Microwave Susceptibility Observation of Interacting Many-Body Andreev States

• Published in: Physical review letters Vol. 129; no. 22; p. 227701
• Main Authors: Fatemi, V, Kurilovich, P D, Hays, M, Bouman, D, Connolly, T, Diamond, S, Frattini, N E, Kurilovich, V D, Krogstrup, P, Nygård, J, Geresdi, A, Glazman, L I, Devoret, M H
• Format: Journal Article
• Language: English
• Published: United States 23-11-2022
• Subjects: Static Electricity
• ISSN: 0031-9007; 1079-7114; 1079-7114
• DOI: 10.1103/PhysRevLett.129.227701

Electrostatic charging affects the many-body spectrum of Andreev states, yet its influence on their microwave properties has not been elucidated. We developed a circuit quantum electrodynamics probe that, in addition to transition spectroscopy, measures the microwave susceptibility of different states of a semiconductor nanowire weak link with a single dominant (spin-degenerate) Andreev level. We found that the microwave susceptibility does not exhibit a particle-hole symmetry, which we qualitatively explain as an influence of Coulomb interaction. Moreover, our state-selective measurement reveals a large, π-phase shifted contribution to the response common to all many-body states which can be interpreted as arising from a phase-dependent continuum in the superconducting density of states.