Excitations of Bose-Einstein condensates in optical lattices

Abstract

In this paper we examine the excitations observable in atoms confined in an optical lattice around the superfluid-insulator transition. We use increases in the number variance of atoms, subsequent to tilting the lattice as the primary diagnostic of excitations in the lattice. We show that this locally determined quantity should be a robust indicator of coherence changes in the atoms observed in recent experiments. This was found to hold for commensurate or non-commensurate fillings of the lattice, implying our results will hold for a wide range of physical cases. Our results are in good agreement with the quantitative factors of recent experiments. We do, howevers, find extra features in the excitation spectra. The variation of the spectra with the duration of the perturbation also turns out to be an interesting diagnostic of atom dynamics.

6 pages, 7 figures, using Revtex4; changes to version 2: new data and substantial revision of text

References in corpus (5)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• Collapse and Revival of the Matter Wave Field of a Bose-Einstein Condensate
• Mott insulators in strong electric fields
• Superfluidity and Interference Pattern of Ultracold Bosons in Optical Lattices
• Bogoliubov approach to superfluidity of atoms in an optical lattice

Cited by in corpus (5)

• The cold atom Hubbard toolbox
• Signatures of the superfluid to Mott-insulator transition in the excitation spectrum of ultracold atoms
• Response of Bose gases in time-dependent optical superlattices
• Collision of one-dimensional fermion clusters
• Drag dynamics in one-dimensional Fermi systems