Applications of superconducting quantum circuits in scalable quantum computing, microwave quantum networks, or quantum-limited amplifiers require the fabrication of low-loss Josephson junction-based devices. Now, by combining advanced fabrication steps, including rigorous surface treatment and argon ion milling, WMI researchers have achieved devices based on nonlinear Josephson resonators with record-high internal quality factors exceeding 10⁵ at the single-photon level. The low loss rates have been verified through microwave scattering and squeezed state microwave measurements. The low-loss superconducting devices are crucial for the quantum-limited amplification, frequency conversion, and generation of high-purity squeezed microwave states.
Quantum communication in the microwave regime is set to play an important role in distributed quantum computing and hybrid quantum networks. To this end, WMI has developed the foundations of microwave-based quantum local area networks (QLAN) for more than a decade. Now, we have reached an important milestone by demonstrating a cryogenic microwave link connecting two dilution fridges over a distance of 6.6 m. We demonstrate the successful distribution of quantum entanglement through this QLAN. The system was set up within the EU flagship project QMiCS and the BMBF project QUARATE with support from VTT Finland, Rohde&Schwarz GmbH & Co. KG, Germany, and Oxford Instruments NanoScience, UK.
WMI Press Release
The Walther-Meißner-Institute of BAdW and its partners at TUM, LMU, MPQ, and Deutsches Museum were once again successful in the highly competitive Excellence Strategy of the German federal and state governments. As announced by the German Research Foundation (DFG), the Cluster of Excellence Munich Center for Quantum Science and Technology (MCQST) will receive funding for seven more years through 2032 to further strengthen its role as a world-leading hub for quantum research. MCQST succeeded in building a vibrant ecosystem of over 60 research groups working across all areas of quantum science and we are very happy that we can continue this success story, the former MCQST spokesperson Rudolf Gross points out.
MCQST Press Release, DFG Press Release
The world around us is made up of two different types of particles: fermions and bosons. Fermions behave like cars on a road, where the motion of one particle is blocked by the one in front of it. In contrast, bosons are much more social. They like to cluster together, and traffic jams are unknown for bosonic quantum vehicles. Despite these differences, we (Y. Minoguchi et al., PRL discover a hidden connection in the transport of fermionic and bosonic particles, which only reveals itself when examining fluctuations on top of the average particle currents. Surprisingly, these fluctuations obey the same universal scaling law for both types of particles—a law that is also known to describe the growth of surfaces, the spread of wildfires, and many other seemingly unrelated physical phenomena.
Our former Bachelor and Master student Johanna Fischer (now at Spintec Grenoble, France) receives the 2025 EMA Young Scientist Award. This Prize is awarded every year by the European Magnetism Association in the fields of fundamental or applied magnetism to a scientist in an early career stage (PhD no more than 5 yeras ago). Johanna did both her Bachelor's thesis (2014) and her Master's thesis (2017) with us in the Walther-Meißner-Institut. We congratulate Johanna on this great success!
On April 4th, the Schoolkindergarten Weltentdecker from Neufahrn b. Freising visited Walther-Meißner-Institut to learn more about magnetism and low temperature physics. The visit was aligned with the pedagogical concept of the Schoolkindergarten, where the children have a weekly natural science class, performing various simple experiments and getting first insights into physics and chemistry sciences. During this visit, total of 19 pre-school children got their first touch to the superconducting levitation (Meißner effect), freezing of matter and Gummi Bärchen in liquid nitrogen (this was full success!), and other fascinating properties of the cryogenic liquids.
