# Unusual Transport Properties with Non-Commutative System-Bath Coupling Operators

## TL;DR

This paper investigates how non-commutative system-bath coupling operators influence heat transport in a non-equilibrium spin-boson model, revealing enhanced heat currents and rectification effects due to quantum effects.

## Contribution

It introduces a generalized NESB model with non-commutative coupling operators, uncovering novel transport phenomena and analytical scaling relations.

## Key findings

- Heat current is greatly enhanced by rotating coupling operators.
- Thermal rectification can be optimized with asymmetry in coupling strength and operators.
- Scaling dependence of heat current changes drastically with non-commutative operators.

## Abstract

Understanding non-equilibrium heat transport is crucial for controling heat flow in nano-scale systems. We study thermal energy transfer in a generalized non-equilibrium spin-boson model (NESB) with non-commutative system-bath coupling operators and discover unusual transport properties. Compared to the conventional NESB, the heat current is greatly enhanced by rotating the coupling operators. Constructive contribution to thermal rectification can be optimized when two sources of asymmetry, system-bath coupling strength and coupling operators, coexist. At the weak coupling and the adiabatic limit, the scaling dependence of heat current on the coupling strength and the system energy gap changes drastically when the coupling operators become non-commutative. These scaling relations can further be explained analytically by the non-equilibrium polaron-transformed Redfield equation. These novel transport properties, arising from the pure quantum effect of non-commutative coupling operators, should generally appear in other non-equilibrium set-ups and driven-systems.