Observation of Transient Momentum-Space Interference During Scattering of a Condensate From an Optical Barrier

TL;DR

This paper experimentally investigates the real-time dynamics of a condensate scattering from a potential barrier, revealing transient momentum-space interference effects that occur during the ongoing collision, which are not captured by traditional asymptotic scattering theory.

Contribution

It provides the first experimental observation of transient momentum-space interference effects during non-asymptotic scattering of a condensate from an optical barrier.

Findings

Transient deceleration of wavepacket components during collision

Interference between incident and transmitted wavepacket portions

Potential for reconstructing phase profiles from interference patterns

Abstract

Scattering theory traditionally deals with the asymptotic behaviour of a system far removed from the actual scattering event. Here we present an experimental study of the one-dimensional scattering of a non-interacting condensate of 87-Rb atoms from a potential barrier in the non-asymptotic regime, for which the collision dynamics are still ongoing. We show that for near-transparent barriers, there are two distinct transient scattering effects that arise and dramatically change the momentum distribution during the collision: a deceleration of wavepacket components in mid-collision, and an interference between incident and transmitted portions of the wavepacket. Both effects lead to the re-distribution of momenta giving rise to a rich interference pattern that can be used to perform reconstruction of the single-particle phase profile.