Collective atomic recoil motion in short-pulse matter-wave superradiance

Abstract

We show that a Bragg resonance is substantially incapacitated in short-pulse, matter-wave superradiant scatterings and both positive- and negative-order scatterings contribute equally. We further show that propagation gain is small and scattering events primarily occur at the ends of the condensate where the generated field has maximum strength. This explains the apparent ``asymmetry'' in the scattered components with respect to the condensate center. In contrast to long-pulse excitation, we prove that the generated field travels near the speed of light in vacuum and show that this has a significant impact on scattering. Finally, we show that when the excitation rate increases, the front-edge steepening and forward shifting of the peak of the generated field are due to depletion of the condensate.