title: Analysis of Kapitza-Dirac diffraction patterns beyond the Raman-Nath regime.
abstract: We study Kapitza-Dirac diffraction of a Bose-Einstein condensate from a standing light wave for a square pulse with variable pulse length but constant pulse area. We find that for sufficiently weak pulses, the usual analytical short-pulse prediction for the Raman-Nath regime continues to hold for longer times, albeit with a reduction of the apparent modulation depth of the standing wave. We quantitatively relate this effect to the Fourier width of the pulse, and draw analogies to the Rabi dynamics of a coupled two-state system. Our findings, combined with numerical modeling for stronger pulses, are of practical interest for the calibration of optical lattices in ultracold atomic systems.
authors.affiliation: Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA. bgadway@ic.sunysb.edu
authors.forename: Bryce
authors.initials: B
authors.lastname: Gadway
authors.forename: Daniel
authors.initials: D
authors.lastname: Pertot
authors.forename: René
authors.initials: R
authors.lastname: Reimann
authors.forename: Martin G
authors.initials: MG
authors.lastname: Cohen
authors.forename: Dominik
authors.initials: D
authors.lastname: Schneble