# Polaron-transformed dissipative Lipkin-Meshkov-Glick Model

## TL;DR

This paper studies how a quantum phase transition in the Lipkin-Meshkov-Glick model persists or changes when the system interacts with a thermal bath, using a polaron transform to analyze the crossover from normal to symmetry-broken phases.

## Contribution

It introduces a polaron transform approach to analyze the dissipative Lipkin-Meshkov-Glick model, revealing that the critical point remains unchanged under certain system-reservoir interactions.

## Key findings

- Critical point position remains unchanged in the open system.
- Signatures of phase transition appear in stationary observables.
- The polaron transform enables analysis of the full crossover regime.

## Abstract

We investigate the Lipkin-Meshkov-Glick model coupled to a thermal bath. Since the isolated model itself exhibits a quantum phase transition, we explore the critical signatures of the open system. Starting from a system-reservoir interaction written in positive definite form, we find that the position of the critical point remains unchanged, in contrast to the popular mean-field prediction. Technically, we employ the polaron transform to be able to study the full crossover regime from the normal to the symmetry-broken phase, which allows us to investigate the fate of quantum-critical points subject to dissipative environments. The signatures of the phase transition are reflected in observables like stationary mode occupation or waiting-time distributions.