New quantum effect of confined magnetic flux on electrons

王瑞峰

G. R. Freeman, Larry D. Coulson, Norman Henry March

When an electron beam passes outside a confined magnetic flux, the motional magnetic field of the electrons overlaps the confined flux. The potential energy of the magnetic dipolar interaction of the motional magnetic field with the confined magnetic flux causes the velocity of the electrons to change slightly, which shifts the phase of the electron de Broglie wave. When portions of an electron beam pass on different sides of a confined flux and are then mixed, they produce an interference pattern. There is a similar magnetic dipolar interaction, with resulting velocity and phase changes, when a beam of magnetic particles interacts with the motional magnetic flux produced by their crossing a strong electric field. These are classical electromagnetic dipolar (not Lorentz) interactions that causes changes in Berry's geometrical phase, but are not ESAB or AC effects. Data that were suggested to demonstrate the ESAB and AC effects have been quantitatively interpreted in terms of motional magnetic fields and velocity changes.

Silviu Olariu

Murray Peshkin, Igal Talmi, Lindsay J Tassie

Akira Tonomura

The Aharonov-Bohm effect is experimentally confirmed to exist under ideal conditions where there is no overlap between an incident electron wave and a confined magnetic field. The experiment not only establishes the physical reality of gauge fields but also opens up a new way, based on the principle behind this effect, to observe microscopic flux lines.

Nobuyuki Osakabe, Tsuyoshi Matsuda, Takeshi Kawasaki +4 more

The electron holography technique was employed to make a crucial test of the existence of the Aharonov-Bohm (AB) effect. The relative phase shift was measured between two electron waves passing through spaces inside and outside a tiny toroidal ferromagnet, covered completely with a superconductor layer and a Cu layer. Below the transition temperature the relative phase shift was measured to be 0 or \ensuremath{\pi} due to the magnetic-flux quantization in units of h/2e. The results directly demonstrated the existence of the AB effect even when the magnetic field was confined by the surrounding superconductor due to the Meissner effect and an electron beam was prevented from penetrating the magnet.