Just to unpack "electronic signals", what propagates is the disturbance ("signal"), not the electrons themselves. Like waves propagating at the beach, where water only moves back and forth a little, and slower.

And specifically what causes the electrons to move each other is the electromagnetic field. The boson of the electromagnetic field is the photon, so the signal is being carried from one electron to the next by photons. (Although the disturbance itself as a whole is not a photon; I think it's often described as a quasiparticle called a plasmon.)

Extremely relevant Veritasium video (skip the first two minutes):

https://www.youtube.com/watch?v=oI_X2cMHNe0

> But you need a medium to use photons

Since the speed of light in a vacuum is the prohibitive speed limit of Relativity, I always felt we should develop a medium in which light moved faster than it did in a vacuum, and I swear I've read an article about such a material which was referred to in the article as "ruby," and the images of it reminded me of those glass things at the Fortress of Solitude in Superman (1978). If such a material exists, it would not only make photon computers very fast, but make it possible to violate causality without violating Relativity.

Any idea of instead of “traditional” fiber photons, if hollow core fiber is used if this changes the calculus?