Charged fluctuators as a limit to the microscopic and macroscopic coherence of superconductors

26 Jul 2019, 12:15
15m
Auditorium G. Testori (Milano)

Auditorium G. Testori

Milano

Piazza Città di Lombardia, 1, 20124 Milano MI
Invited Presentation Low Temperature Detector fabrication techniques and materials Orals LM 003

Speaker

Dr Hélène le Sueur (CNRS)

Description

By analyzing experiments on thin-film resonators of NbSi and TiN, we elucidate a decoherence mechanism at work in disordered superconductors. This decoherence is caused by charged Two Level Systems (TLS) which couple to the conduction electrons in the BCS ground state, inducing fluctuations of the kinetic inductance. Standard theories of mesoscopic disordered conductors are used to describe this effect, linking electronic (microscopic) decoherence and electromagnetic (macroscopic) decoherence in superconductors. Given the omnipresence of charged TLS in solid-state systems, this decoherence mechanism affects all experiments involving disordered superconductors, and more strongly so devices with smaller cross-sections. In particular, we show it easily explains the poor coherence observed in quantum phase slip experiments and may contribute to lowering the quality factors in disordered superconductor resonators.

(arXiv:1810.12801)

Less than 5 years of experience since completion of Ph.D N
Student (Ph.D., M.Sc. or B.Sc.) N

Primary authors

Dr Hélène le Sueur (CNRS) Dr Artis Svilans (CEA) Mr Nicolas Bourlet (CEA) Dr Anil Murani (CEA) Mr Laurent Berge (CSNSM, CNRS) Dr Louis Dumoulin (CSNSM, CNRS) Dr Philippe Joyez (CEA, Saclay)

Presentation Materials