Bragg spectroscopy of a cigar shaped Bose condensate in optical lattices

TL;DR

This paper investigates the excited states of weakly coupled quasi-two-dimensional Bose condensates in optical lattices using hydrodynamic theory, focusing on multibranch Bogoliubov-Bloch spectra and their experimental detection via Bragg spectroscopy.

Contribution

It introduces a detailed analysis of multibranch Bogoliubov-Bloch spectra considering mode coupling effects in optical lattice-confined Bose condensates.

Findings

Spectrum depends on coupling among radial modes

Mode coupling affects dynamic structure factor

Bragg spectroscopy can detect multibranch spectra

Abstract

We study properties of excited states of an array of weakly coupled quasi-two-dimensional Bose condensates by using the hydrodynamic theory. We calculate multibranch Bogoliubov-Bloch spectrums and its corresponding eigenfunctions. The spectrum of the axial excited states and its eigenfunctions strongly depends on the coupling among various discrete radial modes within a given symmetry. This mode coupling is due to the presence of radial trapping potential. The multibranch nature of the Bogoliubov-Bloch spectrum and its dependence on the mode-coupling can be realized by analyzing dynamic structure factor and momentum transferred to the system in Bragg spectroscopy experiments. We also study dynamic structure factor and momentum transferred to the condensate due to the Bragg spectroscopy experiment.