One-norm geometric quantum discord under decoherence

Montealegre, J. D.; Paula, F. M.; Saguia, A.; Sarandy, M. S.

doi:10.1103/physreva.87.042115

Cited by 129 publications

(139 citation statements)

References 52 publications

(56 reference statements)

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“…(9), where the elements of J, M |σ ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae ae aeae aeae aeaeae aeaeaeae aeaeaeaeaeaeaeaeaeaeaeaeaeae aeaeae Until now, the double sudden change have been observed theoretically in the original version of quantum discord [8,9], as first reported in Ref. [33], and in the geometric version of quantum discord [34]. Subsequently, an experimental measurement of its geometric version was reported in Ref.…”

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confidence: 82%

Elucidating Dicke superradiance by quantum uncertainty

Santos¹,

Duzzioni²

2016

Phys. Rev. A

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Recently it was shown in Ref. [Phys. Rev. Lett. 112, 140402 (2014)] that in the idealized Dicke model of superradiance there is no entanglement among any partitions of the system during the total evolution time of the system. This result immediately conducts us to question if other measures from quantum information theory can explain the characteristic release of energy in a short time interval. In this work we identify the uncertainty of purely quantum origin as the property responsible for Dicke superradiance. The quantum uncertainty on the population of each emitter of the sample captured by the Wigner-Yanase skew information (WYSI) is proportional to the correlation radiation rate, which is the part of the total radiated power coming from dipole correlations and responsible for releasing in a short time a great intensity of radiation energy. We also show that the correlation measure called local quantum uncertainty, which is the minimization of the WYSI over all local observables, presents a double sudden change induced by environment. The time window between these two sudden changes is used to define the interval in which symmetric global observables of the system behave classically for N → ∞, although the emitters remain strongly quantum correlated.Unveiling the resources behind several intriguing quantum phenomena is a hard task. It is known that for pure state quantum computation entanglement is necessary to obtain an exponential speed-up in the processing time of some quantum algorithms [1-6] when compared to their best classical performance [7]. However, for mixed state quantum computation, necessary conditions are elusive, although quantum discord [8,9] could be a good candidate in the deterministic quantum computation model [10]. There are other protocols in which discordant states are crucial to take advantage from the quantum world: the work extraction by Maxwell's demon [11] What is interesting in all these protocols is that entanglement, which has been in the spotlight for decades, gives way to new kinds of quantum correlations [17,18].By its turn, Dicke superradiance is a cooperative phenomenon in which a sample composed by N identical emitters can release an amount of radiation energy in a time window N times shorter than the characteristic emission time of one isolated emitter and the intensity of the radiation scales with N 2 [19]. The great interest in Dicke superradiance is not only from the point of view of foundational aspects of quantum theory, but also the possibility of building superradiant lasers [20] is relevant for precision measurement science. Furthermore, for efficient collection and transfer of solar energy in light harvesting complexes, plants benefit from the superradiant processes [21][22][23].In the particular case of superradiance in which all emitters are initially excited, the state of the system remains a linear convex combination of Dicke states the whole time. As a Dicke state (see Eq. (5)) is a highly entangled state, except the states |J, J and |J, −J , it * eduardo...

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confidence: 82%

Elucidating Dicke superradiance by quantum uncertainty

Santos¹,

Duzzioni²

2016

Phys. Rev. A

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“…This motivates us to investigate the behavior of the initial entangled states passing through this channel. The evolution of the state (1) under the effect of the generalized amplitude damped channel [9] is given by,…”

Section: Noise Channelmentioning

confidence: 99%

“…The current manuscript is different from the previous manipulation [9], where it is assumed that both qubit interact with the noise channel. The noise could be correlated or non-correlated.…”

Section: Introductionmentioning

confidence: 98%

Single and double changes of entanglement

Metwally

2014

J. Opt. Soc. Am. B

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Entanglement behavior for different classes of two qubit systems passing through a generalized amplitude damping channel is discussed. The phenomena of sudden single, double changes and the sudden death of entanglement are reported for correlated and non-correlated noise. It is shown that, for less entangled states, these phenomena appear for small values of channel strength. The effect of the channel can be frozen for these classes as one increases the channel strength. Maximum entangled states are more fragile than partial entangled states, where the entanglement decays very fast. However, one can not freeze the effect of the noise channel for systems initially prepared in maximum entangled states. The decay rate of entanglement for systems affected by non-correlated noise is much larger than that affected by correlated noise.

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“…As it can be inferred from figure 2, the quantum discord D 2 in the states (24) reaches its minimal value for c 1 = α 2 . These "minimally discordant" states are given by (37). Recall that the states of type (37) exhibit the maximal amount of total correlation T 2 (see figure 1).…”

Section: Closest Classical Statementioning

confidence: 99%

Unified scheme for correlations using linear relative entropy

Daoud

Laamara²,

Kaydi³

2014

Physics Letters A

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A linearized variant of relative entropy is used to quantify in a unified scheme the different kinds of correlations in a bipartite quantum system. As illustration, we consider a two-qubit state with parity and exchange symmetries for which we determine the total, classical and quantum correlations. We also give the explicit expressions of its closest product state, closest classical state and the corresponding closest product state. A closed additive relation, involving the various correlations quantified by linear relative entropy, is derived.

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One-norm geometric quantum discord under decoherence

Cited by 129 publications

References 52 publications

Elucidating Dicke superradiance by quantum uncertainty

Elucidating Dicke superradiance by quantum uncertainty

Single and double changes of entanglement

Unified scheme for correlations using linear relative entropy

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