Eur. Phys. J. B (2016) 89: 8
https://doi.org/10.1140/epjb/e2015-60787-7

Regular Article

Delocalization of two interacting particles in the 2D Harper model

Laboratoire de Physique Théorique du CNRS, IRSAMC, Université de Toulouse, UPS, 31062 Toulouse, France

^a e-mail: dima@irsamc.ups-tlse.fr

Received: 5 October 2015
Received in final form: 19 November 2015
Published online: 13 January 2016

Abstract

We study the problem of two interacting particles in a two-dimensional quasiperiodic potential of the Harper model. We consider an amplitude of the quasiperiodic potential such that in absence of interactions all eigenstates are exponentially localized while the two interacting particles are delocalized showing anomalous subdiffusive spreading over the lattice with the spreading exponent b ≈ 0.5 instead of a usual diffusion with b = 1. This spreading is stronger than in the case of a correlated disorder potential with a one particle localization length as for the quasiperiodic potential. At the same time we do not find signatures of ballistic pairs existing for two interacting particles in the localized phase of the one-dimensional Harper model.