The processor of the computer you are writing your question on is using tunnelling transistors.
replyModern processors are designed to minimise quantum effects, because phenomena like tunnelling create inefficient leakage currents.
replyAll the idea of valence and conduction bands depends on quantum effects. The holes are quantum effects, the electrons are not plain electrons and in particular they have an effective mass that is not equal to the mass of a plain electron traveling in vacuum.
replyAnyway, I prefer LEDs as an example.