Decoherence and time reversibility: The role of randomness at interfaces

The Wigner formalism is a convenient reformulation of the Schr€odinger equation that allows the simulation of transient behavior of quantum systems in the presence of general boundary conditions. Recently, a Wigner Monte Carlo technique, based on particles signs, has been generalized to twodimensional evolution problems. In this paper, we apply this technique to study the time reversibility of the quantum evolution of a wave packet colliding with a potential wall in the presence of interface roughness, elastic, inelastic, and diffusive interactions with the environment. We show that a wall surface roughness does not necessarily involve time irreversibility. The dynamics of the packet is indeed influenced, but remains coherent, until the boundaries of the system begin to absorb information from the system. Finally, it is shown that in the presence of inelastic scattering or diffusive processes, the time-reversibility of a quantum system is destroyed, whatever the shape of the wall interface is. In particular, we show that the random nature of a process, elastic or inelastic, is responsible for the appearance of quantum decoherence. VC 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4828736]