Testing the electric Aharonov-Bohm effect with superconductors

TL;DR

This paper proposes an experiment using superconductors to observe the electric Aharonov-Bohm effect, demonstrating the physical significance of electric potential without electromagnetic fields.

Contribution

It introduces a novel experimental setup to detect the electric Aharonov-Bohm effect via the Josephson effect in superconductors, which has not been observed before.

Findings

Potential difference induces a measurable phase shift

Demonstrates electric potential's physical significance

Proposes a method to observe electromagnetic memory effect

Abstract

The phase of the wave function of charged matter is sensitive to the value of the electric potential, even when the matter never enters any region with non-vanishing electromagnetic fields. Despite its fundamental character, this archetypal electric Aharonov-Bohm effect has evidently never been observed. We propose an experiment to detect the electric potential through its coupling to the superconducting order parameter. A potential difference between two superconductors will induce a relative phase shift that is observable via the DC Josephson effect even when no electromagnetic fields ever act on the superconductors, and even if the potential difference is later reduced to zero. This is a type of electromagnetic memory effect, and would directly demonstrate the physical significance of the electric potential.