Dynamics Reflects Quantum Phase Transition of Rabi Model

TL;DR

This paper demonstrates that the dynamics of the Rabi model can reveal quantum phase transitions through various physical quantities, providing a non-equilibrium approach to studying phase transitions in open quantum systems.

Contribution

It shows that dynamical properties such as entanglement and quantum Fisher information can detect phase transitions without relying on the thermodynamic limit.

Findings

Physical quantities reflect phase transition during quench.

Temperature negatively impacts phase transition detection.

Model is implementable with current quantum technologies.

Abstract

As the simplest and most fundamental model describing the interaction between light and matter, a breakdown in the rotating wave approximation of the Rabi model leads to phase transition versus coupling strength when the frequency of the qubit greatly surpasses that of the oscillator. Besides the phase transition revealed in the ground state, we show that the dynamics of physical quantities can reflect such a phase transition for this model. In addition to the excitation of the bosonic field in the ground state, we show that the witness of inseparability (entanglement), mutual information, quantum Fisher information, and the variance of cavity quadrature can be employed to detect the phase transition in quench. We also reveal the negative impact of temperature on checking the phase transition by quench. This model can be implemented using trapped ions, superconducting artificial atoms coupled bosonic modes, and quantum simulations. By reflecting the phase transition in a fundamental quantum optics model without imposing the thermodynamic limit, this work offers an idea to explore phase transitions by non-equilibrium process for open quantum systems.