Topological and Geometric Phases
Helmut Rauch, Samuel A. Werner
The usual vector Aharonov–Bohm effect involves the quantum interference of electrons encircling a solenoid due to the magnetic vector potential. The analogous Aharonov–Casher effect was predicted for the neutron, which carries a magnetic dipole moment, encircling a line of electric charge . It was first observed by neutron interferometry, as described in this chapter. An analogous effect using neutrons and a pulsed magnetic solenoid in one leg of the interferometer has also been observed. This experiment using both polarized and unpolarized neutrons is described in this chapter. It is the first observation of the scalar Aharonov-Bohm effect. The idea of geometric phases was later shown to be pervasive in physics. These ideas were brought to full fruition in a neutron interferometry experiment in the late 1990s. The connections of this experiment with the helical field experiment of Bitter and Dubbers and the absorption experiment of Hasegawa are also discussed. The confinement-induced phase when neutrons move between narrow plates is another example of a non-local interaction of neutrons.
Oxford University Press eBooks•Jan 15, 2015•0 citations