Description:

Title: Little's phase slips and Abrikosov vortices in quantum superconducting devices

Speaker: Professor Alexey Bezryadin, University of Illinois at Urbana-Champaign

Abstract: A microwave setup used to detect individual macroscopic quantum tunneling events in thin superconducting wires and loops will be presented. It allows us to observe low-temperature signatures of the Little-Parks effect. We observe single phase slips and pairs of phase slips in the quantum regime. Single phase slips represent a change of the loop vorticity by one. The paired phase slips represent changes of the vorticity quantum number by two, i.e. they preserve the parity of the quantum number. Possible origins of such paired phase slips and their significance for topologically protected quantum computation will be discussed. I will also discuss a modification of our device achieved by replacing two nanowires by two junctions. The resulting transmon-type qubit is controlled by Meissner currents. It is used to quantify the process of non-radiative relaxation.

Keywords: Physics, Astronomy, CMP