Simultaneous bistability of qubit and resonator in circuit quantum electrodynamics

TL;DR

This paper investigates the simultaneous bistability of a superconducting qubit and a cavity mode in circuit quantum electrodynamics, revealing joint switching behavior and its theoretical and experimental signatures.

Contribution

It demonstrates the coexistence of bistability in both qubit and resonator, providing new insights into their coupled dynamics in the dispersive regime.

Findings

Both qubit and cavity exhibit simultaneous switching between metastable states.

Transmission measurements match theoretical predictions of joint bistability.

Partial coherent cancellation observed in ensemble-averaged amplitudes.

Abstract

We explore the joint activated dynamics exhibited by two quantum degrees of freedom: a cavity mode oscillator which is strongly coupled to a superconducting qubit in the strongly coherently driven dispersive regime. Dynamical simulations and complementary measurements show a range of parameters where both the cavity and the qubit exhibit sudden simultaneous switching between two metastable states. This manifests in ensemble averaged amplitudes of both the cavity and qubit exhibiting a partial coherent cancellation. Transmission measurements of driven microwave cavities coupled to transmon qubits show detailed features which agree with the theory in the regime of simultaneous switching.