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Josephson photonics with a two-mode superconducting circuit

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


B. Kubala

J. Ankerhold


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.


Armour, A. D., Kubala, B., & Ankerhold, J. (2015). Josephson photonics with a two-mode superconducting circuit. Physical Review B, 91(184508),

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
Public URL
Publisher URL
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


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