Intrinsic Dissipation in Superconducting Junctions Probed by Qubit Spectroscopy

Abstract

The study of frequency‐dependent intrinsic dissipation in a highly transparent Josephson junction by means of quantum‐bit (qubit) spectroscopy is proposed. The spectral density of the effective dissipative bath may contain significant contributions from Andreev bound states coupled to fluctuations of the Josephson phase. Varying either the bias current applied to the junction or magnetic flux through a superconducting ring in the radiofrequency superconducting quantum interference device (rf‐SQUID) setup, one can tune the level splitting value close to the bottom of the Josephson potential well. Monitoring the qubit energy relaxation time one can probe the spectral density of the effective dissipative bath and unambiguously identify the contribution emerging from Andreev levels.

Topology and Geometry Controlled Properties of Nanoarchitectures

“…Their work particularly emphasizes the role of the system's topology that may have a dramatic impact on the behavior of the thermopower. Dmitry S. Golubev et al [3] analyzed the parameters of phase, or flux qubits, based on a highly transparent Josephson junction. The spectral density of the effective dissipative bath was demonstrated to contain possible significant contributions from Andreev bound states coupled to fluctuations of the Josephson phase.…”