Minimally entangled typical quantum states at finite temperature

TL;DR

This paper introduces minimally entangled typical thermal states (METTS), a new class of states that efficiently represent finite-temperature quantum systems with classical-like properties, improving computational speed significantly.

Contribution

The paper proposes METTS, a novel state class for finite-temperature quantum systems, and an associated DMRG-based algorithm that greatly accelerates thermal calculations.

Findings

METTS reveal short-range order in quantum systems.

The algorithm is 10^3 to 10^10 times faster than previous methods.

METTS provide an intuitive understanding of thermal properties.

Abstract

We introduce a class of states, called minimally entangled typical thermal states (METTS), designed to resemble a typical state of a quantum system at finite temperature with a bias towards classical (minimally entangled) properties. These states reveal in an intuitive way properties such as short-range order which may be hidden in correlation functions. An algorithm is presented which, when used with the density matrix renormalization group (DMRG), is faster by a factor of $10^3 - 10^{10}$ than previous heat-bath approaches for thermally averaged quantities.