Generalized Aharonov-Bohm Effect

TL;DR

This paper extends the understanding of the Aharonov-Bohm effect to time-varying magnetic fluxes, deriving phase shifts for different paths and clarifying the roles of gauge potentials and induced fields in quantum phase phenomena.

Contribution

It provides a generalized theoretical framework for the AB effect under dynamic flux conditions, including path-dependent phase shifts and the influence of external magnetic fields.

Findings

Phase shift proportional to time-averaged flux for circular paths

Path geometry affects phase shift in non-circular paths

External magnetic fields influence phase via Lorentz force

Abstract

The Aharonov-Bohm (AB) effect highlights the fundamental role of electromagnetic potentials in quantum mechanics, manifesting as a phase shift for a charged particle in field-free regions. While well-established for static magnetic fluxes, the effect's behavior under time-varying fluxes remains an open and debated question. Employing the WKB method, we derive the AB phase shift for a time-dependent magnetic vector potential, demonstrating that for circular paths in the quasistatic regime, it is proportional to the time-averaged enclosed magnetic flux, \(\Delta \phi_{\rm AB} = \frac{1}{T} \int_0^T e \Phi(t) \, dt\), with the total phase shift, including kinetic contributions, equaling \(e \Phi(0)\). For non-circular paths, the phase shift depends on both the flux history and path geometry, revealing the effect's hybrid nature involving gauge potentials and induced electric fields. We verify the consistency of our gauge choice with Maxwell's equations and discuss the implications for local versus nonlocal interpretations of the AB effect. We also generalize the results to scenarios with nonzero external magnetic fields, where the enclosed flux is through the actual electron paths, and for circular paths of radius $R$, the AB phase shift is also proportional to the time average of the enclosed flux \(\Phi_{\rm enc}(R,t)\), with the total phase shift depending only on the initial enclosed flux \(e \Phi_{\rm enc}(R,0)\); for general non-circular paths, the external magnetic field affects trajectories and phase accumulation through the Lorentz force, leading to additional path dependence. These findings clarify the role of gauge-dependent potentials and induced fields in the generalized AB effect, offering new theoretical insights and potential applications in quantum technologies.