Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 55: Superconducting Electronics: SQUIDs, Qubits, Circuit QED, Quantum Coherence and Quantum Information Systems 2 (jointly with MA, HL) (joint session TT/HL)

HL 55.10: Talk

Thursday, March 19, 2020, 12:00–12:15, HSZ 03

Theory of injection locking for the Josephson laser — •Ciprian Padurariu, Lukas Danner, Björn Kubala, and Joachim Ankerhold — Institute for Complex Quantum Systems and IQST, Ulm University, 89069 Ulm, Germany

An intriguing recent experiment [1] has observed features of lasing in the microwave emission of a cavity driven by inelastic Cooper pair tunneling across a dc-voltage biased Josephson junction. A successful theory was developed explaining the emission in the lasing regime [2], however, the theory of injection locking remained unexplained.

Here, we provide the theory for injection locking in Josephson photonic devices. Specifically, we provide an analytical derivation of the phenomenological Adler equation for a large class of Josephson devices. We extract detailed guidelines for designing circuits capable of locking the phase against noises and estimate the rate of thermal and quantum phase slips that limit the locking precision.

The work aims at providing the missing ingredient, phase-stabilized Josephson oscillations, required to demonstrate the quantum entanglement of the emitted microwave light.

[1] M.C. Cassidy et al., Science 355, 939 (2017).

[2] S. Simon and N. Cooper, Phys. Rev. Lett. 121, 027004 (2018).