instead of electrons.

The research focuses on developing a 'plasmonic neuron' at the nanoscale. The aim is to incorporate the core functions of biological neurons — receiving, weighing and processing signals — directly into a physical structure.

Light as a computing unit
Rather than using electrical signals, the system uses surface plasmons, which are light waves that travel along metal surfaces. These allow information to be transported extremely quickly and in the smallest of spaces. One notable feature is the use of the orbital angular momentum (OAM) of light, which enables multiple signals to be encoded and processed simultaneously.

For the first time, researchers have demonstrated an integrated platform combining all three key steps of an artificial neuron. Multiple input signals are fed in simultaneously and processed separately, with the strength of each signal precisely adjusted via nanoscale gaps in the waveguides. The result is then evaluated via a nonlinear photoelectric effect, similar to activation functions in neural networks. This integration into a single nanoscale component is considered a significant breakthrough, as previous approaches often required several separate components.

Outlook: Artificial neural networks at the speed of light
In the long term, this new architecture could pave the way for light-based artificial neural networks. Such systems could offer significantly higher speeds and energy efficiency than today's computers, which are limited by the so-called von Neumann bottleneck. The authors see great potential in this fundamental study. In the future, complex, scalable networks could emerge that process information entirely optically — and thus at nearly the speed of light. Plasmonic neural architectures could therefore be pivotal in the development of the next generation of ultra-fast, energy-efficient computers.

The study:
Christopher G. O. Weiß, Tobias Eul, Emily Kruel, Mario F. Pfeiffer, Bert Lägel, Benjamin Stadtmüller, Martin Aeschlimann
“Toward Plasmonic Neuronal Architectures at the Nanometer Scale,”
Nanophotonics: e70066. (2026) https://doi.org/10.1002/nap2.70066.

Her personal impressions and experiences from her stay can be read here.

We are pleased to announce that our research group is now part of this interdisciplinary project. The project combines photonic approaches, quantum sensing based on NV centers in diamonds, and neuromonitoring methods. In the long term, these technologies are intended to be integrated into a surgical instrument to enable real-time visualization of nerves and evaluation of their functionality.

This approach is expected to significantly improve nerve preservation, particularly in complex procedures such as colorectal surgery. In addition, the technology holds great potential for a wide range of further medical applications.

Together with the medical technology company Erbe as project coordinator, we look forward to working on this project.

Link to the project description.

Are you passionate about sustainable and renewable energy and want to learn more about it? On March 31, you’ll gain fascinating insights from physicists and chemists on topics such as material conversion, energy sources, and reaction processes in this free workshop hosted by the WIPOTEC Foundation. We’ll also show you how solar cells and wind turbines work, and how they’re used to provide a home with sustainable electricity.

This workshop will be held in German.

You can find more information and register for this workshop at the RPTU campus in Kaiserslautern here:

https://www.wipotec-stiftung.com/de/workshops/details/green-energy-aus-chemischer-und-pysikalischer-perspektive

You can find the program here.

Magnonics is an emerging technology that uses spin waves – collective excitations of electronic spins in magnetic materials – as an alternative to electrical signals. The spread of this technology has been restricted until now by the need for an external magnetic field, which has prevented it being incorporated into chips.

The new device developed at the Politecnico overcomes this hurdle: it is miniaturised (100 × 150 square micrometres, so much smaller than current radiofrequency signal processing devices based on acoustic waves); it is fully integrated on silicon – and therefore compatible with existing electronic platforms, and it functions without external magnets, thanks to an innovative combination of permanent SmCo micromagnets and magnetic flux concentrators. 

The spin wave guide is made of CoFeB and fitted with two antennas for the input and output of the RF signal. The transverse magnetic field can be modulated very precisely by varying the distance between the magnets and concentrators to between 11 and 20.5 mT. This enables the operating frequency to be adjusted to between 3 and 8 GHz, and the phase shift to be tuned up to 120 degrees at 6 GHz.

As well as demonstrating the principle of the technology, the researchers point out that the prototypes are already functioning as time delay lines and phase shifters, without the application of an external bias field; that the design could be incorporated with MEMS to allow the devices to be reconfigured in real time; and that the choice of SmCo micromagnets ensures they will remain stable in temperatures of up to 200°C and can generate the magnetic field without consuming energy.

As Riccardo Bertacco of the Department of Physics of the Politecnico di Milano has explained: "This result is a decisive step towards moving spin waves from demonstrations in the lab towards a technology that can actually be incorporated into telecommunication systems and electronic circuits."

Silvia Tacchi, from CNR-IOM, adds: "This finding represents a key advancement in the field of magnonics, bringing spin-wave chips closer to being integrated into electronic devices".

The development of these devices is part of the MandMEMS project, funded by the European Union in the context of Horizon Europe. The coordinator of the project, Philipp Pirro from RPTU, incorporates this success into the project roadmap: “Building on this milestone, we can now tackle the next challenges, such as further increasing the transmission efficiency of the devices. Based on the large improvements achieved up to date, we are confident to present soon marketable devices for 6G which are based on standalone spin-wave chips”. 

The consortium involves various European research centres and industrial partners, with expertise ranging from magnonics to MEMS, and RF electronics to materials science. The aim is to develop a technological platform that can make the communication devices of the future more efficient, compact and reconfigurable, paving the way for new applications in telecommunications and high-frequency electronics.

With this innovation, the Politecnico di Milano, RRPTU and Istituto Officina dei Materiali - CNR-IOM have prepared the ground for compact, low-power, high-performance devices, with possible repercussions not only for future telecommunications, but also for consumer electronics, the automotive sector, diagnostics, and more generally for all applications that require integrated processing of high-frequency signals.

Website of the project:
www.mandmems.eu

The study:
M. Cocconcelli, F. Maspero, A. Micelli, A. Toniato, A. Del Giacco, N. Pellizzi, A. E. Plaza, A. Cattoni, M. Madami, R. Silvani, C. Adelmann, A. A. Hamadeh, P. Pirro, S. Tacchi, F. Ciubotaru, R. Bertacco, Standalone Integrated Magnonic Devices. Adv. Mater. 2025, 2503493. https://doi.org/10.1002/adma.202503493

We warmly welcome him and look forward to working with him in the future.

Two superconductors separated by a wafer-thin insulating layer – that's how simple a Josephson junction looks. But despite its simple structure, it harbors a quantum mechanical effect that is now one of the most important tools of modern technology: Josephson contacts form the heart of many quantum computers and enable high-precision measurements – such as the measurement of very weak magnetic fields. This is used, among other things, in magnetoencephalography (MEG), i.e., in medical diagnostics for examining magnetic fields in the brain.

It is important to note that the processes that take place in a Josephson junction occur at the level of individual quanta and are difficult to observe directly in the superconductor. To make the microscopic processes experimentally accessible, researchers use a trick known as quantum simulation. In general terms, this involves transferring a complex quantum system to another, more easily observable system. This allows effects to be investigated that are virtually inaccessible in their conventional environment.

At RPTU, an experimental research team led by Herwig Ott has now applied this principle to the Josephson effect. Instead of superconductors, they used an ultracold gas of atoms, a so-called Bose-Einstein condensate. The researchers separated two such condensates by means of a very thin optical barrier, which was generated with a focused laser beam and moved periodically. In this way, the researchers simulated what happens in a superconducting Josephson junction under microwave irradiation. The microwave radiation serves to generate an additional alternating current through the Josephson contact. 

Shapiro steps are a universal phenomenon

The result of the quantum simulation was impressive: the characteristic Shapiro steps appeared in the atomic system – quantized voltage plateaus that serve to calibrate the electrical voltage. They depend only on natural constants and the frequency of the modulation and form the basis on which the voltage standard for the “volt” is realized worldwide. “In our experiment, we were able to visualize the resulting excitations for the first time. The fact that this effect now appears in a completely different physical system – an ensemble of ultracold atoms – confirms that Shapiro steps are a universal phenomenon,” states Herwig Ott.

The study was conducted in collaboration with the theory groups of Ludwig Mathey from the University of Hamburg and Luigi Amico from the Technology Innovation Institute in Abu Dhabi. The work provides a textbook example of quantum simulation, Herwig Ott summarizes the results: "A quantum mechanical effect from solid-state physics is transferred to a completely different system – and yet its essence remains the same. This builds bridges between the quantum worlds of electrons and atoms.“ 

Using atoms to understand the world of electrons

In the future, Ott and his team want to connect several such ”building blocks“ with each other ”to build real circuits for atoms". Instead of electrons, atoms would then flow through the circuit – a field of work known as “atomtronics”. “Such circuits are particularly well suited for observing coherent effects, i.e., wave-like effects,” says Erik Bernhart, who conducted the experiments as a doctoral student. In addition, the movement of atoms can be “seen” directly in atomic circuits, which is much more difficult with electrons in solids. “We also want to replicate other fundamental components known from electronics for our atoms and understand them precisely at the microscopic level.”

The study:

Erik Bernhart, Marvin Röhrle, Vijay Pal Singh, Ludwig Mathey, Luigi Amico, and Herwig Ott
“Observation of Shapiro steps in an ultracold atomic Josephson junction”
www.science.org/doi/10.1126/science.ads9061

Scientific contact::

Prof. Dr. Herwig Ott
Departement of Physics at
RPTU University Kaiserslautern-Landau

T: +49 631 205 2817
E: herwig.ott(at)rptu.de

Contact Press Matters:

Julia Reichelt
University Communications Office

T: +49 631 205-5784
E: presse(at)rptu.de

Admission costs 7€, and in addition to a wide selection of long drinks, cocktails, wine, and shots, there will be hot mulled wine or punch and, once again, liquid gold from Kirner, as well as food from Boll Burger.

As with every Nikofete, there will be two stages this year. On one stage, MALTÖO and PYROTIK will be playing techno all evening, and on the other stage, EIDI will be playing a party mix.

Please dress warmly in case there are waiting times. Inside, there is a free cloakroom where you can leave your jackets and similar items so that you can party carefree in the foyer.

If you would like to support the party, we are currently still looking for helpers! 
For the first shift, everyone will receive 5 drink vouchers and free admission! You can redeem these for a variety of drinks. If you complete two shifts, you will receive 3 additional drink vouchers and will also be invited to our volunteer meal. Permanent volunteers (min. 3 shifts) will also receive a T-shirt. If you would like to help, please sign up on the lists in front of the AStA office in Building 46.

We look forward to seeing you!

Join Prof. Dr. Akashdeep Kamra on a journey into the remarkable world of quantum physics and discover the groundbreaking achievements honored with the 2025 Nobel Prize in Physics. The lecture will be held in English.

          When: 11th December 2025, 7:00 PM

          Where: Building 46, Room 215 (Lecture Hall)

Students, staff, and guests are all welcome.
We look forward to an inspiring evening!

Acoustic frequency filters, which convert electrical signals into miniaturized sound waves, separate the different frequency bands for mobile communications, Wi-Fi, and GPS in smartphones. Physicists at RPTU University Kaiserslautern-Landau have now been able to show that such miniaturized sound waves can couple strongly with spin waves in yttrium iron garnet. This results in novel hybrid spin-sound waves in the gigahertz frequency range. The use of such nanoscale hybrid spin-sound waves opens up potential for agile frequency filters for the upcoming 6G mobile communications generation. The fundamental study by the RPTU researchers has been published in the journal Nature Communications. 

Surface acoustic waves (SAWs) are ubiquitous. They unleash destructive power in the form of earthquake waves and, at the same time, perform their service completely unnoticed, but used billions of times over, in the form of miniaturized frequency filters in the gigahertz frequency range in smartphones.

The RPTU research team led by Professor Mathias Weiler is working on opening up new fields of application for such miniaturized sound-based microwave components. The key to this is the interconnection of established SAW technology with spin phenomena. "Sound waves can propagate not only in air, but also in matter. This causes the lattice atoms of the material to oscillate," explains the physicist. Since the electrons of the lattice atoms have a quantum mechanical angular momentum, known as spin, this can also be excited to oscillate. The sound waves then generate spin waves in magnetically ordered materials.

Sound waves and spin waves coexisting

The research team investigated such collective acoustic excitations of spins in the ferrimagnetic insulator yttrium iron garnet (YIG). YIG exhibits an extremely long spin wave lifetime, making it an ideal object of study. The recently published paper shows that hybrid excitations—known as magnon-polaron excitations—can be formed in a nanostructured acoustic surface wave resonator. "We have observed that the quantum mechanical coupling of spin and sound can lead to the formation of a novel chimeric wave that is neither a sound wave nor a spin wave. Spin and sound can no longer be separated in this excitation, but coexist," explains Kevin Künstle, first author of the study.

Acoustic filters and ferrimagnetic insulators combined

In particular, the researchers were able to show that this chimeric wave oscillates periodically between the sound and spin states. The characteristic transition frequency of this oscillation—the so-called Rabi frequency—is significantly greater than all loss rates in the system. This is clear evidence that the system is in a strong coupling regime.

To explain these phenomena, a theoretical model was developed in collaboration with colleagues from the RPTU working group led by Professor Akashdeep Kamra, which can quantitatively predict the observed coupling strength.

The quantitative understanding of the coupling phenomena and the control over the strength of the spin-sound coupling, also demonstrated in the work, opens up new perspectives for the technological use of hybrid states of sound and spin waves. “Our hybrid spin-sound excitations combine two pillars of microwave technology: acoustic filters and ferrimagnetic insulators,” adds Professor Weiler. “In the future, such systems could be used to expand the functionality of miniaturized microwave components. For example, agile frequency filters that can be adjusted during operation could be realized. This opens up new concepts for the implementation of 6G communication networks, the mobile communications standard of the future.”

This research is funded by the European Research Council through the ERC Consolidator Grant “MAWiCS – magnetoacoustic waves in complex spin systems” and by the German Research Foundation as part of the Collaborative Research Center “Spin+X.”

The recent study:

K. Künstle, Y. Kunz, T. Moussa, K. Lasinger, K. Yamamoto, P. Pirro, J. F. Gregg, A. Kamra, and M. Weiler, Magnon-polaron control in a surface magnetoacoustic wave resonator, Nat Commun 16, 10116 (2025). https://doi.org/10.1038/s41467-025-66301-x

Scientific contacts:

Kevin Künstle
Phone: 0631 205-4616
E-Mail: kuenstle(at)rptu.de

Prof. Dr. Mathias Weiler
Phone: 0631 205-4099
E-Mail: mweiler(at)rptu.de

“Professor Widera combines outstanding research of international standing, the development of innovative technologies, successful teaching, and commitment to science policy in the particularly promising field of quantum physics. He is being honored with the Academy Award for these exemplary achievements,” said the Academy's president, Prof. Andrea Rapp.

Rhineland-Palatinate's Minister of Science Clemens Hoch also congratulated the award winner: "Excellent teaching thrives on creativity, passion, and the attitude that learning is always a personal encounter that inspires students, encourages them to think for themselves, and initiates forward-looking changes. Professor Widera embodies all of this. With the Academy Award, we are not only recognizing outstanding teaching, but also honoring a personality who has demonstrated excellent achievements in research and exceptional commitment in all areas of science. I congratulate him warmly on this award."

Prof. Malte Drescher, President of RPTU University Kaiserslautern-Landau, also praised the award winner's achievements: "Artur Widera is doing pioneering work at the interface between physics, materials science, and technology. His research work, for example on single-atom systems, ultracold quantum gases, and optically active defects in diamonds, is making a significant contribution to a better understanding of the quantum world and making it usable for future applications. The Academy Prize of the State of Rhineland-Palatinate thus honors a personality who embodies excellence in research and teaching at RPTU in an outstanding way."

The Academy Prize has been awarded since 2001 by the state of Rhineland-Palatinate in cooperation with the Academy of Sciences and Literature | Mainz. It honors individuals who have made excellent and exemplary achievements in teaching and research at the state's universities and have significantly promoted young scientists. The prize is endowed with 25,000 euros.

The team led by Professor Elke Neu-Ruffing, Professor Jan Pielage, and Professor Volker Scheuss is researching genetically encoded quantum sensors (GEQS)—biosensors that are genetically integrated into cells. There, they are designed to monitor disease processes. Until now, genetically encoded fluorescent proteins, i.e., proteins that glow, have been used for this purpose. These proteins change their fluorescence due to chemical interactions. However, the chemical reaction also changes the local concentrations of the reaction partners, thereby disrupting the physiological process.

Sensors from the quantum world

Quantum sensors, on the other hand, can operate non-destructively by detecting cellular pollutants via magnetic interactions. They utilize the intrinsic angular momentum (spin) and the associated magnetic properties that quantum particles naturally possess. When they come into contact with reactive oxygen, their magnetic moment causes the fluorescence and thus the luminescence of the detection proteins used to change.

Impetus for personalized medicine

The sensors will initially be used in nerve cells to contribute to our understanding of neuropsychiatric and neurodegenerative diseases. But there is even more potential: “It is conceivable, for example, that quantum sensors could be used to measure the activity of neurons, as well as signal transmission in the nervous system, which takes place via ion channels,” explains Neu-Ruffing. “Looking beyond the current project, our research could contribute to the advancement of personalized medicine in the future. For example, by examining neurons derived from patients' stem cells. Among other things, this could help to decipher the role of reactive oxygen species in certain patient groups and find the most suitable medications.”

Funded as a “wild” research idea

The CZS Wildcard funding program supports unconventional, “wild” ideas in the STEM field that are radically new, unusual, and therefore particularly daring, and have high innovation potential. CZS Wildcard is aimed at interdisciplinary consortia of at least three researchers.

Scientific contact:

Prof. Dr. Elke Neu-Ruffing
Department of Physics at RPTU

Phone: 0631 205-5788
E-Mail: nruffing(at)rptu.de

Press contact:

Julia Reichelt
university communications

E-Mail: presse(at)rptu.de

+++

About the Carl Zeiss Foundation

The Carl Zeiss Foundation has set itself the goal of creating space for scientific breakthroughs. As a partner to scientific excellence, it supports both basic research and application-oriented research and teaching in the STEM disciplines (science, technology, engineering, and mathematics). Founded in 1889 by physicist and mathematician Ernst Abbe, the Carl Zeiss Foundation is one of the oldest and largest private foundations promoting science in Germany. It is the sole owner of Carl Zeiss AG and SCHOTT AG. Its projects are financed from the dividend distributions of the two foundation companies.

The team led by Professor Elke Neu-Ruffing, Professor Jan Pielage, and Professor Volker Scheuss is researching genetically encoded quantum sensors (GEQS)—biosensors that are genetically integrated into cells. There, they are designed to monitor disease processes. Until now, genetically encoded fluorescent proteins, i.e., proteins that glow, have been used for this purpose. These proteins change their fluorescence due to chemical interactions. However, the chemical reaction also changes the local concentrations of the reaction partners, thereby disrupting the physiological process.

Sensors from the quantum world

Quantum sensors, on the other hand, can operate non-destructively by detecting cellular pollutants via magnetic interactions. They utilize the intrinsic angular momentum (spin) and the associated magnetic properties that quantum particles naturally possess. When they come into contact with reactive oxygen, their magnetic moment causes the fluorescence and thus the luminescence of the detection proteins used to change.

Impetus for personalized medicine

The sensors will initially be used in nerve cells to contribute to our understanding of neuropsychiatric and neurodegenerative diseases. But there is even more potential: “It is conceivable, for example, that quantum sensors could be used to measure the activity of neurons, as well as signal transmission in the nervous system, which takes place via ion channels,” explains Neu-Ruffing. “Looking beyond the current project, our research could contribute to the advancement of personalized medicine in the future. For example, by examining neurons derived from patients' stem cells. Among other things, this could help to decipher the role of reactive oxygen species in certain patient groups and find the most suitable medications.”

Funded as a “wild” research idea

The CZS Wildcard funding program supports unconventional, “wild” ideas in the STEM field that are radically new, unusual, and therefore particularly daring, and have high innovation potential. CZS Wildcard is aimed at interdisciplinary consortia of at least three researchers.

Scientific contact:

Prof. Dr. Elke Neu-Ruffing
Department of Physics at RPTU

Phone: 0631 205-5788
E-Mail: nruffing(at)rptu.de

Press contact:

Julia Reichelt
university communications

E-Mail: presse(at)rptu.de

+++

About the Carl Zeiss Foundation

The Carl Zeiss Foundation has set itself the goal of creating space for scientific breakthroughs. As a partner to scientific excellence, it supports both basic research and application-oriented research and teaching in the STEM disciplines (science, technology, engineering, and mathematics). Founded in 1889 by physicist and mathematician Ernst Abbe, the Carl Zeiss Foundation is one of the oldest and largest private foundations promoting science in Germany. It is the sole owner of Carl Zeiss AG and SCHOTT AG. Its projects are financed from the dividend distributions of the two foundation companies.

The National University of Science and Technology Politehnica Bucharest is Romania’s leading institution for science and technology, recognized for academic excellence and forward-looking educational programs. With 15 faculties in Bucharest and an additional six in Pitești, the university plays a vital role in shaping the next generation of specialists, engineers, researchers, and innovators for the regional and global industry. The educational model of the university is built on excellence in both teaching and research, cultivating the skills and mindsets needed to thrive in a rapidly evolving global landscape.

One of the university's most advanced research assets is the expertise in Nuclear Physics. At the Physics Department from the Faculty of Applied Sciences, professors, specialists and students join their efforts to face the challenges of ultra-intense lasers and high-brilliance gamma beams. These cutting-edge technologies enable pioneering studies in nuclear and photonuclear science.

A key partner in this endeavor is IFIN-HH (Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering), through collaboration on the ELI-NP (Extreme Light Infrastructure – Nuclear Physics) project. This partnership is integrated with the Doctoral School for Lasers and Accelerators – Engineering and Applications, offering exceptional opportunities for doctoral training and cutting-edge research.

Main Objectives of the Collaboration:

• Advance frontier research in nuclear and photonuclear science using ultra-intense laser and gamma-beam technologies.

• Develop human capital by providing doctoral and postdoctoral training, mentorship, and co-supervision across RPTU, Politehnica Bucharest and IFIN-HH.

• Share infrastructure through coordinated access to facilities, experimental halls, and high-performance computing resources.

• Attract competitive funding via coordinated proposals to national and European programs.

• Accelerate technology transfer and innovation, including instrumentation, diagnostics, and advanced control systems.

• Further develop international visibility by hosting workshops, summer schools, and visiting-scholar exchanges that strengthen global networks.

At the Chair of Optical Quantum Metrology at the Faculty of Physics of the RPTU, the new collaboration enables joint experiments in fields including the development of novel power regimes in linear [1,2], as well as nonlinear [3,4] passive optical resonators. A step toward bringing the higher education at the two universities closer together, is the association of Prof. Ioachim Pupeza, head of the Laboratory for Lightwave Metrology with the Doctoral School of Laser and Accelerator Engineering and Applications (S.D.I.A.L.A) at Politehnica Bucharest.

[1] H. Carstens, N. Lilienfein, S. Holzberger, C. Jocher, T. Eidam, J. Limpert, A. Tünnermann, J. Weitenberg, D. C. Yost, A. Alghamdi, Z. Alahmed, A. Azzeer, A. Apolonski, E. Fill, F. Krausz, and I. Pupeza, "Megawatt-scale average-power ultrashort pulses in an enhancement cavity," Optics Letters 39, 2595 (2014)

[2] P. Sulzer, M. Högner, A.-K. Raab, L. Fürst, E. Fill, D. Gerz, C. Hofer, L. Voronina, and I. Pupeza, "Cavity-enhanced field-resolved spectroscopy," Nature Photonics 16, 692–697 (2022)

[3] N. Lilienfein, C. Hofer, M. Högner, T. Saule, M. Trubetskov, V. Pervak, E. Fill, C. Riek, A. Leitenstorfer, J. Limpert, F. Krausz, and I. Pupeza, "Temporal solitons in free-space femtosecond enhancement cavities," Nature Photonics 13, 214–218 (2019)

[4] I. Pupeza, C. Zhang, M. Högner, and J. Ye, "Extreme-ultraviolet frequency combs for precision metrology and attosecond science," Nature Photonics 15, 175–186 (2021)

She motivates students to actively engage with the quantum world, from their introduction to experimental quantum physics to their in-depth study of advanced photonics. At the same time, she develops innovative teaching concepts that more closely integrate theory and practice and promote interdisciplinary skills.

rptu.de/newsroom/neuigkeiten/detail/news/studierenden-die-quantenwelt-hands-on-erschliessen-christina-joerg-erhaelt-lehrpreis-der-rptu-in-kaiserslautern

Christina Jörg guides students academically from the origins of quantum physics to her own field of research, quantum simulation. “I am fascinated by quantum phenomena in solids. Since these are usually not directly accessible, my working group uses light structures as model systems, changes the experimental conditions, and observes the results. This allows us to mimic effects and discover new things—a possible first step toward technological application.”

Integrating research and teaching

Jörg uses new teaching formats to give students on the international master's program in Advanced Quantum Physics practical insights into research. In laboratory exercises accompanying lectures, students learn firsthand how theory and experiment intertwine. “There is always a specific topic, such as photonic crystals,” she explains. “The students create such model systems themselves and then measure them. In this way, they learn common research methods, deepen their knowledge, and prepare themselves optimally for their master's thesis and career entry.”

She recently received a Fulbright-Cottrell Award from the German-American Fulbright Commission for the further development of her practice-oriented teaching and learning concept. “Many international students who come to us have little laboratory experience. With this funding, I would like to consolidate our approach and involve other working groups. In addition, the joint laboratory exercises facilitate integration and promote exchange,” says Jörg.

Focus on active learning

It is particularly important to her to make knowledge transfer an active process. That is why she not only takes on the role of narrator, but also encourages her students to reflect—for example, by sprinkling quiz questions throughout her lectures and having them work on them in teams. “This way, students can immediately see whether they have understood the material,” Jörg emphasizes.

Methods such as the “inverted classroom” are also used: students learn the theoretical basics through self-study via video, and the classroom time is used for joint discussion. “This is particularly suitable for longer derivations, where it is easy to lose concentration as a passive listener.”

“Quantum physics seems unfamiliar, but it's everywhere”

The lecture “Experimental Quantum Physics,” which bachelor's students from various physics programs attend, works its way from the big picture to the small details in order to make it easier to get started with the subject matter: “How were electrons first made visible? How do we know that they are charged? How does this reveal the structure of atoms?” explains Jörg. "This is made tangible by experiments that my colleagues from the lecture collection have prepared very well. Because at first, quantum physics often seems strange and unfamiliar. But that's exactly where its appeal lies: it opens up a completely new view of the world. At the latest when we deduce that lasers only exist thanks to quantum physics or that they are found in smartphones, it becomes clear: quantum physics makes sense and makes our modern world possible in the first place." The teaching assistants, two of whom also received awards for their teaching achievements this year, also help students understand quantum physics.

Nominated by students

Jörg owes her nomination for the Distinguished Teaching Award in particular to her students. They give her top marks for her teaching. "Thanks to her thorough preparation and practical approach, Ms. Jörg conveys the subject matter very clearly, also in connection with other scientific subfields. She encourages active participation and independent learning even beyond the lecture hall. Based on a lecture survey she initiated and conducted herself, she also continuously adapted the lecture to the needs of the students from the very beginning," reads the nomination letter, among other things.

About the Distinguished Teaching Award

The Distinguished Teaching Award was established at the Technical University of Kaiserslautern in 2014 to recognize outstanding commitment and excellence in academic teaching. The award honors teachers who have distinguished themselves in the areas of teaching, examination, counseling, and student support. This commitment may relate to the design and implementation of innovative course elements (curricular elements) as well as the development and successful use of innovative teaching and learning materials (e.g., in the field of e-teaching). Other measures to improve the quality of studies and teaching, e.g., in the area of further development of courses and quality assurance, are also eligible for funding. The award comes with prize money of €10,000.

Press contact:
Hannelore König
Programmkoordination Hochschuldidaktik und Förderprogramme Lehre
Zentrum für Innovation und Digitalisierung in Studium und Lehre (ZIDiS)
Phone: 0631 205-5592
E-Mail: hannelore.koenig(at)rptu.de
www.rptu.de/s/summerschool

IFOS and RPTU
IFOS has close ties to the RPTU and, since its founding, has stood for the combination of basic research and application-oriented development. Of particular importance is its cooperation with small and medium-sized enterprises, which benefit from the institute's technological developments. With today's stop in Kaiserslautern, the minister continues her summer tour, which focuses on exchange with research, business, and society. 

Investment in state-of-the-art research equipment
Thanks to the funding, the institute will significantly expand its research infrastructure. The new equipment includes a ToF-SIMS (time-of-flight secondary ion mass spectrometer) for precise surface analysis, a state-of-the-art transmission electron microscope (TEM), a FIB (Focused Ion Beam) system for microscale material processing, a LIBS microscope, and a Raman microscope for non-destructive material analysis. The portfolio is complemented by a new XPS/AES system and ultra-short pulse laser-based processing equipment.

The devices enable in-depth material characterization with higher resolution and sensitivity. They open up new scientific questions and at the same time increase the attractiveness for students and doctoral candidates, who are integrated into research projects at an early stage.

A boost for research and enterprises
Minister Schmitt emphasized that excellent research always benefits the economy: “We are investing in the IFOS infrastructure because we are convinced that research that is put into practice is a driving force for our location. It creates new knowledge, new processes, and new products—and helps to secure and create jobs.”

Professor L'huillier: Modernization strengthens competitiveness
“The modernization of our infrastructure is a key step toward continuing to deliver scientific and technological excellence in the future,” explains Prof. Dr. Johannes L'huillier. “It not only strengthens our international competitiveness, but also Rhineland-Palatinate as a whole as a location for innovation.”

Further information about IFOS: https://www.ifos.uni-kl.de/

Original press release from MWVLW: https://mwvlw.rlp.de/presse/detail/schmitt-83-millionen-euro-fuer-spitzenforschung-in-der-oberflaechentechnik-land-staerkt-ifos-mit-neuer-geraetegeneration-fuer-die-technologien-der-zukunft

Over three consecutive days, Lefkidis took his audience on a vivid journey through space, time, and the quantum world – and the response was overwhelming. Whether it was gravity, quantum mechanics, or the theory of relativity, the physicist knew how to convey complex concepts in an understandable, exciting way with a dash of humor – without any complicated formulas. Participants praised the accessible concept, which took prior knowledge into account while also offering deeper insights.

The intergenerational audience concept was particularly highlighted: “Finally, an offering that appeals to different age groups—and inspires both sides equally,” was one of the many positive responses. The shared experience of young adults and older interested parties was also very well received: “We marveled together—and continued discussing on the way home.”

“The great enthusiasm for the lectures shows how important it is to communicate science in a lively and understandable way,” says Lefkidis. “I am very pleased that we were able to get so many people interested in physics – and perhaps also sparked some curiosity about other scientific topics.”

Accompanying photo impressions document the participants' intensive engagement with the topics and the special atmosphere of the series. The Junior University Daun is already planning a continuation of the format—with the support of dedicated scientists from the RPTU, who are making their research results accessible to a broad audience beyond the lecture hall.

Contact person:
PD Dr. habil. Georg Lefkidis
lefkidis(at)rptu.de

In their setup, the physicists use a cloud of ultra-cold rubidium-87 atoms, which were cooled to about 40 microkelvin using laser cooling. Subsequently, atoms were transferred to highly excited Rydberg states using a targeted three-photon process. ‘This causes the outermost electron to be brought into an orbit that can be several thousand atomic radii in size,’ explains Professor Ott. "If another atom is now located in this area, it can form a bond with the Rydberg electron through quantum mechanical scattering – a mechanism that has nothing in common with classical chemical bonds.

The trilobite molecules created in this way have particularly high binding energies due to this special bond. With principal quantum numbers n = 22 to 27, several series of such molecules were generated in the current study and their vibration spectra were measured precisely. Thanks to the high binding energy and spectral resolution (better than 0.01%), it was possible for the first time to determine the electron-atom scattering phase with unprecedented accuracy – and in an energy range that is not experimentally accessible for free electrons.

A newly developed functional method was used for the theoretical description. This avoids convergence problems in previous models and allows precise calculation of the vibration spectrum. ‘The agreement between theory and experiment is so precise that even the smallest deviations become visible,’ says Markus Exner, who led the experiments. Particularly noteworthy is the measurement of the largest permanent electric dipole moments to date, at nearly 3000 Debye, which enables a clear assignment of the observed vibrational states.

The work makes a significant contribution to a better understanding of molecular physics in the ultra-cold temperature range and complex electron-atom interactions. In addition, it could serve as a basis for future applications in quantum information and simulation.

The study was conducted as part of the German Research Foundation (DFG) Priority Programme ‘Giant Interactions in Rydberg Systems’ and in the OPTIMAS profile area (State Research Centre for Optics and Materials Science) at the University of Kaiserslautern-Landau.

The results were published in the journal Physical Review Letters:

‘High Precision Spectroscopy of Trilobite Rydberg Molecules’; Markus Exner, Rohan Srikumar, Richard Blättner, Matthew T. Eiles, Peter Schmelcher & Herwig Ott.

More information about the event series can be found here: QUANTum3 https://physik.rptu.de/aktuell/veranstaltungen/quantum3

Accompanied by their loyal fan base, they gave their all. They may not have triumphed in sporting terms, but they were right at the top of the hearts' rankings!

And as always: after the tournament is before the tournament and one thing is certain: the Wild Atomis will strike back!

The annual physics department barbecue took place on 14.07.2025. The event kicked off at 3:30 pm with the traditional soccer tournament, in which seven teams of students and staff from the department competed against each other and the winners even managed to beat the professors' team in a penalty shoot-out in the final.

At the subsequent barbecue at the amphitheater in front of Building 46, a diverse mix of faculty members took the opportunity to get to know each other. The award ceremony for the soccer tournament also took place in this setting. In addition to cold drinks, guests were able to have their food freshly grilled and enjoy a wide selection of salads and desserts prepared by guests and the student council.

We would like to thank the student council for organizing the event, the department for covering the costs and the jDPG for hosting and moderating the soccer tournament. And for all those who missed it: A repeat event is also planned for summer 2026!

The Department of Physics would like to thank the Physics Alumni Association for their generous support of this event and the Physics Student Council for their active help with the catering for the guests!

You will find more impressions and pictures here soon.

The full press release is available here.

Quantum effects such as entanglement, interference, and quantum statistics could make machines more efficient or powerful. “However, the special laws of quantum physics can also hinder the performance of machines,” says Professor Artur Widera, who heads the Individual Quantum Systems department at the Rhineland-Palatinate Technical University of Kaiserslautern-Landau (RPTU). He will now receive €2.5 million in funding from the European Research Council (ERC) for five years for his research work as part of an ERC Advanced Grant. The funding line is aimed at established top researchers with an outstanding track record who want to open up new areas of research.

“We want to find out how quantum properties change the performance of microscopic machines, or more precisely, what the properties of microscopic machines in the quantum world look like and how they can be described,” says Widera, describing the research projects that will be funded. In addition, he and his team want to understand the fundamental mechanisms for the operation of machines from a technological perspective and tailor them to experimental implementations. “And we want to build machines, both single-atom machines and multi-particle machines, that operate according to the laws of quantum physics and both generate work and run autonomously.”

Operation of a single-atom machine demonstrated

In recent years, Artur Widera has been able to realize fundamental quantum mechanisms for the operation of such machines: “A classical machine works, for example, by periodically heating and cooling the working medium, such as fuel. We were able to replace this classical mechanism with fundamentally quantum mechanical mechanisms.”
Widera and his team have already been able to operate a single-atom machine in which the fuel is not in the form of thermal energy but in the form of spin polarization of a quantum bath. Widera and his team use ultra-cold atoms, which make it possible to control both individual atoms and quantum many-body systems very well.

In such systems, a machine can be operated by changing the volume of the container (the cylinder in a classic motor) for the working medium (a quantum gas or single atom) and periodically applying energy changes, as in a classic motor. “To study quantum effects, the bath can be prepared in a wide variety of quantum mechanical states and their influence on the performance of such a motor can be investigated.” In order to extract work from the machine, the excitation energy must be converted from atomic form into photonic and then into mechanical forms. “To ultimately ensure autonomous operation, feedback mechanisms must be developed and incorporated, but these must not destroy the actual quantum state.”

Fascinated by quantum systems

Widera describes the research project as virtually compelling. This is because increasing miniaturization—just think of computers, which are getting smaller and smaller—inevitably raises the question of “what the smallest machine can look like, what the absolute limit of efficiency is,” and whether quantum effects can be used to build a better machine.
How will this field of research develop over the next 5-10 years? Researchers may succeed in “activating” quantum matter, opening up new ways in which quantum materials can self-organize or take on new phases of matter. As a non-physicist, one could imagine this as similar to a flock of birds: quantum particles that gather and move in the same direction. Artur Widera: “The vision is to build independently operating quantum motors whose special properties and applications we want to explore.” The physicist, who has been a professor in Kaiserslautern since 2010, is more than enthusiastic about his field of research: “Seeing the behavior of quantum systems still fascinates me completely.”
 

Questions answered by:
Prof. Dr. Artur Widera
T +49 631 205-4130
E widera@rptu.de

Media contact:
Julia Reichelt
T 0631 205-5784
E julia.reichelt@rptu.de

Kaiserslautern, June 12, 2025 - In bright sunshine, the RPTU physics student council in Kaiserslautern attracted numerous students, staff and party-goers from the region to the campus for its annual Maifete (mm. c. t.).

The guests enjoyed cool drinks and tasty delicacies from the grill. In addition, a number of specials such as candy floss, refreshing slush ice variations and aromatic espresso ensured a particularly good mood. The May party was accompanied by music from various bands, which also ensured an exuberant atmosphere on the dance floor. One of the highlights was the performance by a prominent physics duo, who thrilled the audience with their rousing RPTU song.

The student council would like to thank all the helpers and guests who made this party an unforgettable experience. We are already looking forward to the next party on campus!

The theses is here available.

At the beginning, the 20 students have to present a previously completed assignment and present the results of their work in a colloquium. They are also required to carry out and analyse two experiments independently in the laboratory. The performance in the experiments, the colloquium and the homework are assessed in equal parts and ultimately decide who wins the competition. The winner will be invited by the Department of Physics to take part in an internship where they will gain an insight into laboratory work.

Parallel to the competition, there is a physics seminar for all pupils. In lectures and experiments, they will gain an insight into physics research together with the competition participants. Among other things, they will learn how 3D microprinting with light works, why ultracold quantum gases are so important and what light absorption and colour in flower and plant petals are all about. In addition, all young people will receive information about the Early Studies in Physics (FiPS) and the Physics, Biophysics and TechnoPhysics degree programmes offered by the Department of Physics at RPTU in Kaiserslautern.

The pupils attend various grammar schools in Rhineland-Palatinate.

The state physics competition was initiated by the state of Rhineland-Palatinate. It is sponsored by the Rhineland-Palatinate Ministry of Education, the Heraeus Foundation, the DPG, the State Research Centre for Optics and Materials Science (OPTIMAS), the Collaborative Research Centres SFB-TR185 (OSCAR - Open System Control of Atom and Photonic Matter) and SFB-TR173 (SPIN+X - Spin in its collective environment) as well as the Sparkasse Kaiserslautern.

Questions answered:

Anett Fleischhauer
Deanery Physics
Phone: 0631 205-5251
E-Mail: anett.fleischhauer(at)rptu.de

Prof. Dr. Hartmut Hotop,

deceased on 14 May 2025 at the age of 82.

Professor Dr. Hartmut Hotop was a member of the Department of Physics from 1980 to 2008.

RPTU Kaiserslautern-Landau and the Department of Physics have lost a highly esteemed scientist, a dedicated university lecturer and a reliable colleague in Prof. Dr. Hartmut Hotop, who left a lasting personal mark on the department.

After studying physics and completing his doctorate at the University of Freiburg, Professor Hotop was appointed as a professor in 1975. In 1977, he was called to a professorship of experimental physics at the University of Kiel. In 1980, he was appointed to a C4 professorship in the Physics Department at the former University of Kaiserslautern, where he conducted research and taught until his retirement on 30 September 2008.

He achieved high international recognition for his work in atomic and molecular physics. He was, among other things, spokesman for the Collaborative Research Centre 91, which focused on ‘Energy transfer in atomic and molecular collision processes’, for many years. From 1985 to 1987, he was Dean of the Physics Department and a member of the University Senate. He devoted many years to shaping the department, acting as co-founder of the Foundation for Physics and as initiator and long-standing chairman of the Physics Alumni Association, whose activities were always close to his heart.

In Professor Hotop, we have lost an outstanding researcher, passionate university lecturer and highly esteemed companion. His work will remain unforgotten.

Our condolences go out to his family.

Prof. Dr. Georg von Freymann

Dean of the Department of Physics

On June 12, 2025, the traditional Maifete of the physics student council will take place. With free admission, you are invited to a relaxed outdoor party on the RPTU campus in Kaiserslautern. The beer garden with barbecue at the amphitheater will open at 11:30 a.m. and other drinks such as cocktails and sangria will also be offered throughout the day. For further entertainment, the gladiator game will challenge all courageous fighters and from 16:00 you can party to live music - prominent entertainers from the faculty will also be on stage!

Your physical and mental well-being will be in good hands, so come along and celebrate the summer with us!

No party without the willing helpers, that's why we are looking for you! Every helper receives 5 drinks vouchers for the first shift! You can redeem these for various drinks. If you complete two shifts, you will receive 3 more drinks vouchers and will also be invited to our helpers' barbecue. Permanent helpers (min. 3 shifts) will also receive a T-shirt.

Anyone who would like to help is very welcome to sign up on the lists in the foyer of building 46. These will be handed out a few weeks before the party.

Further and current information about the party can be found on the homepage of the physics student council:
https://fachschaft.physik.rptu.de/en/party-maifete.html

Over four days, early-career scientists from around the world engaged in an intensive program of lectures, discussions, and poster sessions, aimed at fostering collaboration and deepening understanding of cutting-edge developments in the field. The program offered a balanced mix of cutting-edge theoretical insights and recent experimental developments, reflecting the field’s rapidly evolving landscape. A series of invited talks by leading scientists provided participants with deep dives into current challenges and breakthroughs, while interactive sessions encouraged lively scientific discussions and peer engagement in a relaxed, collaborative environment.
One of the highlights of the event were the pitch talks, where participants presented their own research projects in one minute. After the pitch talks they presented their research as posters. These sessions not only allowed attendees to share their work and receive critical feedback but also helped spark new ideas and potential collaborations.
By making an atmosphere of collaboration and discovery, the organizers created a dynamic environment in which young researchers deepened their expertise, built lasting professional connections, and helped shape the future direction of magnetism and spin research.

For more updates and a gallery of event highlights, visit the official website: https://spinup-jss.uni-mainz.de

With hands-on science, the general public was given the opportunity to take a fun and fascinating look behind the scenes of the research landscape in Kaiserslautern. Under the motto “Knowledge creates the future”, the importance of scientific research for our daily lives and our common future was made clear.

After the opening at 42kaiserslautern, visitors were able to explore the other locations with free shuttle buses and enjoy the diverse program of experiments, exhibitions and lectures. Demonstrations, hands-on stations and information stands immersed visitors in the fascinating world of science. Our researchers presented their current projects interactively, providing insights into the innovative work of their city.

After a captivating fire show, everyone celebrated together at the grand finale, the after-science party, with good music and a light show in the RPTU sports hall.

To mark the Year of Quantum Physics, the Department of Physics is offering the lecture series “QUANTum3” at 42 in Kaiserslautern (former C&A building in Eisenbahnstraße 42). Every second Saturday of the month at 3 o'clock there is a 45-minute lecture on the subject of quantum physics by a lecturer from the department. Afterwards, there is an opportunity to chat over coffee and snacks. It already starts on

April the 12th with the lecture  „Macht und Ohnmacht der Quantenphysik“ by Prof. Sebastian Eggert.

You can find more information about the event series here.

The focus is on the interdisciplinary examination of the concept of truth from a scientific and philosophical perspective. Students and staff will have the opportunity to combine the foundations of scientific theory with scientific approaches and discuss central questions of epistemology.

The event, which is funded by RPTU's InterAct program, is aimed at students and staff from various disciplines and promotes dialogue between the natural sciences and the humanities.

Further information on the course: https://www.kis.uni-kl.de/campus/all/event.asp?gguid=0x9DE6E05A9FFB4A3EB10E41A2CD75E2A7&tguid=0xE9A48F1EED9A4ECDB5A5775406C46C8D

At the start of the summer semester 2025, the average housing costs for students at medium-sized university locations (over 5,000 students) amount to EUR 493. This corresponds to a moderate increase of 0.9% (around EUR 4) compared to the previous semester and 2.8% (around EUR 14) compared to the previous year. In only 23 of 88 cities is a normal room available within the current BAföG flat-rate housing allowance and in 39 cities, where almost half of all students in Germany are enrolled, it is almost impossible to find a room within the flat-rate housing allowance. This makes it difficult for students to find accommodation and can play an important role in choosing where to study.

Students in Kaiserslautern can breathe a sigh of relief, as a room in a shared flat here costs an average of just 380 euros. This is well below the national average and makes living in Kaiserslautern much more attractive than in more expensive cities such as Mainz with an average of 530 euros or Freiburg with around 600 euros.

You can find more reasons why you should study in Kaiserslautern here.

You can find the full SWR article here and the press release from the Moses Mendelssohn Institute here.

Vitaliy Vasyuchka is an academic advisor at the Department of Physics at RPTU in the working group of Prof. Weiler.

The department warmly congratulates Vitaliy Vasyuchka and looks forward to further cooperation!

You can find the full-length article here.

In the interview, Kira explains why she would choose Kaiserslautern once again, what she particularly appreciates about RPTU in Kaiserslautern as a familiar university and how well the student representatives look after the students. She also gives tips for interesting excursion destinations, where it's worth taking a tasty detour and what the nightlife has to offer.

Are you also considering whether Kaiserslautern is worthwhile for your studies? Then read  the full-length interview now.

Prof. Dr. Martin Aeschlimann and Prof. Dr. Burkard Hillebrands will retire on December 31, 2024, while Prof. Dr. Henning Fouckhardt will leave active service on March 31, 2025.

Despite their retirement, Prof. Dr. Martin Aeschlimann and Prof. Dr. Burkard Hillebrands will remain closely connected to the university: From January 1, 2025 to December 31, 2027, they will continue to work as senior research professors and contribute their scientific expertise. Prof. Dr. Martin Aeschlimann will also continue in his role as spokesperson for the Collaborative Research Center TRR 173 “Spin+X” during this time.

The Department of Physics would like to express its sincere thanks to the professors for their extraordinary commitment and lifetime achievements!

Master's students assessed the study programs on the basis of ten evaluation criteria: General study situation, support from lecturers, study organization, range of courses, support during studies, digital teaching elements, research orientation, practical orientation, transition to Master's studies and support for studying abroad.

Physics students rated the study conditions as very good: 4.6 out of 5 stars were awarded for the general study situation and support from lecturers, for example. They also praised the organization of studies (4.5 out of 5 stars) as well as the range of courses, the research orientation and the transition to the Master's degree course (4.4 out of 5 stars in each case). Students of physics, technophysics, biophysics and advanced quantum physics took part in the survey.

About the current CHE ranking

The new comparison of the Master's programs shows various criteria - student assessments and facts. In addition to the general study situation, students also rate the courses on offer, the supervision and support during their studies and digital teaching elements. The evaluation is presented on a 5-star scale. A total of around 7,500 students were surveyed at the universities between January and August 2024 for the ranking.

The ranking of Master's degree programs is available at https://studiengaenge.zeit.de/ranking/master. It will also appear in excerpts in the upcoming issue of ZEIT Campus - the publication date is December 12.

This time we have Dr. Lena Scherthan, Fuel & Lubricant Solutions, BASF and Prof. Dr. Helena Reichlová, TU Dresden/Czech Academy of Sciences, as special guests. They will talk about their careers as physicists in industry and science. Lena did her doctorate in the Schüneman group at the TUK. Helena Reichlová will give a lecture at the Physics Colloquium on 16.12.

Therefore, the physicists' meeting will take place from 5 pm. Drinks/mulled wine/punch will be provided and there will be an evening snack.

Please register at sandra.wolff(at)rptu.de. But spontaneous attendance is of course also possible as always.

The Collaborative Research Center SPIN+X supports these meetings, where female physicists can exchange ideas and network informally. We look forward to an inspiring and stimulating evening together!

Questions answered:

Dr.-Ing. Sandra Wolff
Abteilungsleiterin of Nano Structuring Center

Phone: 0631 205-4091
E-mail: sandra.wolff(at)rptu.de

Machine learning, neural networks or artificial intelligence (AI): many groundbreaking developments would be unthinkable without the achievements of this year's Nobel Prize winners in physics. AI is changing the way we live in almost all areas - but what is really behind it? RPTU in Kaiserslautern, in cooperation with DFKI, invites you to an exciting evening lecture on December 12, 2024 at 7 p.m., which will answer these questions and make AI technologies tangible. The lecture, which will take place in Building 46, Room 215 on the RPTU campus, is aimed at all interested parties. Registration is not required.

The occasion for the event is this year's award of the Nobel Prize in Physics to two pioneers of AI research who are considered the “forefathers” of modern developments in this field. The regional group of the Young German Physical Society (jDPG) took this as an opportunity to introduce the principles behind AI systems to the general public.

The evening will be hosted by Prof. Dr. Paul Lukowicz. As a professor at RPTU and head of the “Embedded Intelligence” research department at DFKI, he is a proven expert in the field.

More information here.

Questions answered:

Dr. Kerstin Krauß
Administrative Director Department of Physics

Phone: 0631 205-2377
E-Mail: kerstin.krauss@rptu.de

“Magic or physics?” is the motto for Physics Day on December 7

“Gravitational waves - a new window into the universe”, ‘Physics as a profession...?!’, ‘The power and powerlessness of quantum physics’, ‘Magic or physics - strange effects explained scientifically’: These and other topics awaited over 1,200 pupils and teachers, who were invited to the RPTU Physics Department's Physics Day on the Kaiserslautern campus. More than 40 events provided an insight into physics issues and invited visitors to listen, participate and be amazed. Of course, the day also offered plenty of opportunities to find out about physics degree courses and studying at RPTU in general and to take a look behind the scenes - where physics research takes place.

As part of the event, a physics competition was held in the morning, aimed at pupils in three age groups (8th/9th grade, 10th/11th grade and 12th/13th grade). A total of 800 pupils registered for the competition. The aim was to get pupils interested in physics. The tasks were based on the curriculum content of the respective grade level and included both theoretical and experimental tasks. Meanwhile, the accompanying teachers found a contact point in the teachers' café.

More Information about Physics Day here.

Questions answered:

Dr. Kerstin Krauß
Administrative Director Department of Physics

Phone: 0631 205-2377
E-Mail: kerstin.krauss@rptu.de

The dance floor filled up quickly thanks to the four varied DJs who got the audience going with their beats. In an exuberant atmosphere, the crowd grooved to the fast rhythms and, of course, the odd headbang was not to be missed.

In addition to the music, there was everything a party heart desires: the wide range of drinks on offer left no throat dry - from ice-cold cocktails, freshly tapped beer and fruity wine to colorful shots and warming mulled wine - there was something for everyone! Juicy burgers were available for the small appetite in between, which were devoured in record time.

The Nikofete was once again an absolute highlight for RPTU students. The guests partied until late into the night. An all-round successful event that proves it: The physics student council knows how to throw a party! We are already looking forward to the next Nikofete - hopefully it will be just as legendary!

A big thank you goes out to everyone who helped before, during and after the party to get this event off the ground and ensure it ran so smoothly - THANK YOU SO MUCH!

All information about the Day of Physics 2024 can be found here!

Questions answered:
Dr. Kerstin Krauß
Administrative Director FB Physics
Phone: 0631 205-2377
E-Mail: kerstin.krauss@rptu.de

The challenges in scaling quantum computers and technologies are considerable. Superconducting circuits, which are currently considered a key technology in quantum technology, are limited by energy losses and the high space requirements of conventional microwave components. MagSQuant aims to overcome these hurdles by developing novel materials that enable low-loss, miniaturized and integrable components. These components are to be based on magnetic and superconducting circuits and thus open up new possibilities for the production of high-performance quantum systems.

To realize the vision of a hybrid integration of miniaturized magnetic and superconducting circuits, the project partners are researching new material solutions. A key element is the development of magnetic thin films that exhibit long-lasting magnetic excitations - so-called magnons. These materials will be based on a special oxide substrate thin-film system that guarantees a particularly long magnon lifetime at the ultra-low operating temperatures of superconducting circuits. The use of high-purity zone-melted silicon substrate crystals will also improve the relaxation times of the superconducting quantum bits and thus increase the efficiency and stability of the quantum technology based on them.

By providing these new materials and miniaturized components, MagSQuant is making an important contribution to the further development of quantum technologies. On the one hand, the materials developed within the framework of MagSQuant promote the scalability and performance of quantum systems for industrial applications and, on the other hand, they open up new application possibilities for gas-phase epitaxial coatings and liquid-phase epitaxy. The results from MagSQuant are of great interest to numerous users of superconducting quantum circuits and magnetic excitations, as they enable improved overall performance.

The joint project is coordinated by the Leibniz Institute for Crystal Growth (IKZ) in Berlin and includes as partners the Association for the Promotion of Innovation through Research, Development and Technology Transfer (INNOVENT e.V.) in Jena, the Rhineland-Palatinate Technical University Kaiserslautern-Landau and the Friedrich-Alexander University Erlangen-Nuremberg. The network coordinator is Dr. Christo Guguschev from the IKZ.

Research contribution of the RPTU
A team at RPTU led by Professor Mathias Weiler and Junior Professor Philipp Pirro is contributing its expertise in magnon research. They are developing magnonic components that act as microwave insulators and shield the superconducting quantum bits from external interference like a protective shield. These components are also so small that they take up less than a hundredth of a square millimeter on a chip.

Source: News from Leibniz Institute for Crystal Growth (IKZ)

Michael Fleischhauer receives the prize for key contributions in the field of nonlinear quantum optics and photonic and atomic quantum technologies, in particular for the development of instruments for the coherent control of atoms with light, including the concept of dark-state polaritons and the Rydberg blockade.

Michael Fleischhauer was appointed Professor of Theoretical Physics at the Technical University of Kaiserslautern in 2000 and has been a member of the State Research Centre OPTIMAS since its foundation in 2008. Among other things, he played a key role in the development of one of the most important methods for storing quantum states of light. This method, known as ‘stopping light’, realises a key element of a photon-based quantum communication system. Since 2020, he has been the spokesperson for the Collaborative Research Centre ‘OSCAR - Open System Control of Atomic and Photonic Matter’.

The Department of Physics at RPTU congratulates Mr Fleischhauer!
 

Questions answered:

Prof Dr Michael Fleischhauer

Theoretical Quantum Optics
E-mail: mfleisch(at)rptu.de

 

Important: This year, tickets are only available on the evening of the party. So come in time, secure your place and celebrate an unforgettable night with us!

Like always we are very thankful for everyone who wants to participate as a helper at the Nikofete at different places like the entry or at the bar. If you help us you will get coupons for free drinks and more. There will be some lists in building 46 a few weeks before the Nikofete where you can register yourself for you prefered shift.

More information here.

In total, we are offering more than 40 events that invite you to participate, listen and be amazed. In addition to actively experimenting and taking part in competitions, there are many opportunities to find out details about studying physics or the career prospects of physicists.

The Day of Physics 2024 is the fourteenth event of its kind in the Department of Physics at the Rhineland-Palatinate Technical University of Kaiserslautern-Landau.

We hope that this year will be just as interesting and look forward to 7 December!

All information about the Day of Physics can be found here.

Despite his retirement, Prof. Dr. Diller will remain connected to the university. From 1 October 2024 until 31 May 2025, he will work in the capacity of a senior research professor and continue to contribute his scientific expertise.

The Department of Physics would like to thank Prof. Dr. Diller for his many years of valuable work and looks forward to continuing our successful collaboration.

Dr. Kamra is an internationally renowned scientist in the field of the theory of spin systems. With his expertise, Dr. Kamra will significantly enrich research and teaching at our department.

We look forward to the exciting collaboration and the further development of basic research in the field of theoretical physics.

Suppose you are standing by a swimming pool and have the idea of filling it with even more water. So you grab the garden hose and create a jet that falls in a high arc onto the surface of the pool. Where the jet hits, the water level will rise briefly. However, this is only minimal because the falling water is quickly distributed over the extended surface.

However, the situation is different if you fill a gutter with your garden hose: This creates a wave of water at the point where you point the hose. The walls of the gutter now ensure that the filled water no longer flows freely along a surface, but can only spread in the direction of the gutter. The amplitude of the wave increases the narrower the channel is, i.e. the more ‘one-dimensional’ it becomes.

The physicists at the Institute of Applied Physics (IAP) at the University of Bonn, in collaboration with colleagues from RPTU Kaiserlautern-Landau, have now investigated whether similar dimensionality effects also occur for gases made of light particles. ‘In order to produce such gases, we have to concentrate many photons in a small space and cool them down at the same time,’ explains Dr Frank Vewinger from the IAP, who is also a member of the Transdisciplinary Research Unit “Matter” at the University of Bonn.

Microscopically small rain gutters

In their experiment, the researchers filled a tiny container with a dye solution, which they excited with a laser beam. The photons generated were then reflected back and forth between the mirrored walls of the container. Whenever they collided with a dye molecule, they were cooled down until the photon gas finally condensed.

The dimensionality of the gas can be influenced by modifying the mirror surfaces. The IAP researchers collaborated with the working group led by Prof Dr Georg von Freymann from the RPTU Kaiserslautern-Landau. For the experiments, a high-resolution structuring method was specially adapted to the reflective surfaces of the photon container. ‘This enabled us to apply microscopically small elevations made of a transparent polymer to the mirrors,’ explains Julian Schulz from RPTU. ‘These allow us to capture and condense the photons in either one or two dimensions.’

‘So these polymers act as a kind of gutter, only for light,’ says Kirankumar Karkihalli Umesh, first author of the study. ‘The narrower we make this channel, the more one-dimensional the gas behaves.’

Thermal fluctuations soften the condensation point

In two dimensions, there is an exact temperature limit at which condensation takes place - very similar to water, which freezes at exactly zero degrees Celsius. In physics, this is referred to as a phase transition. ‘But it should be different if we create a one-dimensional gas instead of a two-dimensional one,’ says Vewinger. ‘There are so-called thermal fluctuations in photon gases. These are so small in two dimensions that they don't cause any further disturbance. In one dimension, on the other hand, they create large waves, figuratively speaking.’

These fluctuations destroy the order in one-dimensional systems so that different areas of the gas no longer behave in the same way. This ensures that the phase transition, which is still precisely defined in two dimensions, ‘smears out’ more and more the more one-dimensional the system becomes. Nevertheless, as in the two-dimensional case, its properties are determined by quantum physics - such gases are also known as quantum degenerate. It is roughly the same as water turning into a kind of ice water at low temperatures, but never freezing completely. ‘We have now succeeded for the first time in investigating this behaviour at the transition from a two-dimensional to a one-dimensional photon gas,’ explains Vewinger.

The research groups were able to prove that one-dimensional photon gases do not actually have a sharp condensation point. By making tiny changes to the polymer structures, phenomena based on the transition between different dimensionalities can now be investigated in detail. At the moment, this is basic research. However, it is possible that new applications for quantum optical effects will emerge.

Participating institutions and funding:
The IAP at the University of Bonn, the Fraunhofer Institute for Industrial Mathematics (ITWM) in Kaiserslautern and the Rhineland-Palatinate Technical University of Kaiserslautern-Landau were involved in the study. The study was funded by the European Research Council (ERC) of the EU and the German Research Foundation (DFG) as part of the Collaborative Research Centre SFB TRR 185.

Publication: Kirankumar Karkihalli Umesh, Julian Schulz, Julian Schmitt, Martin Weitz, Georg von Freymann and Frank Vewinger: Dimensional crossover in a quantum gas of light; Nature Physics; DOI: 10.1038/s41567-024-02641-7; URL: www.nature.com/articles/s41567-024-02641-7

Bose-Einstein condensation: atoms versus photons

When bosons are cooled, their indistinguishability leads to impressive quantum effects. In particular, the wave functions of individual bosons overlap in the ground state and form a single macroscopic wave that describes the collective coherent behavior of the particles. This macroscopic quantum phenomenon of Bose-Einstein condensation was realized in 1995 in bosonic alkali atoms in magneto-optical traps at temperatures close to absolute zero. In 2010, the University of Bonn succeeded in doing the same with photons, the quanta of light, in a microcavity filled with dye at room temperature. If one observes the spectrum of the photons leaving the microcavity, it corresponds to a Bose-Einstein distribution. Surprisingly, this is the thermodynamic equilibrium state of an actually open-dissipative many-body quantum system. Since the photons are constantly absorbed and emitted by the dye molecules, the photon gas thermalizes, while at the same time the pumping of the microcavity with a laser compensates for the losses through the mirrors. An experiment on Bose-Einstein condensates of photons in microcavities filled with dye was also recently set up in the Kaiserslautern working group of OPTIMAS member Professor Georg von Freymann. As part of the Collaborative Research Center OSCAR, he and Axel Pelster are investigating the emergent phases of lattice structures of driven, dissipative photon gases in a joint project.

VCSEL

"My experimental colleagues led by Professor Maciej Pieczarka from the Wrocław University of Technology now asked themselves whether such Bose-Einstein condensates of photons could also occur in lasers," reports Axel Pelster. To clarify this, they systematically investigated VCSELs (acronym for Vertical-Cavity Surface-Emitting Lasers). This is a laser diode in which the light is emitted perpendicular to the plane of the semiconductor chip. This special near-infrared semiconductor laser is the key technology for a rapidly growing global market whose turnover is expected to exceed 2 billion euros this year. For example, VCSELs are used in laser printers, fiber optic data transmission, facial recognition for unlocking smartphones, contactless payment and navigation for autonomous vehicles.

Laser or Bose-Einstein condensate?

The core of the VCSEL consists of a quantum well with an n-doped GaAs region located inside a microcavity. Absorption and emission of photons reflected by the two mirrors leads to the creation and annihilation of electrons and holes in the conduction and valence band of the quantum well. The detuning, i.e. the energy difference between the photon energy and the excitation energy of the quantum well, is crucial for the functioning of the VCSEL. It can be changed via the distance between the mirrors, as this determines the photon energy. In the case of negative (positive) detuning, precise experimental investigations show that the light emerging from the VCSEL has the properties of a laser (BEKs). In the case of positive detuning, it is found that so many electron-hole pairs are excited during the lifetime of the photons that effective thermalization to a Bose-Einstein distribution can take place. However, in contrast to the microcavities filled with dye, the resulting spectral temperature is significantly lower than the ambient temperature. A deeper understanding of this astonishing observation is still pending.

For the Bose-Einstein condensation of photons, it is also crucial that the longitudinal component of the wave vector is determined by the boundary conditions at the mirrors, while there are no restrictions in the transverse direction. For sufficiently long-wavelength transverse excitations, the three-dimensional relativistic dispersion relation of massless photons is therefore approximately similar to that of a two-dimensional gas of non-relativistic massive particles. The resulting effective mass corresponds to about one hundred-thousandth of the mass of an electron. By determining the density of states of the photons in the VCSEL experiments, the effective two-dimensionality of the photon gas could be confirmed.

Outlook

The publication discussed here appeared in "Nature Photonics" at the same time as a similar study conducted independently of it, in which the experiments were carried out under the auspices of Imperial College in London. Both research papers impressively demonstrate that photonic Bose-Einstein condensates can also occur in semiconductor lasers. On the one hand, this opens up the possibility of realizing greater photon-photon interaction strengths through a suitable choice of semiconductor material. In the future, it may be possible to demonstrate the superfluidity of a weakly interacting photon gas by observing quantized vortices. On the other hand, the natural integration of a Bose-Einstein condensate of photons into semiconductor technology promises potentially interesting applications.

Bibliographic information on the published study:

Bose-Einstein condensation of photons in a vertical-cavity surface-emitting laser
M. Pieczarka, M. Gębski, A.N. Piasecka, J.A. Lott, A. Pelster, M. Wasiak, and T. Czyszanowski
Nature Photonics, Published online 12. August 2024
https://doi.org/10.1038/s41566-024-01478-z

Bose-Einstein condensation of light in a semiconductor quantum well microcavity
R.C. Schofield, M. Fu, E. Clarke, I. Farrer, A. Trapalis, H.S. Dhar, R. Mukherjee, T.S. Millard, J. Heffernan, F. Mintert, R.A. Nyman, and R.F. Oulton
Nature Photonics, Published online 12. August 2024
https://doi.org/10.1038/s41566-024-01491-2

For further information:
Priv.-Doz. Dr. Axel Pelster
Phone.: 0631 205 2270
E-mail: axel.pelster(at)rptu.de

Thank you to Nanophotonics for the prize and to the organizers for this great conference.

Anulekha is a physicist from India. She is a postdoctoral researcher in the Department of Physics at the Rhineland-Palatinate Technical University (RPTU) in Kaiserslautern, Germany. Anulekha has a background in physics and received her Master’s degree from the University of Burdwan, India (First Rank in University, Gold Medalist) and her Ph.D. from the S. N. Bose National Center for Basic Sciences, India. She then came to Germany for postdoctoral research in 2021. Her research focuses on experimental condensed matter physics to study ultrafast magnetization dynamics in magnetic thin films and nanostructures, as one of the major challenges of modern information technology is to develop new concepts to increase the data storage and processing speed beyond today’s GHz limit. In her research, she investigates the magnetization dynamics of magnetic materials after strong excitation by ultrafast optical pulses and aims to understand the microscopic mechanism of laser-induced magnetization dynamics on femto-, pico-, and nanosecond timescales, which is still a topic of intense debate. For the investigations, she uses all-optical pump-probe spectroscopy based on the time-resolved magneto-optical Kerr effect (TR-MOKE). In addition, she uses other experimental techniques such as Brillouin light scattering (BLS) and THz pump-probe spectroscopy. She also performs numerical simulations and frequently collaborates with other theorists to gain a deeper understanding of the experimental ultrafast magnetization dynamics.

The Department of Physics would like to thank the Physics Alumni Association and the Helmut Ehrhardt Foundation for Physics for their generous support of this event, as well as the Physics Student Council for their active help with the catering!

More impressions and pictures are now available on this page.

On 10 July, Prof. Elke Neu-Ruffing invited all those interested to the exciting question "What do fridge magnets, diamonds and a compass have to do with each other?". In her children's university lecture, there were many fascinating and surprising experiments and even a real pink diamond to see.  Thank you to everyone who attended. For all those who missed it, we also made a video that you can find here.

Further information about the RPTU Children's University and future dates can be found on this page: https://rptu.de/kinderuni.

Congratulations!

The girls explore the campus in small groups, receive information about the degree programmes on offer and can experiment for themselves. They are accompanied by students who give them tips about studying and talk about their everyday lives.

When registering, the schoolgirls can sign up for a day programme consisting of 3 workshops and 3 lectures. There is a total of 40 programmes with different focuses to choose from.

The "People, nature and the environment" section, for example, is about discovering the world of microorganisms, finding out why iron is important to us and how it can be researched, or how flower and plant petals absorb LED light. Under "digital technologies", the students gain an insight into how robots, data portraits, 3D printing and AI can support us in our everyday lives, at work or when planning a graduation party.  Under "Planning, building and designing", for example, there is the opportunity to build a bridge yourself and test it under load, play Monopoly in a completely different way or solder your own diode man.

Further information and the link to registration can be found on the website of the Equal Opportunities, Diversity and Family Office (under Kaiserslautern office, "Our offers for schoolgirls") or here.

Contact:
Office for Equality, Diversity and Family,
RPTU in Kaiserslautern

schuelerinnentag@rptu.de

The departmental barbecue is organised every year by the physics department with the active support of the student council, and the football tournament is organised by the jDPG. We would like to thank all the other helpers and participants who contributed to the organisation of this evening.

The OSCAR research team is breaking with a widespread paradigm in physics: quantum effects, which can lead to completely new properties, do not only occur when microscopic systems are isolated from their environment as much as possible. Rather, they can also be generated and stabilized when the systems are coupled to reservoirs, i.e. "open". OSCAR's novel concept for controlling quantum systems thus represents a fundamentally new approach to quantum technologies.

"In recent years, we have been working on tools for quantum technologies that enable open quantum systems to be used reliably and reproducibly in research and development. In the coming funding period, we will be tackling more complex challenges. We are continuing our basic research, but we want to point the way towards possible applications," explains physics professor Michael Fleischhauer, spokesperson of the Transregional Collaborative Research Center at RPTU.

The research team focuses on application areas such as energy and information transport and nanomachines that could serve as catalysts for more efficient data processing and storage. OSCAR combines the research expertise of the RPTU, which leads the program, and the University of Bonn.

Professor Dr. Werner R. Thiel, Vice President for Research at RPTU in Kaiserslautern, is delighted with this confirmation of the excellent research achievements in quantum physics: "I would like to congratulate our participating scientists on this success, which is the result of many years of pioneering work".

Questions answered:
Prof. Dr. Michael Fleischhauer
field of study: quantum optics / RPTU in Kaiserslautern
T: 0631 205-3206
E: mfleisch(at)rptu.de

Already during the day, the beer garden was buzzing with excitement, offering cool refreshing drinks and this year also scored with the tempting aroma of hot drinks from the coffee roastery in Kaiserslautern. The physical well-being was also catered for with a wide range of food. And there were plenty of sweet treats to be had, not to mention a delicious array of vegetarian and vegan dishes on the barbecue. Despite the cloudy skies, the beer garden was buzzing with guests, who were invited to linger in its relaxed atmosphere and challenge the brave to prove their skills against others in the gladiator game. And the party didn't stop there! The May party continued indoors, where the party animals partied on the dancefloor with great beats from the DJ until late into the night.

10 students participate in the final round of the state physics competition at the RPTU in Kaiserslautern. They are required to present a previously completed assignment and the results of their work in a colloquium. Additionally, they must carry out and evaluate two experiments independently in the laboratory. The performance in the experiments, the colloquium, and the term paper are evaluated in equal parts, and the results determine the winner of the competition.

The winner will be invited by the Department of Physics to participate in a practical course, during which they will gain an insight into laboratory work.

In parallel with the competition, a physics seminar is held for all pupils. Lectures and experiments provide insight into physics research, in addition to the competition participants. Topics include light and color in flower and plant colors, measuring methods and devices from wave optics, and the acoustics of black holes. Furthermore, all young people will receive information about the Early Studies in Physics (FiPS) programme and the physics, biophysics and techno-physics courses offered by the Department of Physics at RPTU in Kaiserslautern.
The students attend various grammar schools in Rhineland-Palatinate.
The state physics competition was launched by the state of Rhineland-Palatinate. The competition is sponsored by the Rhineland-Palatinate Ministry of Education, the State Research Center for Optics and Materials Science (OPTIMAS), the Collaborative Research Centers SFB-TR185 (OSCAR - Open System Control of Atom and Photonic Matter) and SFB-TR173 (SPIN+X - Spin in its collective environment), as well as the Sparkasse Kaiserslautern.

Questions answered:
Anett Fleischhauer
Deanery Physik
Phone.: 0631 205-5251
E-Mail: anett.fleischhauer(at)rptu.de

RPTU students are extremely satisfied with their physics studies and attest to the excellent study conditions. This is reflected in the rating of the general study situation and the range of courses with 4.3 out of a possible five stars. In addition, the comprehensive support provided by lecturers and the introduction to scientific work (4.4 stars each) as well as the library facilities (4.5 stars) were rated particularly positively. The study organization also received a very good rating (4.6 stars) for the smooth access to courses without overlapping compulsory courses.

The university also scored well in the CHE ranking for other degree programs in the natural sciences, computer science, and mathematics:
In Biology, students rated the organization of studies and the teaching of scientific skills with 4.2 stars each. They are also satisfied with the general study situation and the support provided by lecturers (3.9).
Chemistry also scored very well in terms of study organization (4.6 stars). It also scored well for the teaching of scientific and methodological skills, for which students awarded 4.1 stars each.
Computer Science received top marks for study organization (4.4 stars), library facilities (4.6 stars) and IT infrastructure (4.3 stars). Students also awarded 4.1 stars each for the general study situation and the range of courses.
Mathematics students rate their study conditions very positively in many areas, especially the general study situation and the study organization (4.8 stars each). The support provided by lecturers (4.7 stars), the range of courses on offer, the support during studies and the introduction to scientific work also received very good marks (4.6 stars each).

About the CHE Ranking
In the new comparison of study programs, various criteria - student assessments and facts - are reported. In addition to the general study situation, students also evaluate the courses offered, the support and assistance during their studies and the digital teaching elements. The evaluation is presented on a 5-star scale and the ranking of the Bachelor's programs can be accessed at https://studiengaenge.zeit.de/ranking. It will also appear in the next edition of the ZEITStudienführer.

You can find information on the Physics degree program here https://www.physik.rptu.de/studium/

Every year, the Daimler-Benz Foundation awards twelve scholarships to selected post-doctoral students, junior professors and junior research group leaders. The aim of these scholarships is to promote the independence and creativity of young scientists and at the same time to facilitate career advancement for committed researchers in the post-doctoral phase.
Each scholarship is endowed with 40,000€ for two years, which can be used for various purposes, e.g. for support from assistant scientists, the purchase of equipment, the financing of research trips or participation in conferences. In addition, the Daimler and Benz Foundation promotes interdisciplinary dialog and collaboration through regular meetings of young scientists within the growing network of scholarship holders.

https://www.quantum-rlp.de on April 10, 2024.

Congratulations!

Currently, Franziska is working in the AG Magnetismus on her PhD within project B04 of the Transregional Collaborative Research Center 173 "Spin+X“, focusing on the nonlinear dynamics of Bose-Einstein magnon condensates.

Many technical applications today only work thanks to the quantum technology that is built into them. In the future, it will play an increasingly important role, for example in quantum computers or quantum sensors. It is therefore important to understand what happens in such systems and how they interact with their environment.

The experiments were carried out by Widera's team at RPTU in Kaiserslautern; the theoretical work for this study was carried out by Professor Dr. André Eckardt's working group at the Institute for Theoretical Physics at TU Berlin, with Ling-Na Wu from Hainan University in China also involved.

The study has been published in the renowned journal Nature Communications: "Indication of critical scaling in time during the relaxation of an open quantum system"

DOI: doi.org/10.1038/s41467-024-46054-9

At the RPTU in Kaiserslautern, the research work for the study was integrated into the Center for Optics and Materials Science, which is funded as part of the Rhineland-Palatinate Research Initiative.

Questions answered:
Professor Dr. Artur Widera
Lehrgebiet Individual Quantum Systems
RPTU in Kaiserslautern
Tel.: 0631 205-4130
E-Mail: widera(at)rptu.de

For more information, please see the official job opening of the university: https://jobs.rptu.de/jobposting/e5d31c2e7efe001ef57d9681a26ad3dcf14d62db0

Please note that we will accept application only via the universities online portal linked in the official job opening, not via E-Mail

For more information see

https://qnami.ch/proteusq-at-tu-kaiserslautern/

https://optimas.uni-kl.de/en/

For their experiment, the physicists used a cloud of rubidium atoms that was cooled to around 100 microkelvins - 0.0001 degrees above absolute zero - in an ultra-high vacuum. They then used lasers to excite some of these atoms into a so-called Rydberg state. "The outermost electron is brought into distant orbits around the atomic nucleus," explains Professor Herwig Ott, who researches ultracold quantum gases and quantum atom optics at the Rhineland-Palatinate University of Technology Kaiserslautern-Landau (RPTU). "The orbital radius of the electron can be more than one micrometer, making the electron cloud larger than a small bacterium." Such highly excited atoms also form in interstellar space and are extremely chemically reactive.

If there is now another atom inside this huge Rydberg atom, a molecule is formed. While conventional chemical bonds are either covalent (bonding via a pair of electrons), ionic (bonding via positively and negatively charged ions), metallic (freely moving electrons) or dipolar in nature (bonding through dipole forces), the trilobite molecules are bonded by a completely different mechanism. "It is the quantum mechanical scattering of the Rydberg electron on the atom that glues the two together," says Max Althön, first author of the study. Althön continues: "Imagine the electron orbiting the atomic nucleus in a fast orbit. Each time it orbits, it collides with the second atom. Contrary to our intuition, quantum mechanics teaches us that these collisions result in an effective attraction between the electron and the atom."

These molecules have amazing properties: Due to the wave nature of the electron, the multiple collisions result in an interference pattern that looks like a fossil trilobite. In addition, the bond length of the molecule is as large as the Rydberg orbit - much larger than that of any other diatomic molecule. And because the electron is so strongly attracted to the second atom, the permanent electric dipole moment is extremely large at more than 1700 Debye.

In order to observe these molecules, the scientists have developed a special vacuum apparatus. It makes it possible to produce ultracold atoms by laser cooling and then detect the molecules spectroscopically. The results contribute to the understanding of fundamental bonding mechanisms between atoms in the ground state and Rydberg atoms, which have recently also become a platform for quantum computing applications. The researchers' discovery adds to the understanding of Rydberg systems, which can be both exotic and useful.

The work on this study took place as part of the priority program "Giant Interactions in Rydberg Systems", which is funded by the German Research Foundation. The research was carried out in the OPTIMAS profile area (State Research Center for Optics and Materials Science), which has been funded since 2008 as part of the research initiative of the state of Rhineland-Palatinate.

The results of the measurements and a description of the experimental setup have been published in the renowned journal Nature Communications: "Exploring the vibrational series of pure trilobite Rydberg molecules"; Max Althön, Markus Exner, Richard Blättner & Herwig Ott

www.nature.com/articles/s41467-023-43818-7
DOI: doi.org/10.1038/ s41467-023-43818-7

Questions answered:
Prof. Dr. Herwig Ott
Ultrakalte Quantengase und Quanten-Atom-Optik
RPTU in Kaiserslautern
E-Mail: herwig.ott@rptu.de
Telefon: +49 0631 205-2817

Congratulations!

The fact that we are now able to stream music and videos despite immense amounts of data or that cars brake safely thanks to anti-lock braking systems is thanks to the constant progress made in spin research. The findings from this field of research have been continuously incorporated into the development of new technologies for many years. Another example is the formative role that spin research has played in the development of hard disks since the dawn of the computer age, and how it influences the evolution of modern magnetic memory chips and sensors today.

In specialist circles, the term "spin" refers to the intrinsic angular momentum of a quantum particle, be it an electron or a proton, as Professor Dr. Martin Aeschlimann, spokesperson for the Collaborative Research Center (CRC) at RPTU in Kaiserslautern, explains: "Spin is a purely quantum mechanical phenomenon and forms the basis for all magnetic phenomena." This finding is particularly important when it comes to the fast and efficient storage of large amounts of data, as well as in the development of advanced magnetic sensors used in mobile devices and vehicles.

The research team in Kaiserslautern and Mainz dedicates its work to the entire spectrum of spin research. This covers a spectrum ranging from fundamental physical issues to functional and technologically oriented projects. One example of this is the development of innovative components that use spin waves as transmission carriers to transfer data.

Another central focus of the Collaborative Research Center is the promotion of young scientists. The integrated "Spin+X Graduate College" enables young researchers to receive comprehensive training both in their specialist field and across disciplines. This training opportunity is made possible by the close cooperation between the various working groups at both locations.

In the third funding period, particular attention will be paid to the preparation and storage of research data in accordance with the FAIR principles, which stand for findability, accessibility, interoperability and reusability. A separate sub-project will be dedicated to this topic. In close cooperation with the FAIRmat consortium of the NFDI (National Research Data Infrastructure), the results of the "Spin+X" research will be made accessible to the scientific community and future research projects in this area.

The Transregional Collaborative Research Centre "Spin+X - Spin in its Collective Environment" was first approved in 2016. It is currently in its second funding period (2020 to the end of 2023). The third phase of the project will start in January 2024.

"This is a great success for spin research in Rhineland-Palatinate. I congratulate everyone involved in Kaiserslautern and Mainz," says Professor Dr. Werner Thiel, Vice President for Research at RPTU in Kaiserslautern. "At RPTU in Kaiserslautern, we are pooling our work on spin research in a dedicated research building, the Laboratory for Advanced Spin Engineering, or LASE for short. Here, researchers are getting to the bottom of spin phenomena across disciplines and laying the foundations for future key technologies."

The Collaborative Research Center is firmly integrated into the research initiative of the state of Rhineland-Palatinate at both locations. The aim of this initiative is to promote cutting-edge research and offer universities the opportunity to develop their profile.


 

About Collaborative Research Centers of the Deutschen Forschungsgemeinschaft (DFG)
Collaborative Research Centres are long-term research institutions at universities, set up for a period of up to twelve years, in which scientists work together within the framework of an interdisciplinary research program.

They make it possible to work on innovative, demanding, complex and long-term research projects by coordinating and concentrating people and resources at the applicant universities. In this way, they serve to establish institutional priorities and structures.

The SFB/Transregio (TRR) is jointly applied for and supported by two or three universities. It enables close cooperation between these universities and their researchers, including the joint use of resources. The contributions of the applying university partners are essential, complementary and synergetic for the common research objective.
More: www.dfg.de/foerderung/programme/koordinierte_programme/sfb/

Fragen beantworten:
Aneta Daxinger and Matthias Klein
Geschäftsführung SFB/TRR Spin+X
Tel.: 0631 205-3576
E-Mail: spin_gf(at)uni-kl.de
 

About the RPTU

Since January 1, 2023, the Technical University of Kaiserslautern and the University of Landau together form the University Kaiserslautern-Landau. With over 20,000 students and more than 300 professors, RPTU is the second largest academic institution in the state. As a place of top international research and an academic talent factory for business and science, RPTU offers excellent study and research conditions as well as a cosmopolitan environment. RPTU is also an innovation and transfer partner for politics, business and society. Anyone who studies, learns, researches or works at RPTU is part of a vibrant university community and shapes the world of tomorrow.

The two were appointed W3 Professors of Experimental Physics. Mr. Stadtmüller is researching "Ultrafast phenomena at interfaces", Mr. Pupeza in the field of "Optical quantum metrology". Their appointment will undoubtedly help to further sharpen our departmental profile and offer our students even more opportunities.

We warmly welcome them both and look forward to working with them.

Here you can find the paper: https://www.nature.com/articles/s41586-023-06469-8

The project was carried out in collaboration with our theory colleagues K. Menon, E. Cuestas, T. Fogarty and T. Busch from the Okinawa Institute of Science and Technology (Japan), as well as E. Lutz from the Institute for Theoretical Physics in Stuttgart (Germany).

Energy difference as a drive

"In the quantum world, or at the atomic level, we distinguish between two classes of particles: Bosons and fermions," explains Jennifer Koch, research associate in the working group and first author of the study. "These differ in one property, namely their intrinsic angular momentum or spin." When a large number of bosons and fermions come together in a so-called atom trap in an ultracold environment (in which thermal effects play no role), the following happens: "If the bosons are not guided by thermal energy, they remain energetically in their ground state and join each other," explains the physicist. "The fermions, on the other hand, follow the Pauli principle." The Pauli principle states that two identical fermions cannot be in the same energy state. Instead, they move away from each other and assume different excitation states or increasing energy levels. The crucial point for research: "The total energy of the fermion ensemble is higher," summarizes Koch.

In order to tap into the energy difference between the different particle ensembles, the research team took advantage of the fact that fermions are readily convertible under suitable experimental conditions. The physicist explains: "We combined the fermions in pairs - this created bosons. We have thus created a quantum mechanical alternative to igniting a fuel that can be used to operate our quantum engine."

Thermodynamics - yes or no?

The proof of concept has therefore been successful. What will happen with the findings? "At the moment, we are still a long way from a concrete application because our development only works under special test conditions. However, I am convinced that there is valuable potential in our basic research that can provide inspiration for new applications in solid-state physics, for example in superconductors, where fermionic electrons also conduct electricity as pairs without loss," Widera sums up. "Our motor already had a good performance compared to a standard machine. And the more particles the ensembles contain, the higher energy levels and therefore energy yields can be achieved," says Widera. Professor Eric Lutz, one of the co-authors of the study, adds another aspect: "The topic is extremely exciting from the point of view of the scientific community. We are initiating a discussion about how the experimental results should be classified from a scientific point of view. Can we use the laws of thermodynamics? If not, how do we describe the processes that make our engine run?" And Professor Thomas Busch, whose team from Japan was involved in the theoretical modeling, adds: "These questions help to advance our knowledge of the world of the smallest particles and to understand how we can use their properties for further technical innovations."

Together to success

The Kaiserslautern research team, which was responsible for managing the project, included Professor Artur Widera, Jennifer Koch and Sian Barbosa. The project partners included researchers from the Okinawa Institute of Science and Technology (OIST) in Japan - Professor Thomas Busch, Eloisa Cuestas, Keerthy Menon and Thomas Fogarty. They provided the theoretical models for the experimental approach. Also involved was Professor Eric Lutz from the University of Stuttgart (Theoretical Physics), who contributed his expertise in thermodynamics.

The study "A quantum engine in the BEC-BCS crossover" can be viewed in the renowned scientific journal Nature: https://www.nature.com/articles/s41586-023-06469-8

Bibliographic information on the published study:
A quantum engine in the BEC-BCS crossover
Jennifer Koch, Keerthy Menon, Eloisa Cuestas, Sian Barbosa, Eric Lutz, Thomas Fogarty, Thomas Busch, and Artur Widera
Nature, Volume 621 Issue 7980, September 28, 2023
DOI: 10.1038/s41586-023-06469-8

Answer questions:
Dipl.-Phys. Jennifer Koch
Phone: 0631 205 5272
E-Mail: jekoch@rptu.de

Prof. Dr. Artur Widera
Phone: 0631 205-4130
E-Mail: widera@rptu.de

About the RPTU

Since January 1, 2023, the Technical University of Kaiserslautern and the University of Landau together form the Rhineland-Palatinate Technical University of Kaiserslautern-Landau. With over 20,000 students and more than 300 professors, RPTU is the second largest academic institution in the state. As a place of top international research and an academic talent factory for business and science, RPTU offers excellent study and research conditions as well as a cosmopolitan environment. RPTU is also an innovation and transfer partner for politics, business and society. Anyone who studies, learns, researches or works at RPTU is part of a vibrant university community and shapes the world of tomorrow.

Congratulations!

• Orbitronics: How can we use higher order waveguide modes to create artificial fields for light that mimic magnetic or electric interactions?
• Quantum (non-)reversibility: When do processes in quantum systems become non-reversible? How can we explore this with the help of nonlinear waveguides?
• Quantum dot integration into photonic crystals

Want to know more? Please contact cjoerg(at)rptu.de

press release of TU Kaiserslautern

press release of TU Kaiserslautern

press release of the TU Kaiserslautern

Our research is partly motivated by the behavior of flocks of fish and birds as it can be observed in nature. The German Research Foundation funds our research with the collaborative research center with 11 Mio Euro for 4 years. We aim to understand the quantum cooperative behavior of light and matter. Long term goals include to use this behavior to enhance e.g. the sensitivity of qunatum sensors.

Press release of TUK (in German) here.

We wish you a succesfull start for the new position! Thanks for your pioneering work in Kaiserslautern!

Congrats for the new job, we wish you a perfect start! Thank again for your great working during PhD and PostDoc time!

Welcome!

www.mpgc-mainz.de

Find the article here.

Our research is being funded in the  EU Network QuSco. (European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 765267)

We are very pleased that our work has been highlighted in a scilight which summarizes the work for a broader audience. Find the Scilight here.

Pressure or temperature are gas properties reflecting microscopic collisions between atoms. Collisions of the atoms can moreover change the quantum properties of the colliding atoms. Together with our college Prof. E. Tiemann of the university Hannover, we have succeeded in using single atomic impurities as quantum probes in an ultracold gas.

Collisions between ultracold atoms modify the quantum properties of our impurities and allow deducing the temperature of the gas.

Experimentally, we immerse individual neutral cesium (Cs) atoms in an ultracold rubidium (Rb) gas. Subsequent collisions lead to an exchange of quantized angular momentum. The energy associated with such a change is different for the two atomic species. Consequently, two types of processes can occur. In exothermal collisions, excess energy is dissipated in the gas, while endothermal processes are only possible if sufficient additional energy can is available from the thermal (kinetic) energy in a collision. The latter process effectively couples the quantum spin distribution of the Cs probes with the temperature of the gas. Hence, it is possible to extract the system's temperature from the Cs spin distribution.

Moreover, we found that the sensitivity of the thermometer increases, considering the spin dynamic instead of the steady-state distribution. Based on the additional magnetic field dependency of the system, it is also possible to use this physical effect as a multimeter to measure the present magnetic field. Our work is an important step to pave the way for non-destructive quantum many-body system measurements and to operate and optimize new quantum sensors.

In recent years, nitrogen-vacancy (NV) centers in diamond have advanced to a promising, nanometer-scale platform for quantum metrology and quantum information technology. For most applications, bulky, high numerical aperture microscopes grant direct optical access to such quantum emitters.

In our work, we have integrated these quantum systems embedded in nanodiamonds into microscopic, optical polymer waveguides, yielding remote optical access to NV centers. In addition, we have investigated these structures for measuring magnetic fields and ensured that coherence properties are preserved.

Our work is an important step toward realizing photonic chips with integrated quantum emitters.

The next day of physics will be on 04.12.2021.

A single collision between two atomic particles in a vapor constitutes the foundation for the vapor’s macroscopic behavior, such as pressure or heat conductance, but also for its quantum properties. In our work, we study such individual collisions at ultracold temperatures, going beyond the changes of the particles’ motional state, i.e. their velocity or position. Together with our colleague Prof. E. Tiemann (University of Hanover), we rather investigate how the atoms’ internal structure, encoded in their angular momentum state, behaves upon the collision with another particle, and how this outcome can be controlled. Immersing individual Cs atoms at few hundred Nanokelvin temperature into an ultracold Rb gas, we could reveal a series of very narrow so-called Feshbach-Fano resonances, where the probability of a collision between two atoms is tunable via an external magnetic field in a range of few percent of the earth’s magnetic field. By studying single collision events between pairs of atoms, we have obtained information about the origin of these resonances, which is a giant molecular halo state, whose size in the micrometer range is large as our experimental system itself, bound at a very small energy. Furthermore, we have found that the colliding atoms can exchange angular momentum not only by a single quantum, but also by two. These observations yield novel insight into atomic interaction properties and the molecular potential directly at the dissociation threshold, so far not accessed in experiments. Both phenomena reveal only at very low energies in the system, thus they require us to keep relevant experiment parameters, such as the magnetic field and the collision energy under tight control, with fluctuations a level of only few kilo Hertz. With the experiment at hand, two intriguing research directions open. First, our system helps to precisely measure interaction phenomena at the level of a single collision, advancing ultracold chemistry and spectroscopy. Second, the exceptional level of control can help to build up and tailor the behavior of ultracold quantum matter, starting from its fundamental building block, the interaction of two particles.

More information can be found in the press release of the university.

B. Gänger, J. Phieler, B. Nagler, and A. Widera,
„A versatile apparatus for fermionic lithium quantum gases based on an interference-filter laser system“,
Rev. Sci. Instr. 89, 093105 (2018).

We were happy about a huge number of questions, amazed faces and receiving so positive feedback. We are looking forward to seeing all interested visitors again – either in our labs in two years, or maybe in the lecture halls in the upcoming terms.

Kaiserslautern physicists observe diffusion of individual atoms in light bath

In a combination of experiments and theory the diffusion of individual atoms in periodic systems was understood for the first time. The interaction of individual atoms with light at ultralow temperatures close to the absolute zero temperature point provides new insights into ergodicity, the basic assumption of thermodynamics.

Diffusion is a universal physical phenomenon, describing the motion of particles in their particular environment, whether solid, liquid or gaseous. The first observation of Robert Brown and the subsequent explanation by Albert Einstein are already more than a hundred years old: Robert Brown observed the random, irregular dithering movement of pollen in a liquid. Einstein and Smoluchowski interpreted this "Brownian motion" correctly as a result of random collisions of molecules of the liquid with the pollen. The diffusion in complex systems goes one step further and can have very diverse characteristics: Tumor movement in living organisms, DNA transport within cells, ion flow in batteries, moving atoms on surfaces - all these are diffusion processes in complex systems. Uncovering of the underlying mechanisms is of great interest as these could reach far into daily applications one day. Physical studies of ultracold atoms, carried out at the University of Kaiserslautern, now provide an understanding of diffusion in periodic structures, relevant for various complex systems.

Physicists at the University of Kaiserslautern together with scientists from the Universities of Erlangen-Nuremberg and Kyoto in Japan have made an important step towards the fundamental understanding of complex diffusion and the interpretation of their experimental data. For the study, published in the prestigious journal Nature Physics, the Kaiserslautern team around Professor Widera (Department of Physics and State Research Center OPTIMAS) developed a novel model system: A single atom is cooled by lasers near to absolute zero temperature and trapped by light within a near-perfect vacuum. The atom is then transferred into an environment of a light field in which the light-absorption and light-emission of the atoms act as collisions with other particles. In this environment, the diffusion can be readily set and the motion of the atom be tracked by a camera.
In parallel, theoretical physicists from Erlangen-Nuremberg and Kyoto developed a model for the description of the dynamics of the system. A central aspect here was to understand the processes in terms of the physical phenomenon of ergodicity. Due to the excellent agreement between experiment and theory, diffusion processes can now be understood beyond Brownian motion. These results have potentially an impact on the understanding of various complex systems in medicine, biology, physics and engineering in the future.

Fundamentals of diffusion

The motion of individual cells in the body or the transport of charge carriers in energy storage systems can be understood only in the context of the particular environment. The particles within the environment encounter permanent collisions with a cell or a carrier, thus influencing their motion. These processes can in many cases be described through Brownian motion by Einstein’s theory. Sometimes the observations can, however, not be described within this model, and in some cases this non-Brownian dynamics are not obvious at first glance. The scientists of the three universities have succeeded in showing both theoretically and experimentally, how the diffusion in certain complex systems can be characterized.

Ergodicity is a key to understanding complex diffusions

A central aspect of the study was to investigate the atomic system on time scales that are relevant for the establishment of ergodicity. Ergodicity is a basic assumption of thermodynamics and an important factor for the description of diffusion processes. In simple words, the ergodicity hypothesis states that in an ensemble of particles, the motion of a single particle is representative for the entire ensemble. This assumption is usually valid for all observed phenomena in our everyday lives. Strictly seen, this applies, nevertheless, for most systems only on very long time scales. The scientists could now show in their study that even seemingly "normal" diffusion processes in certain cases may violate ergodicity on surprisingly long time scales. These findings have interesting implications for understanding the diffusion in complex systems and can help, for example, to  re-evaluate and interpret observations and measurements in biological systems.

An accompanying article by Sophia Chen in the online journal Physics can be found here.

See the press release of TU Kaiserslautern (german).

The reference of the original publication is: Phys. Rev. A 93, 022507 (2016).