Quantum electronics is an area of physics dealing with the effect of quantum mechanics on the behaviour of electrons in solid-state matter.
It is today rarely considered a subfield in its own right, as it has been absorbed by other fields: Solid-state physics is hardly ever been done without taking quantum mechanics into account, and it is almost always about electrons. The specific importance for electronics is researched by semiconductor physics.
The term was mainly used in the 1950s to the 1970s. Today, the results of this field is mainly of use for quantum optics, especially for that part of it that draws not from atomic physics but from solid-state physics.