https://www.sciencedaily.com/releases/2020/06/200626114740.htm

That visible light holds the character of a wave can be demonstrated in simple optics experiments, or directly witnessed when rainbows appear in the sky. Although the subtle laws of quantum mechanics, that is, wave mechanics, ultimately govern all the processes of electron transportelectrons in solids, their wave-like nature of the electrons is not often apparent to the casual observer. A classical picture of electrons as solid particles goes surprisingly far in explaining electric currents in metals. As high school students see in experiments with water waves, and we observe and use with light waves in many optical devices, interference is a fundamental property associated with wave-like behavior. Indeed, Davisson and Germer's famous observation of interference in experiments with dilute beams of electrons, nearly a century ago, gave key experimental support to the correctness of the then-new quantum theory.

In experiments on solids, however, signatures of quantum interference are rare and hard to observe. This is essentially because there are so many electrons, and so many ways in which they can be 'scrambled up', that most interference effects are invisible to experiments that probe distances of more than a few atomic spacings.