No enhancement of the localization length for two interacting particles in a random potential

TL;DR

This paper investigates whether interactions between two particles in a disordered system genuinely enhance their localization length, concluding that previous observed enhancements are due to finite-size effects.

Contribution

The study clarifies that the previously reported increase in two-particle localization length is an artifact of finite system sizes, not an actual physical effect.

Findings

No real enhancement of localization length due to interactions

Finite-size effects explain previous observations

Interaction types studied include onsite and long-range

Abstract

We study two interacting particles in a random potential chain by means of the transfer matrix method. The dependence of the two-particle localization length $\lambda_2$ on disorder and interaction strength is investigated. Our results demonstrate that the recently proposed enhancement of $\lambda_2$ as compared to the results for single particles is entirely due to the finite size of the systems considered. This is shown for a Hubbard-like onsite interaction and also a long-range interaction.