Dark solitons near the Mott-insulator--superfluid phase transition

TL;DR

This paper investigates dark solitons in ultracold bosonic systems near the Mott-insulator--superfluid transition, revealing their properties, stability, and dependence on system parameters through theoretical analysis.

Contribution

It introduces a Gutzwiller ansatz-based analysis of dark solitons near the phase transition, highlighting their stability and character variations.

Findings

Solitons are unstable and sensitive to perturbations.

On-site solitons have longer lifetimes than off-site modes.

Superfluidity near the phase boundary influences soliton properties.

Abstract

Dark solitons of ultracold bosons in the vicinity of the Mott-insulator--superfluid phase transition are studied. Making use of the Gutzwiller ansatz we have found antisymmetric eigenstates corresponding to standing solitons, as well as propagating solitons created by phase imprinting. Near the phase boundary, superfluidity has either a particle or a hole character depending on the system parameters, which greatly affects the characteristics of both types of solitons. Within the insulating Mott regions, soliton solutions are prohibited by lack of phase coherence between the lattice sites. Linear and modulational stability show that the soliton solutions are sensitive to small perturbations and, therefore, unstable. In general, their lifetimes differ for on-site and off-site modes. For the on-site modes, there are small areas between the Mott-insulator regions where the lifetime is very large, and in particular much larger than that for the off-site modes.