Bragg spectroscopy of a superfluid Bose–Hubbard gas
X Du, Shoupu Wan, Emek Yesilada +4 more
Bragg spectroscopy is used to measure the excitations of a trapped, quantum-degenerate gas of 87 Rb atoms in a three-dimensional (3D) optical lattice. The measurements are carried out over a range of optical lattice depths in the superfluid phase of the Bose–Hubbard model. For a fixed wavevector, the resonant frequency of the excitation is found to decrease with increasing lattice depth. A numerical calculation of the resonant frequencies based on Bogoliubov theory shows a less steep rate of decrease than the measurements.
arXiv:0704.2623•New Journal of Physics•Aug 10, 2010•33 citations