A quantum decoherence simulator based on the Wigner formalism
The ViennaWignerDecoherance simulator comprises methods, approaches, and algorithms for particle simulation of quantum decoherence in the phase space. The theoretical foundation for the implemented algorithms is the Wigner description from the field of quantum mechanics.
ViennaWD provides tools for analysis of the evolution of an initially entangled electron state which evolves in presence of semiconductor lattice vibrations - phonons. The initial electron state is constructed by a superposition of two Gaussian wave packets and has a pronounced interference term comprised of alternating positive and negative values of the Wigner function. The simulations show how the phonons effectively destroy the interference term. The initial coherence in wave vector distribution is pushed towards the equilibrium distribution. Phonons hinder the natural spread of the density with time pushing towards a classical localization. The initially pure electron state evolves towards a state with an entirely different physical interpretation: it is a mixed state where the electron can be with given probability in one of the two Gaussian packets. The decoherence effect of the phonons causing transition from quantum to classical state is demonstrated by the purity of the state, which decreases from it’s initial value of 1, with a speed depending on the lattice temperature.
More information can be found at http://viennawd.sourceforge.net/