Circuit QED and sudden phase switching in a superconducting qubit array

TL;DR

This paper investigates nonlinear phenomena in a superconducting qubit array coupled to a resonator, revealing sudden phase switchings and bistability between ferromagnetic and paramagnetic states, with implications for quantum many-body systems.

Contribution

It introduces a semiclassical analysis of phase switching and bistability in circuit QED systems with superconducting qubits, supported by a realistic circuit implementation.

Findings

Observation of sudden phase switchings in the qubit array

Identification of bistable regimes between ferromagnetic and paramagnetic phases

Proposal of a realistic superconducting circuit for experimental realization

Abstract

Superconducting qubits connected in an array can form quantum many-body systems such as the quantum Ising model. By coupling the qubits to a superconducting resonator, the combined system forms a circuit QED system. Here, we study the nonlinear behavior in the many-body state of the qubit array using a semiclassical approach. We show that sudden switchings as well as a bistable regime between the ferromagnetic phase and the paramagnetic phase can be observed in the qubit array. A superconducting circuit to implement this system is presented with realistic parameters .