The Aharonov–Bohm effect shows that electromagnetic potentials can influence a charged particle’s quantum phase even when the particle travels through a region where the magnetic field is zero.
Yakir Aharonov and David Bohm predicted the effect in 1959. In the classic arrangement, electrons pass on opposite sides of a long, shielded solenoid. The magnetic field is confined inside, but changing the enclosed magnetic flux shifts the interference pattern outside.
The result differs from classical intuition, where forces and fields are usually treated as the direct physical influences. In quantum mechanics, the vector potential contributes to the phase of a wavefunction, and that phase can affect observable interference.
The effect has been demonstrated with electrons and other quantum systems. It is not the same as the Berry phase, which arises from adiabatic evolution through parameter space.