Showing papers on "Concurrence published in 2019"
TL;DR: In this article, the authors provide classes of monogamy and polygamy inequalities of multiqubit entanglement in terms of concurrence and negativity, and show that these inequalities are tighter than the existing ones for some classes of quantum states.
Abstract: Monogamy and polygamy relations characterize the distributions of entanglement in multipartite systems. We provide classes of monogamy and polygamy inequalities of multiqubit entanglement in terms of concurrence, entanglement of formation, negativity, Tsallis-$q$ entanglement and Renyi-$\alpha$ entanglement, respectively. We show that these inequalities are tighter than the existing ones for some classes of quantum states.
27 citations
TL;DR: Application of these results to quantum correlations like squared convex-roof extended negativity, entanglement of formation and Tsallis-qEntanglement gives rise to either tighter inequalities than the existing ones for some classes of quantum states or less restrictions on the quantum states.
Abstract: We study the distribution of quantum correlations characterized by monogamy relations in multipartite systems. By using the Hamming weight of the binary vectors associated with the subsystems, we establish a class of monogamy inequalities for multiqubit entanglement based on the $$\alpha $$th ($$\alpha \ge 2$$) power of concurrence, and a class of polygamy inequalities for multiqubit entanglement in terms of the $$\beta $$th ($$0\le \beta \le 2$$) power of concurrence and concurrence of assistance. Moveover, we give the monogamy and polygamy inequalities for general quantum correlations. Application of these results to quantum correlations like squared convex-roof extended negativity, entanglement of formation and Tsallis-q entanglement gives rise to either tighter inequalities than the existing ones for some classes of quantum states or less restrictions on the quantum states. Detailed examples are presented.
24 citations
21 citations
TL;DR: The generalized concurrence is a suitable measure of entanglement for multi-qubit graph states and is compared with equivalence classes of these graph states under local complementation (LC) operator to suggest that classification by generalized Concurrence is not in contradiction with the LC-rule.
Abstract: We propose a new classification for the entanglement in graph states based on generalized concurrence. The numerical results indicate that the eight different three-qubit graph states in three cate...
17 citations
TL;DR: In this paper, the authors provide classes of monogamy and polygamy inequalities of multiqubit entanglement in terms of concurrence and negativity, and show that these inequalities are tighter than the existing ones for some classes of quantum states.
Abstract: Monogamy and polygamy relations characterize the distributions of entanglement in multipartite systems. We provide classes of monogamy and polygamy inequalities of multiqubit entanglement in terms of concurrence, entanglement of formation, negativity, Tsallis-$q$ entanglement and Renyi-$\alpha$ entanglement, respectively. We show that these inequalities are tighter than the existing ones for some classes of quantum states.
15 citations
TL;DR: In this paper, the authors investigated the quantum correlation properties in the two qubits one-axis spin squeezing model with an external magnetic field by means of concurrence (C) and quantum discord (QD) criteria.
Abstract: In a recent article in this journal Guo-Hui (Int. J. Theor. Phys. 56, 600, 2017) has investigated the quantum correlation properties in the two qubits one-axis spin squeezing model with an external magnetic field by means of concurrence (C) and quantum discord (QD) criteria. We are to reveal numerically and analytically that in the limiting case T→ 0 (ground state) the sudden disappearance phenomenon (SDP) does not occur in the behavior of C and the values obtained for C are incorrect.
13 citations
11 citations
TL;DR: In this paper, it was shown that entanglement between two solitary qubits in quasi-one-dimensional Bose-Einstein condensates can be spontaneously generated due to quantum fluctuations.
Abstract: We show that entanglement between two solitary qubits in quasi-one-dimensional Bose-Einstein condensates can be spontaneously generated due to quantum fluctuations. Recently we have shown that dark solitons are an appealing platform for qubits thanks to their appreciable long lifetime. We investigate the spontaneous generation of entanglement between dark-soliton qubits in the dissipative process of spontaneous emission. By driving the qubits with the help of oscillating magnetic field gradients, we observe the formation of long distance steady-state concurrence. Our results suggest that dark-soliton qubits are good candidates for quantum information protocols based purely on matter-wave phononics.
11 citations
TL;DR: In this article, a generalization of the Bell's inequality for a two-qubit system is proposed, where the maximal violation is related to the entanglement formation in terms of a concurrence.
Abstract: It is well known that the maximal violation of the Bell’s inequality for a two-qubit system is related to the entanglement formation in terms of a concurrence. However, a generalization of this rel...
10 citations
TL;DR: Investigation of monogamy and polygamy relations in terms of concurrence, Rényi α-entropy entanglement and Tsallis q-ent entropy entanglements finds some relations are tighter than the existing monogamyand polygamy relations.
Abstract: In this paper, we investigate some monogamy and polygamy relations in terms of concurrence, Renyi α-entropy entanglement and Tsallis q-entropy entanglement. Those relations are tighter than the existing monogamy and polygamy relations. As application, we give some examples in detail.
10 citations
TL;DR: The purpose is to classify simple graphs of up to seven qubits into 45 categories using the concept of connected, non-isomorphic, and non-LC-equivalent graphs according to several relevant physical properties for quantum information theory.
Abstract: In this paper, we study the multipartite entanglement properties of graph states up to seven qubits. Our analysis shows that the generalized concurrence measure (GCM) is more efficient than geometric entanglement measure (GEM) for measuring entanglement quantity in the multi-qubit graph states.
TL;DR: In this article, the authors proposed an effective multiqubit dissipative-driven entanglement model for a plasmonic system, which takes into account coupling of the cavity and qubits as well as the direct coupling between any two qubits.
Abstract: A dissipative-driven system can generate steady-state entanglement robust to control parameters, while a quantum plasmonic system has the advantages of being strongly coupled to qubits and manipulation of electromagnetic waves in the subwavelength regime. We propose an effective multiqubit dissipative-driven entanglement model for a plasmonic system which takes into account coupling of the plasmonic cavity and qubits as well as the direct coupling between any two qubits and develop a numerical solution of the effective model on a scalable composite plasmonic structure. In this structure, the multiqubit entanglement under asymmetric detuning, especially for those combinations containing pairs of antisymmetric detuning qubits, achieves stronger steady-state entanglement measured by negativity and pairwise concurrence. The robustness of multiqubit entanglement against variations of the control parameters is also presented. In addition, the phenomenon of entanglement sudden death caused by the driving field in entanglement dynamics is investigated. Our model shows evidence that quantum plasmonics has great potential in multiqubit entanglement.
TL;DR: In this article, all measures of quantum correlations satisfy some kind of monogamy relations for arbitrary multipartite quantum states, and by introducing residual quantum correlations, they presented tighter monogamy inequalities that are better than all the existing ones.
TL;DR: In this paper, the authors show that polynomial entanglement measures of degree 2 of even-N qubits X states are in full agreement with the genuine multipartite concurrence.
TL;DR: In this paper, the robustness of entanglement in two qubits maximally entangled mixed states (MEME) have been studied under quantum decoherence channels, and interesting results have been found for sudden death and birth of Entanglement under bit flip and bit-phase-flip channels.
Abstract: In the present article, the robustness of entanglement in two qubits maximally entangled mixed states (MEME) have been studied under quantum decoherence channels. Here we consider bit flip, phase flip, bit-phase-flip, amplitude damping, phase damping and depolarization channels. To quantify the entanglement, the concurrence has been used as an entanglement measure. During this study interesting results have been found for sudden death and birth of entanglement under bit flip and bit-phase-flip channels. While amplitude damping channel produces entanglement sudden death and does not allow re-birth of entanglement. On the other hand, two qubits MEMS exhibit the robust character against the phase flip, phase damping and depolarization channels. The elegant behavior of all the quantum channels have been investigated with varying parameter of quantum state MEMS in different cases.
TL;DR: In this paper, the generalized monogamy and polygamy relations N-qubit systems were investigated and an upper bound of the αth (0 ≤ α ≤ ≤ 2) power of concurrence was derived for pure N-bit pure states under the partition AB and C1...CN− 2.
Abstract: We investigate the generalized monogamy and polygamy relations N-qubit systems. We give a general upper bound of the αth (0 ≤ α ≤ 2) power of concurrence for N-qubit states. The monogamy relations satisfied by the αth (0 ≤ α ≤ 2) power of concurrence are presented for N-qubit pure states under the partition AB and C1...CN− 2, as well as under the partition ABC1 and C2⋯CN− 2. These inequalities give rise to the restrictions on entanglement distribution and the trade off of entanglement among the subsystems. Similar results are also derived for negativity.
TL;DR: In this article, the authors studied quantum entanglement and its relation to transport in a non-equilibrium interacting double-dot system connected to electronic baths using an exact numerical approach.
Abstract: We study quantum entanglement and its relation to transport in a non-equilibrium interacting double dot system connected to electronic baths. The dynamical properties in the non-interacting regime are studied using an exact numerical approach whereas the steady state properties are obtained following the well-known non-equilibrium Green's function (NEGF) approach. By means of mutual information and concurrence we explore the connection between the quantum correlations in the system and the current flowing through the dots. It is observed that entanglement between the dots is heavily influenced by the degeneracy or the lack thereof, of the dot levels. In the non-degenerate case, the concurrence falls sharply when the applied bias crosses a certain critical value. In contrast when the dot energy levels are degenerate, the concurrence reaches a very high asymptotic value of 1/2. When interactions are switched on, the degeneracy is lifted, and once again concurrence falls to zero beyond a critical value of the applied bias. Lastly it is observed that the concurrence can be made to reach almost the value of 1.0 if the chemical potential in both baths is made very large (while keeping the sign the same) provided the dot levels are kept degenerate within the non-interacting limit. A combination of NEGF method, brute-force numerics and asymptotics are employed to corroborate our findings.
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TL;DR: It is shown that the entangling aspect of the so called entanglement fidelity is neither of typeEntanglement of formation and concurrence nor of type negativity.
Abstract: The notion of entanglement fidelity is to measure entanglement preservation through quantum channels. Nevertheless, the amount of entanglement present in a state of a quantum system at any time is measured by quantities known as measures of entanglement. Since there are different types of measures of entanglement, one may expect an entanglement fidelity to associate with its own measure of entanglement counterpart. Here, we aim to investigate association between the so called entanglement fidelity and some measures of entanglement, namely, entanglement of formation, concurrence and negativity. New entanglement fidelities based upon these measures of entanglement are introduced and statistically compared with the so called previously introduced entanglement fidelity. It is shown that the entangling aspect of the so called entanglement fidelity is neither of type entanglement of formation and concurrence nor of type negativity. The results, in addition, expose inability of the so called entanglement fidelity for detecting, in a broad sense, entanglement preservation through quantum channels. Our analyses opens up a new venue in the study of entanglement fidelity and measure of entanglement by demonstrating that each measure of entanglement solely defines its own entanglement fidelity.
TL;DR: In this article, the quantum entanglement of outgoing electrons in a nonrelativistic quantum collision on a target with one active electron is analyzed and quantified in terms of the experimentally measurable spin-resolved $(e,2e)$ triple differential cross sections.
Abstract: The theory of quantum information constitutes the functional value of the quantum entanglement, i.e., quantum entanglement is essential for high fidelity of quantum protocols, while fundamental physical processes behind the formation of quantum entanglement are less relevant for practical purposes. In the present work, we explore physical mechanisms leading to the emergence of quantum entanglement in the initially disentangled system. In particular, we analyze spin entanglement of outgoing electrons in a nonrelativistic quantum $(e,2e)$ collision on a target with one active electron. Our description exploits the time-dependent scattering formalism for typical conditions of scattering experiments, and contrary to the customary stationary formalism operates with realistic scattering states. We quantify the spin entanglement in the final scattering channel through the pair concurrence and express it in terms of the experimentally measurable spin-resolved $(e,2e)$ triple differential cross sections. Besides, we consider Bell's inequality and inspect the regimes of its violation in the final channel. We address both the pure and the mixed initial spin state cases and uncover kinematical conditions of the maximal entanglement of the outgoing electron pair. The numerical results for the pair concurrence, entanglement of formation, and violation of Bell's inequality obtained for the $(e,2e)$ ionization process of atomic hydrogen show that the entangled electron pairs indeed can be formed in the $(e,2e)$ collisions even with spin-unpolarized projectile and target electrons in the initial channel. The positive entanglement balance---the difference between entanglements of the initial and final electron pairs---can be measured in the experiment.
01 Jan 2019
TL;DR: In this paper, a different kind of monogamy and polygamy relations based on concurrence and concurrence of assistance for multiqubit systems is presented, and a smaller upper bound of the power of concurrence for multi-bit states is obtained.
Abstract: We present a different kind of monogamy and polygamy relations based on concurrence and concurrence of assistance for multiqubit systems. By relabeling the subsystems associated with different weights, a smaller upper bound of the $\alpha$th ($0\leq\alpha\leq2$) power of concurrence for multiqubit states is obtained. We also present tighter monogamy relations satisfied by the $\alpha$th ($0\leq\alpha\leq2$) power of concurrence for $N$-qubit pure states under the partition $AB$ and $C_1 . . . C_{N-2}$, as well as under the partition $ABC_1$ and $C_2\cdots C_{N-2}$. These inequalities give rise to the restrictions on entanglement distribution and the trade off of entanglement among the subsystems. Similar results are also derived for negativity.
TL;DR: In this paper, the authors provide an initial characterization of pairwise concurrence in quantum states which are invariant under cyclic permutations of party labeling and give explicit descriptions of those states in specific subsets of four and five-qubit states (X states).
Abstract: We provide an initial characterization of pairwise concurrence in quantum states which are invariant under cyclic permutations of party labeling. We prove that maximal entanglement can be entirely described by adjacent pairs, then give explicit descriptions of those states in specific subsets of four- and five-qubit states (X states). We also construct a monogamy bound on shared concurrences in the same subsets in four and five qubits, finding that above nonmaximal entanglement thresholds, no other entanglements are possible.
TL;DR: In this paper, the authors study the competition between a bank and a mobile operator in a market where services are differentiated horizontally, and show that there is no Nash equilibrium in pure strategy in regard to simultaneous play, but that a leader-follower structure leads to equilibrium and allows firms to make positive profits.
Abstract: L’objet de cet article est d’etudier, sous forme d’un jeu, la concurrence entre une banque et un operateur de telephonie mobile sur un marche ou les services sont differencies horizontalement. L’hypothese retenue dans cette etude est que les firmes se font une concurrence en localisation geographique, et le choix de localisation sera interprete comme un choix dans un espace de produits. Pour ce faire, le modele de Hotelling a ete mobilise pour apprehender d’une part, l’impact de la concurrence sur l’industrie bancaire en Afrique, et d’autre part, les avantages strategiques dont beneficient les deux acteurs. Il ressort de cette etude qu’il n’existe pas d’equilibre de Nash en strategie pure en jeu simultane, mais qu’une structure de « leader-follower » conduit a l’equilibre et permet aux firmes de realiser des profits positifs. Banques et operateurs de telephonie mobile ont donc un avantage mutuel a cooperer, sous des formes diverses qui restent a definir, plutot qu’a se faire concurrence.
This paper focuses on studying, in the form of a game, the competition between a bank and a mobile operator in a market where services are differentiated horizontally. The hypothesis used in this study shows that firms compete with one another within a geographic location. The choice of location will be interpreted using a product space. To achieve this, the Hotelling model was mobilized to understand, on the one hand, the impact of competition on the banking industry in Africa, and on the other hand, the strategic advantages enjoyed by both actors. This study shows that there is no Nash equilibrium in pure strategy in regard to simultaneous play, but that a leader-follower structure leads to equilibrium and allows firms to make positive profits. Banks and mobile phone operators therefore have a mutual advantage to cooperate, in various forms that are yet to be defined, rather than competing with each other.
TL;DR: In the 12th and 13th centuries, devotion to the Three Kings assumes traits of a more sensitive piety as discussed by the authors, and the concurrence of scenic, iconographic and specifically literary elements in the representation of Adoration, in addition to enriching manuscript contexts, propitiates the development of this theme associated with the preeminent affective devotion in the period.
Abstract: Particularly in the 12th and 13th centuries, devotion to the Three Kings assumes traits of a more sensitive piety. This goes to determine the basic components of the legend as we know it today. The Hispanic literary manifestation of the legend of the Magi in this time is concentrated only in two testimonies: Auto de los Reyes Magos and Libro de los tres reyes de Oriente. Comparative analysis makes it possible to distinguish the debate as the unifying structural tool from the theme of the search for truth and the practice of charity in both works. The concurrence of scenic, iconographic and specifically literary elements in the representation of Adoration, in addition to enriching manuscript contexts, propitiates the development of this theme associated with the preeminent affective devotion in the period.
TL;DR: The polygamy relations related to the concurrence for general higher-dimensional systems are investigated and quantum states are derived, better than the results of Zhu et al. (2017).
Abstract: We study monogamy relations for arbitrary dimensional multipartite systems. Monogamy relations based on concurrence and concurrence of assistance for any dimensional $$d_1\otimes d_2\otimes \ldots \otimes d_{n}$$
quantum states are derived, which is better than the results of Zhu et al. (Quantum Inf Process 16:279, 2017). Furthermore, we investigate the polygamy relations related to the concurrence for general higher-dimensional systems.
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TL;DR: In this paper, the concept de conventions de l'Etat peut etre utilise for developper une reflexion sur la politique europeenne, comme le fit Robert Salais en 2015 dans la Revue Francaise de Socio-Economie.
Abstract: Presente dans le cadre des Mondes de Production publie en 1993 par Robert Salais et Michael Storper, le concept de conventions de l’Etat peut etre utilise pour developper une reflexion sur la politique europeenne, comme le fit Robert Salais en 2015 dans la Revue Francaise de Socio-Economie. Cette contribution analyse a travers ce prisme la dynamique historique de la construction et de la mise en œuvre des regles de concurrence europeennes. Elle s’attache a l’influence de l’ordoliberalisme et la met en perspective avec l’approche par les effets. Elle conclut enfin sur les inflexions qu’il est possible d’observer dans la pratique decisionnelle europeenne au travers de preoccupations reliees a l’equite ou encore a l’equilibre des relations contractuelles entre operateurs sur le marche.
TL;DR: In grasping interconnected factors in the social seating of problems, Meier, Warde, and Holmes (2018) argue for a social practice theory that sees the social meaning, settings, and the nature of health-related activities as integrated in people’s daily lives.
Abstract: Mental health and substance use-related problems tend to gather and become part of greater problem nexuses. Researchers of different traditions have tried to devise ways to capture this circumstance. In comorbidity networks, human diseases are mapped broadly in entire populations (e.g., Chmiel, Klimek, & Thurner, 2014), while social epidemiology, for example, attempts to identify structural circumstances by formulating indicators and determinants. An attempt to grasp problems as intertwined is that undertaken by the European PARADISE consortium, which has launched a medical “horizontal epidemiology” (PARADISE, 2010). It challenges previous approaches that look for separate disease trajectories. Instead, horizontal epidemiology is meant to capture the fact that psychosocial difficulties, such as sleep disturbances, emotional instability and difficulties in personal interactions, and their environmental determinants are often related and share commonalities in the brain (Cieza et al., 2015). For people suffering from addiction, this may help to frame their problems as entangled – even if only in the diagnostic and medical sense. In grasping interconnected factors in the social seating of problems, Meier, Warde, and Holmes (2018) argue for a social practice theory that sees the social meaning, settings, and the nature of health-related activities as integrated in people’s daily lives. When practices are conceptualised as routine types of human activity that are made up of, and can be recognised by “the coming together of several interwoven elements” (Meier et al., 2018, p. 206), the authors see that alcohol research can shift its attention away from individuals and recognise contexts that have been neglected, especially in quantitative research. Within its social scientific scope, Nordic Studies on Alcohol and Drugs has sought to keep up to date with the multi-problems
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TL;DR: A fast quantum algorithm is presented to measure the Hamming distance between two or more Boolean functions provided as black-boxes, using concurrence entanglement measure.
Abstract: In this paper, we present a fast quantum algorithm to measure the Hamming distance between two or more Boolean functions provided as black-boxes. The proposed algorithm constructs a new black-box with a certain property which is utilized to solve this problem. The introduced algorithm converts measuring the Hamming distance between Boolean functions to measuring entanglement between qubits, using concurrence entanglement measure.