Impact of dephasing on non-equilibrium steady-state transport in fermionic chains with long-range hopping

TL;DR

This study explores how dephasing influences non-equilibrium steady-state transport in fermionic chains with long-range hopping, revealing distinct diffusive and super-diffusive regimes and a critical long-range parameter affecting transport behavior.

Contribution

It introduces a detailed analysis of dephasing effects on long-range hopping fermionic chains, identifying a critical parameter and crossover behaviors in transport regimes.

Findings

Transport transitions from diffusive to super-diffusive as long-range hopping increases.

A critical long-range parameter $oldsymbol{ extit{ extalpha}_c extasciitilde 1.5}$ marks the onset of super-diffusive transport.

Steady-state resistance exhibits a crossover from logarithmic to power-law dependence with system size.

Abstract

Quantum transport in a non-equilibrium setting plays a fundamental role in understanding the properties of systems ranging from quantum devices to biological systems. Dephasing -- a key aspect of out-of-equilibrium systems -- arises from the interactions with the noisy environment and can profoundly modify transport features. Here, we investigate the impact of dephasing on the non-equilibrium steady-state transport properties of non-interacting fermions on a one-dimensional lattice with long-range hopping ($\sim \frac{1}{r^\alpha}$). We show the emergence of distinct transport regimes as the long-range hopping parameter $\alpha$ is tuned. In the short-range limit ($\alpha \gg 1$), transport is diffusive, while for the long-range limit ($\alpha \sim \mathcal{O}(1)$), we observe a super-diffusive transport regime. Using the numerical simulation of the Lindblad master equation, and corroborated with the analysis of the current operator norm, we identify a critical long-range hopping parameter, $\alpha_c \approx 1.5$, below which super-diffusive transport becomes evident that quickly becomes independent of the dephasing strength. Interstingly, within the super-diffusive regime, we find a crossover from logarithmic to power-law system-size dependence in the non-equilibrium steady-state resistance when $\alpha$ varies from $\alpha \leq 1$ to $\alpha \lesssim 1.5$. Our results, thus, elucidate the intricate balance between dephasing and unitary dynamics, revealing novel steady-state transport features.