Physical and unphysical phases of uniformly accelerated particles

The motion of an electron in a uniform electric held, as in free fall, is c haracterized by the existence of pairs of trajectories that rejoin on the s ame final point. The corresponding interference pattern was first observed in 1996, and explained by the elementary model of uniform acceleration star ting from a motionless electron source. In the experiment, however, the ele ctron source is a fast-moving negative ion, which makes direct application of the model questionable. Relativistic arguments can be used to ascertain that no phase changes are actually produced by the motion of the source. Th e quantum phase of the electron can also be checked all along its two inter fering trajectories. This method, which produces the same reassuring result as relativity, gives us the opportunity to revisit the relativistic transf ormation of the Schrodinger phase. It also makes it possible to calculate t he effect of an acceleration of both the free electron and the electron emi tter. Only in this case is a change of the interference pattern expected, b ut it is quantitatively negligible in the actual experiment. (C) 2001 Ameri can Association of Physics Teachers.