Yes, I know about gravity and antimatter. Let me know when those become relevant to microelectronics.

And, nonlinear optical media do involve electrons -- that was precisely my point. And that's why those "optical" computers perform no better than electrical computers: because they are in fact electrical computers that use photons for communication, not for computation.

But using photons for communication is nothing new, we've been doing that since the late 1970s.