It's kind of hard cause I can't say I fully understand all of it but googling around for analog computing neural networks is a good start.

Check also real computation https://en.m.wikipedia.org/wiki/Real_computation and work of Lenore Blum.

Im super pumped about the research into computational metamaterials http://users.ece.utexas.edu/~aalu/research%20-%20page%203.ht...