The general relativistic interaction of the electric field with the gravitational field may be observable in a charged-particle interferometer containing a suitable arrangement of fields. Observation of the effect in the earth's field would constitute a new laboratory test of the equivalence principle, involving $e$, $h$, $c$, and $g$. The magnitude of the phase shift induced can be comparable to the Colella-Overhauser-Werner phase shift, for electrons.

• Received 7 February 1983

DOI:https://doi.org/10.1103/PhysRevLett.50.1730