SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 54: Quantum Coherence and Quantum Information Systems II
TT 54.5: Vortrag
Donnerstag, 30. März 2023, 16:00–16:15, HSZ 304
Microwave radiation emitted by a phase qubit — •Surangana Sengupta1, Ciprian Padurariu1, Bjoern Kubala1,2, and Joachim Ankerhold1 — 1ICQ and IQST, Ulm University, Germany — 2German Aerospace Center (DLR), Ulm, Germany
Josephson photonics devices consist of a DC-biased Josephson junction in series with a superconducting microwave cavity and are promising sources of bright quantum states of microwave radiation. Such devices realize the regime of strong-coupling circuit quantum electrodynamics, when the effective fine structure constant of the circuit approaches unity. In this case, multi-photon downconversion processes, where one tunnelling Cooper pair emits k photons in the cavity (k≤ 6), have been observed [1].
Here, we propose a new regime for Josephson photonics devices, where both the inductive as well as the capacitive behavior of the Josephson junction is taken into account [2]. Thereby, the Josephson phase is treated as an electronic degree of freedom, characterized by the plasma frequency of the junction, that is independent of the photonic degree of freedom, described by the phase of the cavity. We present a preliminary study of the coupled photonic and electronic dynamics, discuss the nature of the coupling and present a detailed comparison to conventional Josephson photonics dynamics. As an example, we focus on the case when the Josephson junction is operated as a phase qubit and study the resulting statistics of radiation emitted in the cavity.
[1] G. C. Ménard et al., Phys. Rev. X 12, 021006 (2022)
[2] C. Yan et al., Nat. Electron. 4, 885-892 (2021)