An Introduction to Mesoscopic and Nanometer Scale Physics (PDF)

Quantum devices
The operating principles of almost all modern solid state devices
(transistors, diodes, etc.) are based on quantum mechanical
phenomenon. However, these devices are macroscopic in dimension, and
involve averages over a very large number (10 23 ) number of incoherent
quantum states.
Two factors separate distinctly quantum phenomena
Coherence, or the control or manipulation of the quantum
mechanical phase of the wave function
The ability to probe individual quantum states