Josephson photonics with a two-mode superconducting circuit

Armour, Andrew D.; Kubala, B.; Ankerhold, J.

Abstract

We analyze the quantum dynamics of two electromagnetic oscillators coupled in series to a voltage-biased Josephson junction. When the applied voltage leads to a Josephson frequency across the junction which matches the sum of the two mode frequencies, tunneling Cooper pairs excite photons in both modes simultaneously leading to far-from-equilibrium states. These states display highly nonclassical features including strong antibunching, violation of Cauchy-Schwartz inequalities, and number squeezing. We obtain approximate analytic results for both the regimes of low and high photon occupancies which are supported by a full numerical treatment. The impact of asymmetries between the two modes is explored, revealing a pronounced enhancement of number squeezing when the modes are damped at different rates.

• Journal Article Type: Article
• Acceptance Date: Apr 27, 2015
• Publication Date: May 12, 2015
• Deposit Date: Jul 12, 2016
• Publicly Available Date: Jul 14, 2016
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 91
• Issue: 184508
• DOI: https://doi.org/10.1103/PhysRevB.91.184508
• Public URL: https://nottingham-repository.worktribe.com/output/752127
• Publisher URL: http://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.184508
• Additional Information: Josephson photonics with a two-mode superconducting circuit; A. D. Armour, B. Kubala, and J. Ankerhold Phys. Rev. B 91, 184508 – Published 12 May 2015