Quantum reflection of atoms from a solid surface at normal incidence

TL;DR

This study demonstrates quantum reflection of ultracold Bose-Einstein condensates from a solid surface at normal incidence, with reflection probabilities up to 20%, confirming theoretical predictions and showing extended atom lifetime due to reflection.

Contribution

First experimental observation of quantum reflection of ultracold atoms from a solid surface at normal incidence with quantitative agreement to theory.

Findings

Reflection probabilities up to 20% at low velocities

Velocity dependence matches Casimir-Polder potential predictions

Extended atom lifetime due to quantum reflection

Abstract

We observed quantum reflection of ultracold atoms from the attractive potential of a solid surface. Extremely dilute Bose-Einstein condensates of ^{23}Na, with peak density 10^{11}-10^{12}atoms/cm^3, confined in a weak gravito-magnetic trap were normally incident on a silicon surface. Reflection probabilities of up to 20 % were observed for incident velocities of 1-8 mm/s. The velocity dependence agrees qualitatively with the prediction for quantum reflection from the attractive Casimir-Polder potential. Atoms confined in a harmonic trap divided in half by a solid surface exhibited extended lifetime due to quantum reflection from the surface, implying a reflection probability above 50 %.