Here is an interesting paper for the Physics SE community: On the role of potent

Question

Here is an interesting paper for the Physics SE community:

On the role of potentials in the Aharonov-Bohm effect. Lev Vaidman. Phys. Rev. A 86 no. 4, 040101 (R) (2012). arXiv:1110.6169 [quant-ph].

You should check it out because it's an amusing read, but I will summarise the argument to whet your appetite, assuming you have basic familiarity with the Aharonov-Bohm (AB) effect. In the traditional AB setup, one considers an electron in a superposition of paths, taking it in two opposite directions around a solenoid treated as a classical source of the electromagnetic field. The observable relative phase acquired between the electron's paths is attributed to the influence of the magnetic vector potential on the electron, which cannot be globally gauged away - despite the absence of a physical field anywhere along the electron's path(s) - due to a topological obstruction.

Instead, Vaidman considers the effect of the electron on the sources of the field, treating the latter as quantum particles. He shows that the relative phase between the two branches of the wavefunction can be considered as arising from the action of the physical field of the electron, which is not zero at the position of the sources. However, Vaidman uses highly contrived gedankenexperiments and completely semi-classical arguments, which begs a pair of concrete and related questions.

1) Can Vaidman's first, electric AB effect gedankenexperiment be described in a fully quantum manner, by solving (at least approximately) the three-particle Schroedinger equation? If not, why not?

2) Is it possible to explain within this formalism the experiments of Tonomura et al. (Phys. Rev. Lett. 56 no. 8, pp. 792-795 (1986)), who used a superconductor to completely shield the magnetic field of the source?

Explanation / Answer

In this Comment on Macroscopic Test of the Aharonov-Bohm Effect Tomislav Ivezic wrote "...because only the electric field from the solenoid with steady current exists in the region outside the solenoid and it can locally influence the electron travelling through that region." What he describes is nothing else then the interaction between the flying electron and an electric field from the surface of the edge of a slit or a wire. The result is the diffraction of electrons (or photons) by this field. Then more the field is quantized and the diffraction lead to fringes on the observation screen.

This model is applicable to edges, slits and multi slits and works with single photons (as well as with single electrons) too.

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