Dynamical bistability in the driven circuit QED

TL;DR

This paper investigates the nonlinear response of a driven circuit QED system, revealing antiresonant multiphoton transitions, bistability, and dynamical tunneling phenomena through theoretical analysis and modeling.

Contribution

It introduces a semiclassical quasienergy surface model for circuit QED, explaining observed phenomena and uncovering dynamical tunneling effects.

Findings

Identification of antiresonant multiphoton transitions.

Derivation of a bistable semiclassical quasienergy surface.

Observation of signatures of dynamical tunneling.

Abstract

We show that the nonlinear response of a driven circuit quantum electrodynamics setup displays antiresonant multiphoton transitions, as recently observed in a transmon qubit device. By including photon leaking, we explain the lineshape by a perturbative and a semiclassical analysis. We derive a bistable semiclassical quasienergy surface whose lowest quasienergy eigenstate is squeezed, allowing for a squeezing-dependent local effective temperature. We study the escape dynamics out of the metastable state and find signatures of dynamical tunneling, similar as for the quantum Duffing oscillator.