Measurement of Neutron Whispering Gallery States Using a Pulsed Neutron Beam

TL;DR

This study experimentally observed neutron whispering gallery states on a concave mirror using pulsed cold neutrons, confirming theoretical predictions and demonstrating high sensitivity for potential surface and short-range interaction tests.

Contribution

First experimental observation of neutron whispering gallery states on a concave surface with precise measurement matching theory within 1.9%.

Findings

Measured centrifugal acceleration agrees with theory within 1.9%.

Sensitivity of the measurement is two orders of magnitude better than the agreement.

Results enable tests of quantum mechanics and short-range interactions.

Abstract

A neutron whispering gallery state is a quantum state localized on a material surface bound by the centrifugal force and the material potential. Precise measurements of such quantum states enable tests of quantum mechanics in non-inertial frames, characterization of the surface potential, and searches for hypothetical short-range interactions at the nanometer scale. We observed a neutron whispering gallery state on a $\mathrm{SiO}_2$ concave mirror using a pulsed cold neutron beam. The measured results agree with theoretical calculations within $1.9\%$ for the centrifugal acceleration $a \approx 7\times 10^7\,\mathrm{m/s^2}$, which is due to unmodeled deviations of the shape of the concave mirror edge from an ideal one. We found that the sensitivity itself was $1\times 10^{-4}$, which is two orders of magnitude better than the above agreement.