suspended CVD graphene
Physicists of the Budapest University of Technology and Economics (BME) and the University of Basel discovered a surprising result on the extension of Yu-Shiba-Rusinov states. Their joint studies appeared in Nature Communications.
Recently several promising novel qubit concepts have been put forward that are based on low-energy states, appearing in nanoscaled devices that are proximitized by a superconductor (SC). There are several flavours of these states, known as Andreev bound state (ABS), Yu-Shiba-Rusinov (YSR) state and Majorana bound state (MBS). It was predicted that one can build a protected quantum state with an array of YSR states that overlapp. However, the spatial extension was found to be short, so that one could only realize such an object by a very delicate technique of depositing individual ferromagnetic atoms next to each other.
The MTA-BME Momentum Nanoelectronics Research group and the Nano- and Quantum-Electronics group of the University of Basel studied an alternative realization of YSR states, when instead of an atom a quantum dot (QD) is attached to a superconductor surface. The QD which acts as an artificial atom. Measurements of the extension of such a YSR state resulted in a surprising outcome. The size of these states are significantly larger than for real ferromagnetic atoms, their dimensions is in the range of 50-200nm! This opens a way to engineer a YSR chains.
This work was done in collaboration with the Department of Theoretical Physics at BME. Our joint publication appeared in Nature Communications.