Spectroscopic and collisional splitting in the spectrum of a strongly driven Bose condensate

The paper studies the spectrum of a /sup 87/Rb BEC in the presence of a dressing traveling optical lattice. The dressing Rabi frequency /spl Omega//sub d/ is determined by performing Rabi oscillations in the time domain. The spectrum of the dressed condensate is measured with a perturbative Bragg probe and presented without and with the dressing lattice beams, where splitting in frequency with magnitude similar to /spl Omega//sub d/ clearly seen for the latter.