Spotlighting quantum critical points via quantum correlations at finite temperatures

Werlang, T.; Ribeiro, G.A.P.; Rigolin, Gustavo

doi:10.1103/physreva.83.062334

Cited by 83 publications

(81 citation statements)

References 54 publications

(68 reference statements)

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“…All separations between the pairs are considered. Several important studies of the quantum discord in spins chains have been made [41][42][43][44][45][46][47][48][49][50][51][52], but the relation to the generalized information deficit and the differences between their optimizing measurements in these spin pairs have not yet been analyzed in detail. We have recently investigated these aspects for an XX spin chain in [51] and will here extend this analysis to the anisotropic XY case.…”

Section: Introductionmentioning

confidence: 99%

Quantum Discord and Information Deficit in Spin Chains

Canosa

Ciliberti

Rossignoli

2015

Entropy

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Abstract:We examine the behavior of quantum correlations of spin pairs in a finite anisotropic XY spin chain immersed in a transverse magnetic field, through the analysis of the quantum discord and the conventional and quadratic one-way information deficits. We first provide a brief review of these measures, showing that the last ones can be obtained as particular cases of a generalized information deficit based on general entropic forms. All of these measures coincide with an entanglement entropy in the case of pure states, but can be non-zero in separable mixed states, vanishing just for classically correlated states. It is then shown that their behavior in the exact ground state of the chain exhibits similar features, deviating significantly from that of the pair entanglement below the critical field. In contrast with entanglement, they reach full range in this region, becoming independent of the pair separation and coupling range in the immediate vicinity of the factorizing field. It is also shown, however, that significant differences between the quantum discord and the information deficits arise in the local minimizing measurement that defines them. Both analytical and numerical results are provided.

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Section: Introductionmentioning

confidence: 99%

Quantum Discord and Information Deficit in Spin Chains

Canosa

Ciliberti

Rossignoli

2015

Entropy

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“…For the present XXZ model with h = 4.0 and J = 1.0 we obtain ∆ inf ≈ 2.74 [31,38,39]. We have not observed, however, any quantitative or qualitative changes in the behavior of the efficiencies.…”

Section: Efficiency As a Function Of The Coupling Constantsmentioning

confidence: 62%

“…In this scenario the quantum state describing the entangled resource is the canonical ensemble density matrix and any entanglement present in that state is usually dubbed thermal entanglement [24][25][26][27][28][29][30][31][32].…”

Section: Discussionmentioning

confidence: 99%

“…The quantum state of a two-qubit system in equilibrium with a thermal reservoir is described by the canonical ensemble density matrix and whenever entanglement is present between the two qubits it is usually called thermal entanglement [24][25][26][27][28][29][30][31][32]. In this manuscript we model the interaction between the qubits of the entangled resource via the Heisenberg Hamiltonian, either without or with an external magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Probabilistic quantum teleportation via thermal entanglement

Fortes

Rigolin

2017

Phys. Rev. A

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We study the probabilistic (conditional) teleportation protocol when the entanglement needed to its implementation is given by thermal entanglement, i.e., when the entangled resource connecting Alice and Bob is an entangled mixed state described by the canonical ensemble density matrix. Specifically, the entangled resource we employ here is given by two interacting spin-1/2 systems (two qubits) in equilibrium with a thermal reservoir at temperature T . The interaction between the qubits is described by a Heisenberg-like Hamiltonian, encompassing the Ising, the XX, the XY, the XXX, and XXZ models, with or without external fields. For all those models we show analytically that the probabilistic protocol is exactly equal to the deterministic one whenever we have no external field. However, when we turn on the field the probabilistic protocol outperforms the deterministic one in several interesting ways. Under certain scenarios, for example, the efficiency (average fidelity) of the probabilistic protocol is greater than the deterministic one and increases with increasing temperature, a counterintuitive behavior. We also show regimes in which the probabilistic protocol operates with relatively high success rates and, at the same time, with efficiency greater than the classical limit 2/3, a threshold that cannot be surpassed by any protocol using only classical resources (no entanglement shared between Alice and Bob). The deterministic protocol's efficiency under the same conditions is below 2/3, highlighting that the probabilistic protocol is the only one yielding a genuine quantum teleportation. We also show that near the quantum critical points for almost all those models the qualitative and quantitative behaviors of the efficiency change considerably, even at finite T .

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“…In recent years, the techniques of quantum information theory have been implemented for the investigation of quantum critical systems. For instance, several correlation measures have been shown to identify the critical points of QPTs with success in quantum critical spin chains [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Quantum correlations in a few-atom spin-1 Bose–Hubbard model

Çakmak¹,

Karpat²,

Gedik³

2013

Phys. Scr.

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Abstract. We study the thermal quantum correlations and entanglement in spin-1 Bose-Hubbard model with two and three particles. While we use negativity to calculate entanglement, more general non-classical correlations are quantified using a new measure based on a necessary and sufficient condition for zero-discord state. We demonstrate that the energy level crossings in the ground state of the system are signalled by both the behavior of thermal quantum correlations and entanglement.

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Spotlighting quantum critical points via quantum correlations at finite temperatures

Cited by 83 publications

References 54 publications

Quantum Discord and Information Deficit in Spin Chains

Quantum Discord and Information Deficit in Spin Chains

Probabilistic quantum teleportation via thermal entanglement

Quantum correlations in a few-atom spin-1 Bose–Hubbard model

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