Anomalous quantum reflection of Bose-Einstein condensates from a silicon surface: the role of dynamical excitations

TL;DR

This paper studies how inter-atomic interactions affect quantum reflection of Bose-Einstein condensates from a silicon surface, revealing that high density and low velocity induce excitations like solitons and vortices, explaining low reflection probabilities.

Contribution

It demonstrates the impact of dynamical excitations on quantum reflection, linking condensate fragmentation to anomalous reflection measurements.

Findings

Fragmentation occurs at high densities and low velocities.

Dynamical excitations explain low reflection probabilities.

Reflection depends critically on density and incident velocity.

Abstract

We investigate the effect of inter-atomic interactions on the quantum-mechanical reflection of Bose-Einstein condensates from regions of rapid potential variation. The reflection process depends critically on the density and incident velocity of the condensate. For low densities and high velocities, the atom cloud has almost the same form before and after reflection. Conversely, at high densities and low velocities, the reflection process generates solitons and vortex rings that fragment the condensate. We show that this fragmentation can explain the anomalously low reflection probabilities recently measured for low-velocity condensates incident on a silicon surface.