Interaction Effects on Wannier Functions for Bosons in Optical Lattice

TL;DR

This paper numerically investigates how interactions in Bose gases within optical lattices affect Wannier functions, revealing that repulsive interactions broaden these functions and significantly alter tunneling and interaction parameters, explaining experimental atomic clock shifts.

Contribution

It introduces a self-consistent numerical method to calculate interaction-modified Wannier functions for bosons in optical lattices, highlighting the impact of interactions on system parameters.

Findings

Wannier functions are broadened by repulsive interactions.

Tunneling parameter J and on-site interaction U vary significantly with atom number.

The theory explains observed nonuniform atomic clock shifts.

Abstract

We have numerically calculated the single band Wannier functions for interacting Bose gases in optical lattices with a self-consistent approach. We find that the Wannier function is broadened by repulsive atom interaction. The tunneling parameter J and on-site interaction U computed with the broadened Wannier functions are found to change significantly for different atomic number per site. Our theory can explain the nonuniform atomic clock shift observed in [Campbell et al., Science 313, 649 (2006)].