Non-equilibrium processes: driven lattice gases, interface dynamics, and quenched disorder effects on density profiles and currents

TL;DR

This paper investigates the scaling properties and density profiles of the one-dimensional TASEP, connecting interface dynamics with KPZ universality, and explores effects of quenched disorder through analytical and numerical methods.

Contribution

It provides new scaling exponents for TASEP under various boundary conditions and introduces analytical expressions for density profiles with quenched disorder.

Findings

Scaling exponents match Bethe ansatz in some phases

Discrepancy in low-density phase z exponent explained by mean-field relaxation time

Analytical density profiles and bounds on currents derived for disordered TASEP

Abstract

Properties of the one-dimensional totally asymmetric simple exclusion process (TASEP), and their connection with the dynamical scaling of moving interfaces described by a Kardar-Parisi-Zhang (KPZ) equation are investigated. With periodic boundary conditions, scaling of interface widths (the latter defined via a discrete occupation-number-to-height mapping), gives the exponents $\alpha=0.500(5)$, $z=1.52(3)$, $\beta=0.33(1)$. With open boundaries, results are as follows: (i) in the maximal-current phase, the exponents are the same as for the periodic case, and in agreement with recent Bethe ansatz results; (ii) in the low-density phase, curve collapse can be found to a rather good extent, with $\alpha=0.497(3)$, $z=1.20(5)$, $\beta=0.41(2)$, which is apparently at variance with the Bethe ansatz prediction $z=0$; (iii) on the coexistence line between low- and high- density phases, $\alpha=0.99(1)$, $z=2.10(5)$, $\beta=0.47(2)$, in relatively good agreement with the Bethe ansatz prediction $z=2$. From a mean-field continuum formulation, a characteristic relaxation time, related to kinematic-wave propagation and having an effective exponent $z^\prime=1$, is shown to be the limiting slow process for the low density phase, which accounts for the above-mentioned discrepancy with Bethe ansatz results. For TASEP with quenched bond disorder, interface width scaling gives $\alpha=1.05(5)$, $z=1.7(1)$, $\beta=0.62(7)$. From a direct analytic approach to steady-state properties of TASEP with quenched disorder, closed-form expressions for the piecewise shape of averaged density profiles are given, as well as rather restrictive bounds on currents. All these are substantiated in numerical simulations.