Observation of the Spatial Distribution of Gravitationally Bound Quantum States of Ultracold Neutrons and Its Derivation Using the Wigner Function

TL;DR

This paper reports the first observation of gravitationally bound quantum states of ultracold neutrons with submicron spatial resolution, confirming quantum mechanical predictions using the Wigner function.

Contribution

It provides experimental evidence of gravitationally bound UCN states with high spatial resolution and validates quantum mechanical models of these states.

Findings

Observed modulation of UCN distribution matches quantum predictions

Achieved 0.7 micrometer spatial resolution in measurement

First to observe gravitationally bound UCN states with submicron precision

Abstract

Ultracold neutrons (UCNs) can be bound by the potential of terrestrial gravity and a reflecting mirror. The wave function of the bound state has characteristic modulations. We carried out an experiment to observe the vertical distribution of the UCNs above such a mirror at Institut Laue-Langevin in 2011. The observed modulation is in good agreement with that prediction by quantum mechanics using the Wigner function. The spatial resolution of the detector system is estimated to be 0.7 micro meter. This is the first observation of gravitationally bound states of UCNs with submicron spatial resolution.