We have observed tunneling suppression and photon-assisted tunneling of Bose-Einstein condensates in an optical lattice subjected to a constant force plus a sinusoidal shaking. For a sufficiently large constant force, the ground energy levels of the lattice are shifted out of resonance and tunneling is suppressed; when the shaking is switched on, the levels are coupled by low-frequency photons and tunneling resumes. Our results agree well with theoretical predictions and demonstrate the usefulness of optical lattices for studying solid-state phenomena.
@article{arxiv.0709.3137,
title = {Observation of photon-assisted tunneling in optical lattices},
author = {C. Sias and H. Lignier and Y. P. Singh and A. Zenesini and D. Ciampini and O. Morsch and E. Arimondo},
journal= {arXiv preprint arXiv:0709.3137},
year = {2009}
}