High-precision laser system enables record flux of quantum gas mixtures
Mainz physicists pave the way for fundamental space experiments with miniaturized laser technology
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The miniaturized laser system, developed with major contributions from researchers at Johannes Gutenberg University Mainz
view moreCredit: photo/©: Sören Boles
Mainz physicists pave the way for fundamental space experiments with miniaturized laser technology
An international team of researchers has succeeded in producing atomic quantum gas mixtures with an unprecedented particle flux. In the journal Nature Communications, the scientists report on experiments conducted with the MAIUS-B apparatus, in which Bose-Einstein condensates (BECs) consisting of two different atomic species – rubidium and potassium – were generated and studied under microgravity conditions in the Einstein Elevator at Leibniz University Hannover, Germany. A key contribution to this achievement came from a technological development at Johannes Gutenberg University Mainz (JGU): the highly sophisticated and compact optical system used to control the atoms.
Technology as a key to success
Bose-Einstein condensates are considered an "exotic" state of matter that exists near absolute zero temperature, where quantum mechanical phenomena become observable on a macroscopic scale. While the generation of a BEC from a single atomic species was first achieved in space during the MAIUS-1 mission in 2017, simultaneously cooling and manipulating two different atomic species presented the researchers with enormous technological challenges.
To meet these challenges, the Mainz research group led by Professor Patrick Windpassinger and Dr. André Wenzlawski from the Institute of Physics at JGU developed a miniaturized laser system in collaboration with Humboldt-Universität zu Berlin and the Ferdinand-Braun-Institut, Berlin. Despite requiring twice as many lasers as well as additional optical and electronic components, the system maintained almost the same payload volume and mass. "Our task was to develop the optical interfaces between the laser modules and the vacuum system, that are essential for cooling and manipulating the atoms," explained Wenzlawski.
A central technological component of the system is the set of optical benches, which form the interface between the laser modules and the vacuum system. These were developed jointly by JGU and the University of Hamburg. The optical benches are based on the glass-ceramic material Zerodur, which is characterized by an exceptionally low coefficient of thermal expansion. "This stability is crucial for maintaining precise control of the atoms under the extreme mechanical loads of a rocket launch and varying temperature conditions," said Wenzlawski.
The long-term operation of the apparatus in the Einstein Elevator and in laboratory environments has validated the technological concept. The system achieves the atomic flux reported to date for such a dual-species BEC mixture, outperforming existing mobile systems by an order of magnitude.
Pioneering technology for future space missions
The technologies developed in Mainz represent a major milestone in the use of quantum sensors in space. The robustness and precision of the optical modules provide the foundation for future flagship projects such as the German-American BECCAL atom laboratory aboard the International Space Station (ISS). Systems of this kind will enable scientists to test Einstein's equivalence principle with unprecedented precision by measuring whether different atomic species experience exactly the same acceleration during free fall.
The QUANTUS IV – MAIUS project was coordinated by the Center of Applied Space Technology and Microgravity (ZARM) in Bremen and funded by the German Space Agency at German Aerospace Center (DLR).
Journal
Nature Communications
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Apparatus for quantum-mixture research in microgravity
EPFL Professor Ursula Röthlisberger wins Michele Parrinello Award for contribution to computational physical science
MDPI AG
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Professor Ursula Röthlisberger, 2026 Michele Parrinello Award Winner
view moreCredit: MDPI
Open Access scholarly publisher MDPI has named Professor Ursula Röthlisberger, Professor of Computational Chemistry and Biochemistry at the École Polytechnique Fédérale de Lausanne (EPFL), as the recipient of the 2026 Michele Parrinello Award. Professor Ursula Röthlisberger has been recognized for her outstanding contributions to computational chemistry and molecular simulation.
Professor Ursula Roethlisberger said: “I am deeply honored to receive this award, which bears the name of one of my long-time mentors and most inspiring role models. To me, this distinction represents far more than personal recognition—it is a wonderful affirmation of the scientific contributions that I have been privileged to make, together with outstanding students, postdoctoral researchers, collaborators, and colleagues, throughout my career.”
Established by MDPI in 2025, the Michele Parrinello Award commemorates the scientific legacy of Professor Michele Parrinello, whose groundbreaking work transformed atomistic simulation and molecular dynamics. Winners are recognized for their outstanding contributions to computational physical sciences and receive a prize of 50,000 EUR in recognition of their achievements.
Professor Röthlisberger’s work has made pioneering contributions to ab initio molecular dynamics and quantum mechanical/molecular mechanical (QM/MM) multiscale simulation methods. It has provided rigorous computational frameworks for investigating complex molecular processes across different scientific fields, creating important tools for studying molecular processes and guiding scientific discovery. Her research spans quantum chemistry, molecular biology, materials science, and sustainable energy.
A major focus of Professor Röthlisberger’s recent research has been the computational design and understanding of next-generation photovoltaic materials. Through close collaboration with experimental scientists worldwide, she has revealed the fundamental mechanisms governing dye-sensitized and perovskite solar cells, providing insights that have helped guide the development of more efficient, stable, and sustainable solar energy technologies.
Professor Xin-Gao Gong, chair of the Michele Parrinello Award Committee, added: “Professor Ursula Röthlisberger has been recognized by the Michele Parrinello Award Committee as an exceptional leader in computational chemistry and molecular simulation. Her innovative research has significantly advanced the predictive modeling of complex chemical and biological systems and has created lasting impact across multiple scientific disciplines. Through her outstanding scientific achievements, dedication to education, and leadership in the international research community, she has played a vital role in shaping the development of modern computational science.”
Professor Röthlisberger's scientific achievements have earned international recognition throughout her career. She is an elected Fellow of the American Association for the Advancement of Science (AAAS), a member of the International Academy of Quantum Molecular Science, and a recipient of the Dirac Medal from the World Association of Theoretical and Computational Chemists (WATOC) and the Ruzicka Prize.
The Michele Parrinello Award forms part of MDPI’s commitment to recognizing scientific excellence and supporting outstanding researchers whose work advances fundamental knowledge and addresses global scientific challenges.
Researchers unveil a scalable chip platform for next-generation quantum technologies
Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS
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Figure | Scalable quantum photonic platform based on site-controlled quantum dots (SCQDs) integrated with circular Bragg grating (CBG) resonators. (a) Artistic illustration of a wafer-scale SCQD-CBG array, where emitters are deterministically positioned at the centers of the resonators and emit vertically directed single-photons. The schematic highlights the scalable architecture and efficient vertical photon extraction enabled by the resonator design. (b) Low-temperature cathodoluminescence maps of the fabricated 6×6 SCQD-CBG device array overlaid with the corresponding SEM image. Bright emission is confined to the CBG-mesa centers for all devices, demonstrating deterministic QD growth, uniform fabrication, and 100% integration yield across the array. (c) Representative optical and quantum-optical characterization of the best-performing SCQD-CBG device. Top: high-resolution micro-photoluminescence spectra showing spectrally isolated emission with narrow linewidths. Middle: second-order autocorrelation measurement confirming a single-photon purity of 99.6%. Bottom: Hong-Ou-Mandel two-photon interference histogram revealing a raw visibility of 81%. Together, these results establish the SCQD-CBG platform as a scalable, high-performance semiconductor quantum light source architecture.
view moreCredit: Kartik Gaur et al.
Imagine a future where digital information is fundamentally secure, powerful new computers solve problems beyond the reach of today’s machines, and communication networks operate using the laws of quantum physics. Realizing this vision depends on one deceptively demanding component: a source that can emit single particles of light, known as photons, one by one, with high brightness, exceptional purity, and nearly identical properties. Although remarkable progress has been made in recent years, producing many such sources in a scalable manner on a semiconductor chip has remained one of quantum technology’s most persistent challenges. Researchers now report an important step toward overcoming this barrier.
In a new paper published in Light: Science & Applications, Kartik Gaur and co-workers, under the leadership of Prof. Stephan Reitzenstein at the Technical University of Berlin, together with collaborators from the group of Prof. Christopher Gies at Carl von Ossietzky University of Oldenburg, have developed a scalable quantum photonic chip architecture that integrates deterministically positioned semiconductor quantum emitters into nanoscale photonic resonators. The result is a platform capable of generating bright, pure, and highly indistinguishable single photons, key resources for quantum communication, quantum networks, and optical quantum computing.
At the heart of the technology are quantum dots, nanoscale structures often described as artificial atoms because they can emit single photons with exceptional quantum control. In conventional approaches, however, such emitters form at random positions during growth. Suitable quantum dots must therefore be identified individually before photonic devices can be fabricated around them, a highly successful strategy for single demonstrator devices, but one that becomes increasingly demanding when extended to wafer-scale arrays containing hundreds or thousands of emitters.
TU Berlin researchers addressed this challenge using a deterministic growth concept based on a buried-stressor layer that guide each quantum dot into predefined positions during crystal growth. These site-controlled emitters are then directly integrated into circular Bragg grating resonators, compact nanophotonic structures designed to efficiently extract and direct the emitted light.
Using this concept, the team fabricated a 6×6 array with 100% yield of working devices, demonstrating a level of reproducibility rarely achieved in solid-state quantum photonics. Rather than relying on a single optimized structure, the study shows that high-performance quantum light sources can be realized repeatedly across an integrated semiconductor chip platform.
The best-performing device delivered an exceptional combination of metrics: nearly half of the generated photons were extracted into the collection optics, single-photon purity exceeded 99%, narrow optical linewidths were maintained, and two-photon interference measurements revealed high indistinguishability, a key requirement for advanced photonic quantum processors.
Equally important, the researchers established how nanometer-scale emitter misalignment influences device performance. By combining structural imaging, optical spectroscopy, lifetime analysis, photon-correlation measurements, two-photon interference experiments, and electromagnetic simulations, they identified quantitative fabrication tolerances relevant for future large-scale device integration.
The team from Carl von Ossietzky University of Oldenburg, led by Prof. Christopher Gies, carried out the quantum-optical modelling, providing a theoretical framework that explains how emitter position influences charge-noise-induced decoherence and directly links fabrication accuracy to linewidth broadening and photon indistinguishability. The close agreement between experiment and theory provides valuable design rules for next-generation quantum photonic chips.
The authors say that the work addresses a longstanding bottleneck in the field: not simply whether one excellent quantum light source can be demonstrated, but whether many can be fabricated with predictable quality on the same wafer. The marker-free integration strategy removes the need for labor-intensive emitter localization and alignment procedures that have traditionally limited scalability.
Beyond the immediate device performance, the technology offers a realistic route toward wafer-scale quantum photonic hardware using established semiconductor manufacturing methods. This could accelerate the development of secure quantum communication systems, compact quantum sensors, and optical quantum computing architectures based on large arrays of deterministic single-photon sources.
The researchers describe the platform as an important transition from individually optimized laboratory devices toward reproducible quantum photonic technologies manufactured with the precision, uniformity, and scale required for practical applications.
Journal
Light: Science & Applications
Article Title
Scalable Quantum Photonic Platform Based on Site-Controlled Quantum Dots Coupled to Circular Bragg Grating Resonators
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