Electromagnetic Memory
Leonard Susskind
TL;DR
The paper investigates the electromagnetic memory effect arising from charged-particle emission, presenting an elementary derivation on a large enclosing sphere within the temporal gauge. It connects the memory to a local conservation law that equates the time evolution of the gauge-field divergence to net charge flux, predicting a frozen-in gauge phase detectable as relative superconducting node phases. The memory can be read out via Josephson junctions, linking the phenomenon to observable phase differences and soft-photon considerations. A generalization to non-lightlike (radial) motion extends the framework, showing the memory persists with velocity-dependent relations and integral forms, broadening potential experimental setups.
Abstract
An elementary derivation of the electromagnetic memory effect is given. An experimental setup to detect it is suggested.