The researchers, who come from MIPT, the Institute of Microelectronics and High Purity Materials of the Russian Academy of Sciences, and Royal Holloway, University of London
The detector consists of two superconducting aluminum loops coupled by Josephson junctions. A phase difference between the wave functions on loop segments causes the critical current in the device to change from zero to maximum and back to zero in a steplike manner with the change of the quantum numbers in each of the loops. The two loops are placed one on top of the other on a flat chip. Importantly, they are coupled by Josephson junctions.
The schematic on the left shows two superconducting loops coupled by two Josephson junctions. The currents flowing through the Josephson junctions a and b are represented by Ja sin(?a) and Jb sin(?b), respectively, where ? is the phase of the wave function — a quantum value characterizing the system as a whole. To the right is a false color image of the experimental system. Image courtesy of the authors of the research.