Tunable and nonlinearity-enhanced dispersive-plus-dissipative coupling in photon-pressure circuits

TL;DR

This paper demonstrates a tunable photon-pressure system with enhanced nonlinearity, enabling control over dispersive and dissipative interactions, leading to novel interference effects and modified backaction in superconducting circuits.

Contribution

It introduces a superconducting photon-pressure platform with tunable dispersive and dissipative coupling, enhanced by nonlinearities, and explores interference and backaction effects in this regime.

Findings

Observation of Fano-like response in photon-pressure transparency

Enhanced multi-photon coupling rates scaling with pump photon number

Modified dynamical backaction including parametric instability

Abstract

Photon-pressure circuits are the circuit implementation of the cavity optomechanical Hamiltonian and discussed for qubit readout, low-frequency quantum photonics and dark matter axion detection. Due to the enormous design flexibility of superconducting circuits, photon-pressure systems provide fascinating possibilities to explore unusual parameter regimes of the optomechanical Hamiltonian. Here, we report the realization of a photon-pressure platform, in which a GHz circuit interacts with a MHz circuit via a magnetic-flux-tunable combination of dispersive and dissipative photon-pressure. In addition, both coupling rates are considerably enhanced by nonlinearities of the GHz-mode, which leads to the multi-photon coupling rates scaling stronger with the pump photon number $n_\mathrm{c}$ than the usual $\sqrt{n_\mathrm{c}}$ dependence. We demonstrate that interference of the two interaction paths leads to a Fano-like response in photon-pressure induced transparency, and that the dynamical backaction is considerably modified compared to the dispersive case, including a parametric instability caused by a red-detuned pump tone.