Atom-optics knife-edge: Measuring narrow momentum distributions

TL;DR

This paper introduces a novel knife-edge technique for matter-waves that precisely measures ultra-low momentum distributions, achieving near-thermal limits and revealing tunneling phenomena in cold-atom systems.

Contribution

The authors develop a matter-wave knife-edge measurement method that surpasses standard techniques in resolution and provides new insights into tunneling in one-dimensional cold-atom systems.

Findings

Measured momentum width corresponding to 0.9 nK temperature

Achieved higher resolution than standard methods

Provided evidence of tunneling in a 1D system

Abstract

By employing the equivalent of a knife-edge measurement for matter-waves, we are able to characterize ultra-low momentum widths. We measure a momentum width corresponding to an effective temperature of 0.9 $\pm$ 0.2 nK, limited only by our cooling performance. To achieve similar resolution using standard methods would require hundreds of milliseconds of expansion or Bragg beams with tens of Hz frequency stability. Furthermore, we show evidence of tunneling in a 1D system when the "knife-edge" barrier is spatially thin. This method is a useful tool for atomic interferometry and for other areas in cold-atom physics where a robust and precise technique for characterizing the momentum distribution is crucial.