Environment-induced decoherence and the transition from quantum to classical

The environment surrounding a quantum system can, in effect, monitor some of the systems observables. As a result, the eigenstates of those observables continuously decohere and can behave like classical states, since their superpositions are rendered unobservable by the effective superselection rule induced by such interaction. This process is a key ingredient of the transition from quantum to classical. It suggests an explanation of the apparent reduction of the wavepacket in course of quantum measurements. (author) 24 refs