External Time-Varying Fields and Electron Coherence

The effect of time-varying electromagnetic fields on electron coherence is investigated. A sinusoidal electromagnetic field produces a time-varying Aharonov-Bohm phase. In a measurement of the interference pattern which averages over this phase, the effect is a loss of contrast. This is effectively a form of decoherence. We calculate the magnitude of this effect for various electromagnetic field configurations. The result seems to be sufficiently large to be observable.

Figure 1

The two possible electron paths, $C_1$ and $C_2$, are illustrated. The electrons start at point $A$ and end at point $D$ after traversing a path which is approximated by three straight line segments. Here $\Theta$ is the time required for the first and last segments, and $T$ is the time required for the middle segment.