Transport and spectral properties of the XX$+$XXZ diode and stability to dephasing

TL;DR

This paper investigates the transport and spectral characteristics of an XX$+$XXZ spin chain diode, revealing different regimes under bias and the effects of dephasing, including reduced rectification and quantum Zeno phenomena.

Contribution

It provides numerical analysis of transport regimes and spectral properties of a spin chain diode, highlighting the impact of anisotropy and dephasing on rectification and spectral convergence.

Findings

Reverse bias exhibits ballistic, diffusive, and insulating regimes depending on anisotropy.

Forward bias shows ballistic and diffusive regimes, with spectral properties differing from reverse bias.

Dephasing reduces rectification, increases relaxation gap initially, then decreases it due to Quantum Zeno effects.

Abstract

We study the transport and spectral property of a segmented diode formed by an XX $+$ XXZ spin chain. This system has been shown to become an ideal rectifier for spin current for large enough anisotropy. Here we show numerical evidence that the system in reverse bias has three different transport regimes depending on the value of the anisotropy: ballistic, diffusive and insulating. In forward bias we encounter two regimes, ballistic and diffusive. The system in forward and reverse bias shows significantly different spectral properties, with distribution of rapidities converging towards different functions. In the presence of dephasing the system becomes diffusive, rectification is significantly reduced, the relaxation gap increases and the spectral properties in forward and reverse bias tend to converge. For large dephasing the relaxation gap decreases again as a result of Quantum Zeno physics.