Asymptotic entanglement in open quantum systems

Аурелиан Исар

Diplomarbeit von Marc Busse

K. Berrada, Hichem Eleuch, Y. Hassouni

It is well known that quantum entanglement makes certain tasks in quantum information theory possible. However, there are also quantum tasks that display a quantum advantage without entanglement. Distinguishing classical and quantum correlations in quantum systems is therefore of both practical and fundamental importance. Realistic quantum systems are not closed, and therefore it is important to study the various correlations when the system loses its coherence due to interactions with the environment. In this paper, we study in detail the dynamics of different kinds of correlations, classical correlation, quantum discord and entanglement in open quantum systems, in particular, a two-qubit system evolving under Kossakowski-type quantum dynamical semigroups of completely positive maps. In such an environment, classical and quantum correlations can even persist asymptotically. By analytic and numerical analysis, we find that the quantum discord is larger than the classical correlation for asymptotic states. Furthermore, we show that the quantum discord is more resistant to the action of the environment than quantum entanglement, and it can persist even in the asymptotic long-time regime.

Robert Olkiewicz

Description of Quantum Entanglement with Nilpotent Polynomials (V Akulin) Quantum Memories as Open Systems (R Alicki) Entanglement in Many-Body Systems (J Anders) Asymptotic Entanglement in Open Quantum Systems (F Benatti) Models for Qubits Open System Dynamics (M Fannes) Nilpotents, Quantum Mechanics and Flavor of Entanglement (A Frydryszak) Experiments on Quantum Coherence with Cold Atoms (W Gawlik) Superadditivity Effects in Quantum Communication - A Selection (P Horodecki) Dynamical Entanglement of Three-Level Atoms (L Jakobczyk) PPT States, Entanglement and Its Measures (W A Majewski) Sudden Death and Sudden Birth of Entanglement (R Tanaś) Asymptotic Bahavior of Quantum Walks with Disorder in Space and Time (R F Werner) Quantum Infodynamics (M Ziman) Dynamics and Entropy Growth in Interacting Quantum Systems (K Życzkowski).

Fabio Benatti, Alexandra M Liguori-Schremp, Giacomo Paluzzano

We study a recent conjecture about the behavior of the quantum relative entropy compared to the relative entropy of entanglement in open bipartite systems. The conjecture states that, under a dissipative time evolution, the positive rate of change of the relative entropy will always be larger than that of the relative entropy of entanglement. After explicitly solving a 2-qubit master equation of Lindblad type with separable and entangled stationary states, we show that the conjecture can be violated for initial states with an entangled asymptotic state, while it appears to be confirmed when the asymptotic states are separable.

V. M. Akulin