arXiv:0805.0295 · Physical Review Letters
Bragg Spectroscopy of a Strongly Interacting Rb 85 Bose-Einstein Condensate
Scott B. Papp, J. M. Pino, Robert J. Wild, Shai Ronen, Carl Wieman, D. S. Jin, Eric Cornell
Abstract
We report on measurements of the excitation spectrum of a strongly interacting Bose-Einstein condensate. A magnetic-field Feshbach resonance is used to tune atom-atom interactions in the condensate and to reach a regime where quantum depletion and beyond mean-field corrections to the condensate chemical potential are significant. We use two-photon Bragg spectroscopy to probe the condensate excitation spectrum; our results demonstrate the onset of beyond mean-field effects in a gaseous Bose-Einstein condensate.