Where to learn about 'Electrical Sound'?

Question

Here is a thought experiment.

Consider a thin superconducting circular loop of wire. Suppose there is a supercurrent flowing through the loop. Let $v$ be the tangential drift velocity of the electrons and $r$ the radius of the loop.

Now suppose you place an observer at the center of the loop and they begin to rotate with angular velocity $\frac{v}{r}$. Then from their perspective the electrons are static. Now suppose you somehow "pushed" a set of electrons in the wire a little ahead, that would creative effectively an electrical pressure that should appear to propagate around the loop like a sound wave (from the rotating observer's point of view), (and could potentially be quantized).

Where can I learn more about this type of "electrical sound"?

Answer 1

You don't need complicated setups with superconductors. To a surprisingly good approximation the conduction electrons in a metal behave as a nearly ideal gas. This is the free electron gas model, or unexcitingly named nearly free electron gas model.

This electron gas supports oscillations that are the equivalent of sound waves, and with these comes a quasiparticle analogous to the phonon called the plasmon.

When I was doing my PhD there was lots of interest in plasmons. I'm not sure how active an area it is these days - I get the impression that the more esoteric aspects of electronic structure have largely taken over - but a quick Google will find lots of related material.