Twisted-Boundary-Condition Formalism for Thermal Transport and an Application to the One-Dimensional XY Spin Chain

TL;DR

This paper introduces a new boundary condition formalism for analyzing thermal transport in quantum systems and applies it to estimate thermal stiffness in a 1D XY spin chain.

Contribution

It develops a twisted-boundary-condition formalism for thermal transport and demonstrates its application to a specific quantum spin model.

Findings

Quantifies thermal analogues of Drude weight and Meissner stiffness.

Estimates the thermal Meissner stiffness in the XY spin chain.

Provides a new framework for studying thermal transport in quantum many-body systems.

Abstract

We introduce and formulate the boundary condition twisted by the energy (time translation) in one-dimensional quantum many-body systems. The stiffness against this boundary condition quantifies thermal analogues of the Drude weight and the Meissner stiffness. We apply this formalism to the one-dimensional quantum XY spin chain and estimate the thermal Meissner stiffness.