Self-trapping of excitations: Two-dimensional quasiparticle solitons in an extended Bose-Hubbard dimer array

TL;DR

This paper investigates how energy can become localized in a 2D Bose-Hubbard lattice, revealing conditions under which excitations form stable, localized solitons similar to those in photonic systems, with implications for quantum energy transport.

Contribution

It introduces the concept of self-trapped excitations and quasiparticle solitons in a 2D Bose-Hubbard dimer array, extending understanding of energy localization in quantum lattices.

Findings

Localized energy breathers and solitons form beyond a critical interaction strength.

Low energy excitations disperse quickly, while stronger ones remain localized.

One-particle entropy also exhibits localization in the system.

Abstract

Considering a two-dimensional Bose-Hubbard spinor lattice with weak nearest neighbour interactions and no particle transfer between sites, we theoretically study the transport of energy from one initially excited dimer, to the rest of the lattice. Beyond a critical interaction strength, low energy on-site excitations are quickly dispersed throughout the array, while stronger excitations are self trapped, resulting in localized energy breathers and solitons. These structures are quasiparticle analogues to the discrete 2D solitons in photonic lattices. Full many-body simulations additionally demonstrate the localization of one-particle entropy.