Superradiant strongly correlated quantum states in cavity Hubbard model

TL;DR

This paper introduces a new quantum Monte Carlo method to study a cavity Hubbard model, revealing novel superradiant and correlated quantum phases driven by electron-photon interactions.

Contribution

It develops a sign-problem-free fermion-photon QMC algorithm and maps out the phase diagram of a 2D cavity Hubbard model, uncovering new quantum phases and transitions.

Findings

Discovery of superradiant antiferromagnetic and chiral/$ackslash$pi-flux states.

Identification of first-order superradiant phase transition.

Observation of continuous phase transition with Gross-Neveu universality class.

Abstract

In cavity quantum materials, entangling strongly correlated electrons with quantum light provides a unique opportunity to explore novel quantum phases and phase transitions absent in conventional solid-state materials. In this study, we develop a sign-problem-free fermion-photon hybrid Quantum Monte Carlo (QMC) algorithm, and use it to systematically investigate the ground-state phase diagram of a two-dimensional cavity Hubbard model. It is shown that the interplay between the electron correlation and photon condensation gives rise to intriguing quantum phases ({\it e.g.} superradiant antiferromagnetic and chiral/$\pi$-flux states), and different quantum phase transitions, such as a first-order superradiant phase transition and a continuous phase transition with Gross-Neveu universality class. The methodology can be readily generalized to more complicated cavity strongly correlated models.