SKM 2021 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 5: Poster Session: Superconductivity

TT 5.24: Poster

Monday, September 27, 2021, 13:30–16:00, P

Injection locking and synchronization in Josephson photonics devices — •Lukas Danner^{1, 2}, Ciprian Padurariu², Joachim Ankerhold², and Björn Kubala^{1, 2} — ¹Institute of Quantum Technologies, German Aerospace Center (DLR), Ulm, Germany — ²ICQ and IQST, Ulm University, Ulm, Germany

Injection locking can stabilize a source of radiation, leading to an efficient suppression of noise-induced spectral broadening and therefore, to a narrow spectrum. The technique is well established in laser physics, where a phenomenological description due to Adler is usually sufficient. Recently, locking experiments were performed in 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. An in-depth theory of locking for such devices however is lacking.

Here, we study injection locking in a typical Josephson photonics device where the environment consists of a single mode cavity, operated in the classical regime [1]. We show that an in-series resistance, however small, is an important ingredient in describing self-sustained Josephson oscillations and enables the locking region. We derive a dynamical equation describing locking, similar to an Adler equation, from the specific circuit equations. Phase slips due to noise are also studied. The synchronization of two Josephson photonics devices can be described by the Kuramoto model. For an extension of this classical analysis to the quantum regime, see the contribution by F. Höhe.

[1] L. Danner et al., arXiv:2105.02564 (submitted to PRB).