  We study an effect of quenching of antihydrogen quantum states near material
surface in the gravitational field of the Earth by local charges randomly
distributed along the mirror surface. The quenching mechanism reduces the
quantum reflection probability because of additional atom-charge interaction
and nonadiabatic transitions to excited gravitational states. Our approach is
suitable for accounting for quenching caused by any kind of additional
interaction with the characteristic range much smaller than the typical
gravitational state wave-length.
