Projected Entangled Pair States at Finite Temperature: Imaginary Time Evolution with Ancillas

TL;DR

This paper introduces a method for evolving PEPS with ancillas in imaginary time to efficiently represent thermal states of 2D quantum systems, demonstrated on the quantum Ising model.

Contribution

It presents a novel approach for finite temperature simulation of 2D quantum systems using PEPS with ancillas and imaginary time evolution.

Findings

Finite temperature phase diagram of 2D quantum Ising model obtained.

Method effectively captures thermal states in tensor network framework.

Benchmark results validate the approach.

Abstract

A projected entangled pair state (PEPS) with ancillas is evolved in imaginary time. This tensor network represents a thermal state of a 2D lattice quantum system. A finite temperature phase diagram of the 2D quantum Ising model in a transverse field is obtained as a benchmark application.