Locality of temperature in spin chains

TL;DR

This paper investigates whether temperature can be meaningfully assigned to subsystems of strongly interacting quantum spin chains, exploring how correlations and criticality affect this concept and its implications for simulating thermal quantum systems.

Contribution

It introduces a framework for defining effective thermal states in strongly interacting spin chains, analyzing the impact of correlations and criticality on locality of temperature.

Findings

Temperature locality breaks down in strongly interacting systems.

Correlations and criticality influence the effective thermal state.

Implications for classical simulation of thermal quantum systems.

Abstract

In traditional thermodynamics, temperature is a local quantity: a subsystem of a large thermal system is in a thermal state at the same temperature as the original system. For strongly interacting systems, however, the locality of temperature breaks down. We study the possibility of associating an effective thermal state to subsystems of infinite chains of interacting spin particles of arbitrary finite dimension. We study the effect of correlations and criticality in the definition of this effective thermal state and discuss the possible implications for the classical simulation of thermal quantum systems.