Quantum disentanglement eraser: A cavity QED implementation

Zubairy, M. Suhail; Agarwal, G. S.; Scully, Marlan O.

doi:10.1103/physreva.70.012316

Cited by 37 publications

(23 citation statements)

References 24 publications

(23 reference statements)

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“…Recently, Zubairy et all [58] have suggested a new scheme in their examination of the quantum disentanglement eraser. In this simple scheme, the concurrence can be directly measured from the visibility for an explicit class of entangled states.…”

Section: Bipartite Model Systemmentioning

confidence: 99%

Entanglement in two-mode continuous variable open quantum systems

Исар

2011

Phys. Scr.

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Abstract. Entanglement plays a crucial role in quantum information protocols, thus the dynamical behavior of entangled states is of a great importance. In this paper we suggest a useful scheme that permits a direct measure of entanglement in a two-qubit cavity system. It is realized in the cavity-QED technology utilizing atoms as flying qubits. To quantify entanglement we use the concurrence. We derive the conditions, which assure that the state remains entangled in spite of the interaction with the reservoir. The phenomenon of sudden death entanglement (ESD) in a bipartite system subjected to squeezed vacuum reservoir is examined. We show that the sudden death time of the entangled states depends on the initial preparation of the entangled state and the parameters of the squeezed vacuum reservoir.

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Section: Bipartite Model Systemmentioning

confidence: 99%

Entanglement in two-mode continuous variable open quantum systems

Исар

2011

Phys. Scr.

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“…There are two possible paths for the atom to end up in |e , that is it can absorb a photon and transmit to |e in Cavity A or B [95]. The visibility of this interference pattern is 2|αβ|, which coincides with the concurrence of the initial cavity state |ϕ 1 .…”

Section: The Concurrence Measures For the Atomic Statementioning

confidence: 90%

“…The key element of the protocol is the single-particle interference, whose principle is shown in Figure 14 [95]. The two cavities A and B are prepared in the entangled state as |ϕ 1 = α|0 A |1 B + β|1 A |0 B , where α = |α|e iθa , β = |β|e iθa and |α| 2 + |β| 2 = 1.…”

Section: The Concurrence Measures For the Atomic Statementioning

confidence: 99%

Concurrence Measurement for the Two-Qubit Optical and Atomic States

Zhou

Sheng

2015

Entropy

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Concurrence provides us an effective approach to quantify entanglement, which is quite important in quantum information processing applications. In the paper, we mainly review some direct concurrence measurement protocols of the two-qubit optical or atomic system. We first introduce the concept of concurrence for a two-qubit system. Second, we explain the approaches of the concurrence measurement in both a linear and a nonlinear optical system. Third, we introduce some protocols for measuring the concurrence of the atomic entanglement system.

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“…1 that was considered by Zubairy, et al [31] in their investigation of the quantum disentanglement eraser. In this simple scheme, the concurrence can be directly measured from the visibility for a specific class of entangled state.…”

mentioning

confidence: 99%

Proposal for direct measurement of concurrence via visibility in a cavity QED system

Lee

et al. 2008

Phys. Rev. A

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An experimental scheme is proposed that allows direct measurement of the concurrence of a twoqubit cavity system. It is based on the cavity-QED technology using atoms as flying qubits and relies on the identity of the two-particle visibility of the atomic probability with the concurrence of the cavity system. The scheme works for any arbitrary pure initial state of the two-qubit cavity system.The question of how to detect the presence and amount of entanglement is one of the central issues in quantum information science. There exist theoretical criteria and measures such as the positive partial transpose (PPT) criterion [1,2], entanglement of formation [3] and concurrence [4] that, in principle, allow one to determine the presence and amount of entanglement. It is, however, difficult to observe such criteria and measures experimentally. The PPT criterion involves a nonphysical operation of partial transposition (complex conjugation) of the density matrix elements, while the entanglement of formation and the concurrence are complicated nonlinear functions of the system state. One is thus led to think that one may have to rely on the technique of a full tomographic reconstruction of the quantum state to measure the entanglement of an unknown quantum state. This technique, although successfully implemented for small systems [5,6], is highly inefficient and difficult especially for large systems, as a large number of observables need to be measured. The question naturally arises whether entanglement can be estimated without having to fully reconstruct the unknown state. It has been shown that the answer to this question is yes at least for the case of pure two-qubit states [7,8], although, even in this case, more than one observable need to be measured.In recent years, several methods [9,10,11,12,13] have been proposed for detecting and measuring entanglement without a full reconstruction of the state; e.g., the method [9] based on the technique of minimal and optimal tomography [14,15] performed on one of the entangled pair, the method [10] based on entanglement witness [16,17] which was realized experimentally [18], the method [11,12] based on PPT criterion [1,2], and the method [13] based on two-particle interferometry [19,20]. These methods, although much simpler than the full state reconstruction, are not completely free of experimental difficulties, as they require either controlled unitary operations or some prior knowledge about the quantum state in question, or they can detect entanglement but not measure its amount.Very recently, direct measurement of the concurrence of a two-photon pure entangled state was demonstrated experimentally using linear optical means [21]. The experiment is based on the realization [22] that entanglement properties are well captured by the expectation value of a certain Hermitian operator with respect to two copies of a pure state. As such, this method requires measurements on two copies of a state. It also requires CNOT operations. Application of this method to matter qubits (a...

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Quantum disentanglement eraser: A cavity QED implementation

Cited by 37 publications

References 24 publications

Entanglement in two-mode continuous variable open quantum systems

Entanglement in two-mode continuous variable open quantum systems

Concurrence Measurement for the Two-Qubit Optical and Atomic States

Proposal for direct measurement of concurrence via visibility in a cavity QED system

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