Symmetric Minimally Entangled Typical Thermal States

TL;DR

The paper introduces SYMETTS, a method extending METTS to incorporate symmetries for calculating finite-temperature response functions in 1D quantum systems, enabling high-resolution low-temperature spectra analysis.

Contribution

It develops SYMETTS, a novel approach that exploits symmetries in METTS to improve finite-temperature response calculations in 1D quantum systems.

Findings

Successfully applied to a model of azurite, revealing temperature effects on magnetization and spectra.

Provides microscopic understanding of the magnetization plateau at low temperatures.

Enhances resolution of low-temperature spectra in 1D quantum systems.

Abstract

We extend White's minimally entangled typically thermal states approach (METTS) to allow Abelian and non-Ablian symmetries to be exploited when computing finite-temperature response functions in one-dimensional (1D) quantum systems. Our approach, called SYMETTS, starts from a METTS sample of states that are not symmetry eigenstates, and generates from each a symmetry eigenstate. These symmetry states are then used to calculate dynamic response functions. SYMETTS is ideally suited to determine the low-temperature spectra of 1D quantum systems with high resolution. We employ this method to study a generalized diamond chain model for the natural mineral azurite Cu${}_3$(CO${}_3)_2$(OH$)_2$, which features a plateau at $\frac{1}{3}$ in the magnetization curve at low temperatures. Our calculations provide new insight into the effects of temperature on magnetization and excitation spectra in the plateau phase, which can be fully understood in terms of the microscopic model.