Entanglement versus mixedness for coupled qubits under a phase damping channel

Cardoso, E. S.; Oliveira, M. C. de; Furuya, K.

doi:10.1103/physreva.72.042320

Cited by 5 publications

(4 citation statements)

References 25 publications

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“…In this case, we may follow the procedure adopted in ref. [20], in which entanglement has been evaluated by means of two-qubits measures, as for instance, the negativity. This quantity has the following definition [21,22]:…”

Section: Disentanglement Induced By Phase Decoherencementioning

confidence: 99%

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Decoherence induced by a phase-damping reservoir

2006

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A phase damping reservoir composed by $N$-bosons coupled to a system of interest through a cross-Kerr interaction is proposed and its effects on quantum superpo sitions are investigated. By means of analytical calculations we show that: i-) the reservoir induces a Gaussian decay of quantum coherences, and ii-) the inher ent incommensurate character of the spectral distribution yields irreversibility . A state-independent decoherence time and a master equation are both derived an alytically. These results, which have been extended for the thermodynamic limit, show that nondissipative decoherence can be suitably contemplated within the EI D approach. Finally, it is shown that the same mechanism yielding decoherence ar e also responsible for inducing dynamical disentanglement.Comment: 8 pages, 3 figure

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Section: Disentanglement Induced By Phase Decoherencementioning

confidence: 99%

“…where λ neg (t) is the negative eigenvalue of the partially transposed density matrix in the joint space E ab . Following [20] we obtain analytically:…”

Section: Disentanglement Induced By Phase Decoherencementioning

confidence: 99%

Decoherence induced by a phase-damping reservoir

2006

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“…The scope of this paper is to provide new insights about the non-Markovian dynamics of the quantum correlations captured by entanglement from the perspective of its interplay with purity, which identifies the degree of mixedness of a quantum state being related to coherence. Such a study is still little addressed [46,47], particularly in the presence of local non-Markovian environments [48]. Knowledge of relationships between entanglement and purity in specific dynamical contexts is important not only from a fundamental viewpoint but also from a practical one.…”

Section: Introductionmentioning

confidence: 99%

Relations between entanglement and purity in non-Markovian dynamics

González-Gutiérrez

Román-Ancheyta

Espitia

et al. 2016

Int. J. Quantum Inform.

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Knowledge of the relationships among different features of quantumness, like entanglement and state purity, is important from both fundamental and practical viewpoints. Yet, this issue remains little explored in dynamical contexts for open quantum systems. We address this problem by studying the dynamics of entanglement and purity for two-qubit systems using paradigmatic models of radiation-matter interaction, with a qubit being isolated from the environment (spectator configuration). We show the effects of the corresponding local quantum channels on an initial two-qubit pure entangled state in the concurrence–purity diagram and find the conditions which enable dynamical closed formulas of concurrence, used to quantify entanglement, as a function of purity. We finally discuss the usefulness of these relations in assessing entanglement and purity thresholds which allow noisy quantum teleportation. Our results provide new insights about how different properties of composite open quantum systems behave and relate each other during quantum evolutions

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“…Recently several authors [13][14][15][16][17][18][19] have investigated time evolution of the entanglement when a bi-partite system has been subjected to either local or global transformations (time evolution). In these studies, usually it has been investigated how a maximally entangled state is affected by the action of the corresponding evolution operation.…”

Section: Local Unitary Invariancementioning

confidence: 99%

Entanglement-induced state ordering under local operations

Ziman

Bužek

2006

Phys. Rev. A

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We analyze how entanglement between two components of a bipartite system behaves under the action of local channels of the form E ⊗ I. We show that a set of maximally entangled states is by the action of E ⊗ I transformed into the set of states that exhibit the same degree of entanglement. Moreover, this degree represents an upper bound on entanglement that is available at the output of the channel irrespective what is the input state of the composite system. We show that within this bound the the entanglement-induced state ordering is "relative" and can be changed by the action of local channels. That is, two states ̺ The success of quantum information theory [1,2] is intimately related to the phenomenon of quantum entanglement. The better we will understand properties of this purely quantum phenomenon the deeper will be our insight into the quantum realm. Even though the importance of quantum entanglement has been clearly acknowledged by founding fathers of quantum mechanics [3], the true potential of this phenomenon has been appreciated just recently with the development of quantum information science. Over last ten years many results of fundamental importance illuminating properties of quantum entanglement have been reported. In spite of all the progress, there are still many questions that are to be answered. In particular, criteria of non-separability of arbitrarily-dimensional bi-partite systems, the study of intrinsic multi-partite entanglement in composite quantum systems [4,5], or the role of quantum entanglement in macroscopic systems is presently under investigation [6]. One of the problems that has attracted interest of researchers for quite some time is the issue of "proper" measures of entanglement [7].In general, we can identify two conceptually different approaches in various attempt to define measures of entanglement. These can be named as i) the operational approach, and ii) the formal (abstract) approach. The operational approach is based on an assumption that there exists a process, or an information protocol, in which the quantum entanglement plays the role of a new resource that provides some improvement in the performance of the protocol compared to its "classical analogue". The second approach [7] is based on postulation of the desired properties that an entanglement measure has to satisfy and defines a functional with these properties (see below).In this paper we will adopt this second approach. We will start our discussion by addressing a specific question concerning the entanglement measures. First, we will answer the question: Do local operations preserve the entanglement-induced ordering? Then we will analyze how entangled states that exhibit the same degree of entanglement are transformed under the action of local channels.Let us start with a trivial observation: States of bipartite quantum systems can be either entangled or separable (this is almost a tautological statement since the presence of entanglement is defined as an absence of the separability, and vice versa). On the oth...

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Entanglement versus mixedness for coupled qubits under a phase damping channel

Cited by 5 publications

References 25 publications

Decoherence induced by a phase-damping reservoir

Decoherence induced by a phase-damping reservoir

Relations between entanglement and purity in non-Markovian dynamics

Entanglement-induced state ordering under local operations

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