The Aharonov-Bohm Effect and its Applications to Magnetic Field Observation

Akira Tonomura

This article describes the Aharonov-Bohm (AB) effect of electron waves travelling in free space and its application to the observation of gauge fields (vector potentials). The AB effect is inconceivable in classical physics since an observable effect is produced on electrons passing through field-free spaces. Electrons can be affected only by Lorentz forces due to electromagnetic fields. The situation is different in quantum mechanics, where electrons show wave properties: the concept of force is no longer relevant, so electric field E and magnetic field B, defined as forces acting on a unit charge, take on secondary meanings. “Phase shifts” come into play, and the primary physical entities become neither E nor B but electrostatic potential V and vector potential A. These potentials interact with electron waves and shift their phases.

A. N. Ageev, Sergei Yu. Davydov

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.

Akira Tonomura

Akira Tonomura

Le-Chuan Wang, Sai Li, Jia Liu +1 more

Aharonov-Bohm (AB) caging is the complete wavefunction localization effect in translational-invariant lattices induced by destructive phase interference. These phases originate from the gauge fields such as the penetrated magnetic fields, which are directly related to several novel topological quantum states of matter. Recently, this effect has shown significant potential for applications in quantum simulation and topological quantum computation. Here, we propose a scalable protocol to derive universal conditions for AB caging with multi-flux. The numerical simulations validate the theoretical predictions by directly observing AB caging phenomena. We also investigate the breakage of the caging effect with onsite detuning, decoherence and non-Hermitian transitions. Our protocol provides an alternative approach for advancing quantum simulation of exotic states of matter.