Interaction-induced delocalization of quasiparticle pairs in the Anderson insulator

TL;DR

This paper explores whether short-range interactions can delocalize quasiparticle pairs in an Anderson insulator, finding that delocalization occurs at energies near the bandwidth, similar to particle pairs.

Contribution

It demonstrates, through numerical evaluation, that quasiparticle pairs in an Anderson insulator can become delocalized at certain excitation energies, extending the understanding of interaction effects in disordered systems.

Findings

Quasiparticle pairs are localized at the Fermi energy.

Delocalization occurs when excitation energy approaches the bandwidth.

Interaction effects can induce delocalization in quasiparticle pairs.

Abstract

It has recently been established that a short-range interaction can strongly delocalize a pair of particles moving in a disordered potential. We investigate whether an analogous effect exists also for pairs of quasiparticles in the Anderson insulator by employing an approximate numerical evaluation of the two-particle Green function of the many-body system. At the Fermi energy, the quasiparticle pair is localized on the scale of the single-particle localization length. The delocalization effect is recovered when the excitation energy of the pair is comparable to the bandwidth.