Quantum decoherence without a master equation

With a choice of boundary conditions for the Schr\"odinger equation, one finds asymmetric time evolution even for closed systems. When the theory is applied to open systems, standard quantum mechanics with unitary time evolution already predicts quantum decoherence. The practical result is a new framework for the treatment of open systems, in which no master equation is required. Preliminary calculations show very good quantitative agreement with experiments.