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TT: Fachverband Tiefe Temperaturen

TT 27: Transport: Quantum Coherence and Quantum Information Systems - Theory 1
(Joint session of HL, MA and TT organized by TT)

TT 27.7: Talk

Tuesday, March 8, 2016, 11:00–11:15, H22

Nonlinearities in Josephson-Photonics — •Björn Kubala and Joachim Ankerhold — Institute for Complex Quantum Systems and IQST, Ulm University, Ulm, Germany

Embedding a voltage-biased Josephson junction within a high-Q superconducting microwave cavity provides a new way to explore the interplay of the tunneling transfer of charges and the emission and absorption of light. While for weak driving the system can be reduced to simple cases, such as a (damped) harmonic or parametric oscillator, the inherent nonlinearity of the Josephson junction allows to access regimes of strongly non-linear quantum dynamics.

Classically, dynamical phenomena such as thresholds for higher-order resonances, other bifurcations, and up- and down-conversion have been found [1]. Here, we will investigate how and to which extent these features appear in the deep quantum regime, where charge quantization effects are crucial. Theory allows to employ phase-space quantities, such as the Wigner-density of the cavity mode(s) [2], but also observables amenable to more immediate experimental access, such as correlations in light emission and charge transport, to probe these novel non-equilibrium transitions.
S. Meister, M. Mecklenburg, V. Gramich, J. T. Stockburger,

J. Ankerhold, B. Kubala, PRB 92, 174532 (2015).

[2] A. D. Armour, B. Kubala, J. Ankerhold, PRB 91, 184508 (2015).