SKM 2021 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 5: Poster Session: Superconductivity
TT 5.23: Poster
Montag, 27. September 2021, 13:30–16:00, P
Quantum Locking and Synchronization in Josephson Photonics Devices — •Florian Höhe1, Lukas Danner1, 2, Ciprian Padurariu1, Björn Kubala1, 2, and Joachim Ankerhold1 — 1ICQ and IQST, Ulm University, Ulm, Germany — 2Institute of Quantum Technologies, German Aerospace Center (DLR), Ulm, Germany
Phase stability is an important characteristic of radiation sources. For quantum sources exploitation and characterization of many quantum properties, such as entanglement and squeezing, may be hampered by phase instability. Josephson photonics devices, where microwave radiation is created by inelastic Cooper pair tunneling across a dc-biased Josephson junction connected in-series with a microwave resonator are particularly vulnerable lacking the reference phase provided by an ac-drive. To counter this issue, sophisticated measurement schemes have been used in [1] to prove entanglement, while in [2] a weak ac-signal was put in to lock phase and frequency of the emission.
Here, we extend a recent classical theory [3] to describe locking and the synchronization of several Josephson-photonics devices to the quantum regime. Our description relies on linking the current shot-noise at a residual in-series resistor, which is crucial for phase diffusion, to the Full Counting Statistics of emitted radiation. From this full numerical description, phenomenological Adler-type equations for locking are derived to analyze quantum locking and synchronization.
[1] A. Peugeot et al., Phys. Rev. X 11, 031008 (2021).
[2] M. C. Cassidy et al., Science 355, 939 (2017).
[3] L. Danner et al., arXiv:2105.02564 (see also contribution here).