Optical lattices as a tool to study defect-induced superfluidity

TL;DR

This paper investigates defect-induced superfluidity in a one-dimensional ultracold Bose gas within optical lattices, analyzing superfluid response, structural properties, and excitation spectra using advanced computational methods.

Contribution

It introduces a detailed study of defect effects on superfluidity in optical lattices, employing Bose-Fermi mapping and diffusion Monte Carlo methods for different interaction regimes.

Findings

Superfluid behavior observed at slightly incommensurate fillings.

Differences in excitation spectrum and structure factor depend on defect fraction.

Provides a controlled model for studying defect-induced superfluidity.

Abstract

We study the superfluid response, the energetic and structural properties of a one-dimensional ultracold Bose gas in an optical lattice of arbitrary strength. We use the Bose-Fermi mapping in the limit of infinitely large repulsive interaction and the diffusion Monte Carlo method in the case of finite interaction. For slightly incommensurate fillings we find a superfluid behavior which is discussed in terms of vacancies and interstitials. It is shown that both the excitation spectrum and static structure factor are different for the cases of microscopic and macroscopic fractions of defects. This system provides a extremely well-controlled model for studying defect-induced superfluidity.