Quantum and Classical Dynamics of BEC in a Large-Period Optical Lattice
Ian B. Spielman, Johnny H. Huckans, Bruno Laburthe-Tolra, James V. Porto, William D. Phillips
We experimentally investigate diffraction of a ^u87 Rb Bose-Einstein Condensate from a 1D optical lattice. We use a range of lattice periods and timescales, including those beyond the Raman-Nath limit. We compare the results to quantum mechanical and classical simulations, with quantitative and qualitative agreement, respectively. The classical simulation predicts that the envelope of the time-evolving diffraction pattern is shaped by caustics: singularities in the phase space density of classical trajectories. This behavior becomes increasingly clear as the lattice period grows.
Physical Review A (Atomic, Molecular and Optical Physics)