Neutron interference induced by gravity: New results and interpretations

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%.