Entanglement increase from local interaction in the absence of initial quantum correlation in the environment and between the system and the environment

Sargolzahi, Iman; Mirafzali, Sayyed Yahya

doi:10.1103/physreva.97.022331

Cited by 7 publications

(4 citation statements)

References 35 publications

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“…Other examples of bipartite system and environment evolutions which lead to similar effects of entanglement increase (but not during pure dephasing) can be found in Ref. [65,66].…”

Section: Enhancement Of Two-qubit Entanglement Under Local Decohementioning

confidence: 78%

Equivalence of qubit-environment entanglement and discord generation via pure dephasing interactions and the resulting consequences

Roszak

Cywiński

2018

Phys. Rev. A

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We find that when a qubit initialized in a pure state experiences pure dephasing due to interaction with an environment, separable qubit-environment states generated during the evolution also have zero quantum discord with respect to the environment. What follows is that the set of separable states which can be reached during the evolution has zero volume and hence, such effects as sudden death of qubit-environment entanglement are very unlikely. In case of the discord with respect to the qubit, a vast majority of separable states qubit-environment is discordant, but in specific situations zero-discord states are possible. This is conceptually important since there is a connection between the discordance with respect to a given subsystem and the possibility of describing the evolution of this subsystem using completely positive maps. Finally, we use the formalism to find an exemplary evolution of an entangled state of two qubits that is completely positive, occurs solely due to interaction of only one of the qubits with its environment (so one could guess that it corresponds to a local operation, since it is local in a physical sense), but which nevertheless causes the enhancement of entanglement between the qubits. While this simply means that the considered evolution is completely positive, but does not belong to LOCC, it shows how much caution has to be exercised when identifying evolution channels that belong to that class.

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“…Other examples of bipartite system and environment evolutions which lead to similar effects of entanglement increase (but not during pure dephasing) can be found in Ref. [65,66].…”

Section: Enhancement Of Two-qubit Entanglement Under Local Decohementioning

confidence: 78%

Equivalence of qubit-environment entanglement and discord generation via pure dephasing interactions and the resulting consequences

Roszak

Cywiński

2018

Phys. Rev. A

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“…A similar case has been studied in Ref. [9]. There, it has been shown that the entanglement between W and S can exceed its initial value, indicating that the reduced dynamics of the witness-system cannot be written as E W ⊗ E S , since, under such local evolution, entanglement cannot increase [10].…”

Section: Introductionmentioning

confidence: 58%

Requiring linearity leads to complete positivity

Sargolzahi

2021

Preprint

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The reduced dynamics of an open quantum system S, interacting with its environment E, is not completely positive, in general. In this paper, we demonstrate that if the two following conditions are satisfied, simultaneously, then the reduced dynamics is completely positive: (1) the reduced dynamics of the system is linear, for arbitrary system-environment unitary evolution U ; and (2) the reduced dynamics of the system is linear, for arbitrary initial state of the system ρS.

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“…which gives the amount of entanglement, though present between A and B, is hidden (inaccessible) for us (see also Ref. [17]).…”

Section: Example: the Classical Environmentmentioning

confidence: 98%

Entanglement revival can occur only when the system–environment state is not a Markov state

Sargolzahi

2018

Quantum Inf Process

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Markov states have been defined for tripartite quantum systems. In this paper, we generalize the definition of the Markov states to arbitrary multipartite case and find the general structure of an important subset of them, which we will call strong Markov states. In addition, we focus on an important property of the Markov states: If the initial state of the whole system-environment is a Markov state, then each localized dynamics of the whole system-environment reduces to a localized subdynamics of the system. This provides us a necessary condition for entanglement revival in an open quantum system: Entanglement revival can occur only when the system-environment state is not a Markov state. To illustrate (a part of) our results, we consider the case that the environment is modeled as classical. In this case, though the correlation between the system and the environment remains classical during the evolution, the change of the state of the system-environment, from its initial Markov state to a state which is not a Markov one, leads to the entanglement revival in the system. This shows that the non-Markovianity of a state is not equivalent to the existence of non-classical correlation in it, in general.

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Entanglement increase from local interaction in the absence of initial quantum correlation in the environment and between the system and the environment

Cited by 7 publications

References 35 publications

Equivalence of qubit-environment entanglement and discord generation via pure dephasing interactions and the resulting consequences

Equivalence of qubit-environment entanglement and discord generation via pure dephasing interactions and the resulting consequences

Requiring linearity leads to complete positivity

Entanglement revival can occur only when the system–environment state is not a Markov state

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