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TT: Fachverband Tiefe Temperaturen

TT 79: Superconductivity: Superconducting Electronics - Circuit QED

TT 79.6: Talk

Thursday, March 15, 2018, 10:45–11:00, H 2053

Non-degenerate Parametric Resonance in Superconducting Cavity — Waltraut Wustmann¹ and •Vitaly Shumeiko² — ¹Laboratory for Physical Sciences, College Park, Maryland 20740, USA — ²Chalmers University of Technology, S-41296 Göteborg, Sweden

We present a theory for non-degenerate parametric resonance in a tunable superconducting cavity. We consider both regimes of down- and up- conversion. In the first, parametric amplification regime we focus a nonlinear gain close to the parametric instability threshold. Here the quantum noise undergoes four-mode squeezing and less efficient amplification than the coherent signal. This results in enhancement of output signal-to-noise ratio compared to the input.

Above the instability threshold, the system enters the parametric oscillation regime with two correlated beams having uncertain phase difference. Continuous degeneracy of the oscillator state is in drastic contrast to the two-fold degeneracy of the degenerate parametric oscillator. This property leads to a broadening of the output radiation spectrum, and divergence of the linear response at the oscillation frequencies. Application of a small on-resonance input lifts the degeneracy and locks the radiation phases.

For the frequency conversion regime we evaluate a nonlinear conversion coefficient, and identify an optimum pump strength at which a full inter-mode conversion can be achieved.
W. Wustmann, V. Shumeiko, Phys. Rev. Appl. 8 (2017) 024018.