Excitations of Bose-Einstein condensates in a one-dimensional periodic potential

TL;DR

This paper experimentally investigates how a three-dimensional Bose-Einstein condensate responds to a one-dimensional optical lattice by probing its excitation spectrum and observing band structure resonances through Bragg spectroscopy.

Contribution

It provides new experimental insights into the excitation spectrum and band structure of BECs in 1D optical lattices using Bragg spectroscopy.

Findings

Identification of resonances corresponding to different energy bands

Dependence of resonance properties on lattice amplitude

Observation of excitation transfer dynamics in BECs

Abstract

We report on the experimental investigation of the response of a three-dimensional Bose-Einstein condensate (BEC) in the presence of a one-dimensional (1D) optical lattice. By means of Bragg spectroscopy we probe the band structure of the excitation spectrum in the presence of the periodic potential. We selectively induce elementary excitations of the BEC choosing the transferred momentum and we observe different resonances in the energy transfer, corresponding to the transitions to different bands. The frequency, the width and the strength of these resonances are investigated as a function of the amplitude of the 1D optical lattice.