What is the name of the quantum effect where magnetic vector potentials influence charged particles?

The quantum effect in which magnetic vector potentials influence charged particles is the Aharonov–Bohm effect. It shows that a particle can acquire a measurable quantum-mechanical phase even while traveling through a region where the magnetic and electric fields are zero.

The classic setup sends electrons along two paths around a long, shielded solenoid. The magnetic field is confined inside the solenoid, but the vector potential outside it changes the relative phase of the electron wavefunctions. When the paths reunite, the altered phase shifts the interference fringes.

The effect was described by Yakir Aharonov and David Bohm in 1959, although related ideas had been discussed earlier by Werner Ehrenberg and Raymond Siday. It is a striking example of how electromagnetic potentials, not only fields, enter quantum theory.

A common mistake is to confuse it with the Zeeman effect, which is the splitting or shifting of atomic energy levels in a magnetic field. The Aharonov–Bohm effect instead concerns phase and interference, even where the local magnetic field vanishes.