Quantum reflection: The invisible quantum barrier

TL;DR

This paper constructs and analyzes the invisible quantum barrier responsible for quantum reflection, using data inversion and studying atom and BEC reflections from a silicon surface, revealing size and interaction effects.

Contribution

It introduces a method to construct the invisible quantum barrier from experimental data and explores its properties for atoms and Bose-Einstein Condensates.

Findings

The invisible quantum barrier is double-valued in both axes.

BEC behaves similarly to single atoms with size effects influencing reflectivity.

Atom-atom interactions significantly affect BEC reflection at low velocities.

Abstract

We construct the invisible quantum barrier which represents the phenomenon of quantum reflection using the available data. We use the Abel equation to invert the data. The resulting invisible quantum barrier is double-valued in both axes. We study this invisible barrier in the case of atom and Bose-Einstein Condensate reflection from a solid silicon surface. A time-dependent, one-spatial dimension Gross-Pitaevskii equation is solved for the BEC case. We found that the BEC behaves very similarly to the single atom except for size effects, which manifest themselves in a maximum in the reflectivity at small distances from the wall. The effect of the atom-atom interaction on the BEC reflection and correspondingly on the invisible barrier is found to be appreciable at low velocities and comparable to the finite size effect. The trapping of ultracold atom or BEC between two walls is discussed.