Generation of Werner states and preservation of entnglement in a noisy environment

We study the influence of noisy environment on the evolution of two-atomic system in the presence of collective damping. Generation of Werner states as asymptotic states of evolution is described. We also show that for some initial states the amount of entanglement is preserved during the evolution.Comment: 9 pages, 2 figures, content changed, references adde

Quantum interference and evolution of entanglement in a system of three-level atoms

We consider a pair of three-level atoms interacting with the vacuum. The process of disentanglement due to spontaneous emission and the role of quantum interference between principal transitions in this process, are analysed. We show that the presence of interference can slow down disentanglement. In the limit of maximal interference, some part of initial entanglement can survive.Comment: 6 pages, 8 figure

Local aspects of disentanglement induced by spontaneous emission

We consider spontaneous emission of two two-level atoms interacting with vacuum fluctuations. We study the process of disentanglement in this system and show the possibility of changing disentanglement time by local operations.Comment: 7 pages, 2 figure

Vacuum - induced stationary entanglement in radiatively coupled three - level atoms

We consider a pair of three - level atoms interacting with a common vacuum and analyze the process of entanglement production due to spontaneous emission. We show that in the case of closely separated atoms, collective damping can generate robust entanglement of the asymptotic states.Comment: published versio

CHSH violation and entropy - concurrence plane

We characterize violation of CHSH inequalities for mixed two-qubit states by their mixedness and entanglement. The class of states that have maximum degree of CHSH violation for a given linear entropy is also constructed

Entanglement and nonlocality versus spontaneous emission in two-atom system

We study evolution of entanglement of two two-level atoms in the presence of dissipation caused by spontaneous emission. We find explicit fromulas for the amount of entanglement as a function of time, in the case of destruction of the initial entanglement and possible creation of a transient entanglement between atoms. We also discuss how spontaneous emission influences nonlocality of states expressed by violation of Bell - CHSH inequality. It is shown that evolving system very quickly becomes local, even if entanglement is still present or produced.Comment: 15 pages, 7 figure

Gentrification Processes In The City

Published in: Society and Space in Contemporary Poland in Łódź University Geographical Research, edited by T.MarszałDue to the fact that gentrification is a phenomenon of a global nature, it was considered important to survey it in post-socialist city. Both scientific literature and research in Central Europe have appeared only recently therefore it was decided to examine the gentrification in Łódź. It turned out that the gentrification processes in Łódź are in the initial phase and they are carried out mostly by the local authorities, developers, private tenement owners. In Łódź academic centre a certain part in the gentrification process is played by students who choose as their residence the peripheral housing estates and the old, renovated tenements in the inner-city of Łódź. The perspective of further studies of gentrification in Łódź would be to trace the displacement of the middle class within the city, as well as the influx of new gentrifiers

Generation of Werner-like stationary states of two qubits in a thermal reservoir

The dynamics of entanglement between two-level atoms immersed in a common photon reservoir at finite temperature is investigated. It is shown that in the regime of strong correlations there are nontrivial asymptotic states which can be interpreted in terms of thermal generalization of Werner states.Comment: Published versio

Stochastically positive structures on Weyl algebras. The case of quasi-free states

We consider quasi-free stochastically positive ground and thermal states on Weyl algebras in Euclidean time formulation. In particular, we obtain a new derivation of a general form of thermal quasi-free state and give conditions when such state is stochastically positive i.e. when it defines periodic stochastic process with respect to Euclidean time, so called thermal process. Then we show that thermal process completely determines modular structure canonically associated with quasi-free state on Weyl algebra. We discuss a variety of examples connected with free field theories on globally hyperbolic stationary space-times and models of quantum statistical mechanics.Comment: 46 pages, amste

Delayed birth of distillable entanglement in the evolution of bound entangled states

The dynamical creation of entanglement between three-level atoms coupled to the common vacuum is investigated. For the class of bound entangled initial states we show that the dynamics of closely separated atoms generates stationary distillable entanglement of asymptotic states. We also find that the effect of delayed sudden birth of distillable entanglement occurs in the case of atoms separated by a distance comparable with the radiation wavelength.Comment: published versio