260056 VO Decoherence and physics of open quantum systems (2013S)

We give an introduction into the formalism of density matrices, for pure, mixed and composite (entangled) quantum states. The several notions of quantum entropy as measure for an information loss are discussed. Furthermore we study the phenomenon of decoherence in single quantum systems and in composite ones that are entangled. We present the theory open quantum systems, the dynamical maps (operator representation) and the master equation. With help of the master equation the decoherence of open quantum systems is described and examples are discussed, like spontaneous emission, particle decay, special quantum channels (spin flip, amplitude damping, …) and also scattering processes inclusive Wigner functions. The Jaynes-Cummings model of quantum optics will be considered. Finally, we also investigate special quantum systems in particle physics, kaonic qubits, together with the decoherence of entangled kaons.