R. Clothier

Neutron interference induced by gravity: New results and interpretations☆

Abstract We report the results of neutron interferometric experiments, extending the range and precision of the COW gravitationally-induced quantum interference experiment of Staudenmann and co-workers. These experiments provide a test of the principle of equivalence in the quantum limit. High precision data (1 part in 1000) is presented. The frequency of the quantum interference oscillations, and the loss of contrast observed as a function of increasing gravitational potential energy difference are compared with the recent interferometer dynamical diffraction calculations of Bonse and Wroblewski and of Horne. Theory and experiment are found to differ by 0.8%.

Fizeau effect for neutrons passing through matter at a nuclear resonance

Abstract We have measured the phase shift of a neutron de Broglie wave induced by the motion of Sm-149 through which the neutron is propagating. This experiment differs from a number of ‘neutron Fizeau’ experiments carried out in recent years. The observed phase shift is caused by the motion of the matter itself, and not by the motion of its boundaries, as was the case with the earlier experiments. In this regard our experiment is a true neutron analog of the famous Fizeau experiment of 1859, where phase shift of the light wave interference pattern was induced by the motion of matter.

Neutron interferometry investigation of the Aharonov-Casher effect☆

Abstract This paper describes our progress on a neutron interferometry search for the Aharonov-Casher (A-C) effect. Unpolarized neutrons are passed through a 40 kV/mm vacuum electrode system. The spin-dependent phase is set to maximum sensitivity with a magnetic field, and the spin-independent phase is adjusted to zero (modulo 2π) using the Earths gravitational field. Upon reversal of the electric field, the predicted A-C phase shift is 0.2°. Currently, our results are statistically limited.

Neutron interferometric observation of the topological Aharonov-Casher effect

Abstract The Aharonov-Casher effect has been observed experimentally using a single crystal neutron interferometer.

Neutron interferometric measurement of the topological Aharonov‐Casher phase shift

We have measured the phase shift predicted by Aharonov and Casher (AC) for a magnetic dipole diffracting around a charged electrode for the case of thermal neutrons, using a neutron interferometer containing a 30‐kV/mm vacuum electrode system. Tilting the interferometer about the incident beam direction introduces a spin‐independent gravitationally‐induced phase shift which enables unpolarized neutrons to be used. A supplementary magnetic bias field of the correct magnitude allows first‐order sensitivity to the AC phase shift to be achieved. Nevertheless, the theoretically predicted phase shift is only 1.52 mrad for the geometry and conditions of the experiment. We observe a phase shift of 2.11±0.34 mrad. A detailed description of the experiment and its interpretation is given in this paper.