Two-dimensional particle motion in a random potential under ac bias

TL;DR

This paper investigates how a particle moves in a two-dimensional random potential under an ac field, revealing large-scale vorticity patterns at small fields and random currents at large fields, with correlation lengths scaling with system size and field amplitude.

Contribution

It uncovers the emergence of large-scale vorticity patterns and their scaling behavior in particle motion under ac bias in a 2D random potential, highlighting the role of local symmetry breaking.

Findings

Large-scale vorticity patterns emerge at small ac fields.

Correlation length scales as a power law with system size and field amplitude.

At large fields, correlations vanish and random current patterns dominate.

Abstract

We study the Brownian motion of a single particle coupled to an external ac field in a two-dimensional random potential. We find that for small fields a large-scale vorticity pattern of the steady-state net currents emerges, a consequence of local symmetry breaking. In this regime the net currents are highly correlated, the spatial correlation function follows a logarithmic dependence, and the correlation length is of the order of the system size. For large external fields correlations disappear and only random net currents patterns are observed. The numerical analysis indicates that the correlation length scales as a power law with both the size of the system and the amplitude of the ac field.