How to build Hamiltonians that transport noncommuting charges in quantum thermodynamics

TL;DR

This paper introduces a systematic method for constructing Hamiltonians that conserve noncommuting charges and facilitate their transport, bridging theoretical quantum thermodynamics with potential experimental implementations.

Contribution

It provides a novel prescription for designing Hamiltonians that conserve noncommuting quantities and enable their transport across quantum systems.

Findings

Hamiltonians can be constructed to conserve noncommuting charges globally.

The method applies to both integrable and nonintegrable systems.

Potential physical realizations include superconducting qudits, ultracold atoms, and trapped ions.

Abstract

Noncommuting conserved quantities have recently launched a subfield of quantum thermodynamics. In conventional thermodynamics, a system of interest and an environment exchange quantities -- energy, particles, electric charge, etc. -- that are globally conserved and are represented by Hermitian operators. These operators were implicitly assumed to commute with each other, until a few years ago. Freeing the operators to fail to commute has enabled many theoretical discoveries -- about reference frames, entropy production, resource-theory models, etc. Little work has bridged these results from abstract theory to experimental reality. This paper provides a methodology for building this bridge systematically: We present a prescription for constructing Hamiltonians that conserve noncommuting quantities globally while transporting the quantities locally. The Hamiltonians can couple arbitrarily many subsystems together and can be integrable or nonintegrable. Our Hamiltonians may be realized physically with superconducting qudits, with ultracold atoms, and with trapped ions.