Dynamics and evaporation of defects in Mott-insulating clusters of boson pairs

TL;DR

This paper investigates the dynamics and evaporation of hole defects in Mott-insulating clusters of boson pairs within the Bose-Hubbard model, revealing mechanisms of defect tunneling, quasi-thermalization, and cluster purification through analytical and numerical methods.

Contribution

It introduces an effective strong-interaction model for long-time dynamics and explores defect behavior in multi-species bosonic systems, extending understanding of Mott insulator stability.

Findings

Hole defects can tunnel out only within certain quasi-momentum ranges.

Quasi-thermalization of defects occurs with catalyzing particles.

The effective model enables longer-time simulations of defect dynamics.

Abstract

Repulsively bound pairs of particles in a lattice governed by the Bose-Hubbard model can form stable incompressible clusters of dimers corresponding to finite-size n=2 Mott insulators. Here we study the dynamics of hole defects in such clusters corresponding to unpaired particles which can resonantly tunnel out of the cluster into the lattice vacuum. Due to bosonic statistics, the unpaired particles have different effective mass inside and outside the cluster, and "evaporation" of hole defects from the cluster boundaries is possible only when their quasi-momenta are within a certain transmission range. We show that quasi-thermalization of hole defects occurs in the presence of catalyzing particle defects which thereby purify the Mott insulating clusters. We study the dynamics of one-dimensional system using analytical techniques and numerically exact t-DMRG simulations. We derive an effective strong-interaction model that enables simulations of the system dynamics for much longer times. We also discuss a more general case of two bosonic species which reduces to the fermionic Hubbard model in the strong interaction limit.