Long-Time Preservation of Nonlocal Entanglement

Bellomo, Bruno; Franco, Rosario Lo

doi:10.1166/asl.2009.1054

Cited by 40 publications

(43 citation statements)

References 28 publications

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“…It can be expressed as B = max{B 1 ,B 2 }, where B 1 , B 2 are functions of the density-matrix elements [49,55]. This quantity has been studied for independent qubits each coupled to a bosonic reservoir (cavity) with Markovian [56] and non-Markovian [11,57] features. For independent qubits subject to local pure dephasing noise, the two functions B 1 ,B 2 have the same form for the initial EWL states of Eq.…”

Section: Relation Between Entanglement and Nonlocality At Pure Dementioning

confidence: 99%

Preserving entanglement and nonlocality in solid-state qubits by dynamical decoupling

et al. 2014

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In this paper, we study how to preserve entanglement and nonlocality under dephasing produced by classical noise with large low-frequency components, such as 1/f noise, using dynamical decoupling techniques. We first show that quantifiers of entanglement and nonlocality satisfy a closed relation valid for two independent qubits locally coupled to a generic environment under pure dephasing and starting from a general class of initial states. This result allows us to assess the efficiency of pulse-based dynamical decoupling for protecting nonlocal quantum correlations between two qubits subject to pure-dephasing local random telegraph and 1/f noise. We investigate the efficiency of an "entanglement memory" element under two-pulse echo and under sequences of periodic, Carr-Purcell, and Uhrig dynamical decoupling. The Carr-Purcell sequence is shown to outperform the other sequences in preserving entanglement against both random telegraph and 1/f noise. For typical 1/f flux-noise figures in superconducting nanocircuits, we show that entanglement and its nonlocal features can be efficiently stored up to times one order of magnitude longer than natural entanglement disappearance times employing pulse timings of current experimental reach.

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Section: Relation Between Entanglement and Nonlocality At Pure Dementioning

confidence: 99%

Preserving entanglement and nonlocality in solid-state qubits by dynamical decoupling

et al. 2014

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“…Bell states, Werner states and Bell diagonal states belong to this class of states [34]. X-structure density matrices may arise in a wide variety of physical situations and are also experimentally achievable [35].…”

Section: Two-qubit X Statesmentioning

confidence: 99%

Unified view of correlations using the square-norm distance

et al. 2012

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The distance between a quantum state and its closest state not having a certain property has been used to quantify the amount of correlations corresponding to that property. This approach allows a unified view of the various kinds of correlations present in a quantum system. In particular, using relative entropy as a distance measure, total correlations can be meaningfully separated in a quantum and a classical part thanks to an additive relation involving only distances between states. Here, we investigate a unified view of correlations using as distance measure the square norm, already used to define the so-called geometric quantum discord. We thus consider geometric quantifiers also for total and classical correlations finding, for a quite general class of bipartite states, their explicit expressions. We analyze the relationship among geometric total, quantum and classical correlations and we find that they do not satisfy anymore a closed additivity relation.

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“…With regard to the initial state |Ψ(0) ABE of the whole system, it is interesting to find that the entanglement between two qubits can be trapped after a certain time t in the photonic band gap without any measurements to qubits [18][19][20][21][22]. And we know that entanglement can be protected and increased by weak measurement and quantum measurement reversal [26].…”

Section: Scheme For Enhancing Entanglement Trappingmentioning

confidence: 99%

“…Hence, methods that can prevent the decay of the excited-state population would be applicable. One way widely applied is to place the qubits in a structured environment, say, microcavity [15,16] or in the photonic band gap of photonic crystals [17][18][19]. In particular, in the photonic band gaps so as to inhibit spontaneous emission, a trapping state is formed and permanent entanglement is observed.…”

Section: Introductionmentioning

confidence: 99%