The observation of diffraction phases in matter wave scattering

TL;DR

This paper experimentally observes diffraction phases in matter wave scattering using a Bose-Einstein condensate and a Talbot-Lau interferometer, revealing effects beyond traditional Raman-Nath approximations.

Contribution

It introduces an experimental method to observe diffraction phases in matter wave scattering and demonstrates their influence using a two-pulse interferometer with ultracold atoms.

Findings

Diffraction phases affect the population distribution in momentum states.

Experimental results agree with theoretical predictions including diffraction phases.

Asymmetry in population dependence reveals diffraction phase differences.

Abstract

We study the diffraction phase of different orders via the Dyson expansion series, for ultracold atomic gases scattered by a standing-wave pulse. As these diffraction phases are not observable in a single pulse scattering process, a temporal Talbot-Lau interferometer consisting of two standing-wave pulses is demonstrated experimentally with a Bose-Einstein condensate to explore this physical effect. The role of the diffraction phases is clearly shown by the second standing-wave pulse in the relative population of different momentum states. Our experiments demonstrate obvious effects beyond the Raman-Nath method, while agree well with our theory by including the diffraction phases. In particular, the observed asymmetry in the dependence of the relative population on the interval between two standing-wave pulses reflects the diffraction phase differences. The role of interatomic interaction in the Talbot-Lau interferometer is also discussed.