Negative differential conductivity in Heisenberg XXZ chain far from equilibrium

TL;DR

This paper reports the observation and analysis of negative differential conductivity in the far-from-equilibrium quantum spin transport of finite Heisenberg XXZ chains, combining analytical and numerical methods.

Contribution

It provides the first analytical and numerical investigation of negative differential conductivity in the insulating regime of Heisenberg XXZ chains far from equilibrium.

Findings

Negative differential conductivity observed in finite Heisenberg XXZ chains.

Analytical reproduction of the phenomenon for N=4 spins.

Numerical analysis extending up to N=16 spins using efficient simulation.

Abstract

Negative differential conductivity is reported for the far from equilibrium quantum spin transport in the insulating regime (J_x < J_z) of finite Heisenberg XXZ spin 1/2 chains. The phenomenon is reproduced analytically for small chains of N=4 spins and further analyzed numerically, for up to N=16, using an efficient pure-state simulation with stochastic spin baths.