B. Velický

Fast dynamics of molecular bridges

We address the dynamics of open quantum systems, in which complex finite time initial conditions, an ensuing rapid non-equilibrium transient, quantum interferences and their attenuation play important roles. To study all these phenomena in conditions of general non-equilibrium, open systems are represented by a simple structure of a molecular island between two leads. We treat this model using the non-equilibrium Green functions (NGF) method for a finite initial condition. We demonstrate that the non-interacting molecular bridge model captures well many features of general open quantum systems. Three stages of its non-equilibrium evolution, the first described by the full NGF description, the second ruled by the asymptotically exact generalized master equation and the third governed by a Markovian master equation, are delineated and related to each other.

Electron systems out of equilibrium: Nonequilibrium Green's function approach

This review deals with the state of the art and perspectives of description of nonequilibrium many-body systems using the nonequilibrium Greens function (NGF) method. The basic aim is to describe time evolution of the many-body system from its initial state over its transient dynamics to its long time asymptotic evolution. First, we discuss basic aims of transport theories to motivate the introduction of the NGF techniques. Second, this article summarizes the present view on construction of the electron transport equations formulated within the NGF approach to nonequilibrium. We discuss incorporation of complex initial conditions to the NGF formalism, and the NGF reconstruction theorem, which serves as a tool to derive simplified kinetic equations. Three stages of evolution of the nonequilibrium, the first described by the full NGF description, the second by a non-Markovian generalized master equation and the third by a Markovian master equation will be related to each other.

Fast transients in mesoscopic systems

We study fast transient dynamics of an open quantum system at the initial stage of its equilibration starting far from equilibrium from correlated initial conditions reflecting entanglement with the environment. These correlations rapidly decay and the process enters the non‐equilibrium quasi‐particle mode controlled by a generalized master equation. As a model system, the nanoscopic molecular bridge between two leads is considered. The coupling to the leads is assumed to be intermittent. Properties of the resulting transients are demonstrated and analyzed.