Microwave sensing of Andreev bound states in a gate-defined superconducting quantum point contact

Autor: Vivek Chidambaram, Anders Kringhøj, Lucas Casparis, Ferdinand Kuemmeth, Tiantian Wang, Candice Thomas, Sergei Gronin, Geoffrey C. Gardner, Zhengyi Cui, Chenlu Liu, Kristof Moors, Michael J. Manfra, Karl D. Petersson, Malcolm R. Connolly
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Physical Review Research, Vol 4, Iss 2, p 023170 (2022)
Druh dokumentu: article
ISSN: 2643-1564
DOI: 10.1103/PhysRevResearch.4.023170
Popis: We use a superconducting microresonator as a cavity to sense absorption of microwaves by a superconducting quantum point contact defined by surface gates over a proximitized two-dimensional electron gas. Renormalization of the cavity frequency with phase difference across the point contact is consistent with coupling to Andreev bound states. Near π phase difference, we observe random fluctuations in absorption with gate voltage, related to quantum interference-induced modulations in the electron transmission. Close to pinch-off, we identify features consistent with the presence of a single Andreev bound state and describe the Andreev-cavity interaction using a Jaynes-Cummings model. By fitting the weak Andreev-cavity coupling, we extract ∼GHz decoherence consistent with charge noise and the transmission dispersion associated with a localized state.
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