Facets of tripartite entanglement
Indian Academy of Sciences (India)
Tripartite entangled states of systems 1, 2 and 3 involving nonorthogonal states are used to reveal two hitherto unexplored quantum effects. The ﬁrst shows that kinematic entanglement between the states of 1 and 2 can affect the result of dynamical interaction between 2 and 3, though 1 and 2 may be spatially separated so ...
Facets of tripartite entanglement
Indian Academy of Sciences (India)
Tripartite entanglement; nonorthogonality; unitarity; residual interaction; Einstein locality. PACS No. ... systems show testable violations of constraints derived from what is known as 'Einstein locality' or 'local ..... [6] A Einstein, in Albert Einstein: Philosopher-Scientist edited by P A Schilpp (Open Court, La. Salle, 1970) p. 85.
Tripartite Entanglement via Microwave Driven Atomic Coherence
Jin, Li-Xia; Lü, Xin-You; Song, Pei-Jun; Yang, Xiao-Xue
2010-04-01
We propose a new scheme to achieve the tripartite entanglement based on the standard criteria [Phys. Rev. A 67 (2003) 052315] in a inverse-tripod atomic system. In our scheme, the atomic coherence is introduced by two microwave fields which drive the upper three levels of atom. By numerically simulating the dynamics of system, we investigate the generation and evolution of entanglement in the presence of atom and cavity decay. As a result, the present research provides an efficient approach to achieve fully tripartite entanglement with different frequencies and initial states for each entangled mode, which may have impact on the progress of multicolored multi-notes quantum information networks.
Continuous Variable Tripartite Entanglement and a Teleportation Network
Aoki, Takao; Furusawa, Akira
2004-11-01
We experimentally generate a continuous variable tripartite entangled state and prove its full inseparability. By using this state, we develop a tripartite quantum teleportation network and perform teleportation of a coherent state with three different combinations of the sender, the receiver, and the controller.
$E_7$ and the tripartite entanglement of seven qubits
Duff, Michael J
2007-01-01
In quantum information theory, it is well known that the tripartite entanglement of three qubits is described by the group [SL(2,C)]^3 and that the entanglement measure is given by Cayley's hyperdeterminant. This has provided an analogy with certain N=2 supersymmetric black holes in string theory, whose entropy is also given by the hyperdeterminant. In this paper, we extend the analogy to N=8. We propose that a particular tripartite entanglement of seven qubits is described by the exceptional group E_7(C) and that the entanglement measure is given by Cartan's quartic E_7 invariant.
Detection of genuine tripartite entanglement and steering in hybrid optomechanics.
Xiang, Y; Sun, F X; Wang, M; Gong, Q H; He, Q Y
2015-11-16
Multipartite quantum entanglement is a key resource for ensuring security in quantum network. We show that by using a unified parameter in terms of reduced noise variances one can determine different types of tripartite entanglement of a given state generated in a hybrid optomechanical system, where an atomic ensemble is located inside a single-mode cavity with a movable mirror, with different thresholds for each type. In particular, the special quantum states which allow both entanglement and steering genuinely shared among atom-light-mirror modes can be observed, even though there is no direct interaction between the mirror and the atomic ensemble. We further show the robustness against mechanical thermal noise and damping, the relaxation time of atomic ensemble, as well as the effect of gain factors involved in the criteria. Our analysis provides an experimentally achievable method to determine the type of tripartite quantum correlation in a way.
Quantum frequency doubling based on tripartite entanglement with cavities
Juan, Guo; Zhi-Feng, Wei; Su-Ying, Zhang
2016-02-01
We analyze the entanglement characteristics of three harmonic modes, which are the output fields from three cavities with an input tripartite entangled state at fundamental frequency. The entanglement properties of the input beams can be maintained after their frequencies have been up-converted by the process of second harmonic generation. We have calculated the parametric dependences of the correlation spectrum on the initial squeezing factor, the pump power, the transmission coefficient, and the normalized analysis frequency of cavity. The numerical results provide references to choose proper experimental parameters for designing the experiment. The frequency conversion of the multipartite entangled state can also be applied to a quantum communication network. Project supported by the National Natural Science Foundation of China (Grant No. 91430109), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20111401110004), and the Natural Science Foundation of Shanxi Province, China (Grant No. 2014011005-3).
Tripartite entangled Wigner operator, the Wigner function and its marginal distributions
Fan Hong Yi
2003-01-01
For a tripartite entangled system, based on the newly constructed tripartite Einstein-Podolsky-Rosen entangled state, we find the entangled state representation of the Wigner operator. The corresponding Wigner function then leads us to obtain the physical marginal distributions. We emphasize that, for an entangled-particle system, the physical meaning of the Wigner distribution function should lie in that its marginal distributions give the probability of finding the particles in an entangled way.
Entanglement and quantum teleportation via decohered tripartite entangled states
Energy Technology Data Exchange (ETDEWEB)
Metwally, N., E-mail: nmohamed31@gmail.com
2014-12-15
The entanglement behavior of two classes of multi-qubit system, GHZ and GHZ like states passing through a generalized amplitude damping channel is discussed. Despite this channel causes degradation of the entangled properties and consequently their abilities to perform quantum teleportation, one can always improve the lower values of the entanglement and the fidelity of the teleported state by controlling on Bell measurements, analyzer angle and channel’s strength. Using GHZ-like state within a generalized amplitude damping channel is much better than using the normal GHZ-state, where the decay rate of entanglement and the fidelity of the teleported states are smaller than those depicted for GHZ state.
Thermal tripartite quantum correlations: quantum discord and entanglement perspectives
Behzadi, Naghi; Ahansaz, Bahram
2013-06-01
We investigate thermal tripartite quantum correlations for a spin star network and for a new extended version of it. In a spin star network, three peripheral spins interact with the central spin identically while in extended spin star network, three peripheral spins interact with two central spatially separated spins in the same way. We exploit the method of [C.C. Rulli, M.S. Sarandy, Phys. Rev. A 84, 042109 (2011)] to evaluate the tripartite quantum discord (TQD) and the method of [M. Li, S. Fei, Z. Wang, Rep. Math. Phys 65, 289 (2010)] called as lower bound of tripartite concurrence (LBTC) to evaluate the tripartite entanglement (TE) of the the peripheral parties in both systems. It is found that thermal TQD is much more robust than thermal TE as a function of temperature T. Also, the peripheral parties of the extended spin star network, in comparison with those of the spin star one, can exhibit higher values of TQD at T > 0. This, indeed, motivates us to realise improved quantum information and quantum computation tasks at finite temperatures.
Experimental generation of tripartite polarization entangled states of bright optical beams
Wu, Liang; Yan, Zhihui; Liu, Yanhong; Deng, Ruijie; Jia, Xiaojun; Xie, Changde; Peng, Kunchi
2017-01-01
The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite en...
Genuine Tripartite Entanglement in a Spin-Star Network at Thermal Equilibrium
Militello, B.; Messina, A.
2010-01-01
In a recent paper [M. Huber {\\it et al}, Phys. Rev. Lett. {\\bf 104}, 210501 (2010)] new criteria to find out the presence of multipartite entanglement have been given. We exploit these tools in order to study thermal entanglement in a spin-star network made of three peripheral spins interacting with a central one. Genuine tripartite entanglement is found in a wide range of the relevant parameters. A comparison between predictions based on the new criteria and on the tripartite negativity is a...
Genuine tripartite entanglement in a spin-star network at thermal equilibrium
Militello, B.; Messina, A.
2011-04-01
In a recent paper [M. Huber , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.104.210501 104, 210501 (2010)], new criteria to determine the presence of multipartite entanglement were given. We exploit these tools to study thermal entanglement in a spin-star network made of three peripheral spins interacting with a central one. Genuine tripartite entanglement is found in a wide range of the relevant parameters. A comparison between predictions based on the new criteria and those based on the tripartite negativity is also made.
Experimental generation of tripartite polarization entangled states of bright optical beams
Energy Technology Data Exchange (ETDEWEB)
Wu, Liang; Liu, Yanhong; Deng, Ruijie [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China); Yan, Zhihui; Jia, Xiaojun, E-mail: jiaxj@sxu.edu.cn; Xie, Changde; Peng, Kunchi [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006 (China)
2016-04-18
The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.
Experimental generation of tripartite polarization entangled states of bright optical beams
Wu, Liang; Yan, Zhihui; Liu, Yanhong; Deng, Ruijie; Jia, Xiaojun; Xie, Changde; Peng, Kunchi
2016-04-01
The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.
Tripartite entanglement from the cavity with second-order harmonic generation
Zhai, Shuqin; Yang, Rongguo; Fan, Daihe; Guo, Juan; Liu, Kui; Zhang, Junxiang; Gao, Jiangrui
2008-07-01
In this paper, tripartite entanglement among the two pump fields and the second-order harmonic field is established in the process of type-II second-order harmonic generation (SHG) with a triply resonant optical cavity below threshold. A sufficient inseparability criterion for continuous-variable tripartite entanglement proposed by van Loock and Furusawa is used to evaluate the degree of the quadrature-phase-amplitude correlations between the three modes. The dependence of the entanglement on the pump parameter and analysis frequency is also discussed. It is shown that the best entanglement appears at the appropriate pump power and analysis frequency. These three entangled states with different frequencies generated directly from a simple SHG process make the scheme useful for the application in quantum communication and network.
Directory of Open Access Journals (Sweden)
M Soltani
2015-12-01
Full Text Available In this work, we generalize the entanglement of three-qbit Bosonic systems beyond the single-mode approximation when one of the observers is accelerated. For this purpose, we review the effects of acceleration on field modes and quantum states. The single-mode approximation and beyond the single-mode approximation methods are introduced. After this brief introduction, the main problem of this paper, tripartite entanglement of bosonic systems in a noninertial frame beyond the single- mode approximation is investigated. The tripartite entangled states have different classes with GHZ and W states being most important. Here, we choose &pi-tangle as a measure of tripartite entanglement. If the three parties share GHZ state, the corresponding &pi-tangle will increase by increasing acceleration for some Unruh modes. This phenomenon, increasing entanglement, has never been observed in the single-mode approximation for bosonic case. Moreover, the &pi-tangle dose not exhibit a monotonic behavior with increasing acceleration. In the infinite acceleration limit, the &pi-tangle goes to different nonzero values for distinct Unruh modes. Unlike GHZ state, the entanglement of the W state shows only monotonically increasing and decreasing behaviors with increasing acceleration. Also, the entanglement for all possible choices of Unruh modes approaches only 0.176 in the high acceleration limit. Therefore, according to the quantum entanglement, there is no distinction between the single-mode approximation and beyond the single-mode approximation methods in this limit.
Generation of robust tripartite entanglement with a single-cavity optomechanical system
Yang, Xihua; Ling, Yang; Shao, Xuping; Xiao, Min
2017-05-01
We present a proposal to generate robust tripartite optomechanical entanglement with a single-cavity optomechanical system driven by a single input laser field. The produced stationary tripartite entanglement among two longitudinal cavity modes and a mirror oscillation mode via radiation pressure force exhibits robustness to the variation of the environment temperature when the cavity free spectral range is close to the mechanical oscillation frequency. The present optomechanical system can serve as an alternative intermediary for quantum-state exchange between two microwave (or optical) fields as well as between photons and the macroscopic mechanical oscillator, and may be potentially useful for quantum information processing and quantum networks.
Armstrong, Seiji; Wang, Meng; Teh, Run Yan; Gong, Qihuang; He, Qiongyi; Janousek, Jiri; Bachor, Hans-Albert; Reid, Margaret D.; Lam, Ping Koy
2015-02-01
Einstein, Podolsky and Rosen (EPR) pointed out in their famous paradox that two quantum-entangled particles can have perfectly correlated positions and momenta. Such correlations give evidence for the nonlocality of quantum mechanics and form the basis for quantum cryptography and teleportation. EPR steering is the nonlocality associated with the EPR paradox and has traditionally been investigated between only two parties. Using optical networks and efficient detection, we present experimental observations of multiparty EPR steering and of the genuine entanglement of three intense optical beams. We entangle the quadrature phase amplitudes of distinct fields, in analogy to the position-momentum entanglement of the original paradox. Our experiments complement tests of quantum mechanics that have entangled small systems or have demonstrated tripartite inseparability. Our methods establish principles for the development of multiparty quantum communication protocols with asymmetric observers, and can be extended to qubits, whether photonic, atomic, superconducting, or otherwise.
Daoud, M.; Jellal, A.; Choubabi, E. B.; El Kinani, E. H.
2011-08-01
We introduce a special class of truncated Weyl-Heisenberg algebra and discuss the corresponding Hilbertian and analytical representations. Subsequently, we study the effect of a quantum network of beam splitting on coherent states of this nonlinear class of harmonic oscillators. We particularly focus on quantum networks involving one and two beam splitters and examine the degree of bipartite as well as tripartite entanglement using the linear entropy.
Daoud, M.; Jellal, A.; Choubabi, E. B.; Kinani, E. H. El
2012-01-01
We introduce a special class of truncated Weyl-Heisenberg algebra and discuss the corresponding Hilbertian and analytical representations. Subsequently, we study the effect of a quantum network of beam splitting on coherent states of this nonlinear class of harmonic oscillators. We particularly focus on quantum networks involving one and two beam splitters and examine the degree of bipartite as well as tripartite entanglement using the linear entropy.
International Nuclear Information System (INIS)
Kenfack, Lionel Tenemeza; Tchoffo, Martin; Fai, Lukong Cornelius; Fouokeng, Georges Collince
2017-01-01
We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.
Energy Technology Data Exchange (ETDEWEB)
Kenfack, Lionel Tenemeza, E-mail: kenfacklionel300@gmail.com [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Tchoffo, Martin; Fai, Lukong Cornelius [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Fouokeng, Georges Collince [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Laboratoire de Génie des Matériaux, Pôle Recherche-Innovation-Entrepreneuriat (PRIE), Institut Universitaire de la Côte, BP 3001 Douala (Cameroon)
2017-04-15
We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.
Energy Technology Data Exchange (ETDEWEB)
Ding, Zhi-yong [School of Physics & Material Science, Anhui University, Hefei 230039 (China); School of Physics & Electronic Engineering, Fuyang Normal University, Fuyang 236037 (China); He, Juan, E-mail: juanhe78@163.com [School of Physics & Electronic Engineering, Fuyang Normal University, Fuyang 236037 (China); Ye, Liu, E-mail: yeliu@ahu.edu.cn [School of Physics & Material Science, Anhui University, Hefei 230039 (China)
2017-02-15
A feasible scheme for protecting the Greenberger–Horne–Zeilinger (GHZ) entanglement state in non-Markovian environments is proposed. It consists of prior weak measurement on each qubit before the interaction with decoherence environments followed by post quantum measurement reversals. It is shown that both the fidelity and concurrence of the GHZ state can be effectively improved. Meanwhile, we also verified that our scenario can enhance tripartite nonlocality remarkably. In addition, the result indicates that the larger the weak measurement strength, the better the effectiveness of the scheme with the lower success probability.
Directory of Open Access Journals (Sweden)
Gerardo Adesso
2013-05-01
Full Text Available We study a system represented by a Bose-Einstein condensate interacting with a cavity field in presence of a strong off-resonant pumping laser. This system can be described by a three-mode Gaussian state, where two are the atomic modes corresponding to atoms populating upper and lower momentum sidebands and the third mode describes the scattered cavity field light. We show that, as a consequence of the collective atomic recoil instability, these modes possess a genuine tripartite entanglement that increases unboundedly with the evolution time and is larger than the bipartite entanglement in any reduced two-mode bipartition. We further show that the state of the system exhibits genuine tripartite nonlocality, which can be revealed by a robust violation of the Svetlichny inequality when performing displaced parity measurements. Our exact results are obtained by exploiting the powerful machinery of phase-space informational measures for Gaussian states, which we briefly review in the opening sections of the paper.
Li, Yinan; Qiao, Youming; Wang, Xin; Duan, Runyao
2018-01-01
We study the problem of transforming a tripartite pure state to a bipartite one using stochastic local operations and classical communication (SLOCC). It is known that the tripartite-to-bipartite SLOCC convertibility is characterized by the maximal Schmidt rank of the given tripartite state, i.e. the largest Schmidt rank over those bipartite states lying in the support of the reduced density operator. In this paper, we further study this problem and exhibit novel results in both multi-copy and asymptotic settings, utilizing powerful results from the structure of matrix spaces. In the multi-copy regime, we observe that the maximal Schmidt rank is strictly super-multiplicative, i.e. the maximal Schmidt rank of the tensor product of two tripartite pure states can be strictly larger than the product of their maximal Schmidt ranks. We then provide a full characterization of those tripartite states whose maximal Schmidt rank is strictly super-multiplicative when taking tensor product with itself. Notice that such tripartite states admit strict advantages in tripartite-to-bipartite SLOCC transformation when multiple copies are provided. In the asymptotic setting, we focus on determining the tripartite-to-bipartite SLOCC entanglement transformation rate. Computing this rate turns out to be equivalent to computing the asymptotic maximal Schmidt rank of the tripartite state, defined as the regularization of its maximal Schmidt rank. Despite the difficulty caused by the super-multiplicative property, we provide explicit formulas for evaluating the asymptotic maximal Schmidt ranks of two important families of tripartite pure states by resorting to certain results of the structure of matrix spaces, including the study of matrix semi-invariants. These formulas turn out to be powerful enough to give a sufficient and necessary condition to determine whether a given tripartite pure state can be transformed to the bipartite maximally entangled state under SLOCC, in the asymptotic
Li, Yinan; Qiao, Youming; Wang, Xin; Duan, Runyao
2018-03-01
We study the problem of transforming a tripartite pure state to a bipartite one using stochastic local operations and classical communication (SLOCC). It is known that the tripartite-to-bipartite SLOCC convertibility is characterized by the maximal Schmidt rank of the given tripartite state, i.e. the largest Schmidt rank over those bipartite states lying in the support of the reduced density operator. In this paper, we further study this problem and exhibit novel results in both multi-copy and asymptotic settings, utilizing powerful results from the structure of matrix spaces. In the multi-copy regime, we observe that the maximal Schmidt rank is strictly super-multiplicative, i.e. the maximal Schmidt rank of the tensor product of two tripartite pure states can be strictly larger than the product of their maximal Schmidt ranks. We then provide a full characterization of those tripartite states whose maximal Schmidt rank is strictly super-multiplicative when taking tensor product with itself. Notice that such tripartite states admit strict advantages in tripartite-to-bipartite SLOCC transformation when multiple copies are provided. In the asymptotic setting, we focus on determining the tripartite-to-bipartite SLOCC entanglement transformation rate. Computing this rate turns out to be equivalent to computing the asymptotic maximal Schmidt rank of the tripartite state, defined as the regularization of its maximal Schmidt rank. Despite the difficulty caused by the super-multiplicative property, we provide explicit formulas for evaluating the asymptotic maximal Schmidt ranks of two important families of tripartite pure states by resorting to certain results of the structure of matrix spaces, including the study of matrix semi-invariants. These formulas turn out to be powerful enough to give a sufficient and necessary condition to determine whether a given tripartite pure state can be transformed to the bipartite maximally entangled state under SLOCC, in the asymptotic
Tang, Jingwu; Peng, Zhaohui
2010-01-01
We propose teleporting a specific family of tripartite entangled pure states, which include both the Greenberger-Horne-Zeilinger (GHZ) state and the W-class state, with the five-qubit cluster state. In this scheme, two different measurement strategies are introduced and the successful probability of both is one theoretically. In cavity quantum electrodynamics (QED), we propose generating the five-qubit cluster state and discuss the local measurement of the Bell state and the five-qubit cluster state. It is shown that our scheme may be realizable based on present cavity QED technology. In future, our scheme may be useful for establishing general tripartite entanglement in remote nodes of the communication network.
Scheme for demonstrating the Bell theorem in tripartite entanglement between atomic ensembles
Zhou Xi Bin; Guo Guang Can
2003-01-01
We propose an experimentally feasible scheme to demonstrate quantum nonlocality, using Greenberger-Horne-Zeilinger and W entanglement between atomic ensembles generated by a newly developed method based on laser manipulation and single-photon detection.
Genuine tripartite entanglement in quantum brachistochrone evolution of a three-qubit system
Zhao, Bao-Kui; Deng, Fu-Guo; Zhang, Feng-Shou; Zhou, Hong-Yu
2009-11-01
We explore the connection between quantum brachistochrone (time-optimal) evolution of a three-qubit system and its residual entanglement called three-tangle. The result shows that the entanglement between two qubits is not required for some brachistochrone evolutions of a three-qubit system. However, the evolution between two distinct states cannot be implemented without its three-tangle, except for the trivial cases in which less than three qubits attend evolution. Although both the probability density function of the time-averaged three-tangle and that of the time-averaged squared concurrence between two subsystems become more and more uniform with the decrease in angles of separation between an initial state and a final state, the features of their most probable values exhibit a different trend.
Quantum cobwebs: Universal entangling of quantum states
Indian Academy of Sciences (India)
Note that this tripartite entangled state is not a maximally entangled state. The ZSA states are not maximally fragile ... The combined state of the input and the tripartite. ZSA entangled state ψ a ª Ψ 123 can be .... be N parties in a network of N nodes each having access to a single qubit. They share. N-partite ZSA entangled ...
Quantum Entanglement Swapping between Two Multipartite Entangled States
Su, Xiaolong; Tian, Caixing; Deng, Xiaowei; Li, Qiang; Xie, Changde; Peng, Kunchi
2016-12-01
Quantum entanglement swapping is one of the most promising ways to realize the quantum connection among local quantum nodes. In this Letter, we present an experimental demonstration of the entanglement swapping between two independent multipartite entangled states, each of which involves a tripartite Greenberger-Horne-Zeilinger (GHZ) entangled state of an optical field. The entanglement swapping is implemented deterministically by means of a joint measurement on two optical modes coming from the two multipartite entangled states respectively and the classical feedforward of the measurement results. After entanglement swapping the two independent multipartite entangled states are merged into a large entangled state in which all unmeasured quantum modes are entangled. The entanglement swapping between a tripartite GHZ state and an Einstein-Podolsky-Rosen entangled state is also demonstrated and the dependence of the resultant entanglement on transmission loss is investigated. The presented experiment provides a feasible technical reference for constructing more complicated quantum networks.
Controlled dense coding for continuous variables using three-particle entangled states
Jing Zhang; Kun Chi Peng; 10.1103/PhysRevA.66.032318
2002-01-01
A simple scheme to realize quantum controlled dense coding with a bright tripartite entangled state light generated from nondegenerate optical parametric amplifiers is proposed in this paper. The quantum channel between Alice and Bob is controlled by Claire. As a local oscillator and balanced homodyne detector are not needed, the proposed protocol is easy to be realized experimentally. (15 refs)
Charcterization of multipartite entanglement
International Nuclear Information System (INIS)
Chong, Bo
2006-01-01
In this thesis, we discuss several aspects of the characterization of entanglement in multipartite quantum systems, including detection, classification and quantification of entanglement. First, we discuss triqubit pure entanglement and propose a special true tripartite entanglement, the mixed entanglement, besides the Greenberger-Horne-Zeilinger (GHZ) entanglement and the W entanglement. Then, based on quantitative complementarity relations, we draw entanglement Venn diagrams for triqubit pure states with different entanglements and introduce the total tangle τ (T) to quantify total entanglement of triqubit pure states by defining the union I that is equivalent to the total tangle τ (T) from the mathematical point of view. The generalizations of entanglement Venn diagrams and the union I to N-qubit pure states are also discussed. Finally, based on the ranks of reduced density matrices, we discuss the separability of multiparticle arbitrary-dimensional pure and mixed states, respectively. (orig.)
Charcterization of multipartite entanglement
Energy Technology Data Exchange (ETDEWEB)
Chong, Bo
2006-06-23
In this thesis, we discuss several aspects of the characterization of entanglement in multipartite quantum systems, including detection, classification and quantification of entanglement. First, we discuss triqubit pure entanglement and propose a special true tripartite entanglement, the mixed entanglement, besides the Greenberger-Horne-Zeilinger (GHZ) entanglement and the W entanglement. Then, based on quantitative complementarity relations, we draw entanglement Venn diagrams for triqubit pure states with different entanglements and introduce the total tangle {tau}{sup (T)} to quantify total entanglement of triqubit pure states by defining the union I that is equivalent to the total tangle {tau}{sup (T)} from the mathematical point of view. The generalizations of entanglement Venn diagrams and the union I to N-qubit pure states are also discussed. Finally, based on the ranks of reduced density matrices, we discuss the separability of multiparticle arbitrary-dimensional pure and mixed states, respectively. (orig.)
Residual entanglement and sudden death: A direct connection
Energy Technology Data Exchange (ETDEWEB)
Oliveira, J.G.G. de, E-mail: zgeraldo@ufrb.edu.br [Centro de Formação de Professores, Universidade Federal do Recôncavo da Bahia, 45.300-000, Amargosa, BA (Brazil); Departamento de Física, CP 702, Universidade Federal de Minas Gerais, 30123-970, Belo Horizonte, MG (Brazil); Peixoto de Faria, J.G., E-mail: jgpfaria@des.cefetmg.br [Departamento de Física e Matemática, Centro Federal de Educação Tecnológica de Minas Gerais, 30510-000, Belo Horizonte, MG (Brazil); Nemes, M.C., E-mail: carolina@fisica.ufmg.br [Departamento de Física, CP 702, Universidade Federal de Minas Gerais, 30123-970, Belo Horizonte, MG (Brazil)
2011-11-21
We explore the results of [V. Coffman, et al., Phys. Rev. A 61 (2000) 052306] derived for general tripartite states in a dynamical context. We study a class of physically motivated tripartite systems. We show that whenever entanglement sudden death occurs in one of the partitions residual entanglement will appear. For fourpartite systems however, the appearance of residual entanglement is not conditioned by sudden death of entanglement. We can only say that if sudden death of entanglement occurs in some partition there will certainly be residual entanglement. -- Highlights: ► For tripartite systems we show there exists residual entanglement if sudden death occurs. ► For fourpartite systems, the residual entanglement is not conditioned by sudden death. ► If sudden death of entanglement occurs there will certainly be residual entanglement.
Tripartite correlations over two octaves from cascaded harmonic generation
Olsen, M. K.
2018-03-01
We analyse the output quantum tripartite correlations from an intracavity nonlinear optical system which uses cascaded nonlinearities to produce both second and fourth harmonic outputs from an input field at the fundamental frequency. Using fully quantum equations of motion, we investigate two parameter regimes and show that the system produces tripartite inseparability, entanglement and EPR steering, with the detection of these depending on the correlations being considered.
Driven optomechanical systems for mechanical entanglement distribution
Paternostro, Mauro; Mazzola, Laura; Li, Jie
2012-08-01
We consider the distribution of entanglement from a multimode optical driving source to a network of remote and independent optomechanical systems. By focusing on the tripartite case, we analyse the effects that the features of the optical input states have on the degree and sharing structure of the distributed, fully mechanical, entanglement. This study, which is conducted looking at the mechanical steady state, highlights the structure of the entanglement distributed among the nodes and determines the relative efficiency between bipartite and tripartite entanglement transfer. We discuss a few open points, some of which are directed towards the bypassing of such limitations.
Conservation law for distributed entanglement of formation and quantum discord
International Nuclear Information System (INIS)
Fanchini, Felipe F.; Cornelio, Marcio F.; Oliveira, Marcos C. de; Caldeira, Amir O.
2011-01-01
We present a direct relation, based upon a monogamic principle, between entanglement of formation (EOF) and quantum discord (QD), showing how they are distributed in an arbitrary tripartite pure system. By extending it to a paradigmatic situation of a bipartite system coupled to an environment, we demonstrate that the EOF and the QD obey conservation relation. By means of this relation we show that in the deterministic quantum computer with one pure qubit the protocol has the ability to rearrange the EOF and the QD, which implies that quantum computation can be understood on a different basis as a coherent dynamics where quantum correlations are distributed between the qubits of the computer. Furthermore, for a tripartite mixed state we show that the balance between distributed EOF and QD results in a stronger version of the strong subadditivity of entropy.
Detection of Genuine Multipartite Entanglement in Quantum Network Scenario
Paul, Biswajit; Mukherjee, Kaushiki; Karmakar, Sumana; Sarkar, Debasis; Mukherjee, Amit; Roy, Arup; Bhattacharya, Some Sankar
2017-01-01
Experimental demonstration of entanglement needs to have a precise control of experimentalist over the system on which the measurements are performed as prescribed by an appropriate entanglement witness. To avoid such trust problem, recently device-independent entanglement witnesses (\\emph{DIEW}s) for genuine tripartite entanglement have been proposed where witnesses are capable of testing genuine entanglement without precise description of Hilbert space dimension and measured operators i.e a...
Entanglement via atomic coherence induced by two strong classical fields
Lü, Xin-You; Huang, Pei; Yang, Wen-Xing; Yang, Xiaoxue
2009-09-01
Based on the standard criteria [P. van Loock and A. Furusawa, Phys. Rev. A 67, 052315 (2003)], we propose a scheme to achieve the fully tripartite continuous-variable (CV) entanglement in a Y -type atomic system driven by two strong classical fields. By numerically simulating the dynamics of system, we show that the generation of entanglement does not depend intensively on the initial condition of cavity field and the time for which the cavity modes remain entangled can be prolonged via enhancing the intensities of classical fields in our scheme. Moreover, our numerical results also show that a tripartite entanglement amplifier can be realized in the present scheme. The present research provides an efficient approach to achieve fully tripartite CV entangled state even when the three entangled modes have different frequencies and initial states, which may be useful for the progress of quantum information networks with many nodes.
Graphical Classification of Entangled Qutrits
Directory of Open Access Journals (Sweden)
Kentaro Honda
2012-10-01
Full Text Available A multipartite quantum state is entangled if it is not separable. Quantum entanglement plays a fundamental role in many applications of quantum information theory, such as quantum teleportation. Stochastic local quantum operations and classical communication (SLOCC cannot essentially change quantum entanglement without destroying it. Therefore, entanglement can be classified by dividing quantum states into equivalence classes, where two states are equivalent if each can be converted into the other by SLOCC. Properties of this classification, especially in the case of non two-dimensional quantum systems, have not been well studied. Graphical representation is sometimes used to clarify the nature and structural features of entangled states. SLOCC equivalence of quantum bits (qubits has been described graphically via a connection between tripartite entangled qubit states and commutative Frobenius algebras (CFAs in monoidal categories. In this paper, we extend this method to qutrits, i.e., systems that have three basis states. We examine the correspondence between CFAs and tripartite entangled qutrits. Using the symmetry property, which is required by the definition of a CFA, we find that there are only three equivalence classes that correspond to CFAs. We represent qutrits graphically, using the connection to CFAs. We derive equations that characterize the three equivalence classes. Moreover, we show that any qutrit can be represented as a composite of three graphs that correspond to the three classes.
Greenberger-Horne-Zeilinger and W entanglement witnesses for the noninteracting Fermi gas
International Nuclear Information System (INIS)
Habibian, Hessam; Clark, John W.; Behbood, Naeimeh; Hingerl, Kurt
2010-01-01
The existence and nature of tripartite entanglement of a noninteracting Fermi gas (NIFG) is investigated. Three classes of parametrized entanglement witnesses (EWs) are introduced with the aim of detecting genuine tripartite entanglement in the three-body reduced density matrix and discriminating between the presence of the two types of genuine tripartite entanglement, W/B and GHZ/W (the convex set of B states is comprised of mixed states of product and biseparable states; that of W states is comprised of mixed states of B states and W-type pure entangled states; and the GHZ (Greenberger-Horne-Zeilinger) set contains generic mixtures of any kind for a tripartite system). By choosing appropriate EW operators, the problem of finding GHZ and W EWs is reduced to linear programming. Specifically, we devise W EWs based on a spin-chain model with periodic boundary conditions, and we construct a class of parametrized GHZ EWs by linearly combining projection operators corresponding to all the different state-vector types arising for a three-fermion system. A third class of EWs is provided by a GHZ stabilizer operator capable of distinguishing W/B from GHZ/B entanglement, which is not possible with W EWs. Implementing these classes of EWs, it is found that all states containing genuine tripartite entanglement are of W type, and hence states containing GHZ/W genuine tripartite entanglement do not arise. Some genuine tripartite entangled states that have a positive partial transpose (PPT) with respect to some bipartition are detected. Finally, it is demonstrated that a NIFG does not exhibit 'pure'W/B genuine tripartite entanglement: three-party entanglement without any separable or biseparable admixture does not occur.
Three qubit entanglement within graphical Z/X-calculus
Directory of Open Access Journals (Sweden)
Bob Coecke
2011-03-01
Full Text Available The compositional techniques of categorical quantum mechanics are applied to analyse 3-qubit quantum entanglement. In particular the graphical calculus of complementary observables and corresponding phases due to Duncan and one of the authors is used to construct representative members of the two genuinely tripartite SLOCC classes of 3-qubit entangled states, GHZ and W. This nicely illustrates the respectively pairwise and global tripartite entanglement found in the W- and GHZ-class states. A new concept of supplementarity allows us to characterise inhabitants of the W class within the abstract diagrammatic calculus; these method extends to more general multipartite qubit states.
Bipartite and Multipartite Entanglement of Gaussian States
Adesso, Gerardo; Illuminati, Fabrizio
In this chapter we review the characterization of entanglement in Gaussian states of continuous variable systems. For two-mode Gaussian states, we discuss how their bipartite entanglement can be accurately quantified in terms of the global and local amounts of mixedness, and efficiently estimated by direct measurements of the associated purities. For multimode Gaussian states endowed with local symmetry with respect to a given bipartition, we show how the multimode block entanglement can be completely and reversibly localized onto a single pair of modes by local, unitary operations. We then analyze the distribution of entanglement among multiple parties in multimode Gaussian states. We introduce the continuous-variable tangle to quantify entanglement sharing in Gaussian states and we prove that it satisfies the Coffman-Kundu-Wootters monogamy inequality. Nevertheless, we show that pure, symmetric three-mode Gaussian states, at variance with their discrete-variable counterparts, allow a promiscuous sharing of quantum correlations, exhibiting both maximum tripartite residual entanglement and maximum couplewise entanglement between any pair of modes. Finally, we investigate the connection between multipartite entanglement and the optimal fidelity in a continuous-variable quantum teleportation network. We show how the fidelity can be maximized in terms of the best preparation of the shared entangled resources and, viceversa, that this optimal fidelity provides a clearcut operational interpretation of several measures of bipartite and multipartite entanglement, including the entanglement of formation, the localizable entanglement, and the continuous-variable tangle.
E6 and the bipartite entanglement of three qutrits
International Nuclear Information System (INIS)
Duff, M. J.; Ferrara, S.
2007-01-01
Recent investigations have established an analogy between the entropy of four-dimensional supersymmetric black holes in string theory and entanglement in quantum information theory. Examples include: (1) N=2 STU black holes and the tripartite entanglement of three qubits (2-state systems), where the common symmetry is [SL(2)] 3 and (2) N=8 black holes and the tripartite entanglement of seven qubits where the common symmetry is E 7 superset of [SL(2)] 7 . Here we present another example: N=8 black holes (or black strings) in five dimensions and the bipartite entanglement of three qutrits (3-state systems), where the common symmetry is E 6 superset of [SL(3)] 3 . Both the black hole (or black string) entropy and the entanglement measure are provided by the Cartan cubic E 6 invariant. Similar analogies exist for magic N=2 supergravity black holes in both four and five dimensions
$E_{6}$ and the bipartite entanglement of three qutrits
Duff, M J
2007-01-01
Recent investigations have established an analogy between the entropy of four-dimensional supersymmetric black holes in string theory and entanglement in quantum information theory. Examples include: (1) N=2 STU black holes and the tripartite entanglement of three qubits (2-state systems), where the common symmetry is [SL(2)]^3 and (2) N=8 black holes and the tripartite entanglement of seven qubits where the common symmetry is E_7 which contains [SL(2)]^7. Here we present another example: N=8 black holes (or black strings) in five dimensions and the bipartite entanglement of three qutrits (3-state systems), where the common symmetry is E_6 which contains [SL(3)]^3. Both the black hole (or black string) entropy and the entanglement measure are provided by the Cartan cubic E_6 invariant. Similar analogies exist for ``magic'' N=2 supergravity black holes in both four and five dimensions.
Entanglement dynamics in quantum information theory
Energy Technology Data Exchange (ETDEWEB)
Cubitt, T.S.
2007-03-29
This thesis contributes to the theory of entanglement dynamics, that is, the behaviour of entanglement in systems that are evolving with time. Progressively more complex multipartite systems are considered, starting with low-dimensional tripartite systems, whose entanglement dynamics can nonetheless display surprising properties, progressing through larger networks of interacting particles, and finishing with infinitely large lattice models. Firstly, what is perhaps the most basic question in entanglement dynamics is considered: what resources are necessary in order to create entanglement between distant particles? The answer is surprising: sending separable states between the parties is sufficient; entanglement can be created without it being carried by a ''messenger'' particle. The analogous result also holds in the continuous-time case: two particles interacting indirectly via a common ancilla particle can be entangled without the ancilla ever itself becoming entangled. The latter result appears to discount any notion of entanglement flow. However, for pure states, this intuitive idea can be recovered, and even made quantitative. A ''bottleneck'' inequality is derived that relates the entanglement rate of the end particles in a tripartite chain to the entanglement of the middle one. In particular, no entanglement can be created if the middle particle is not entangled. However, although this result can be applied to general interaction networks, it does not capture the full entanglement dynamics of these more complex systems. This is remedied by the derivation of entanglement rate equations, loosely analogous to the rate equations describing a chemical reaction. A complete set of rate equations for a system reflects the full structure of its interaction network, and can be used to prove a lower bound on the scaling with chain length of the time required to entangle the ends of a chain. Finally, in contrast with these more
Entanglement dynamics in quantum information theory
International Nuclear Information System (INIS)
Cubitt, T.S.
2007-01-01
This thesis contributes to the theory of entanglement dynamics, that is, the behaviour of entanglement in systems that are evolving with time. Progressively more complex multipartite systems are considered, starting with low-dimensional tripartite systems, whose entanglement dynamics can nonetheless display surprising properties, progressing through larger networks of interacting particles, and finishing with infinitely large lattice models. Firstly, what is perhaps the most basic question in entanglement dynamics is considered: what resources are necessary in order to create entanglement between distant particles? The answer is surprising: sending separable states between the parties is sufficient; entanglement can be created without it being carried by a ''messenger'' particle. The analogous result also holds in the continuous-time case: two particles interacting indirectly via a common ancilla particle can be entangled without the ancilla ever itself becoming entangled. The latter result appears to discount any notion of entanglement flow. However, for pure states, this intuitive idea can be recovered, and even made quantitative. A ''bottleneck'' inequality is derived that relates the entanglement rate of the end particles in a tripartite chain to the entanglement of the middle one. In particular, no entanglement can be created if the middle particle is not entangled. However, although this result can be applied to general interaction networks, it does not capture the full entanglement dynamics of these more complex systems. This is remedied by the derivation of entanglement rate equations, loosely analogous to the rate equations describing a chemical reaction. A complete set of rate equations for a system reflects the full structure of its interaction network, and can be used to prove a lower bound on the scaling with chain length of the time required to entangle the ends of a chain. Finally, in contrast with these more abstract results, the entanglement and
Multipartite entanglement detection with nonsymmetric probing
DEFF Research Database (Denmark)
Dellantonio, Luca; Das, Sumanta; Appel, Jürgen
2017-01-01
We show that spin-squeezing criteria commonly used for entanglement detection can be erroneous if the probe is not symmetric. We then derive a lower bound on squeezing for separable states in spin systems probed asymmetrically. Using this we further develop a procedure that allows us to verify th...... the degree of entanglement of a quantum state in the spin system. Finally, we apply our method for entanglement verification to existing experimental data, and use it to prove the existence of tripartite entanglement in a spin-squeezed atomic ensemble.......We show that spin-squeezing criteria commonly used for entanglement detection can be erroneous if the probe is not symmetric. We then derive a lower bound on squeezing for separable states in spin systems probed asymmetrically. Using this we further develop a procedure that allows us to verify...
Avoiding disentanglement of multipartite entangled optical beams with a correlated noisy channel
Deng, Xiaowei; Tian, Caixing; Su, Xiaolong; Xie, Changde
2017-03-01
A quantum communication network can be constructed by distributing a multipartite entangled state to space-separated nodes. Entangled optical beams with highest flying speed and measurable brightness can be used as carriers to convey information in quantum communication networks. Losses and noises existing in real communication channels will reduce or even totally destroy entanglement. The phenomenon of disentanglement will result in the complete failure of quantum communication. Here, we present the experimental demonstrations on the disentanglement and the entanglement revival of tripartite entangled optical beams used in a quantum network. We experimentally demonstrate that symmetric tripartite entangled optical beams are robust in pure lossy but noiseless channels. In a noisy channel, the excess noise will lead to the disentanglement and the destroyed entanglement can be revived by the use of a correlated noisy channel (non-Markovian environment). The presented results provide useful technical references for establishing quantum networks.
Brachistochrone of entanglement for spin chains
Carlini, Alberto; Koike, Tatsuhiko
2017-03-01
We analytically investigate the role of entanglement in time-optimal state evolution as an application of the quantum brachistochrone, a general method for obtaining the optimal time-dependent Hamiltonian for reaching a target quantum state. As a model, we treat two qubits indirectly coupled through an intermediate qubit that is directly controllable, which represents a typical situation in quantum information processing. We find the time-optimal unitary evolution law and quantify residual entanglement by the two-tangle between the indirectly coupled qubits, for all possible sets of initial pure quantum states of a tripartite system. The integrals of the motion of the brachistochrone are determined by fixing the minimal time at which the residual entanglement is maximized. Entanglement plays a role for W and Greenberger-Horne-Zeilinger (GHz) initial quantum states, and for the bi-separable initial state in which the indirectly coupled qubits have a nonzero value of the 2-tangle.
Klyachko, Alexander A.; Shumovsky, Alexander S
2005-01-01
The paper contains a brief review of an approach to quantum entanglement based on analysis of dynamic symmetry of systems and quantum uncertainties, accompanying the measurement of mean value of certain basic observables. The latter are defined in terms of the orthogonal basis of Lie algebra, corresponding to the dynamic symmetry group. We discuss the relativity of entanglement with respect to the choice of basic observables and a way of stabilization of robust entanglement in physical systems.
Page curves for tripartite systems
International Nuclear Information System (INIS)
Hwang, Junha; Lee, Deok Sang; Nho, Dongju; Oh, Jeonghun; Park, Hyosub; Zoe, Heeseung; Yeom, Dong-han
2017-01-01
We investigate information flow and Page curves for tripartite systems. We prepare a tripartite system (say, A , B , and C ) of a given number of states and calculate information and entropy contents by assuming random states. Initially, every particle was in A (this means a black hole), and as time goes on, particles move to either B (this means Hawking radiation) or C (this means a broadly defined remnant, including a non-local transport of information, the last burst, an interior large volume, or a bubble universe, etc). If the final number of states of the remnant is smaller than that of Hawking radiation, then information will be stored by both the radiation and the mutual information between the radiation and the remnant, while the remnant itself does not contain information. On the other hand, if the final number of states of the remnant is greater than that of Hawking radiation, then the radiation contains negligible information, while the remnant and the mutual information between the radiation and the remnant contain information. Unless the number of states of the remnant is large enough compared to the entropy of the black hole, Hawking radiation must contain information; and we meet the menace of black hole complementarity again. Therefore, this contrasts the tension between various assumptions and candidates of the resolution of the information loss problem. (paper)
Svetlichny's inequality and genuine tripartite nonlocality in three-qubit pure states
International Nuclear Information System (INIS)
Ajoy, Ashok; Rungta, Pranaw
2010-01-01
The violation of the Svetlichny's inequality (SI) [Phys. Rev. D 35, 3066 (1987)] is sufficient but not necessary for genuine tripartite nonlocal correlations. Here we quantify the relationship between tripartite entanglement and the maximum expectation value of the Svetlichny operator (which is bounded from above by the inequality) for the two inequivalent subclasses of pure three-qubit states: the Greenberger-Horne-Zeilinger (GHZ) class and the W class. We show that the maximum for the GHZ-class states reduces to Mermin's inequality [Phys. Rev. Lett. 65, 1838 (1990)] modulo a constant factor, and although it is a function of the three tangle and the residual concurrence, large numbers of states do not violate the inequality. We further show that by design SI is more suitable as a measure of genuine tripartite nonlocality between the three qubits in the W-class states, and the maximum is a certain function of the bipartite entanglement (the concurrence) of the three reduced states, and only when their sum attains a certain threshold value do they violate the inequality.
Adesso, Gerardo; Serafini, Alessio; Illuminati, Fabrizio
2007-03-01
We present a novel, detailed study on the usefulness of three-mode Gaussian states for realistic processing of continuous variable (CV) quantum information, with a particular emphasis on the possibilities opened up by their genuine tripartite entanglement. We describe practical schemes to engineer several classes of pure and mixed three-mode states that stand out for their informational and/or entanglement properties. In particular, we introduce a simple procedure—based on passive optical elements—to produce pure three-mode Gaussian states with arbitrary entanglement structure (upon availability of an initial two-mode squeezed state). We analyse in depth the properties of distributed entanglement and the origin of its sharing structure, showing that the promiscuity of entanglement sharing is a feature peculiar to symmetric Gaussian states that survives even in the presence of significant degrees of mixedness and decoherence. Next, we discuss the suitability of the considered tripartite entangled states to the implementation of quantum information and communication protocols with CVs. This will lead to a feasible experimental proposal to test the promiscuous sharing of CV tripartite entanglement, in terms of the optimal fidelity of teleportation networks with Gaussian resources. We finally focus on the application of three-mode states to symmetric and asymmetric telecloning, and single out the structural properties of the optimal Gaussian resources for the latter protocol in different settings. Our analysis aims to lay the basis for a practical quantum communication with CVs beyond the bipartite scenario.
Structure and operation of bacterial tripartite pumps.
Hinchliffe, Philip; Symmons, Martyn F; Hughes, Colin; Koronakis, Vassilis
2013-01-01
In bacteria such as Pseudomonas aeruginosa and Escherichia coli, tripartite membrane machineries, or pumps, determine the efflux of small noxious molecules, such as detergents, heavy metals, and antibiotics, and the export of large proteins including toxins. They are therefore influential in bacterial survival, particularly during infections caused by multidrug-resistant pathogens. In these tripartite pumps an inner membrane transporter, typically an ATPase or proton antiporter, binds and translocates export or efflux substrates. In cooperation with a periplasmic adaptor protein it recruits and opens a TolC family cell exit duct, which is anchored in the outer membrane and projects across the periplasmic space between inner and outer membranes. Assembled tripartite pumps thus span the entire bacterial cell envelope. We review the atomic structures of each of the three pump components and discuss how these have allowed high-resolution views of tripartite pump assembly, operation, and possible inhibition.
Entanglement of mixed quantum states for qubits and qudit in double photoionization of atoms
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, M., E-mail: bminakshi@yahoo.com [Department of Physics, Asansol Girls’ College, Asansol 713304 (India); Sen, S. [Department of Physics, Triveni Devi Bhalotia College, Raniganj 713347 (India)
2015-08-15
Highlights: • We study tripartite entanglement between two electronic qubits and an ionic qudit. • We study bipartite entanglement between any two subsystems of a tripartite system. • We have presented a quantitative application of entangled properties in Neon atom. - Abstract: Quantum entanglement and its paradoxical properties are genuine physical resources for various quantum information tasks like quantum teleportation, quantum cryptography, and quantum computer technology. The physical characteristic of the entanglement of quantum-mechanical states, both for pure and mixed, has been recognized as a central resource in various aspects of quantum information processing. In this article, we study the bipartite entanglement of one electronic qubit along with the ionic qudit and also entanglement between two electronic qubits. The tripartite entanglement properties also have been investigated between two electronic qubits and an ionic qudit. All these studies have been done for the single-step double photoionization from an atom following the absorption of a single photon without observing spin orbit interaction. The dimension of the Hilbert space of the qudit depends upon the electronic state of the residual photoion A{sup 2+}. In absence of SOI, when Russell–Saunders coupling (L–S coupling) is applicable, dimension of the qudit is equal to the spin multiplicity of A{sup 2+}. For estimations of entanglement and mixedness, we consider the Peres–Horodecki condition, concurrence, entanglement of formation, negativity, linear and von Neumann entropies. In case of L–S coupling, all the properties of a qubit–qudit system can be predicted merely with the knowledge of the spins of the target atom and the residual photoion.
DEFF Research Database (Denmark)
Strand, Anete Mikkala Camille
the body of research on a quantum approach to storytelling coined as Material Storytelling (Strand, 2012). Fragments that are then read through one-another and thereby themselves becoming entangled becomings with no independent existence. Co-shapes as part of the intra-activity of the process....
Studying entanglement-assisted entanglement transformation
International Nuclear Information System (INIS)
Hsu Liyi
2004-01-01
In this paper, we study catalysis of entanglement transformations for n-level pure entangled states. We propose an algorithm of finding the required catalystic entanglement. We introduce several examples by way of demonstration. We evaluate the lower and upper bound of the required inequalities for deciding whether there are m-level appropriate catalyst states for entanglement transformations for two n-level pure entangled states
Energy Technology Data Exchange (ETDEWEB)
Adesso, Gerardo; Illuminati, Fabrizio [Dipartimento di Fisica ' E R Caianiello' , Universita degli Studi di Salerno (Italy); CNISM and CNR-Coherentia, Gruppo di Salerno (Italy); and INFN Sezione di Napoli-Gruppo Collegato di Salerno (Italy); Via S Allende, 84081 Baronissi, SA (Italy)
2006-01-15
For continuous-variable (CV) systems, we introduce a measure of entanglement, the CV tangle (contangle), with the purpose of quantifying the distributed (shared) entanglement in multimode, multipartite Gaussian states. This is achieved by a proper convex-roof extension of the squared logarithmic negativity. We prove that the contangle satisfies the Coffman-Kundu-Wootters monogamy inequality in all three-mode Gaussian states, and in all fully symmetric N-mode Gaussian states, for arbitrary N. For three-mode pure states, we prove that the residual entanglement is a genuine tripartite entanglement monotone under Gaussian local operations and classical communication. We show that pure, symmetric three-mode Gaussian states allow a promiscuous entanglement sharing, having both maximum tripartite residual entanglement and maximum couplewise entanglement between any pair of modes. These states are thus simultaneous CV analogues of both the GHZ and the W states of three qubits: in CV systems monogamy does not prevent promiscuity, and the inequivalence between different classes of maximally entangled states, holding for systems of three or more qubits, is removed.
Energy Technology Data Exchange (ETDEWEB)
Hu, Ming-Liang, E-mail: mingliang0301@163.com
2012-09-15
Dynamics of disentanglement as measured by the tripartite negativity and Bell nonlocality as measured by the extent of violation of the multipartite Bell-type inequalities are investigated in this work. It is shown definitively that for the initial three-qubit Greenberger-Horne-Zeilinger (GHZ) or W class state preparation, the Bell nonlocality suffers sudden death under the influence of thermal reservoirs. Moreover, all the Bell-nonlocal states are useful for nonclassical teleportation, while there are entangled states that do not violate any Bell-type inequalities, but still yield nonclassical teleportation fidelity. - Highlights: Black-Right-Pointing-Pointer Comparison of different aspects of quantum correlations. Black-Right-Pointing-Pointer Robustness of the initial tripartite GHZ and W class states against decoherence. Black-Right-Pointing-Pointer Bell-nonlocality sudden death under the influence of thermal reservoir. Black-Right-Pointing-Pointer A nonzero minimum tripartite negativity is needed for nonclassical teleportation. Black-Right-Pointing-Pointer All the Bell-nonlocal states yield nonclassical teleportation fidelity.
Constructing Robust Entangled Coherent GHZ and W States via a Cavity QED System
Behzadi, N.; Ahansaz, B.; Kazemi, S.
2016-03-01
Using a system of three distant cavities, we propose a method for constructing tripartite entangled coherent GHZ and W states which are robust due to the photon losses in the cavities. Each of cavities is doped with a semiconductor quantum dot. By the dynamics, the excitonic modes of quantum dots are enabled to exhibit entangled coherent GHZ and W states. Apart from the exciton losses, the master equation approach shows that when the populations of the field modes in the cavities are negligible the destruction of entanglement due to dissipation arises from photon losses, is effectively suppressed.
Carmichael, H.
1953-01-01
A torsional-type analytical balance designed to arrive at its equilibrium point more quickly than previous balances is described. In order to prevent external heat sources creating air currents inside the balance casing that would reiard the attainment of equilibrium conditions, a relatively thick casing shaped as an inverted U is placed over the load support arms and the balance beam. This casing is of a metal of good thernnal conductivity characteristics, such as copper or aluminum, in order that heat applied to one portion of the balance is quickly conducted to all other sensitive areas, thus effectively preventing the fornnation of air currents caused by unequal heating of the balance.
The entanglement evolution between two entangled atoms
Indian Academy of Sciences (India)
... entanglement sudden death (ESD) and sudden birth at some time. The entanglement properties between the field and the atom insidethe cavity are dependent on the photon number. Most interestingly, the entanglement between the field and the atom in the field is influenced significantly by manipulating the atom outside ...
Kenfack, Lionel Tenemeza; Tchoffo, Martin; Fouokeng, Georges Collince; Fai, Lukong Cornelius
2018-04-01
The effects of 1/f^{α } (α =1,2) noise stemming from one or a collection of random bistable fluctuators (RBFs), on the evolution of entanglement, of three non-interacting qubits are investigated. Three different initial configurations of the qubits are analyzed in detail: the Greenberger-Horne-Zeilinger (GHZ)-type states, W-type states and mixed states composed of a GHZ state and a W state (GHZ-W). For each initial configuration, the evolution of entanglement is investigated for three different qubit-environment (Q-E) coupling setups, namely independent environments, mixed environments and common environment coupling. With the help of tripartite negativity and suitable entanglement witnesses, we show that the evolution of entanglement is extremely influenced not only by the initial configuration of the qubits, the spectrum of the environment and the Q-E coupling setup considered, but also by the number of RBF modeling the environment. Indeed, we find that the decay of entanglement is accelerated when the number of fluctuators modeling the environment is increased. Furthermore, we find that entanglement can survive indefinitely to the detrimental effects of noise even for increasingly larger numbers of RBFs. On the other hand, we find that the proficiency of the tripartite entanglement witnesses to detect entanglement is weaker than that of the tripartite negativity and that the symmetry of the initial states is broken when the qubits are coupled to the noise in mixed environments. Finally, we find that the 1 / f noise is more harmful to the survival of entanglement than the 1/f2 noise and that the mixed GHZ-W states followed by the GHZ-type states preserve better entanglement than the W-type ones.
Preparation and measurement of three-qubit entanglement in a superconducting circuit.
Dicarlo, L; Reed, M D; Sun, L; Johnson, B R; Chow, J M; Gambetta, J M; Frunzio, L; Girvin, S M; Devoret, M H; Schoelkopf, R J
2010-09-30
Traditionally, quantum entanglement has been central to foundational discussions of quantum mechanics. The measurement of correlations between entangled particles can have results at odds with classical behaviour. These discrepancies grow exponentially with the number of entangled particles. With the ample experimental confirmation of quantum mechanical predictions, entanglement has evolved from a philosophical conundrum into a key resource for technologies such as quantum communication and computation. Although entanglement in superconducting circuits has been limited so far to two qubits, the extension of entanglement to three, eight and ten qubits has been achieved among spins, ions and photons, respectively. A key question for solid-state quantum information processing is whether an engineered system could display the multi-qubit entanglement necessary for quantum error correction, which starts with tripartite entanglement. Here, using a circuit quantum electrodynamics architecture, we demonstrate deterministic production of three-qubit Greenberger-Horne-Zeilinger (GHZ) states with fidelity of 88 per cent, measured with quantum state tomography. Several entanglement witnesses detect genuine three-qubit entanglement by violating biseparable bounds by 830 ± 80 per cent. We demonstrate the first step of basic quantum error correction, namely the encoding of a logical qubit into a manifold of GHZ-like states using a repetition code. The integration of this encoding with decoding and error-correcting steps in a feedback loop will be the next step for quantum computing with integrated circuits.
Establishing and storing of deterministic quantum entanglement among three distant atomic ensembles.
Yan, Zhihui; Wu, Liang; Jia, Xiaojun; Liu, Yanhong; Deng, Ruijie; Li, Shujing; Wang, Hai; Xie, Changde; Peng, Kunchi
2017-09-28
It is crucial for the physical realization of quantum information networks to first establish entanglement among multiple space-separated quantum memories and then, at a user-controlled moment, to transfer the stored entanglement to quantum channels for distribution and conveyance of information. Here we present an experimental demonstration on generation, storage, and transfer of deterministic quantum entanglement among three spatially separated atomic ensembles. The off-line prepared multipartite entanglement of optical modes is mapped into three distant atomic ensembles to establish entanglement of atomic spin waves via electromagnetically induced transparency light-matter interaction. Then the stored atomic entanglement is transferred into a tripartite quadrature entangled state of light, which is space-separated and can be dynamically allocated to three quantum channels for conveying quantum information. The existence of entanglement among three released optical modes verifies that the system has the capacity to preserve multipartite entanglement. The presented protocol can be directly extended to larger quantum networks with more nodes.Continuous-variable encoding is a promising approach for quantum information and communication networks. Here, the authors show how to map entanglement from three spatial optical modes to three separated atomic samples via electromagnetically induced transparency, releasing it later on demand.
International Nuclear Information System (INIS)
Hadjiivanov, L.; Todorov, I.
2015-01-01
Expository paper providing a historical survey of the gradual transformation of the 'philosophical discussions' between Bohr, Einstein and Schrödinger on foundational issues in quantum mechanics into a quantitative prediction of a new quantum effect, its experimental verification and its proposed (and loudly advertised) applications. The basic idea of the 1935 paper of Einstein-Podolsky-Rosen (EPR) was reformulated by David Bohm for a finite dimensional spin system. This allowed John Bell to derive his inequalities that separate the prediction of quantum entanglement from its possible classical interpretation. We reproduce here their later (1971) version, reviewing on the way the generalization (and mathematical derivation) of Heisenberg's uncertainty relations (due to Weyl and Schrödinger) needed for the passage from EPR to Bell. We also provide an improved derivation of the quantum theoretic violation of Bell's inequalities. Soon after the experimental confirmation of the quantum entanglement (culminating with the work of Alain Aspect) it was Feynman who made public the idea of a quantum computer based on the observed effect
Anyonic entanglement and topological entanglement entropy
Bonderson, Parsa; Knapp, Christina; Patel, Kaushal
2017-10-01
We study the properties of entanglement in two-dimensional topologically ordered phases of matter. Such phases support anyons, quasiparticles with exotic exchange statistics. The emergent nonlocal state spaces of anyonic systems admit a particular form of entanglement that does not exist in conventional quantum mechanical systems. We study this entanglement by adapting standard notions of entropy to anyonic systems. We use the algebraic theory of anyon models (modular tensor categories) to illustrate the nonlocal entanglement structure of anyonic systems. Using this formalism, we present a general method of deriving the universal topological contributions to the entanglement entropy for general system configurations of a topological phase, including surfaces of arbitrary genus, punctures, and quasiparticle content. We analyze a number of examples in detail. Our results recover and extend prior results for anyonic entanglement and the topological entanglement entropy.
Collaborative tagging as a tripartite network
Lambiotte, R.; Ausloos, M.
2005-01-01
We describe online collaborative communities by tripartite networks, the nodes being persons, items and tags. We introduce projection methods in order to uncover the structures of the networks, i.e. communities of users, genre families... To do so, we focus on the correlations between the nodes, depending on their profiles, and use percolation techniques that consist in removing less correlated links and observing the shaping of disconnected islands. The structuring of the network is visualis...
Tripartite assembly of RND multidrug efflux pumps.
Daury, Laetitia; Orange, François; Taveau, Jean-Christophe; Verchère, Alice; Monlezun, Laura; Gounou, Céline; Marreddy, Ravi K R; Picard, Martin; Broutin, Isabelle; Pos, Klaas M; Lambert, Olivier
2016-02-12
Tripartite multidrug efflux systems of Gram-negative bacteria are composed of an inner membrane transporter, an outer membrane channel and a periplasmic adaptor protein. They are assumed to form ducts inside the periplasm facilitating drug exit across the outer membrane. Here we present the reconstitution of native Pseudomonas aeruginosa MexAB-OprM and Escherichia coli AcrAB-TolC tripartite Resistance Nodulation and cell Division (RND) efflux systems in a lipid nanodisc system. Single-particle analysis by electron microscopy reveals the inner and outer membrane protein components linked together via the periplasmic adaptor protein. This intrinsic ability of the native components to self-assemble also leads to the formation of a stable interspecies AcrA-MexB-TolC complex suggesting a common mechanism of tripartite assembly. Projection structures of all three complexes emphasize the role of the periplasmic adaptor protein as part of the exit duct with no physical interaction between the inner and outer membrane components.
Toward a tripartite model of intrinsic motivation.
Carbonneau, Noémie; Vallerand, Robert J; Lafrenière, Marc-André K
2012-10-01
Intrinsic motivation (IM) refers to engaging in an activity for the pleasure inherent in the activity. The present article presents a tripartite model of IM consisting of IM to know (i.e., engaging in an activity to experience pleasure while learning and trying to understand something new), IM toward accomplishment (i.e., engaging in an activity for the pleasure experienced when attempting task mastery), and IM to experience stimulation (i.e., engaging in an activity for feelings of sensory pleasure). The tripartite model of IM posits that each type of IM can result from task, situational, and personality determinants and can lead to specific types of cognitive, affective, and behavioral outcomes. The purpose of this research was to test some predictions derived from this model. Across 4 studies (Study 1: N = 331; Study 2: N = 113; Study 3: N = 58; Study 4: N = 135), the 3 types of IM as well as potential determinants and consequences were assessed. Results revealed that experiencing one type of IM over the others depends in part on people's personality styles. Also, each type of IM was found to predict specific outcomes (i.e., affective states and behavioral choices). The implications of the tripartite model of IM for motivation research are discussed. © 2011 The Authors. Journal of Personality © 2011, Wiley Periodicals, Inc.
Tripartite assembly of RND multidrug efflux pumps
Daury, Laetitia; Orange, François; Taveau, Jean-Christophe; Verchère, Alice; Monlezun, Laura; Gounou, Céline; Marreddy, Ravi K. R.; Picard, Martin; Broutin, Isabelle; Pos, Klaas M.; Lambert, Olivier
2016-02-01
Tripartite multidrug efflux systems of Gram-negative bacteria are composed of an inner membrane transporter, an outer membrane channel and a periplasmic adaptor protein. They are assumed to form ducts inside the periplasm facilitating drug exit across the outer membrane. Here we present the reconstitution of native Pseudomonas aeruginosa MexAB-OprM and Escherichia coli AcrAB-TolC tripartite Resistance Nodulation and cell Division (RND) efflux systems in a lipid nanodisc system. Single-particle analysis by electron microscopy reveals the inner and outer membrane protein components linked together via the periplasmic adaptor protein. This intrinsic ability of the native components to self-assemble also leads to the formation of a stable interspecies AcrA-MexB-TolC complex suggesting a common mechanism of tripartite assembly. Projection structures of all three complexes emphasize the role of the periplasmic adaptor protein as part of the exit duct with no physical interaction between the inner and outer membrane components.
Remote entanglement distribution
International Nuclear Information System (INIS)
Sanders, B.C.; Gour, G.; Meyer, D.A.
2005-01-01
Full text: Shared bipartite entanglement is a crucial shared resource for many quantum information tasks such as teleportation, entanglement swapping, and remote state preparation. In general different nodes of a quantum network share an entanglement resource, such as ebits, that are consumed during the task. In practice, generating entangled states is expensive, but here we establish a protocol by which a quantum network requires only a single supplier of entanglement to all nodes who, by judicious measurements and classical communication, provides the nodes with a unique pair wise entangled state independent of the measurement outcome. Furthermore, we extend this result to a chain of suppliers and nodes, which enables an operational interpretation of concurrence. In the special case that the supplier shares bipartite states with two nodes, and such states are pure and maximally entangled, our protocol corresponds to entanglement swapping. However, in the practical case that initial shared entanglement between suppliers and nodes involves partially entangled or mixed states, we show that general local operations and classical communication by all parties (suppliers and nodes) yields distributions of entangled states between nodes. In general a distribution of bipartite entangled states between any two nodes will include states that do not have the same entanglement; thus we name this general process remote entanglement distribution. In our terminology entanglement swapping with partially entangled states is a particular class of remote entanglement distribution protocols. Here we identify which distributions of states that can or cannot be created by remote entanglement distribution. In particular we prove a powerful theorem that establishes an upper bound on the entanglement of formation that can be produced between two qubit nodes. We extend this result to the case of a linear chain of parties that play the roles of suppliers and nodes; this extension provides
Einstein-Podolsky-Rosen-steering swapping between two Gaussian multipartite entangled states
Wang, Meihong; Qin, Zhongzhong; Wang, Yu; Su, Xiaolong
2017-08-01
Multipartite Einstein-Podolsky-Rosen (EPR) steering is a useful quantum resource for quantum communication in quantum networks. It has potential applications in secure quantum communication, such as one-sided device-independent quantum key distribution and quantum secret sharing. By distributing optical modes of a multipartite entangled state to space-separated quantum nodes, a local quantum network can be established. Based on the existing multipartite EPR steering in a local quantum network, secure quantum communication protocol can be accomplished. In this manuscript, we present swapping schemes for EPR steering between two space-separated Gaussian multipartite entangled states, which can be used to connect two space-separated quantum networks. Two swapping schemes, including the swapping between a tripartite Greenberger-Horne-Zeilinger (GHZ) entangled state and an EPR entangled state and that between two tripartite GHZ entangled states, are analyzed. Various types of EPR steering are presented after the swapping of two space-separated independent multipartite entanglement states without direct interaction, which can be used to implement quantum communication between two quantum networks. The presented schemes provide technical reference for more complicated quantum networks with EPR steering.
Entanglement in continuous-variable systems: recent advances and current perspectives
Energy Technology Data Exchange (ETDEWEB)
Adesso, Gerardo [Dipartimento di Fisica, Universita degli Studi di Roma ' La Sapienza' , Piazzale Aldo Moro 5, I-00185 Rome (Italy); Illuminati, Fabrizio [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)
2007-07-13
We review the theory of continuous-variable entanglement with special emphasis on foundational aspects, conceptual structures and mathematical methods. Much attention is devoted to the discussion of separability criteria and entanglement properties of Gaussian states, for their great practical relevance in applications to quantum optics and quantum information, as well as for the very clean framework that they allow for the study of the structure of nonlocal correlations. We give a self-contained introduction to phase-space and symplectic methods in the study of Gaussian states of infinite-dimensional bosonic systems. We review the most important results on the separability and distillability of Gaussian states and discuss the main properties of bipartite entanglement. These include the extremal entanglement, minimal and maximal, of two-mode mixed Gaussian states, the ordering of two-mode Gaussian states according to different measures of entanglement, the unitary (reversible) localization and the scaling of bipartite entanglement in multimode Gaussian states. We then discuss recent advances in the understanding of entanglement sharing in multimode Gaussian states, including the proof of the monogamy inequality of distributed entanglement for all Gaussian states. Multipartite entanglement of Gaussian states is reviewed by discussing its qualification by different classes of separability, and the main consequences of the monogamy inequality, such as the quantification of genuine tripartite entanglement in three-mode Gaussian states, the promiscuous nature of entanglement sharing in symmetric Gaussian states and the possible coexistence of unlimited bipartite and multipartite entanglement. We finally review recent advances and discuss possible perspectives on the qualification and quantification of entanglement in non-Gaussian states, a field of research that is to a large extent yet to be explored.
The entanglement evolution between two entangled atoms
Indian Academy of Sciences (India)
Entanglement is an important resource for quantum information processing. [1–3] and also one of the most important nonclassical properties in quantum theory. Quan- tum entanglement is seen not only as a puzzle, but also as a resource to be manipulated for communication, information processing and quantum computing ...
Completely mixed state is a critical point for three-qubit entanglement
International Nuclear Information System (INIS)
Tamaryan, Sayatnova
2011-01-01
Pure three-qubit states have five algebraically independent and one algebraically dependent polynomial invariants under local unitary transformations and an arbitrary entanglement measure is a function of these six invariants. It is shown that if the reduced density operator of a some qubit is a multiple of the unit operator, than the geometric entanglement measure of the pure three-qubit state is absolutely independent of the polynomial invariants and is a constant for such tripartite states. Hence a one-particle completely mixed state is a critical point for the geometric measure of entanglement. -- Highlights: → Geometric measure of pure three-qubits is expressed in terms of polynomial invariants. → When one Bloch vector is zero the measure is independent of the remaining invariants. → Hence a one-particle completely mixed state is a critical point for the geometric measure. → The existence of the critical points is an inherent feature of the entanglement.
Wang, Fei; Shi, Wenxing; Ding, Linjie
2013-10-01
We propose a scheme to generate multipartite continuous variable atom-field entanglement via two-fold phase-dependent electromagnetically induced transparency in a five-level atomic system. Due to quantum interference, the six fields act as two collection modes to interact with the atomic ensemble. Under proper conditions, it is shown that the genuine tripartite entanglement arises between the atomic ensemble and the two collection modes. Moreover, the seven-partite Greenberger-Horne-Zeilinger entangled state included six individual field modes and the atomic ensemble is achievable. Physically, the intrinsic nonlinear interactions are responsible for the quantum correlation. The hybrid multipartite entangled state may be useful for the progress of quantum network between different objects.
Geometric measure of entanglement of mixed three-qubit-GHZ-symmetric states
Energy Technology Data Exchange (ETDEWEB)
Buchholz, Lars Erik; Moroder, Tobias; Guehne, Otfried [Theoretische Quantenoptik, Universitaet Siegen, Department Physik, Emmy-Noether-Campus, Walter-Flex-Strasse 3, 57068 Siegen (Germany)
2013-07-01
Quantifying entanglement is one of the challenging tasks in quantum information theory. The simplest case containing entanglement is the two-qubit system. This was intensively studied and significant results were distilled out of it. Progressive achievements on the experimental sector makes a consideration of multipartite entanglement essential. This problem is not a trivial extension of the bipartite entanglement due to different types of entanglement classes. Consequently, there exists not just one measure but a variety of possible quantifiers. To improve our understanding about this quantum phenomenon, one has started to investigate special cases, like the mixed GHZ-symmetric-three-qubit states. This set of states exposed to be interesting due to the fact that the GHZ-Class is a nontrivial class of genuine tripartite entanglement and because of its high symmetric properties. Partial results were already obtained like the ''three-tangle'' as a measure for the three particle entanglement. To complete our understanding of these states we give an explicit expression of the geometric measure of entanglement with respect to fully separable states as well as for the concurrence for this class of states.
Generalized Remote Preparation of Arbitrary m-qubit Entangled States via Genuine Entanglements
Directory of Open Access Journals (Sweden)
Dong Wang
2015-03-01
Full Text Available Herein, we present a feasible, general protocol for quantum communication within a network via generalized remote preparation of an arbitrary m-qubit entangled state designed with genuine tripartite Greenberger–Horne–Zeilinger-type entangled resources. During the implementations, we construct novel collective unitary operations; these operations are tasked with performing the necessary phase transfers during remote state preparations. We have distilled our implementation methods into a five-step procedure, which can be used to faithfully recover the desired state during transfer. Compared to previous existing schemes, our methodology features a greatly increased success probability. After the consumption of auxiliary qubits and the performance of collective unitary operations, the probability of successful state transfer is increased four-fold and eight-fold for arbitrary two- and three-qubit entanglements when compared to other methods within the literature, respectively. We conclude this paper with a discussion of the presented scheme for state preparation, including: success probabilities, reducibility and generalizability.
Entanglement, non-Markovianity, and causal non-separability
Milz, Simon; Pollock, Felix A.; Le, Thao P.; Chiribella, Giulio; Modi, Kavan
2018-03-01
Quantum mechanics, in principle, allows for processes with indefinite causal order. However, most of these causal anomalies have not yet been detected experimentally. We show that every such process can be simulated experimentally by means of non-Markovian dynamics with a measurement on additional degrees of freedom. In detail, we provide an explicit construction to implement arbitrary a causal processes. Furthermore, we give necessary and sufficient conditions for open system dynamics with measurement to yield processes that respect causality locally, and find that tripartite entanglement and nonlocal unitary transformations are crucial requirements for the simulation of causally indefinite processes. These results show a direct connection between three counter-intuitive concepts: entanglement, non-Markovianity, and causal non-separability.
Role of thermal noise in tripartite quantum steering
Wang, Meng; Gong, Qihuang; Ficek, Zbigniew; He, Qiongyi
2014-08-01
The influence of thermal noise on bipartite and tripartite quantum steering induced by a short laser pulse in a hybrid three-mode optomechanical system is investigated. The calculation is carried out under the bad cavity limit, the adiabatic approximation of a slowly varying amplitude of the cavity mode, and with the assumption of driving the cavity mode with a blue detuned strong laser pulse. Under such conditions, explicit expressions of the bipartite and tripartite steering parameters are obtained, and the concept of collective tripartite quantum steering, recently introduced by He and Reid [Phys. Rev. Lett. 111, 250403 (2013), 10.1103/PhysRevLett.111.250403], is clearly explored. It is found that both bipartite and tripartite steering parameters are sensitive functions of the initial state of the modes and distinctly different steering behavior could be observed depending on whether the modes were initially in a thermal state or not. For the modes initially in a vacuum state, the bipartite and tripartite steering occur simultaneously over the entire interaction time. This indicates that collective tripartite steering cannot be achieved. The collective steering can be achieved for the modes initially prepared in a thermal state. We find that the initial thermal noise is more effective in destroying the bipartite rather than the tripartite steering which, on the other hand, can persist even for a large thermal noise. For the initial vacuum state of a steered mode, the tripartite steering exists over the entire interaction time even if the steering modes are in very noisy thermal states. When the steered mode is initially in a thermal state, it can be collectively steered by the other modes. There are thresholds for the average number of the thermal photons above which the existing tripartite steering appears as the collective steering. Finally, we point out that the collective steering may provide a resource in a hybrid quantum network for quantum secret sharing
Tripartite community structure in social bookmarking data
Neubauer, Nicolas; Obermayer, Klaus
2011-12-01
Community detection is a branch of network analysis concerned with identifying strongly connected subnetworks. Social bookmarking sites aggregate datasets of often hundreds of millions of triples (document, user, and tag), which, when interpreted as edges of a graph, give rise to special networks called 3-partite, 3-uniform hypergraphs. We identify challenges and opportunities of generalizing community detection and in particular modularity optimization to these structures. Two methods for community detection are introduced that preserve the hypergraph's special structure to different degrees. Their performance is compared on synthetic datasets, showing the benefits of structure preservation. Furthermore, a tool for interactive exploration of the community detection results is introduced and applied to examples from real datasets. We find additional evidence for the importance of structure preservation and, more generally, demonstrate how tripartite community detection can help understand the structure of social bookmarking data.
Plugge, Stephan; Zazunov, Alex; Sodano, Pasquale; Egger, Reinhold
2015-06-01
We study the concurrence of entanglement between two quantum dots in contact to Majorana bound states on a floating superconducting island. The distance between the Majorana states, the charging energy of the island, and the average island charge are shown to be decisive parameters for the efficiency of entanglement generation. We find that long-range entanglement with basically distance-independent concurrence is possible over wide parameter regions, where the proposed setup realizes a "Majorana entanglement bridge." We also study the time-dependent concurrence obtained after one of the tunnel couplings is suddenly switched on, which reveals the time scales for generating entanglement. Accurate analytical expressions for the concurrence are derived both for the static and the time-dependent cases. Our results indicate that entanglement formation in interacting Majorana devices can be fully understood in terms of an interplay of elastic cotunneling (also referred to as "teleportation") and crossed Andreev reflection processes.
Ma, Chen-Te
2016-01-01
Entanglement is a physical phenomenon that each state cannot be described individually. Entanglement entropy gives quantitative understanding to the entanglement. We use decomposition of the Hilbert space to discuss properties of the entanglement. Therefore, partial trace operator becomes important to define the reduced density matrix from different centers, which commutes with all elements in the Hilbert space, corresponding to different entanglement choices or different observations on entangling surface. Entanglement entropy is expected to satisfy the strong subadditivity. We discuss decomposition of the Hilbert space for the strong subadditivity and other related inequalities. The entanglement entropy with centers can be computed from the Hamitonian formulations systematically, provided that we know wavefunctional. In the Hamitonian formulation, it is easier to obtain symmetry structure. We consider massless p-form theory as an example. The massless p-form theory in (2 p + 2)-dimensions has global symmetry, similar to the electric-magnetic duality, connecting centers in ground state. This defines a duality structure in centers. Because it is hard to exactly compute the entanglement entropy from partial trace operator, we propose the Lagrangian formulation from the Hamitonian formulation to compute the entanglement entropy with centers. From the Lagrangian method and saddle point approximation, the codimension two surface term (leading order) in the Einstein gravity theory or holographic entanglement entropy should correspond to non-tensor product decomposition (center is not identity). Finally, we compute the entanglement entropy of the SU( N) Yang-Mills lattice gauge theory in the fundamental representation using the strong coupling expansion in the extended lattice model to obtain spatial area term in total dimensions larger than two for N > 1.
Energy Technology Data Exchange (ETDEWEB)
Ma, Chen-Te [Department of Physics and Center for Theoretical Sciences, National Taiwan University, Taipei 10617 (China)
2016-01-13
Entanglement is a physical phenomenon that each state cannot be described individually. Entanglement entropy gives quantitative understanding to the entanglement. We use decomposition of the Hilbert space to discuss properties of the entanglement. Therefore, partial trace operator becomes important to define the reduced density matrix from different centers, which commutes with all elements in the Hilbert space, corresponding to different entanglement choices or different observations on entangling surface. Entanglement entropy is expected to satisfy the strong subadditivity. We discuss decomposition of the Hilbert space for the strong subadditivity and other related inequalities. The entanglement entropy with centers can be computed from the Hamitonian formulations systematically, provided that we know wavefunctional. In the Hamitonian formulation, it is easier to obtain symmetry structure. We consider massless p-form theory as an example. The massless p-form theory in (2p+2)-dimensions has global symmetry, similar to the electric-magnetic duality, connecting centers in ground state. This defines a duality structure in centers. Because it is hard to exactly compute the entanglement entropy from partial trace operator, we propose the Lagrangian formulation from the Hamitonian formulation to compute the entanglement entropy with centers. From the Lagrangian method and saddle point approximation, the codimension two surface term (leading order) in the Einstein gravity theory or holographic entanglement entropy should correspond to non-tensor product decomposition (center is not identity). Finally, we compute the entanglement entropy of the SU(N) Yang-Mills lattice gauge theory in the fundamental representation using the strong coupling expansion in the extended lattice model to obtain spatial area term in total dimensions larger than two for N>1.
Renormalized entanglement entropy
Energy Technology Data Exchange (ETDEWEB)
Taylor, Marika; Woodhead, William [Mathematical Sciences and STAG Research Centre, University of Southampton,Highfield, Southampton, SO17 1BJ (United Kingdom)
2016-08-29
We develop a renormalization method for holographic entanglement entropy based on area renormalization of entangling surfaces. The renormalized entanglement entropy is derived for entangling surfaces in asymptotically locally anti-de Sitter spacetimes in general dimensions and for entangling surfaces in four dimensional holographic renormalization group flows. The renormalized entanglement entropy for disk regions in AdS{sub 4} spacetimes agrees precisely with the holographically renormalized action for AdS{sub 4} with spherical slicing and hence with the F quantity, in accordance with the Casini-Huerta-Myers map. We present a generic class of holographic RG flows associated with deformations by operators of dimension 3/2<Δ<5/2 for which the F quantity increases along the RG flow, hence violating the strong version of the F theorem. We conclude by explaining how the renormalized entanglement entropy can be derived directly from the renormalized partition function using the replica trick i.e. our renormalization method for the entanglement entropy is inherited directly from that of the partition function. We show explicitly how the entanglement entropy counterterms can be derived from the standard holographic renormalization counterterms for asymptotically locally anti-de Sitter spacetimes.
Role of thermal noise in tripartite quantum steering
Wang, Meng; Gong, Qihuang; Ficek, Zbigniew; He, Qiongyi
2014-01-01
The influence of thermal noise on bipartite and tripartite quantum steering induced by a short laser pulse in a hybrid three-mode optomechanical system is investigated. The calculation is carried out under the bad cavity limit, the adiabatic approximation of a slowly varying amplitude of the cavity mode, and with the assumption of driving the cavity mode with a blue detuned strong laser pulse. Under such conditions, explicit expressions of the bipartite and tripartite steering parameters are ...
Simultaneous cooling and entanglement of mechanical modes of a micromirror in an optical cavity
International Nuclear Information System (INIS)
Genes, Claudiu; Vitali, David; Tombesi, Paolo
2008-01-01
Laser cooling of a mechanical mode of a resonator by the radiation pressure of a detuned optical cavity mode has been recently demonstrated by various groups in different experimental configurations. Here, we consider the effect of a second mechanical mode with a close but different resonance frequency. We show that the nearby mechanical resonance is simultaneously cooled by the cavity field, provided that the difference between the two mechanical frequencies is not too small. When this frequency difference becomes smaller than the effective mechanical damping of the secondary mode, the two cooling processes interfere destructively similarly to what happens in electromagnetically induced transparency, and cavity cooling is suppressed in the limit of identical mechanical frequencies. We show that also the entanglement properties of the steady state of the tripartite system crucially depend upon the difference between the two mechanical frequencies. If the latter is larger than the effective damping of the second mechanical mode, the state shows fully tripartite entanglement and each mechanical mode is entangled with the cavity mode. If instead, the frequency difference is smaller, the steady state is a two-mode biseparable state, inseparable only when one splits the cavity mode from the two mechanical modes. In this latter case, the entanglement of each mechanical mode with the cavity mode is extremely fragile with respect to temperature.
Quantifying entanglement in two-mode Gaussian states
Tserkis, Spyros; Ralph, Timothy C.
2017-12-01
Entangled two-mode Gaussian states are a key resource for quantum information technologies such as teleportation, quantum cryptography, and quantum computation, so quantification of Gaussian entanglement is an important problem. Entanglement of formation is unanimously considered a proper measure of quantum correlations, but for arbitrary two-mode Gaussian states no analytical form is currently known. In contrast, logarithmic negativity is a measure that is straightforward to calculate and so has been adopted by most researchers, even though it is a less faithful quantifier. In this work, we derive an analytical lower bound for entanglement of formation of generic two-mode Gaussian states, which becomes tight for symmetric states and for states with balanced correlations. We define simple expressions for entanglement of formation in physically relevant situations and use these to illustrate the problematic behavior of logarithmic negativity, which can lead to spurious conclusions.
Entanglement negativity in the multiverse
Energy Technology Data Exchange (ETDEWEB)
Kanno, Sugumi [Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao (Spain); Laboratory for Quantum Gravity & Strings and Astrophysics, Cosmology & Gravity Center, Department of Mathematics & Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7701 (South Africa); Shock, Jonathan P. [Laboratory for Quantum Gravity & Strings and Astrophysics, Cosmology & Gravity Center, Department of Mathematics & Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7701 (South Africa); National Institute for Theoretical Physics, Private Bag X1, Matieland, 7602 (South Africa); Soda, Jiro [Department of Physics, Kobe University, Kobe 657-8501 (Japan)
2015-03-10
We explore quantum entanglement between two causally disconnected regions in the multiverse. We first consider a free massive scalar field, and compute the entanglement negativity between two causally separated open charts in de Sitter space. The qualitative feature of it turns out to be in agreement with that of the entanglement entropy. We then introduce two observers who determine the entanglement between two causally disconnected de Sitter spaces. When one of the observers remains constrained to a region of the open chart in a de Sitter space, we find that the scale dependence enters into the entanglement. We show that a state which is initially maximally entangled becomes more entangled or less entangled on large scales depending on the mass of the scalar field and recovers the initial entanglement in the small scale limit. We argue that quantum entanglement may provide some evidence for the existence of the multiverse.
Entanglement negativity in the multiverse
Energy Technology Data Exchange (ETDEWEB)
Kanno, Sugumi [Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); Shock, Jonathan P. [Laboratory for Quantum Gravity and Strings and Astrophysics, Cosmology and Gravity Center, Department of Mathematics and Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7701 (South Africa); Soda, Jiro, E-mail: sugumi.kanno@ehu.es, E-mail: jonathan.shock@uct.ac.za, E-mail: jiro@phys.sci.kobe-u.ac.jp [Department of Physics, Kobe University, Kobe 657-8501 (Japan)
2015-03-01
We explore quantum entanglement between two causally disconnected regions in the multiverse. We first consider a free massive scalar field, and compute the entanglement negativity between two causally separated open charts in de Sitter space. The qualitative feature of it turns out to be in agreement with that of the entanglement entropy. We then introduce two observers who determine the entanglement between two causally disconnected de Sitter spaces. When one of the observers remains constrained to a region of the open chart in a de Sitter space, we find that the scale dependence enters into the entanglement. We show that a state which is initially maximally entangled becomes more entangled or less entangled on large scales depending on the mass of the scalar field and recovers the initial entanglement in the small scale limit. We argue that quantum entanglement may provide some evidence for the existence of the multiverse.
Characterizing Genuine Multilevel Entanglement
Kraft, Tristan; Ritz, Christina; Brunner, Nicolas; Huber, Marcus; Gühne, Otfried
2018-02-01
Entanglement of high-dimensional quantum systems has become increasingly important for quantum communication and experimental tests of nonlocality. However, many effects of high-dimensional entanglement can be simulated by using multiple copies of low-dimensional systems. We present a general theory to characterize those high-dimensional quantum states for which the correlations cannot simply be simulated by low-dimensional systems. Our approach leads to general criteria for detecting multilevel entanglement in multiparticle quantum states, which can be used to verify these phenomena experimentally.
DEFF Research Database (Denmark)
Ateniese, Giuseppe; Dagdelen, Özgür; Damgård, Ivan Bjerre
2012-01-01
Entangled cloud storage enables a set of clients {P_i} to “entangle” their files {f_i} into a single clew c to be stored by a (potentially malicious) cloud provider S. The entanglement makes it impossible to modify or delete significant part of the clew without affecting all files in c. A clew...... keeps the files in it private but still lets each client P_i recover his own data by interacting with S; no cooperation from other clients is needed. At the same time, the cloud provider is discouraged from altering or overwriting any significant part of c as this will imply that none of the clients can...... recover their files. We provide theoretical foundations for entangled cloud storage, introducing the notion of an entangled encoding scheme that guarantees strong security requirements capturing the properties above. We also give a concrete construction based on privacy-preserving polynomial interpolation...
Holographic Entanglement Entropy
Rangamani, Mukund
2016-01-01
We review the developments in the past decade on holographic entanglement entropy, a subject that has garnered much attention owing to its potential to teach us about the emergence of spacetime in holography. We provide an introduction to the concept of entanglement entropy in quantum field theories, review the holographic proposals for computing the same, providing some justification for where these proposals arise from in the first two parts. The final part addresses recent developments linking entanglement and geometry. We provide an overview of the various arguments and technical developments that teach us how to use field theory entanglement to detect geometry. Our discussion is by design eclectic; we have chosen to focus on developments that appear to us most promising for further insights into the holographic map. This is a preliminary draft of a few chapters of a book which will appear sometime in the near future, to be published by Springer. The book in addition contains a discussion of application o...
Hwang, W. Y.; Lee, J.; Ahn, D.; Hwang, S. W.
2000-01-01
It has recently been suggested that various entanglement measures for bipartite mixed states do not in general give the same ordering even in the asymptotic cases [S. Virmani and M. B. Plenio, Phys. Lett. A {\\bf 268}, 31 (2000)]. That is, for two certain mixed states, the order of the degree of entanglement depends on the measures. Therefore, incomparable pairs of mixed states which cannot be transformed to each other with unit efficiency by any combinations of local quantum operations and cl...
Directory of Open Access Journals (Sweden)
Leonardo T. Rosa
2018-02-01
Full Text Available The ability to efficiently scavenge nutrients in the host is essential for the viability of any pathogen. All catabolic pathways must begin with the transport of substrate from the environment through the cytoplasmic membrane, a role executed by membrane transporters. Although several classes of cytoplasmic membrane transporters are described, high-affinity uptake of substrates occurs through Solute Binding-Protein (SBP dependent systems. Three families of SBP dependant transporters are known; the primary ATP-binding cassette (ABC transporters, and the secondary Tripartite ATP-independent periplasmic (TRAP transporters and Tripartite Tricarboxylate Transporters (TTT. Far less well understood than the ABC family, the TRAP transporters are found to be abundant among bacteria from marine environments, and the TTT transporters are the most abundant family of proteins in many species of β-proteobacteria. In this review, recent knowledge about these families is covered, with emphasis on their physiological and structural mechanisms, relating to several examples of relevant uptake systems in pathogenicity and colonization, using the SiaPQM sialic acid uptake system from Haemophilus influenzae and the TctCBA citrate uptake system of Salmonella typhimurium as the prototypes for the TRAP and TTT transporters, respectively. High-throughput analysis of SBPs has recently expanded considerably the range of putative substrates known for TRAP transporters, while the repertoire for the TTT family has yet to be fully explored but both types of systems most commonly transport carboxylates. Specialized spectroscopic techniques and site-directed mutagenesis have enriched our knowledge of the way TRAP binding proteins capture their substrate, while structural comparisons show conserved regions for substrate coordination in both families. Genomic and protein sequence analyses show TTT SBP genes are strikingly overrepresented in some bacteria, especially in the
Entanglement from topology in Chern-Simons theory
Salton, Grant; Swingle, Brian; Walter, Michael
2017-05-01
The way in which geometry encodes entanglement is a topic of much recent interest in quantum many-body physics and the AdS/CFT duality. This relation is particularly pronounced in the case of topological quantum field theories, where topology alone determines the quantum states of the theory. In this work, we study the set of quantum states that can be prepared by the Euclidean path integral in three-dimensional Chern-Simons theory. Specifically, we consider arbitrary three-manifolds with a fixed number of torus boundaries in both Abelian U (1 ) and non-Abelian S O (3 ) Chern-Simons theory. For the Abelian theory, we find that the states that can be prepared coincide precisely with the set of stabilizer states from quantum information theory. This constrains the multipartite entanglement present in this theory, but it also reveals that stabilizer states can be described by topology. In particular, we find an explicit expression for the entanglement entropy of a many-torus subsystem using only a single replica, as well as a concrete formula for the number of GHZ states that can be distilled from a tripartite state prepared through path integration. For the non-Abelian theory, we find a notion of "state universality," namely that any state can be prepared to an arbitrarily good approximation. The manifolds we consider can also be viewed as toy models of multiboundary wormholes in AdS/CFT.
Nuclear shell effect and collinear tripartition of nuclei
Indian Academy of Sciences (India)
2015-08-04
Aug 4, 2015 ... new decay mode has been observed for the spontaneous decay of 252Cf(sf, fff) and for neutron-induced .... Theoretical interpretation of the collinear tripartition of 252Cf and 236U [6–8] requires the knowledge ..... WvO thanks the FLNR and BLTP of JINR for their hospitality extended to him during his stay in ...
Policy modes for climate change: the role of tripartite partnerships
Kolk, A.; Pinkse, J.
2010-01-01
This position paper provides an initial overview of the role of tripartite partnerships for climate change in the broader framework of policy options available to address the issue. First, we will position partnerships in relation to other policy modes for climate change, including emissions trading
The Gettier Illusion, the Tripartite Analysis, and the Divorce Thesis
Booth, Anthony Robert
2014-01-01
Stephen Hetherington has defended the tripartite analysis of knowledge (Hetherington in Philos Q 48:453–469, 1998; J Philos 96:565–587, 1999; J Philos Res 26:307–324, 2001a; Good knowledge, bad knowledge, Oxford University Press, Oxford, 2001b). His defence has recently come under attack (Madison in
Manipulating continuous variable photonic entanglement
International Nuclear Information System (INIS)
Plenio, M.B.
2005-01-01
I will review our work on photonic entanglement in the continuous variable regime including both Gaussian and non-Gaussian states. The feasibility and efficiency of various entanglement purification protocols are discussed this context. (author)
Holographic entanglement entropy
Rangamani, Mukund
2017-01-01
This book provides a comprehensive overview of developments in the field of holographic entanglement entropy. Within the context of the AdS/CFT correspondence, it is shown how quantum entanglement is computed by the area of certain extremal surfaces. The general lessons one can learn from this connection are drawn out for quantum field theories, many-body physics, and quantum gravity. An overview of the necessary background material is provided together with a flavor of the exciting open questions that are currently being discussed. The book is divided into four main parts. In the first part, the concept of entanglement, and methods for computing it, in quantum field theories is reviewed. In the second part, an overview of the AdS/CFT correspondence is given and the holographic entanglement entropy prescription is explained. In the third part, the time-dependence of entanglement entropy in out-of-equilibrium systems, and applications to many body physics are explored using holographic methods. The last part f...
Entanglement in the Bogoliubov vacuum
DEFF Research Database (Denmark)
Poulsen, Uffe Vestergaard; Meyer, T.; Lewenstein, M.
2005-01-01
We analyze the entanglement properties of the Bogoliubov vacuum, which is obtained as a second-order approximation to the ground state of an interacting Bose-Einstein condensate. We work in one- and two-dimensional lattices and study the entanglement between two groups of sites as a function...... and to be favoured by strong interactions. Conversely, long-range entanglement is favoured by relatively weak interactions. No examples of bound entanglement are found....
Quantum Statistics and Entanglement Problems
Trainor, L. E. H.; Lumsden, Charles J.
2002-01-01
Interpretations of quantum measurement theory have been plagued by two questions, one concerning the role of observer consciousness and the other the entanglement phenomenon arising from the superposition of quantum states. We emphasize here the remarkable role of quantum statistics in describing the entanglement problem correctly and discuss the relationship to issues arising from current discussions of intelligent observers in entangled, decohering quantum worlds.
Generic entangling through quantum indistinguishability
Indian Academy of Sciences (India)
We show that this entanglement generation procedure works for completely random initial states of the variable to be entangled. We also demonstrate a curious complementarity exhibited by our scheme and its applications in estimating the generated entanglement as a function of wave packet overlap at the beamsplitter.
Universal entanglement transformations without communication
International Nuclear Information System (INIS)
Dam, Wim van; Hayden, Patrick
2003-01-01
We show that in the presence of finite catalysts, any pure bipartite entangled state can be converted into any other, to unlimited accuracy, without the use of any communication, quantum or classical. We call this process embezzling entanglement because it involves removing a small amount of entanglement from the catalyst in a physically unnoticeable way
International Nuclear Information System (INIS)
John C Baez; Vicary, Jamie
2014-01-01
Maldacena and Susskind have proposed a correspondence between wormholes and entanglement, dubbed ER=EPR. We study this in the context of three-dimensional topological quantum field theory (TQFT), where we show that the formation of a wormhole is the same process as creating a particle–antiparticle pair. A key feature of the ER=EPR proposal is that certain apparently entangled degrees of freedom turn out to be the same. We name this phenomenon ‘fake entanglement’, and show how it arises in our TQFT model. (paper)
Entanglement-annihilating and entanglement-breaking channels
International Nuclear Information System (INIS)
Moravcikova, Lenka; Ziman, Mario
2010-01-01
We introduce and investigate a family of entanglement-annihilating channels. These channels are capable of destroying any quantum entanglement within the system they act on. We show that they are not necessarily entanglement breaking. In order to achieve this result we analyze the subset of locally entanglement-annihilating channels. In this case, the same local noise applied on each subsystem individually is less entanglement annihilating (with respect to multi-partite entanglement) as the number of subsystems is increasing. Therefore, the bipartite case provides restrictions on the set of local entanglement-annihilating channels for the multipartite case. The introduced concepts are illustrated on the family of single-qubit depolarizing channels.
Multi-particle entanglement via two-party entanglement
Brassard, Gilles; Mor, Tal
2001-09-01
Entanglement between n particles is a generalization of the entanglement between two particles, and a state is considered entangled if it cannot be written as a mixture of tensor products of the n particles' states. We present the key notion of semi-separability, used to investigate n-particle entanglement by looking at two-party entanglement between its various subsystems. We provide necessary conditions for n-particle separability (that is, sufficient conditions for n-particle entanglement). We also provide necessary and sufficient conditions in the case of pure states. By surprising examples, we show that such conditions are not sufficient for separability in the case of mixed states, suggesting entanglement of a strange type.
Postcolonial Entanglements: Unruling Stories
Pacini-Ketchabaw, Veronica
2012-01-01
In this article, I use Donna Haraway's philosophy to think about postcolonial encounters between different species. I follow entangled stories of the deer/settler-child figure to trouble colonialisms and untangle the histories and trajectories that we inhabit with other species through colonial histories. I shy away from generalizations and…
International Nuclear Information System (INIS)
Borsten, L.
2011-01-01
An unexpected interplay between the seemingly disparate fields of M-theory and Quantum Information has recently come to light. We summarise these developments, culminating in a classification of 4-qubit entanglement from the physics of STU black holes. Based on work done in collaboration with D. Dahanayake, M. J. Duff, H. Ebrahim, A. Marrani and W. Rubens.
Borsten, L.
2011-07-01
An unexpected interplay between the seemingly disparate fields of M-theory and Quantum Information has recently come to light. We summarise these developments, culminating in a classification of 4-qubit entanglement from the physics of STU black holes. Based on work done in collaboration with D. Dahanayake, M. J. Duff, H. Ebrahim, A. Marrani and W. Rubens.
Multipartite entangled quantum states: Transformation, Entanglement monotones and Application
Cui, Wei
Entanglement is one of the fundamental features of quantum information science. Though bipartite entanglement has been analyzed thoroughly in theory and shown to be an important resource in quantum computation and communication protocols, the theory of entanglement shared between more than two parties, which is called multipartite entanglement, is still not complete. Specifically, the classification of multipartite entanglement and the transformation property between different multipartite states by local operators and classical communications (LOCC) are two fundamental questions in the theory of multipartite entanglement. In this thesis, we present results related to the LOCC transformation between multipartite entangled states. Firstly, we investigate the bounds on the LOCC transformation probability between multipartite states, especially the GHZ class states. By analyzing the involvement of 3-tangle and other entanglement measures under weak two-outcome measurement, we derive explicit upper and lower bound on the transformation probability between GHZ class states. After that, we also analyze the transformation between N-party W type states, which is a special class of multipartite entangled states that has an explicit unique expression and a set of analytical entanglement monotones. We present a necessary and sufficient condition for a known upper bound of transformation probability between two N-party W type states to be achieved. We also further investigate a novel entanglement transformation protocol, the random distillation, which transforms multipartite entanglement into bipartite entanglement ii shared by a non-deterministic pair of parties. We find upper bounds for the random distillation protocol for general N-party W type states and find the condition for the upper bounds to be achieved. What is surprising is that the upper bounds correspond to entanglement monotones that can be increased by Separable Operators (SEP), which gives the first set of
Extended non-local games and monogamy-of-entanglement games.
Johnston, Nathaniel; Mittal, Rajat; Russo, Vincent; Watrous, John
2016-05-01
We study a generalization of non-local games-which we call extended non-local games -in which the players, Alice and Bob, initially share a tripartite quantum state with the referee. In such games, the winning conditions for Alice and Bob may depend on the outcomes of measurements made by the referee, on its part of the shared quantum state, in addition to Alice and Bob's answers to randomly selected questions. Our study of this class of games was inspired by the monogamy-of-entanglement games introduced by Tomamichel, Fehr, Kaniewski and Wehner, which they also generalize. We prove that a natural extension of the Navascués-Pironio-Acín hierarchy of semidefinite programmes converges to the optimal commuting measurement value of extended non-local games, and we prove two extensions of results of Tomamichel et al. concerning monogamy-of-entanglement games.
Sun, Hong; Hu, Xiangming
2012-03-01
It has been known that one reservoir of driven two-level atoms can establish two-mode interactions and generate bipartite continuous-variable entangled light. Here we show that three-mode interactions can be created by combining two such reservoirs, each of which interacts with two adjacent fields in frequency. It is shown that the van Loock-Furusawa criteria [Phys. Rev. A1050-2947PLRAAN10.1103/PhysRevA.67.052315 67, 052315 (2003)] are well satisfied for a wide range of the relevant parameters. This determines that tripartite continuous-variable Greenberger-Horne-Zeilinger entanglement is obtainable. The scalability to more fields is straightforward, allowing an alternative implementation of a multipartite quantum networks with continuous variables.
Diffusion-based recommendation with trust relations on tripartite graphs
Wang, Ximeng; Liu, Yun; Zhang, Guangquan; Xiong, Fei; Lu, Jie
2017-08-01
The diffusion-based recommendation approach is a vital branch in recommender systems, which successfully applies physical dynamics to make recommendations for users on bipartite or tripartite graphs. Trust links indicate users’ social relations and can provide the benefit of reducing data sparsity. However, traditional diffusion-based algorithms only consider rating links when making recommendations. In this paper, the complementarity of users’ implicit and explicit trust is exploited, and a novel resource-allocation strategy is proposed, which integrates these two kinds of trust relations on tripartite graphs. Through empirical studies on three benchmark datasets, our proposed method obtains better performance than most of the benchmark algorithms in terms of accuracy, diversity and novelty. According to the experimental results, our method is an effective and reasonable way to integrate additional features into the diffusion-based recommendation approach.
Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?
Charron, Giselle; Doudnikoff, Evelyne; Canron, Marie-Helene; Li, Qin; Véga, Céline; Marais, Sebastien; Baufreton, Jérôme; Vital, Anne; Oliet, Stéphane H. R.; Bezard, Erwan
2014-01-01
International audience; The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e., the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson's disease (PD) remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified " tripartite " synapses in the basal ganglia in general and the striatum ...
Entanglement reactivation in separable environments
International Nuclear Information System (INIS)
Pirandola, Stefano
2013-01-01
Combining two entanglement-breaking channels into a correlated-noise environment restores the distribution of entanglement. Surprisingly, this reactivation can be induced by the injection of separable correlations from the composite environment. In any dimension (finite or infinite), we can construct classically correlated ‘twirling’ environments which are entanglement-breaking in the transmission of single systems but entanglement-preserving when two systems are transmitted. Here entanglement is simply preserved by the existence of decoherence-free subspaces. Remarkably, even when such subspaces do not exist, a fraction of the input entanglement can still be distributed. This is found in separable Gaussian environments, where distillable entanglement is able to survive the two-mode transmission, despite being broken in any single-mode transmission by the strong thermal noise. In the Gaussian setting, entanglement restoration is a threshold process, occurring only after a critical amount of correlations has been injected. Such findings suggest new perspectives for distributing entanglement in realistic environments with extreme decoherence, identifying separable correlations and classical memory effects as physical resources for ‘breaking entanglement-breaking’. (paper)
Entangled network and quantum communication
Energy Technology Data Exchange (ETDEWEB)
Metwally, Nasser, E-mail: Nmetwally@gmail.com [Math. Dept., Faculty of Science, South Valley University, Aswan (Egypt); Math. Dept., College of Science, University of Bahrain, P.O. Box 32038 (Bahrain)
2011-11-21
A theoretical scheme is introduced to generate entangled network via Dzyaloshinskii–Moriya (DM) interaction. The dynamics of entanglement between different nodes, which is generated by direct or indirect interaction, is investigated. It is shown that, the direction of (DM) interaction and the locations of the nodes have a sensational effect on the degree of entanglement. The minimum entanglement generated between all the nodes is quantified. The upper and lower bounds of the entanglement depend on the direction of DM interaction, and the repetition of the behavior depends on the strength of DM. The generated entangled nodes are used as quantum channel to perform quantum teleportation, where it is shown that the fidelity of teleporting unknown information between the network members depends on the locations of the members.
Jensen, Sturle
2003-01-01
The subject of this thesis is the development of tripartite arrangements between representatives of the trade union organisations, the employers’ organisations and the government or the state bureaucracy in Estonia, Latvia and Lithuania after the three countries regained their independence from the Soviet Union in 1991. I have studied and compared the contents of tripartite agreements and the work of tripartite councils. I have divided the time into the two periods from 1991 to...
Holographic entanglement chemistry
Caceres, Elena; Nguyen, Phuc H.; Pedraza, Juan F.
2017-05-01
We use the Iyer-Wald formalism to derive an extended first law of entanglement that includes variations in the cosmological constant, Newton's constant and—in the case of higher-derivative theories—all the additional couplings of the theory. In Einstein gravity, where the number of degrees of freedom N2 of the dual field theory is a function of Λ and G , our approach allows us to vary N by keeping the field theory scale fixed or to vary the field theory scale by keeping N fixed. We also derive an extended first law of entanglement for Gauss-Bonnet and Lovelock gravity and show that in these cases all the extra variations reorganize nicely in terms of the central charges of the theory. Finally, we comment on the implications for renormalization group flows and c -theorems in higher dimensions.
Untangling Quantum Entanglement
Fellows, Jeremy L.
2005-01-01
The phenomenon of quantum entanglement is explained in a way which is fully consistent with Einstein's Special Theory of Relativity. A subtle flaw is identified in the logic supporting the view that Bell's Inequality precludes all local hidden-variable theories, and it is shown how EPR-type experiments can be constructed to produce statistical correlation results in a purely classical manner which match exactly the predictions made by quantum theory.
Entanglement of neutrino states
Khokhlov, D. L.
2007-01-01
Muon and muon antineutrino born in the decay of charged pion form the entangled spin state. The decay of muon with the left helicity triggers the left helicity for muon antineutrino to preserve the null total angular momentum of muon and muon antineutrino. This is forbidden for antineutrino hence one cannot detect the muon antineutrino after the decay of muon. This effect may explain the deficit of muon neutrino flux in the Super-Kamiokande, K2K, MINOS experiments.
Geometric Aspects of Quantum Entanglement
Hansen, Leif Ove
2016-01-01
Summary: Entanglement is a strange feature contained in the quantum mechanical framework, first observed theoretically by Erwin Schrödinger and Albert Einstein. An inherent attribute of entanglement is non-locality, and in the continuation of this, several non-reductionist features, which are conceptually challenging and philosophically interesting. A considerable growth of the interest in quantum entanglement has occurred since the early 1990s, and much of the reason for this is that ...
DEFF Research Database (Denmark)
Flindt, Christian; Sørensen, A. S.; Lukin, M. D.
2007-01-01
We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control...... of the diode bias and local gating allow for the generation of single photons that are entangled with a robust quantum memory based on the electron spins. Practical performance of this approach to controlled spin-photon entanglement is analyzed....
Experimental Entanglement Distribution by Separable States
Vollmer, Christina E.; Schulze, Daniela; Eberle, Tobias; Händchen, Vitus; Fiurášek, Jaromír; Schnabel, Roman
2013-12-01
Distribution of entanglement between macroscopically separated parties is crucial for future quantum information networks. Surprisingly, it has been theoretically shown that two distant systems can be entangled by sending a third system that is not entangled with either of them. Here, we experimentally distribute entanglement and successfully prove that our transmitted light beam is indeed not entangled with the parties’ local systems. Our work demonstrates an unexpected variant of entanglement distribution and improves the understanding necessary to engineer multipartite quantum networks.
Entangling power of the quantum baker's map
International Nuclear Information System (INIS)
Scott, A J; Caves, Carlton M
2003-01-01
We investigate entanglement production in a class of quantum baker's maps. The dynamics of these maps is constructed using strings of qubits, providing a natural tensor-product structure for application of various entanglement measures. We find that, in general, the quantum baker's maps are good at generating entanglement, producing multipartite entanglement amongst the qubits close to that expected in random states. We investigate the evolution of several entanglement measures: the subsystem linear entropy, the concurrence to characterize entanglement between pairs of qubits and two proposals for a measure of multipartite entanglement. Also derived are some new analytical formulae describing the levels of entanglement expected in random pure states
Multi-Photon Entanglement and Quantum Teleportation
National Research Council Canada - National Science Library
Shih, Yanhua
1999-01-01
The project 'Multi-Photon Entanglement and Quantum Teleportation' concerns a series of experimental and theoretical investigations on multi-photon entangled states and the applications, for example...
Emergence of Symmetries from Entanglement
CERN. Geneva
2016-01-01
Maximal Entanglement appears to be a key ingredient for the emergence of symmetries. We first illustrate this phenomenon using two examples: the emergence of conformal symmetry in condensed matter systems and the relation of tensor networks to holography. We further present a Principle of Maximal Entanglement that seems to dictate to a large extend the structure of gauge symmetry.
Entanglement Entropy of Black Holes
Directory of Open Access Journals (Sweden)
Sergey N. Solodukhin
2011-10-01
Full Text Available The entanglement entropy is a fundamental quantity, which characterizes the correlations between sub-systems in a larger quantum-mechanical system. For two sub-systems separated by a surface the entanglement entropy is proportional to the area of the surface and depends on the UV cutoff, which regulates the short-distance correlations. The geometrical nature of entanglement-entropy calculation is particularly intriguing when applied to black holes when the entangling surface is the black-hole horizon. I review a variety of aspects of this calculation: the useful mathematical tools such as the geometry of spaces with conical singularities and the heat kernel method, the UV divergences in the entropy and their renormalization, the logarithmic terms in the entanglement entropy in four and six dimensions and their relation to the conformal anomalies. The focus in the review is on the systematic use of the conical singularity method. The relations to other known approaches such as ’t Hooft’s brick-wall model and the Euclidean path integral in the optical metric are discussed in detail. The puzzling behavior of the entanglement entropy due to fields, which non-minimally couple to gravity, is emphasized. The holographic description of the entanglement entropy of the black-hole horizon is illustrated on the two- and four-dimensional examples. Finally, I examine the possibility to interpret the Bekenstein-Hawking entropy entirely as the entanglement entropy.
Entanglement transfer between bipartite systems
International Nuclear Information System (INIS)
Bougouffa, Smail; Ficek, Zbigniew
2012-01-01
The problem of a controlled transfer of an entanglement initially encoded into two two-level atoms that are successively sent through two single-mode cavities is investigated. The atoms and the cavity modes form a four-qubit system and we demonstrate the conditions under which the initial entanglement encoded into the atoms can be completely transferred to other pairs of qubits. We find that in the case of non-zero detuning between the atomic transition frequencies and the cavity mode frequencies, no complete transfer of the initial entanglement is possible to any of the other pairs of qubits. In the case of exact resonance and equal coupling strengths of the atoms to the cavity modes, an initial maximally entangled state of the atoms can be completely transferred to the cavity modes. Complete transfer of the entanglement is restricted to the cavity modes, with transfer to the other pairs being limited to 50%. We find that complete transfer of an initial entanglement to other pairs of qubits may take place if the initial state is not the maximally entangled state and the atoms couple to the cavity modes with unequal strengths. Depending on the ratio between the coupling strengths, optimal entanglement can be created between the atoms and one of the cavity modes.
Holographic Storage of Biphoton Entanglement
Dai, Han-Ning; Zhang, Han; Yang, Sheng-Jun; Zhao, Tian-Ming; Rui, Jun; Deng, You-Jin; Li, Li; Liu, Nai-Le; Chen, Shuai; Bao, Xiao-Hui; Jin, Xian-Min; Zhao, Bo; Pan, Jian-Wei
2012-05-01
Coherent and reversible storage of multiphoton entanglement with a multimode quantum memory is essential for scalable all-optical quantum information processing. Although a single photon has been successfully stored in different quantum systems, storage of multiphoton entanglement remains challenging because of the critical requirement for coherent control of the photonic entanglement source, multimode quantum memory, and quantum interface between them. Here we demonstrate a coherent and reversible storage of biphoton Bell-type entanglement with a holographic multimode atomic-ensemble-based quantum memory. The retrieved biphoton entanglement violates the Bell inequality for 1μs storage time and a memory-process fidelity of 98% is demonstrated by quantum state tomography.
CSIR Research Space (South Africa)
Mc
2012-07-01
Full Text Available stream_source_info McLaren_2012.pdf.txt stream_content_type text/plain stream_size 2190 Content-Encoding ISO-8859-1 stream_name McLaren_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 High dimensional... entanglement M. McLAREN1,2, F.S. ROUX1 & A. FORBES1,2,3 1. CSIR National Laser Centre, PO Box 395, Pretoria 0001 2. School of Physics, University of the Stellenbosch, Private Bag X1, 7602, Matieland 3. School of Physics, University of Kwazulu...
Energy Technology Data Exchange (ETDEWEB)
Nomura, Yasunori [Berkeley Center for Theoretical Physics, Department of Physics, University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, Kashiwa 277-8583 (Japan); Salzetta, Nico, E-mail: nsalzetta@berkeley.edu [Berkeley Center for Theoretical Physics, Department of Physics, University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Sanches, Fabio; Weinberg, Sean J. [Berkeley Center for Theoretical Physics, Department of Physics, University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)
2016-12-10
We study the Hilbert space structure of classical spacetimes under the assumption that entanglement in holographic theories determines semiclassical geometry. We show that this simple assumption has profound implications; for example, a superposition of classical spacetimes may lead to another classical spacetime. Despite its unconventional nature, this picture admits the standard interpretation of superpositions of well-defined semiclassical spacetimes in the limit that the number of holographic degrees of freedom becomes large. We illustrate these ideas using a model for the holographic theory of cosmological spacetimes.
Chin, Eu Gene; Ebesutani, Chad; Young, John
2013-01-01
The tripartite model of anxiety and depression has received strong support among child and adolescent populations. Clinical samples of children and adolescents in these studies, however, have usually been referred for treatment of anxiety and depression. This study investigated the fit of the tripartite model with a complicated sample of…
An Evaluation of the Applicability of the Tripartite Constructs to Social Anxiety in Adolescents
Anderson, Emily R.; Veed, Glen J.; Inderbitzen-Nolan, Heidi M.; Hansen, David J.
2010-01-01
The current study examined the tripartite model of anxiety and depression in relation to social phobia in a nonclinical sample of adolescents (ages 13-17). Adolescent/parent dyads participated in a semistructured interview and completed self-report measures of the tripartite constructs and social anxiety. Adolescents gave an impromptu speech, and…
Bidens tripartite L.: A Cd-accumulator confirmed by pot culture and site sampling experiment
International Nuclear Information System (INIS)
Wei Shuhe; Niu Rongcheng; Srivastava, Mrittunjai; Zhou Qixing; Wu Zhijie; Sun Tieheng; Hu Yahu; Li Yunmeng
2009-01-01
Characteristics of accumulation and tolerance of cadmium (Cd) in Bidens tripartite L. were investigated to identify Cd-accumulating properties. In this study, pot culture experiment and site sampling experiments were conducted to assess whether this plant is a heavy metal hyperaccumulator or accumulator. The results indicated that the Cd enrichment factor (concentration in plant/soil) and Cd translocation factor (concentration in shoot/root) of B. tripartite was principally >1 in pot culture and concentration gradient experiments. Shoot biomass was not reduced significantly (p -1 , the threshold concentration for a Cd-hyperaccumulator. In the site sampling experiment, B. tripartite also showed Cd-accumulator properties. Based on these results, B. tripartite could be identified as a Cd-accumulator. Thus, B. tripartite should only be considered as a Cd-accumulator.
A unique tripartite collision tumor of the esophagus
Schizas, Dimitrios; Michalinos, Adamantios; Alexandrou, Paraskevi; Moris, Demetrios; Baliou, Evangelia; Tsilimigras, Diamantis; Throupis, Theodore; Liakakos, Theodore
2017-01-01
Abstract Rationale: We report a unique case of a tripartite esophageal collision tumor consisting of three separate histologic types. Patients concerns: Therapeutic dilemmas on the proper treatment of those rare neoplasms remain unanswered considering both proper surgical therapy and adjuvant therapy. Diagnose: In this paper, we report a unique case of a patient with a tripartite esophageal collision tumor consisting of a small cell carcinoma, an adenocarcinoma of medium differentiation and a signet ring cell carcinoma. Diagnosis is difficult as clinical presentation of the patient was undistinguishable from other, commoner tumor types. Interventions: The patient's diagnostic and therapeutic course along with available data on the collisions tumor's biological behavior and treatment are briefly discussed. Outcomes: Esophagectomy is the best treatment options for these patients. Unique nature of this tumor demands aggresive oncologic treatment. Lessons: Collision tumors are rare neoplasms consisting of distinct cell populations developing in juxtaposition to one another without any areas of intermingling. Various cell types can be found. However, collision neoplasms of the esophagus combining adenomatous and neuroendocrine components are exceedingly rare, with only 5 cases described to date in the literature. Given their rarity, limited information is available on their tumorigenesis, biological behavior and clinical course. In general, these tumors are aggressive neoplasms and significantly affect patient treatment and prognosis. PMID:29245236
Information-theoretic treatment of tripartite systems and quantum channels
International Nuclear Information System (INIS)
Coles, Patrick J.; Yu Li; Gheorghiu, Vlad; Griffiths, Robert B.
2011-01-01
A Holevo measure is used to discuss how much information about a given positive operator valued measure (POVM) on system a is present in another system b, and how this influences the presence or absence of information about a different POVM on a in a third system c. The main goal is to extend information theorems for mutually unbiased bases or general bases to arbitrary POVMs, and especially to generalize ''all-or-nothing'' theorems about information located in tripartite systems to the case of partial information, in the form of quantitative inequalities. Some of the inequalities can be viewed as entropic uncertainty relations that apply in the presence of quantum side information, as in recent work by Berta et al. [Nature Physics 6, 659 (2010)]. All of the results also apply to quantum channels: For example, if E accurately transmits certain POVMs, the complementary channel F will necessarily be noisy for certain other POVMs. While the inequalities are valid for mixed states of tripartite systems, restricting to pure states leads to the basis invariance of the difference between the information about a contained in b and c.
On holographic entanglement density
Gushterov, Nikola I.; O'Bannon, Andy; Rodgers, Ronnie
2017-10-01
We use holographic duality to study the entanglement entropy (EE) of Conformal Field Theories (CFTs) in various spacetime dimensions d, in the presence of various deformations: a relevant Lorentz scalar operator with constant source, a temperature T , a chemical potential μ, a marginal Lorentz scalar operator with source linear in a spatial coordinate, and a circle-compactified spatial direction. We consider EE between a strip or sphere sub-region and the rest of the system, and define the "entanglement density" (ED) as the change in EE due to the deformation, divided by the sub-region's volume. Using the deformed CFTs above, we show how the ED's dependence on the strip width or sphere radius, L, is useful for characterizing states of matter. For example, the ED's small- L behavior is determined either by the dimension of the perturbing operator or by the first law of EE. For Lorentz-invariant renormalization group (RG) flows between CFTs, the "area theorem" states that the coefficient of the EE's area law term must be larger in the UV than in the IR. In these cases the ED must therefore approach zero from below as L→∞. However, when Lorentz symmetry is broken and the IR fixed point has different scaling from the UV, we find that the ED often approaches the thermal entropy density from above, indicating area theorem violation.
Squashed entanglement in infinite dimensions
Shirokov, M. E.
2016-03-01
We analyse two possible definitions of the squashed entanglement in an infinite-dimensional bipartite system: direct translation of the finite-dimensional definition and its universal extension. It is shown that the both definitions produce the same lower semicontinuous entanglement measure possessing all basis properties of the squashed entanglement on the set of states having at least one finite marginal entropy. It is also shown that the second definition gives an adequate lower semicontinuous extension of this measure to all states of the infinite-dimensional bipartite system. A general condition relating continuity of the squashed entanglement to continuity of the quantum mutual information is proved and its corollaries are considered. Continuity bound for the squashed entanglement under the energy constraint on one subsystem is obtained by using the tight continuity bound for quantum conditional mutual information (proved in the Appendix by using Winter's technique). It is shown that the same continuity bound is valid for the entanglement of formation. As a result the asymptotic continuity of the both entanglement measures under the energy constraint on one subsystem is proved.
Squashed entanglement in infinite dimensions
International Nuclear Information System (INIS)
Shirokov, M. E.
2016-01-01
We analyse two possible definitions of the squashed entanglement in an infinite-dimensional bipartite system: direct translation of the finite-dimensional definition and its universal extension. It is shown that the both definitions produce the same lower semicontinuous entanglement measure possessing all basis properties of the squashed entanglement on the set of states having at least one finite marginal entropy. It is also shown that the second definition gives an adequate lower semicontinuous extension of this measure to all states of the infinite-dimensional bipartite system. A general condition relating continuity of the squashed entanglement to continuity of the quantum mutual information is proved and its corollaries are considered. Continuity bound for the squashed entanglement under the energy constraint on one subsystem is obtained by using the tight continuity bound for quantum conditional mutual information (proved in the Appendix by using Winter’s technique). It is shown that the same continuity bound is valid for the entanglement of formation. As a result the asymptotic continuity of the both entanglement measures under the energy constraint on one subsystem is proved.
Local cloning of entangled states
International Nuclear Information System (INIS)
Gheorghiu, Vlad; Yu Li; Cohen, Scott M.
2010-01-01
We investigate the conditions under which a set S of pure bipartite quantum states on a DxD system can be locally cloned deterministically by separable operations, when at least one of the states is full Schmidt rank. We allow for the possibility of cloning using a resource state that is less than maximally entangled. Our results include that: (i) all states in S must be full Schmidt rank and equally entangled under the G-concurrence measure, and (ii) the set S can be extended to a larger clonable set generated by a finite group G of order |G|=N, the number of states in the larger set. It is then shown that any local cloning apparatus is capable of cloning a number of states that divides D exactly. We provide a complete solution for two central problems in local cloning, giving necessary and sufficient conditions for (i) when a set of maximally entangled states can be locally cloned, valid for all D; and (ii) local cloning of entangled qubit states with nonvanishing entanglement. In both of these cases, we show that a maximally entangled resource is necessary and sufficient, and the states must be related to each other by local unitary 'shift' operations. These shifts are determined by the group structure, so need not be simple cyclic permutations. Assuming this shifted form and partially entangled states, then in D=3 we show that a maximally entangled resource is again necessary and sufficient, while for higher-dimensional systems, we find that the resource state must be strictly more entangled than the states in S. All of our necessary conditions for separable operations are also necessary conditions for local operations and classical communication (LOCC), since the latter is a proper subset of the former. In fact, all our results hold for LOCC, as our sufficient conditions are demonstrated for LOCC, directly.
Bound entanglement and local realism
International Nuclear Information System (INIS)
Kaszlikowski, Dagomir; Zukowski, Marek; Gnacinski, Piotr
2002-01-01
We show using a numerical approach, which gives necessary and sufficient conditions for the existence of local realism, that the bound entangled state presented in Bennett et al. [Phys. Rev. Lett. 82, 5385 (1999)] admits a local and realistic description. We also find the lowest possible amount of some appropriate entangled state that must be ad-mixed to the bound entangled state so that the resulting density operator has no local and realistic description and as such can be useful in quantum communication and quantum computation
Quantum entanglement distillation with metamaterials.
al Farooqui, Md Abdullah; Breeland, Justin; Aslam, Muhammad I; Sadatgol, Mehdi; Özdemir, Şahin K; Tame, Mark; Yang, Lan; Güney, Durdu Ö
2015-07-13
We propose a scheme for the distillation of partially entangled two-photon Bell and three-photon W states using metamaterials. The distillation of partially entangled Bell states is achieved by using two metamaterials with polarization dependence, one of which is rotated by π/2 around the direction of propagation of the photons. On the other hand, the distillation of three-photon W states is achieved by using one polarization dependent metamaterial and two polarization independent metamaterials. Upon transmission of the photons of the partially entangled states through the metamaterials the entanglement of the states increases and they become distilled. This work opens up new directions in quantum optical state engineering by showing how metamaterials can be used to carry out a quantum information processing task.
Transverse correlations in multiphoton entanglement
International Nuclear Information System (INIS)
Wen Jianming; Rubin, Morton H.; Shih Yanhua
2007-01-01
We have analyzed the transverse correlation in multiphoton entanglement. The generalization of quantum ghost imaging is extended to the N-photon state. The Klyshko's two-photon advanced-wave picture is generalized to the N-photon case
Nanorheology of Entangled Polymer Melts
Ge, Ting; Grest, Gary S.; Rubinstein, Michael
2018-02-01
We use molecular simulations to probe the local viscoelasticity of an entangled polymer melt by tracking the motion of embedded nonsticky nanoparticles (NPs). As in conventional microrheology, the generalized Stokes-Einstein relation is employed to extract an effective stress relaxation function GGSE(t ) from the mean square displacement of NPs. GGSE(t ) for different NP diameters d are compared with the stress relaxation function G (t ) of a pure polymer melt. The deviation of GGSE(t ) from G (t ) reflects the incomplete coupling between NPs and the dynamic modes of the melt. For linear polymers, a plateau in GGSE(t ) emerges as d exceeds the entanglement mesh size a and approaches the entanglement plateau in G (t ) for a pure melt with increasing d . For ring polymers, as d increases towards the spanning size R of ring polymers, GGSE(t ) approaches G (t ) of the ring melt with no entanglement plateau.
Continuous-Variable Entanglement Swapping
Directory of Open Access Journals (Sweden)
Kevin Marshall
2015-05-01
Full Text Available We present a very brief overview of entanglement swapping as it relates to continuous-variable quantum information. The technical background required is discussed and the natural link to quantum teleportation is established before discussing the nature of Gaussian entanglement swapping. The limitations of Gaussian swapping are introduced, along with the general applications of swapping in the context of to quantum communication and entanglement distribution. In light of this, we briefly summarize a collection of entanglement swapping schemes which incorporate a non-Gaussian ingredient and the benefits of such schemes are noted. Finally, we motivate the need to further study and develop such schemes by highlighting requirements of a continuous-variable repeater.
Entangled Bessel-Gaussian beams
CSIR Research Space (South Africa)
McLaren, M
2012-10-01
Full Text Available by performing a Bell-type experiment and showing a violation of the Clauser-Horne-Shimony-Holt inequality. In addition, we use quantum state tomography to indicate higher-dimensional entanglement in terms of BG modes....
Entanglement distribution in quantum networks
Energy Technology Data Exchange (ETDEWEB)
Perseguers, Sebastien
2010-04-15
This Thesis contributes to the theory of entanglement distribution in quantum networks, analyzing the generation of long-distance entanglement in particular. We consider that neighboring stations share one partially entangled pair of qubits, which emphasizes the difficulty of creating remote entanglement in realistic settings. The task is then to design local quantum operations at the stations, such that the entanglement present in the links of the whole network gets concentrated between few parties only, regardless of their spatial arrangement. First, we study quantum networks with a two-dimensional lattice structure, where quantum connections between the stations (nodes) are described by non-maximally entangled pure states (links). We show that the generation of a perfectly entangled pair of qubits over an arbitrarily long distance is possible if the initial entanglement of the links is larger than a threshold. This critical value highly depends on the geometry of the lattice, in particular on the connectivity of the nodes, and is related to a classical percolation problem. We then develop a genuine quantum strategy based on multipartite entanglement, improving both the threshold and the success probability of the generation of long-distance entanglement. Second, we consider a mixed-state definition of the connections of the quantum networks. This formalism is well-adapted for a more realistic description of systems in which noise (random errors) inevitably occurs. New techniques are required to create remote entanglement in this setting, and we show how to locally extract and globally process some error syndromes in order to create useful long-distance quantum correlations. Finally, we turn to networks that have a complex topology, which is the case for most real-world communication networks such as the Internet for instance. Besides many other characteristics, these systems have in common the small-world feature, stating that any two nodes are separated by a
Entanglement distribution in quantum networks
International Nuclear Information System (INIS)
Perseguers, Sebastien
2010-01-01
This Thesis contributes to the theory of entanglement distribution in quantum networks, analyzing the generation of long-distance entanglement in particular. We consider that neighboring stations share one partially entangled pair of qubits, which emphasizes the difficulty of creating remote entanglement in realistic settings. The task is then to design local quantum operations at the stations, such that the entanglement present in the links of the whole network gets concentrated between few parties only, regardless of their spatial arrangement. First, we study quantum networks with a two-dimensional lattice structure, where quantum connections between the stations (nodes) are described by non-maximally entangled pure states (links). We show that the generation of a perfectly entangled pair of qubits over an arbitrarily long distance is possible if the initial entanglement of the links is larger than a threshold. This critical value highly depends on the geometry of the lattice, in particular on the connectivity of the nodes, and is related to a classical percolation problem. We then develop a genuine quantum strategy based on multipartite entanglement, improving both the threshold and the success probability of the generation of long-distance entanglement. Second, we consider a mixed-state definition of the connections of the quantum networks. This formalism is well-adapted for a more realistic description of systems in which noise (random errors) inevitably occurs. New techniques are required to create remote entanglement in this setting, and we show how to locally extract and globally process some error syndromes in order to create useful long-distance quantum correlations. Finally, we turn to networks that have a complex topology, which is the case for most real-world communication networks such as the Internet for instance. Besides many other characteristics, these systems have in common the small-world feature, stating that any two nodes are separated by a
Tripartite synapses: astrocytes process and control synaptic information.
Perea, Gertrudis; Navarrete, Marta; Araque, Alfonso
2009-08-01
The term 'tripartite synapse' refers to a concept in synaptic physiology based on the demonstration of the existence of bidirectional communication between astrocytes and neurons. Consistent with this concept, in addition to the classic 'bipartite' information flow between the pre- and postsynaptic neurons, astrocytes exchange information with the synaptic neuronal elements, responding to synaptic activity and, in turn, regulating synaptic transmission. Because recent evidence has demonstrated that astrocytes integrate and process synaptic information and control synaptic transmission and plasticity, astrocytes, being active partners in synaptic function, are cellular elements involved in the processing, transfer and storage of information by the nervous system. Consequently, in contrast to the classically accepted paradigm that brain function results exclusively from neuronal activity, there is an emerging view, which we review herein, in which brain function actually arises from the coordinated activity of a network comprising both neurons and glia.
Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?
Charron, Giselle; Doudnikoff, Evelyne; Canron, Marie-Helene; Li, Qin; Véga, Céline; Marais, Sebastien; Baufreton, Jérôme; Vital, Anne; Oliet, Stéphane H R; Bezard, Erwan
2014-01-01
The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e., the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson's disease (PD) remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified "tripartite" synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dys) regulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.
Astrocytosis in parkinsonism: considering tripartite striatal synapses in physiopathology?
Directory of Open Access Journals (Sweden)
Giselle eCharron
2014-09-01
Full Text Available The current concept of basal ganglia organization and function in physiological and pathophysiological conditions excludes the most numerous cells in the brain, i.e. the astrocytes, present with a ratio of 10:1 neuron. Their role in neurodegenerative condition such as Parkinson’s disease (PD remains to be elucidated. Before embarking into physiological investigations of the yet-to-be-identified tripartite synapses in the basal ganglia in general and the striatum in particular, we therefore characterized anatomically the PD-related modifications in astrocytic morphology, the changes in astrocytic network connections and the consequences on the spatial relationship between astrocytic processes and asymmetric synapses in normal and PD-like conditions in experimental and human PD. Our results unravel a dramatic regulation of striatal astrocytosis supporting the hypothesis of a key role in (dysregulating corticostriatal transmission. Astrocytes and their various properties might thus represent a therapeutic target in PD.
Support for an expanded tripartite influence model with gay men.
Tylka, Tracy L; Andorka, Michael J
2012-01-01
This study investigated whether an expanded tripartite influence model would represent gay men's experiences. This model was extended by adding partners and gay community involvement as sources of social influence and considering dual body image pathways (muscularity and body fat dissatisfaction) to muscularity enhancement and disordered eating behaviors. Latent variable structural equation modeling analyses upheld this model for 346 gay men. Dual body image pathways to body change behaviors were supported, although three unanticipated interrelationships emerged, suggesting that muscularity and body fat concerns and behaviors may be more integrated for gay men. Internalization of the mesomorphic ideal, appearance comparison, muscularity dissatisfaction, and body fat dissatisfaction were key mediators in the model. Of the sources of social influence, friend and media pressure to be lean, gay community involvement, and partner, friend, media, and family pressures to be muscular made incremental contributions. Unexpectedly, certain sources were directly connected to body change behaviors. Copyright © 2011 Elsevier Ltd. All rights reserved.
Generic entangling through quantum indistinguishability
Indian Academy of Sciences (India)
known mechanisms for entanglement generation [1–4] which involve either a direct inter- .... y ),ˆb. ¼ = 1Ô2 (σD x σD y ) and dividing the result by. ¦2Ô2. Equation (3) also helps us to estimate the amount of entanglement generated by our scheme if S1 and S2 are Gaussian wave-packet states of the incident particles arriving.
Quantum Entanglement and Chemical Reactivity.
Molina-Espíritu, M; Esquivel, R O; López-Rosa, S; Dehesa, J S
2015-11-10
The water molecule and a hydrogenic abstraction reaction are used to explore in detail some quantum entanglement features of chemical interest. We illustrate that the energetic and quantum-information approaches are necessary for a full understanding of both the geometry of the quantum probability density of molecular systems and the evolution of a chemical reaction. The energy and entanglement hypersurfaces and contour maps of these two models show different phenomena. The energy ones reveal the well-known stable geometry of the models, whereas the entanglement ones grasp the chemical capability to transform from one state system to a new one. In the water molecule the chemical reactivity is witnessed through quantum entanglement as a local minimum indicating the bond cleavage in the dissociation process of the molecule. Finally, quantum entanglement is also useful as a chemical reactivity descriptor by detecting the transition state along the intrinsic reaction path in the hypersurface of the hydrogenic abstraction reaction corresponding to a maximally entangled state.
Antibunching dynamics of plasmonically mediated entanglement generation
Dumitrescu, Eugene; Lawrie, Benjamin
2017-11-01
Dissipative entanglement-generation protocols embrace environmental interactions to generate long-lived entangled states. In this paper, we report on the antibunching dynamics for a pair of actively driven quantum emitters coupled to a shared dissipative plasmonic reservoir. We find that antibunching is a universal signature for entangled states generated by dissipative means and examine its use as an entanglement diagnostic. We discuss the experimental validation of plasmonically mediated entanglement generation by Hanbury Brown-Twiss interferometry with picosecond timing resolution determined by an effective two-qubit Rabi frequency, and we analyze the robustness of entanglement generation with respect to perturbations in local detunings, couplings, and driving fields.
Optimal simulation of a perfect entangler
International Nuclear Information System (INIS)
Yu Nengkun; Duan Runyao; Ying Mingsheng
2010-01-01
A 2 x 2 unitary operation is called a perfect entangler if it can generate a maximally entangled state from some unentangled input. We study the following question: How many runs of a given two-qubit entangling unitary operation are required to simulate some perfect entangler with one-qubit unitary operations as free resources? We completely solve this problem by presenting an analytical formula for the optimal number of runs of the entangling operation. Our result reveals an entanglement strength of two-qubit unitary operations.
Cell adhesion and matricellular support by astrocytes of the tripartite synapse
Hillen, Anne E J; Burbach, J Peter H; Hol, Elly M
2018-01-01
Astrocytes contribute to the formation, function, and plasticity of synapses. Their processes enwrap the neuronal components of the tripartite synapse, and due to this close interaction they are perfectly positioned to modulate neuronal communication. The interaction between astrocytes and synapses
Tripartite states' Bell-nonlocality sudden death in an environmental spin chain
International Nuclear Information System (INIS)
Liu Benqiong; Shao Bin; Zou Jian
2010-01-01
The tripartite nonlocality is investigated by the extent of violation of the Bell inequality in a three-qubit system coupled to an environmental Ising spin chain. In the weak-coupling region, we show that the tripartite Bell-inequality violations can be fully destroyed in a finite time under decoherence induced by the coupling with the spin environment. In addition, how the environment affects the Bell-nonlocality sudden death is demonstrated.
Protecting single-photon entanglement with practical entanglement source
Zhou, Lan; Ou-Yang, Yang; Wang, Lei; Sheng, Yu-Bo
2017-06-01
Single-photon entanglement (SPE) is important for quantum communication and quantum information processing. However, SPE is sensitive to photon loss. In this paper, we discuss a linear optical amplification protocol for protecting SPE. Different from the previous protocols, we exploit the practical spontaneous parametric down-conversion (SPDC) source to realize the amplification, for the ideal entanglement source is unavailable in current quantum technology. Moreover, we prove that the amplification using the entanglement generated from SPDC source as auxiliary is better than the amplification assisted with single photons. The reason is that the vacuum state from SPDC source will not affect the amplification, so that it can be eliminated automatically. This protocol may be useful in future long-distance quantum communications.
Robust entangled qutrit states in atmospheric turbulence
CSIR Research Space (South Africa)
Brunner, T
2013-06-01
Full Text Available The entangled quantum state of a photon pair propagating through atmospheric turbulence suffers decay of entanglement due to the scintillation it experiences. Here we investigate the robustness against this decay for different qutrit states. We use...
HMSRP Hawaiian Monk Seal Entanglement data
National Oceanic and Atmospheric Administration, Department of Commerce — The data set contains records of all entanglements of Hawaiian monk seals in marine debris. The data set comprises records of seals entangled by derelict fishing...
Experimental distribution of entanglement with separable carriers
Fedrizzi, Alessandro; Zuppardo, Margherita; Gillett, Geoff; Broome, Matthew; de Almeida, Marcelo; Paternostro, Mauro; White, Andrew; Paterek, Tomasz
2014-03-01
Quantum networks will allow us to overcome distance limitations in quantum communication, and to share quantum computing tasks between remote quantum processors. The key requirement for quantum networking is the distribution of entanglement between nodes. Surprisingly, entanglement can be generated across a network without directly being communicated between nodes. In contrast to information gain, which cannot exceed the communicated information, the entanglement gain is bounded by the communicated quantum discord, a more general measure of quantum correlation that includes but is not limited to entanglement. Here we report an experiment in which two communicating parties who share three initially separable photonic qubits are entangled by exchange of a carrier photon that is not entangled with either party at all times. We show that distributing entanglement with separable carriers is resilient to noise and in some cases becomes the only way of distributing entanglement over noisy environments.
Experimental entanglement distillation of mesoscopic quantum states
DEFF Research Database (Denmark)
Dong, Ruifang; Lassen, Mikael Østergaard; Heersink, Joel
2008-01-01
The distribution of entangled states between distant parties in an optical network is crucial for the successful implementation of various quantum communication protocols such as quantum cryptography, teleportation and dense coding(1-3). However, owing to the unavoidable loss in any real optical...... channel, the distribution of loss-intolerant entangled states is inevitably afflicted by decoherence, which causes a degradation of the transmitted entanglement. To combat the decoherence, entanglement distillation, a process of extracting a small set of highly entangled states from a large set of less...... entangled states, can be used(4-14). Here we report on the distillation of deterministically prepared light pulses entangled in continuous variables that have undergone non-Gaussian noise. The entangled light pulses(15-17) are sent through a lossy channel, where the transmission is varying in time similarly...
International Nuclear Information System (INIS)
Liu Tang-Kun; Zhang Kang-Long; Tao Yu; Shan Chuan-Jia; Liu Ji-Bing
2016-01-01
The temporal evolution of the degree of entanglement between two atoms in a system of the binomial optical field interacting with two arbitrary entangled atoms is investigated. The influence of the strength of the dipole–dipole interaction between two atoms, probabilities of the Bernoulli trial, and particle number of the binomial optical field on the temporal evolution of the atomic entanglement are discussed. The result shows that the two atoms are always in the entanglement state. Moreover, if and only if the two atoms are initially in the maximally entangled state, the entanglement evolution is not affected by the parameters, and the degree of entanglement is always kept as 1. (paper)
Entropy of random entangling surfaces
Solodukhin, Sergey N.
2012-09-01
We consider the situation when a globally defined four-dimensional field system is separated on two entangled sub-systems by a dynamical (random) two-dimensional surface. The reduced density matrix averaged over ensemble of random surfaces of fixed area and the corresponding average entropy are introduced. The average entanglement entropy is analyzed for a generic conformal field theory in four dimensions. Two important particular cases are considered. In the first, both the intrinsic metric on the entangling surface and the spacetime metric are fluctuating. An important example of this type is when the entangling surface is a black hole horizon, the fluctuations of which cause necessarily the fluctuations in the spacetime geometry. In the second case, the spacetime is considered to be fixed. The detailed analysis is carried out for the random entangling surfaces embedded in flat Minkowski spacetime. In all cases, the problem reduces to an effectively two-dimensional problem of random surfaces which can be treated by means of the well-known conformal methods. Focusing on the logarithmic terms in the entropy, we predict the appearance of a new ln ln(A) term. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical in honour of Stuart Dowker's 75th birthday devoted to ‘Applications of zeta functions and other spectral functions in mathematics and physics’.
Entanglement in mutually unbiased bases
Energy Technology Data Exchange (ETDEWEB)
Wiesniak, M; Zeilinger, A [Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Paterek, T, E-mail: tomasz.paterek@nus.edu.sg [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore (Singapore)
2011-05-15
One of the essential features of quantum mechanics is that most pairs of observables cannot be measured simultaneously. This phenomenon manifests itself most strongly when observables are related to mutually unbiased bases. In this paper, we shed some light on the connection between mutually unbiased bases and another essential feature of quantum mechanics, quantum entanglement. It is shown that a complete set of mutually unbiased bases of a bipartite system contains a fixed amount of entanglement, independent of the choice of the set. This has implications for entanglement distribution among the states of a complete set. In prime-squared dimensions we present an explicit experiment-friendly construction of a complete set with a particularly simple entanglement distribution. Finally, we describe the basic properties of mutually unbiased bases composed of product states only. The constructions are illustrated with explicit examples in low dimensions. We believe that the properties of entanglement in mutually unbiased bases may be one of the ingredients to be taken into account to settle the question of the existence of complete sets. We also expect that they will be relevant to applications of bases in the experimental realization of quantum protocols in higher-dimensional Hilbert spaces.
Quantum entanglement and special relativity
International Nuclear Information System (INIS)
Nishikawa, Yoshihisa
2008-01-01
Quantum entanglement was suggested by Einstein to indicate that quantum mechanics was incomplete. However, against Einstein's expectation, the phenomenon due to quantum entanglement has been verified by experiments. Recently, in quantum information theory, it has been also treated as a resource for quantum teleportation and so on. In around 2000, it is recognized that quantum correlations between two particles of one pair state in an entangled spin-state are affected by the non-trivial effect due to the successive Lorentz transformation. This relativistic effect is called the Wigner rotation. The Wigner rotation has to been taken into account when we observe spin-correlation of moving particles in a different coordinate frame. In this paper, first, we explain quantum entanglement and its modification due to the Wigner rotation. After that, we introduce an extended model instead of one pair state model. In the extended model, quantum entanglement state is prepared as a superposition state of various pair states. We have computed the von Neumann entropy and the Shannon entropy to see the global behavior of variation for the spin correlation due to the relativistic effect. We also discuss distinguishability between the two particles of the pair. (author)
Quantum walks with entangled coins
International Nuclear Information System (INIS)
Venegas-Andraca, S E; Ball, J L; Burnett, K; Bose, S
2005-01-01
We present a mathematical formalism for the description of un- restricted quantum walks with entangled coins and one walker. The numerical behaviour of such walks is examined when using a Bell state as the initial coin state, with two different coin operators, two different shift operators, and one walker. We compare and contrast the performance of these quantum walks with that of a classical random walk consisting of one walker and two maximally correlated coins as well as quantum walks with coins sharing different degrees of entanglement. We illustrate that the behaviour of our walk with entangled coins can be very different in comparison to the usual quantum walk with a single coin. We also demonstrate that simply by changing the shift operator, we can generate widely different distributions. We also compare the behaviour of quantum walks with maximally entangled coins with that of quantum walks with non-entangled coins. Finally, we show that the use of different shift operators on two and three qubit coins leads to different position probability distributions in one- and two-dimensional graphs
Communication cost of entanglement transformations
International Nuclear Information System (INIS)
Hayden, Patrick; Winter, Andreas
2003-01-01
We study the amount of communication needed for two parties to transform some given joint pure state into another one, either exactly or with some fidelity. Specifically, we present a method to lower bound this communication cost even when the amount of entanglement does not increase. Moreover, the bound applies even if the initial state is supplemented with unlimited entanglement in the form of EPR (Einstein-Podolsky-Rosen) pairs and the communication is allowed to be quantum mechanical. We then apply the method to the determination of the communication cost of asymptotic entanglement concentration and dilution. While concentration is known to require no communication whatsoever, the best known protocol for dilution, discovered by H.-K. Lo and S. Popescu [Phys. Rev. Lett. 83, 1459 (1999)], requires exchange of a number of bits that is of the order of the square root of the number of EPR pairs. Here we prove a matching lower bound of the same asymptotic order, demonstrating the optimality of the Lo-Popescu protocol up to a constant factor and establishing the existence of a fundamental asymmetry between the concentration and dilution tasks. We also discuss states for which the minimal communication cost is proportional to their entanglement, such as the states recently introduced in the context of 'embezzling entanglement' (W. van Dam and P. Hayden, e-print quant-ph/0201041)
Entanglement concentration for two-mode Gaussian states in non-inertial frames
International Nuclear Information System (INIS)
Di Noia, Maurizio; Giraldi, Filippo; Petruccione, Francesco
2017-01-01
Entanglement creation and concentration by means of a beam splitter (BS) is analysed for a generic two-mode bipartite Gaussian state in a relativistic framework. The total correlations, the purity and the entanglement in terms of logarithmic negativity are analytically studied for observers in an inertial state and in a non-inertial state of uniform acceleration. The dependence of entanglement on the BS transmissivity due to the Unruh effect is analysed in the case when one or both observers undergo uniform acceleration. Due to the Unruh effect, depending on the initial Gaussian state parameters and observed accelerations, the best condition for entanglement generation limited to the two modes of the observers in their regions is not always a balanced beam splitter, as it is for the inertial case. (paper)
Entanglement witnesses and characterizing entanglement properties of some PPT states
Jafarizadeh, M. A.; Behzadi, N.; Akbari, Y.
2009-10-01
On the basis of linear programming, new sets of entanglement witnesses (EWs) for 3⊗3 and 4⊗4 systems are constructed. In both cases, the constructed EWs correspond to the hyper-planes contacting, without intersecting, the related feasible regions at line segments and restricted planes respectively. Due to the special property of the contacting area between the hyper-planes and the feasible regions, the corresponding hyper-planes can be turned around the contacting area throughout a bounded interval and hence create an infinite number of EWs. As these EWs are able to detect entanglement of some PPT states, they are non-decomposable (nd-EWs).
Universal distortion-free entanglement concentration
International Nuclear Information System (INIS)
Matsumoto, Keiji; Hayashi, Masahito
2007-01-01
We propose a new protocol of universal entanglement concentration, which converts many copies of an unknown pure state to an exact maximally entangled state. The yield of the protocol, which is outputted as a classical information, is probabilistic, and achieves the entropy rate with high probability, just as nonuniversal entanglement concentration protocols do
Remarks on entanglement assisted classical capacity
Fan, Heng
2003-01-01
The property of the optimal signal ensembles of entanglement assisted channel capacity is studied. A relationship between entanglement assisted channel capacity and one-shot capacity of unassisted channel is obtained. The data processing inequalities, convexity and additivity of the entanglement assisted channel capacity are reformulated by simple methods.
Linear response of entanglement entropy from holography
Lokhande, S.F.; Oling, G.W.J.; Pedraza, J.F.
2017-01-01
For time-independent excited states in conformal field theories, the entanglement entropy of small subsystems satisfies a ‘first law’-like relation, in which the change in entanglement is proportional to the energy within the entangling region. Such a law holds for time-dependent scenarios as long
Quantum entanglement and quantum computational algorithms
Indian Academy of Sciences (India)
We discuss in this paper how entanglement prevents the mapping or realisation of a quantum computation using ... possibility of mapping a quantum computer onto classical optical fields breaks down. To mathematically ..... sesses the capacity to generate entangled states from non-entangled ones. To see this clearly, let us ...
Quantum entanglement and quantum computational algorithms
Indian Academy of Sciences (India)
Abstract. The existence of entangled quantum states gives extra power to quantum computers over their classical counterparts. Quantum entanglement shows up qualitatively at the level of two qubits. We demonstrate that the one- and the two-bit Deutsch-Jozsa algorithm does not require entanglement and can be mapped ...
Structural entanglements in protein complexes
Zhao, Yani; Chwastyk, Mateusz; Cieplak, Marek
2017-06-01
We consider multi-chain protein native structures and propose a criterion that determines whether two chains in the system are entangled or not. The criterion is based on the behavior observed by pulling at both termini of each chain simultaneously in the two chains. We have identified about 900 entangled systems in the Protein Data Bank and provided a more detailed analysis for several of them. We argue that entanglement enhances the thermodynamic stability of the system but it may have other functions: burying the hydrophobic residues at the interface and increasing the DNA or RNA binding area. We also study the folding and stretching properties of the knotted dimeric proteins MJ0366, YibK, and bacteriophytochrome. These proteins have been studied theoretically in their monomeric versions so far. The dimers are seen to separate on stretching through the tensile mechanism and the characteristic unraveling force depends on the pulling direction.
Entanglement renormalization for disordered systems
Goldsborough, Andrew M.; Evenbly, Glen
2017-10-01
We propose a tensor network method for investigating strongly disordered systems that is based on an adaptation of entanglement renormalization [G. Vidal, Phys. Rev. Lett. 99, 220405 (2007), 10.1103/PhysRevLett.99.220405]. This method makes use of the strong disorder renormalization group to determine the order in which lattice sites are coarse-grained, which sets the overall structure of the corresponding tensor network ansatz, before optimization using variational energy minimization. Benchmark results from the disordered X X Z model demonstrates that this approach accurately captures ground-state entanglement in disordered systems, even at long distances. This approach leads to a new class of efficiently contractible tensor network ansatz for one-dimensional systems, which may be understood as a generalization of the multiscale entanglement renormalization ansatz for disordered systems.
Entanglement in open quantum systems
International Nuclear Information System (INIS)
Isar, A.
2007-01-01
In the framework of the theory of open systems based on quantum dynamical semigroups, we solve the master equation for two independent bosonic oscillators interacting with an environment in the asymptotic long-time regime. We give a description of the continuous-variable entanglement in terms of the covariance matrix of the quantum states of the considered system for an arbitrary Gaussian input state. Using the Peres-Simon necessary and sufficient condition for separability of two-mode Gaussian states, we show that the two non-interacting systems immersed in a common environment and evolving under a Markovian, completely positive dynamics become asymptotically entangled for certain environments, so that their non-local quantum correlations exist in the long-time regime. (author) Key words: quantum information theory, open systems, quantum entanglement, inseparable states
Berry phase in entangled systems
International Nuclear Information System (INIS)
Bertlmann, R.A.; Hasegawa, Y.; Hiesmayr, B.C.; Durstberger, C.
2005-01-01
Full text: The influence of the geometric phase, in particular the Berry phase, on an entangled spin-1/2 system is studied. We discuss in detail the case, where the geometric phase is generated only by one part of the Hilbert space. We are able to cancel the effects of the dynamical phase by using the 'spin-echo' method. We analyze how the Berry phase affects the Bell angles and the maximal violation of a CHSH-Bell inequality. Furthermore, we suggest an experimental realization of our setup within neutron interferometry. It is possible to create entanglement between different degrees of freedom (spin and spatial degree of freedom) for a single neutron. The influence of the geometrical phase on the entangled neutron state is tested experimentally which is work in progress. (author)
Quantum Entanglements: Selected Papers
International Nuclear Information System (INIS)
Giannetto, E
2005-01-01
This book is a sort of tribute to Rob Clifton (1964-2002), Associate Professor of Philosophy and Associate Director of the Center for Philosophy of Science at the University of Pittsburgh, philosopher of physics and editor of the journal Studies in the History and Philosophy of Modern Physics, who tragically died of cancer. It contains fourteen papers by Clifton, for the most part written in collaboration with other authors (Jeffrey Bub (2), Sheldon Goldstein, Michael Dickson, Hans Halvorson (6), Adrian Kent (2)), published between 1995 and 2002. The choice of papers made by the editors is very impressive. They concern the foundations of quantum mechanics and quantum field theory. Among the issues discussed are the modal interpretations of quantum mechanics, the problems of hidden variables theories, non-locality, Bell's inequality, the Einstein-Podolsky-Rosen paradox, Lorentz invariance, de-coherence, non-contextuality, complementarity, entanglement and quantum information. A consequence of such investigations is that non-separability is a more complex issue than violation of Bell's inequality. Apart from the perspective one can follow-whether one agrees or not with Clifton-these papers are effective contributions to an understanding of the problems involved in the foundations of quantum mechanics. The most interesting parts, in my opinion, are related to the extension of the discussion of foundational problems to quantum field theory: on the algebraic approach, and on the twin concepts of particle and vacuum. Non-locality appears to be 'worse' in relativistic quantum field theory than in non-relativistic quantum mechanics. All the papers deal with relevant epistemological and even historical aspects of quantum mechanics interpretations, but all the issues are discussed from a technical, logical and mathematical approach. A complete bibliography of Clifton's papers is given at the end of the volume. (book review)
Entanglement evolution for quantum trajectories
International Nuclear Information System (INIS)
Vogelsberger, S; Spehner, D
2011-01-01
Entanglement is a key resource in quantum information. It can be destroyed or sometimes created by interactions with a reservoir. In recent years, much attention has been devoted to the phenomena of entanglement sudden death and sudden birth, i.e., the sudden disappearance or revival of entanglement at finite times resulting from a coupling of the quantum system to its environment. We investigate the evolution of the entanglement of noninteracting qubits coupled to reservoirs under monitoring of the reservoirs by means of continuous measurements. Because of these measurements, the qubits remain at all times in a pure state, which evolves randomly. To each measurement result (or 'realization') corresponds a quantum trajectory in the Hilbert space of the qubits. We show that for two qubits coupled to independent baths subjected to local measurements, the average of the qubits' concurrence over all quantum trajectories is either constant or decays exponentially. The corresponding decay rate depends on the measurement scheme only. This result contrasts with the entanglement sudden death phenomenon exhibited by the qubits' density matrix in the absence of measurements. Our analysis applies to arbitrary quantum jump dynamics (photon counting) as well as to quantum state diffusion (homodyne or heterodyne detections) in the Markov limit. We discuss the best measurement schemes to protect the entanglement of the qubits. We also analyze the case of two qubits coupled to a common bath. Then, the average concurrence can vanish at discrete times and may coincide with the concurrence of the density matrix. The results explained in this article have been presented during the 'Fifth International Workshop DICE2010' by the first author and have been the subject of a prior publication.
A tripartite complex containing MRCK modulates lamellar actomyosin retrograde flow.
Tan, Ivan; Yong, Jeffery; Dong, Jing Ming; Lim, Louis; Leung, Thomas
2008-10-03
Actomyosin retrograde flow underlies the contraction essential for cell motility. Retrograde flow in both lamellipodia and lamella is required for membrane protrusion and for force generation by coupling to cell adhesion. We report that the Rac/Cdc42-binding kinase MRCK and myosin II-related MYO18A linked by the adaptor protein LRAP35a form a functional tripartite complex, which is responsible for the assembly of lamellar actomyosin bundles and of a subnuclear actomyosin network. LRAP35a binds independently to MYO18A and MRCK. This binding leads to MRCK activation and its phosphorylation of MYO18A, independently of ROK and MLCK. The MRCK complex moves in concert with the retrograde flow of actomyosin bundles, with MRCK being able to influence other flow components such as MYO2A. The promotion of persistent protrusive activity and inhibition of cell motility by the respective expression of wild-type and dominant-negative mutant components of the MRCK complex show it to be crucial to cell protrusion and migration.
Bosonic behavior of entangled fermions
DEFF Research Database (Denmark)
C. Tichy, Malte; Alexander Bouvrie, Peter; Mølmer, Klaus
2012-01-01
Two bound, entangled fermions form a composite boson, which can be treated as an elementary boson as long as the Pauli principle does not affect the behavior of many such composite bosons. The departure of ideal bosonic behavior is quantified by the normalization ratio of multi-composite-boson st......Two bound, entangled fermions form a composite boson, which can be treated as an elementary boson as long as the Pauli principle does not affect the behavior of many such composite bosons. The departure of ideal bosonic behavior is quantified by the normalization ratio of multi...
Entangled wavepackets in the vacuum
Kattemölle, Joris; Freivogel, Ben
2017-10-01
Motivated by the black hole firewall problem, we find highly entangled pairs of spatially localized modes in quantum field theory. We demonstrate that appropriately chosen wavepackets localized outside the horizon are nearly purified by `mirror' modes behind the horizon. In addition, we calculate the entanglement entropy of a single localized wavepacket in the Minkowski vacuum. In all cases we study, the quantum state of the system becomes pure in the limit that the wavepackets delocalize; we quantify the trade-off between localization and purity.
Quantum entanglement: theory and applications
Energy Technology Data Exchange (ETDEWEB)
Schuch, N.
2007-10-10
This thesis deals with various questions concerning the quantification, the creation, and the application of quantum entanglement. Entanglement arises due to the restriction to local operations and classical communication. We investigate how the notion of entanglement changes if additional restrictions in form of a superselection rule are imposed and show that they give rise to a new resource. We characterize this resource and demonstrate that it can be used to overcome the restrictions, very much as entanglement can overcome the restriction to local operations by teleportation. We next turn towards the optimal generation of resources. We show how squeezing can be generated as efficiently as possible from noisy squeezing operations supplemented by noiseless passive operations, and discuss the implications of this result to the optimal generation of entanglement. The difficulty in describing the behaviour of correlated quantum many-body systems is ultimately due to the complicated entanglement structure of multipartite states. Using quantum information techniques, we investigate the ground state properties of lattices of harmonic oscillators. We derive an exponential decay of correlations for gapped systems, compute the dependence of correlation length and gap, and investigate the notion of criticality by relating a vanishing energy gap to an algebraic decay of correlations. Recently, ideas from entanglement theory have been applied to the description of many-body systems. Matrix Product States (MPS), which have a particularly simple interpretation from the point of quantum information, perform extremely well in approximating the ground states of local Hamiltonians. It is generally believed that this is due to the fact that both ground states and MPS obey an entropic area law. We clarify the relation between entropy scaling laws and approximability by MPS, and in particular find that an area law does not necessarily imply approximability. Using the quantum
Quantum identification schemes with entanglements
International Nuclear Information System (INIS)
Mihara, Takashi
2002-01-01
We need secure identification schemes because many situations exist in which a person must be identified. In this paper, we propose three quantum identification schemes with entanglements. First, we propose a quantum one-time pad password scheme. In this scheme, entanglements play the role of a one-time pad password. Next, we propose a quantum identification scheme that requires a trusted authority. Finally, we propose a quantum message authentication scheme that is constructed by combining a different quantum cryptosystem with an ordinary authentication tag
Quantum entanglement: theory and applications
International Nuclear Information System (INIS)
Schuch, N.
2007-01-01
This thesis deals with various questions concerning the quantification, the creation, and the application of quantum entanglement. Entanglement arises due to the restriction to local operations and classical communication. We investigate how the notion of entanglement changes if additional restrictions in form of a superselection rule are imposed and show that they give rise to a new resource. We characterize this resource and demonstrate that it can be used to overcome the restrictions, very much as entanglement can overcome the restriction to local operations by teleportation. We next turn towards the optimal generation of resources. We show how squeezing can be generated as efficiently as possible from noisy squeezing operations supplemented by noiseless passive operations, and discuss the implications of this result to the optimal generation of entanglement. The difficulty in describing the behaviour of correlated quantum many-body systems is ultimately due to the complicated entanglement structure of multipartite states. Using quantum information techniques, we investigate the ground state properties of lattices of harmonic oscillators. We derive an exponential decay of correlations for gapped systems, compute the dependence of correlation length and gap, and investigate the notion of criticality by relating a vanishing energy gap to an algebraic decay of correlations. Recently, ideas from entanglement theory have been applied to the description of many-body systems. Matrix Product States (MPS), which have a particularly simple interpretation from the point of quantum information, perform extremely well in approximating the ground states of local Hamiltonians. It is generally believed that this is due to the fact that both ground states and MPS obey an entropic area law. We clarify the relation between entropy scaling laws and approximability by MPS, and in particular find that an area law does not necessarily imply approximability. Using the quantum
Benchmarks and statistics of entanglement dynamics
International Nuclear Information System (INIS)
Tiersch, Markus
2009-01-01
In the present thesis we investigate how the quantum entanglement of multicomponent systems evolves under realistic conditions. More specifically, we focus on open quantum systems coupled to the (uncontrolled) degrees of freedom of an environment. We identify key quantities that describe the entanglement dynamics, and provide efficient tools for its calculation. For quantum systems of high dimension, entanglement dynamics can be characterized with high precision. In the first part of this work, we derive evolution equations for entanglement. These formulas determine the entanglement after a given time in terms of a product of two distinct quantities: the initial amount of entanglement and a factor that merely contains the parameters that characterize the dynamics. The latter is given by the entanglement evolution of an initially maximally entangled state. A maximally entangled state thus benchmarks the dynamics, and hence allows for the immediate calculation or - under more general conditions - estimation of the change in entanglement. Thereafter, a statistical analysis supports that the derived (in-)equalities describe the entanglement dynamics of the majority of weakly mixed and thus experimentally highly relevant states with high precision. The second part of this work approaches entanglement dynamics from a topological perspective. This allows for a quantitative description with a minimum amount of assumptions about Hilbert space (sub-)structure and environment coupling. In particular, we investigate the limit of increasing system size and density of states, i.e. the macroscopic limit. In this limit, a universal behaviour of entanglement emerges following a ''reference trajectory'', similar to the central role of the entanglement dynamics of a maximally entangled state found in the first part of the present work. (orig.)
Benchmarks and statistics of entanglement dynamics
Energy Technology Data Exchange (ETDEWEB)
Tiersch, Markus
2009-09-04
In the present thesis we investigate how the quantum entanglement of multicomponent systems evolves under realistic conditions. More specifically, we focus on open quantum systems coupled to the (uncontrolled) degrees of freedom of an environment. We identify key quantities that describe the entanglement dynamics, and provide efficient tools for its calculation. For quantum systems of high dimension, entanglement dynamics can be characterized with high precision. In the first part of this work, we derive evolution equations for entanglement. These formulas determine the entanglement after a given time in terms of a product of two distinct quantities: the initial amount of entanglement and a factor that merely contains the parameters that characterize the dynamics. The latter is given by the entanglement evolution of an initially maximally entangled state. A maximally entangled state thus benchmarks the dynamics, and hence allows for the immediate calculation or - under more general conditions - estimation of the change in entanglement. Thereafter, a statistical analysis supports that the derived (in-)equalities describe the entanglement dynamics of the majority of weakly mixed and thus experimentally highly relevant states with high precision. The second part of this work approaches entanglement dynamics from a topological perspective. This allows for a quantitative description with a minimum amount of assumptions about Hilbert space (sub-)structure and environment coupling. In particular, we investigate the limit of increasing system size and density of states, i.e. the macroscopic limit. In this limit, a universal behaviour of entanglement emerges following a ''reference trajectory'', similar to the central role of the entanglement dynamics of a maximally entangled state found in the first part of the present work. (orig.)
Quantum trajectory description of entanglement dynamics
Energy Technology Data Exchange (ETDEWEB)
Guevara, Ivonne [Departamento de Fisica, Universidad Nacional de Colombia, Carrera 30 No.45-03, Bogota D.C. (Colombia); Centre for Quantum Dynamics, Griffith University, Brisbane, Queensland 4111 (Australia); Viviescas, Carlos [Departamento de Fisica, Universidad Nacional de Colombia, Carrera 30 No.45-03, Bogota D.C. (Colombia)
2013-07-01
We present and overview of the characterization of the dynamical evolution of entanglement in open quantum system by means of diffusive quantum trajectories. We show how this method allows for a complete description of this phenomenon providing deterministic evolution equations for some experimentally relevant cases, and excellent upper bounds for the entanglement dynamics in some other cases. Remarkably, for a family of entanglement measures, all the information of the entanglement dynamics can be recovered from a single trajectory. For some of the cases considered we propose quantum optical experimental setups which allow for a real time measurement of the entanglement time evolution.
Transverse entanglement migration in Hilbert space
International Nuclear Information System (INIS)
Chan, K. W.; Torres, J. P.; Eberly, J. H.
2007-01-01
We show that, although the amount of mutual entanglement of photons propagating in free space is fixed, the type of correlations between the photons that determine the entanglement can dramatically change during propagation. We show that this amounts to a migration of entanglement in Hilbert space, rather than real space. For the case of spontaneous parametric down-conversion, the migration of entanglement in transverse coordinates takes place from modulus to phase of the biphoton state and back again. We propose an experiment to observe this migration in Hilbert space and to determine the full entanglement
Multi-frequency entanglement router system
Erdmann, Reinhard; Hughes, David
2017-05-01
A high performance free-space Wavelength Division Multiplexed (WDM) transceiver system is assessed as to its viability for routing collinear entangled photons in place of the classical optical signals for which it was designed. Explicit calculations demonstrate that entanglement in the input state is retained through transit of the system without intrinsic loss. Introducing spatial degrees of freedom changed the entanglement so that it could be manifested at remote locations, as required in non-local Bell test measurements or Quantum Key Distribution (QKD) Protocols. It was also found that by adding proper components, the exit state could be changed from being frequency entangled to polarization entangled, with respect to the (remote) paths of the photons. Finally it was found possible to route a complete entangled state to either of the two remote users by proper selection of the discrete frequencies in the input state. Each entanglement in the photon states was maximal, hence suited for Quantum Information Processing (QIP) applications.
Classical-driving-assisted entanglement dynamics control
Energy Technology Data Exchange (ETDEWEB)
Zhang, Ying-Jie, E-mail: yingjiezhang@qfnu.edu.cn [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Han, Wei [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Xia, Yun-Jie, E-mail: yjxia@qfnu.edu.cn [Shandong Provincial Key Laboratory of Laser Polarization and Information Technology, Department of Physics, Qufu Normal University, Qufu 273165 (China); Fan, Heng, E-mail: hfan@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing, 100190 (China)
2017-04-15
We propose a scheme of controlling entanglement dynamics of a quantum system by applying the external classical driving field for two atoms separately located in a single-mode photon cavity. It is shown that, with a judicious choice of the classical-driving strength and the atom–photon detuning, the effective atom–photon interaction Hamiltonian can be switched from Jaynes–Cummings model to anti-Jaynes–Cummings model. By tuning the controllable atom–photon interaction induced by the classical field, we illustrate that the evolution trajectory of the Bell-like entanglement states can be manipulated from entanglement-sudden-death to no-entanglement-sudden-death, from no-entanglement-invariant to entanglement-invariant. Furthermore, the robustness of the initial Bell-like entanglement can be improved by the classical driving field in the leaky cavities. This classical-driving-assisted architecture can be easily extensible to multi-atom quantum system for scalability.
Entangled wavepackets in the vacuum
H.J.J. Kattemölle (Joris); B. Freivogel (Ben)
2017-01-01
textabstractMotivated by the black hole firewall problem, we find highly entangled pairs of spatially localized modes in quantum field theory. We demonstrate that appropriately chosen wavepackets localized outside the horizon are nearly purified by ‘mirror’ modes behind the horizon. In addition, we
Entangled wavepackets in the vacuum
Kattemölle, J.; Freivogel, B.
2017-01-01
Motivated by the black hole firewall problem, we find highly entangled pairs of spatially localized modes in quantum field theory. We demonstrate that appropriately chosen wavepackets localized outside the horizon are nearly purified by ‘mirror’ modes behind the horizon. In addition, we calculate
Remote entanglement of transmon qubits
Hatridge, M.; Sliwa, K.; Narla, A.; Shankar, S.; Leghtas, Z.; Mirrahimi, M.; Girvin, S. M.; Schoelkopf, R. J.; Devoret, M. H.
2014-03-01
An open challenge in quantum information processing with superconducting circuits is to entangle distant (non-nearest neighbor) qubits. This can be accomplished by entangling the qubits with flying microwave oscillators (traveling pulses), and then performing joint operations on a pair of these oscillators. Remarkably, such a process is embedded in the act of phase-preserving amplification, which transforms two input modes (termed signal and idler) into a two-mode squeezed output state. For an ideal system, this process generates heralded, perfectly entangled states between remote qubits with a fifty percent success rate. For an imperfect system, the loss of information from the flying states degrades the purity of the entanglement. We show data on such a protocol involving two transmon qubits imbedded in superconducting cavities connected to the signal and idler inputs of a Josephson Parametric Converter (JPC) operated as a nearly-quantum limited phase-preserving amplifier. Strategies for optimizing performance will also be discussed. Work supported by: IARPA, ARO, and NSF.
Bessel-Gaussian entanglement; presentation
CSIR Research Space (South Africa)
Mclaren, M
2013-07-01
Full Text Available mode Hologram Page 9 Violation of Bell’s inequality demonstrates entanglement © CSIR 2013 www.csir.co.za P ro b ab il it y Classical Quantum mechanical M. McLaren et al.,2012, Opt. Express, 20, 23589 Page 10 Comparison...
Senegalese Immigrant Entrepreneurial Entanglements and ...
African Journals Online (AJOL)
Senegalese entrepreneurship in South Africa is a typical example of how entrepreneurial entanglements are beginning to pose huge challenges to the theorization and understanding of modern African forms of business. This group of immigrant entrepreneurs finds it difficult to separate the use of charms and magic in the ...
Entangling light in high dimensions
Pors, Jan Bardeus
2011-01-01
Quantum entanglement is a fundamental trait of quantum mechanics that causes the information about the properties of two (or more) objects to be inextricably linked. When a measurement on one of the objects is performed, the state of the other object is immediately altered, even when these objects
A Tripartite Neurocognitive Model of Internet Gaming Disorder
Directory of Open Access Journals (Sweden)
Lei Wei
2017-12-01
Full Text Available Playing Internet games has emerged as a growing in prevalence leisure activity. In some cases, excess gaming can lead to addiction-like symptoms and aversive outcomes that may be seen by some as manifestations of a behavioral addiction. Even though agreement regarding the pathologizing of excessive video gaming is not yet achieved and perhaps because the field requires more research, many works have examined the antecedents and outcomes of what is termed internet gaming disorder (IGD. In this article, we aim at summarizing perspectives and findings related to the neurocognitive processes that may underlie IGD and map such findings onto the triadic-system that governs behavior and decision-making, the deficits in which have been shown to be associated with many addictive disorders. This tripartite system model includes the following three brain systems: (1 the impulsive system, which often mediates fast, automatic, unconscious, and habitual behaviors; (2 the reflective system, which mediates deliberating, planning, predicting future outcomes of selected behaviors, and exerting inhibitory control; and (3 the interoceptive awareness system, which generates a state of craving through the translation of somatic signals into a subjective state of drive. We suggest that IGD formation and maintenance can be associated with (1 a hyperactive “impulsive” system; (2 a hypoactive “reflective” system, as exacerbated by (3 an interoceptive awareness system that potentiates the activity of the impulsive system, and/or hijacks the goal-driven cognitive resources needed for the normal operation of the reflective system. Based on this review, we propose ways to improve the therapy and treatment of IGD and reduce the risk of relapse among recovering IGD populations.
A Tripartite Neurocognitive Model of Internet Gaming Disorder
Wei, Lei; Zhang, Shuyue; Turel, Ofir; Bechara, Antoine; He, Qinghua
2017-01-01
Playing Internet games has emerged as a growing in prevalence leisure activity. In some cases, excess gaming can lead to addiction-like symptoms and aversive outcomes that may be seen by some as manifestations of a behavioral addiction. Even though agreement regarding the pathologizing of excessive video gaming is not yet achieved and perhaps because the field requires more research, many works have examined the antecedents and outcomes of what is termed internet gaming disorder (IGD). In this article, we aim at summarizing perspectives and findings related to the neurocognitive processes that may underlie IGD and map such findings onto the triadic-system that governs behavior and decision-making, the deficits in which have been shown to be associated with many addictive disorders. This tripartite system model includes the following three brain systems: (1) the impulsive system, which often mediates fast, automatic, unconscious, and habitual behaviors; (2) the reflective system, which mediates deliberating, planning, predicting future outcomes of selected behaviors, and exerting inhibitory control; and (3) the interoceptive awareness system, which generates a state of craving through the translation of somatic signals into a subjective state of drive. We suggest that IGD formation and maintenance can be associated with (1) a hyperactive “impulsive” system; (2) a hypoactive “reflective” system, as exacerbated by (3) an interoceptive awareness system that potentiates the activity of the impulsive system, and/or hijacks the goal-driven cognitive resources needed for the normal operation of the reflective system. Based on this review, we propose ways to improve the therapy and treatment of IGD and reduce the risk of relapse among recovering IGD populations. PMID:29312016
Displacement-enhanced entanglement distillation of single-mode-squeezed entangled states
DEFF Research Database (Denmark)
Tipsmark, Anders; Neergaard-Nielsen, Jonas Schou; Andersen, Ulrik Lund
2013-01-01
It has been shown that entanglement distillation of Gaussian entangled states by means of local photon subtraction can be improved by local Gaussian transformations. Here we show that a similar effect can be expected for the distillation of an asymmetric Gaussian entangled state that is produced...... by a single squeezed beam. We show that for low initial entanglement, our largely simplified protocol generates more entanglement than previous proposed protocols. Furthermore, we show that the distillation scheme also works efficiently on decohered entangled states as well as with a practical photon...
Yamamiya, Yuko; Shroff, Hemal; Thompson, J Kevin
2008-01-01
To examine the tripartite influence model of body image and eating disturbance as a viable sociocultural explanation for the development of eating and body image problems with young Japanese females. A sample of 289 Japanese female undergraduates completed a variety of measures designed to index family, peer, and media influences, as well as levels of body dissatisfaction, eating disturbances, and self-esteem. The data were evaluated with structural equation modeling to test the tripartite model. Fit indices indicated a moderate fit to the overall tripartite model, replicating previous findings. This study suggests that the sociocultural variables found to influence body image and eating disturbances in Japan are similar to those observed with US samples. The implications for prevention and intervention programs are discussed.
Shroff, Hemal; Thompson, J Kevin
2006-03-01
The tripartite influence model of body image and eating disturbance is a recent theoretical approach that includes a test of direct (peer, parental, and media factors) and mediational links (internalization of societal appearance standards, appearance comparison processes) as factors potentially leading to body dissatisfaction and eating disturbance. The theory was evaluated in the current study in a sample of 391 adolescent females. A structural equation model that evaluated the tripartite model replicated previous findings reported by Keery, van den Berg and Thompson (2004) [Keery, H., van den Berg, & Thompson, J. K. (2004). A test of the tripartite influence model of body image and eating disturbance in adolescent girls. Body Image: An International Journal of Research, 1, 237-251.]. Additionally, a second model extended these findings, suggesting that peer and media influences are more important than parental influences. The results are discussed in light of the need for prevention programs to incorporate formative influences and mediational processes in the construction of intervention strategies.
Keery, Helene; van den Berg, Patricia; Thompson, J Kevin
2004-09-01
The Tripartite Influence Model of body image and eating disturbance proposes that three formative influences (peer, parents, and media) affect body image and eating problems through two mediational mechanisms: internalization of the thin-ideal and appearance comparison processes. The current study evaluated this model in a sample of 325 sixth through eighth grade girls. Simple path analyses indicated that internalization and comparison fully mediated the relationship between parental influence and body dissatisfaction and partially mediated the relationship between peer influence and body dissatisfaction. Additionally, internalization and comparison partially mediated the relationship between media influence and body dissatisfaction. Six a priori SEM models based on the full Tripartite Influence Model were also evaluated. A resulting model was found to be an adequate fit to the data, supporting the viability of the Tripartite Model as a useful framework for understanding processes that may predispose young women to develop body image disturbances and eating dysfunction.
Araki, Hiromu; Fukui, Takahiro; Hatsugai, Yasuhiro
2017-10-01
We propose characterization of the three-dimensional topological insulator by using the Chern number for the entanglement Hamiltonian (entanglement Chern number). Here we take the extensive spin partition of the system, that pulls out the quantum entanglement between up spin and down spin of the many-body ground state. In three dimensions, the topological insulator phase is described by the section entanglement Chern number, which is the entanglement Chern number for a periodic plane in the Brillouin zone. The section entanglement Chern number serves as an interpolation of the Z2 invariants defined on time-reversal invariant planes. We find that the change of the section entanglement Chern number protects the Weyl point of the entanglement Hamiltonian, and the parity of the number of Weyl points distinguishes the strong topological insulator phase from the weak topological insulator phase.
Entanglement rules for holographic Fermi surfaces
Directory of Open Access Journals (Sweden)
Dibakar Roychowdhury
2016-08-01
Full Text Available In this paper, based on the notion of Gauge/Gravity duality, we explore the laws of entanglement thermodynamics for most generic classes of Quantum Field Theories with hyperscaling violation. In our analysis, we note that for Quantum Field Theories with compressible quark like excitation, the first law of entanglement thermodynamics gets modified due to the presence of an additional term that could be identified as the entanglement chemical potential associated with hidden Fermi surfaces of the boundary theory. Most notably, we find that the so called entanglement chemical potential does not depend on the size of the entangling region and is purely determined by the quark d.o.f. encoded within the entangling region.
3-qubit entanglement: A Jordan algebraic perspective
Borsten, L.
2014-09-01
It is by now well known that three qubits can be totally entangled in two physically distinct ways. Here we review work classifying the physically distinct forms of 3-qubit entanglement using the elegant framework of Jordan algebras, Freudenthal-Kantor triple systems and groups of type E7. In particular, it is shown that the four Freudenthal-Kantor ranks correspond precisely to the four 3-qubit entanglement classes: (1) Totally separable A-B-C, (2) Biseparable A-BC, B-CA, C-AB, (3) Totally entangled W, (4) Totally entangled GHZ. The rank 4 GHZ class is regarded as maximally entangled in the sense that it has non-vanishing quartic norm, the defining invariant of the Freudenthal-Kantor triple system. While this framework is specific to three qubits, we show here how the essential features may be naturally generalised to an arbitrary number of qubits.
3-qubit entanglement: A Jordan algebraic perspective
International Nuclear Information System (INIS)
Borsten, L
2014-01-01
It is by now well known that three qubits can be totally entangled in two physically distinct ways. Here we review work classifying the physically distinct forms of 3-qubit entanglement using the elegant framework of Jordan algebras, Freudenthal-Kantor triple systems and groups of type E 7 . In particular, it is shown that the four Freudenthal-Kantor ranks correspond precisely to the four 3-qubit entanglement classes: (1) Totally separable A-B-C, (2) Biseparable A-BC, B-CA, C-AB, (3) Totally entangled W, (4) Totally entangled GHZ. The rank 4 GHZ class is regarded as maximally entangled in the sense that it has non-vanishing quartic norm, the defining invariant of the Freudenthal-Kantor triple system. While this framework is specific to three qubits, we show here how the essential features may be naturally generalised to an arbitrary number of qubits.
Efficient entanglement distillation without quantum memory.
Abdelkhalek, Daniela; Syllwasschy, Mareike; Cerf, Nicolas J; Fiurášek, Jaromír; Schnabel, Roman
2016-05-31
Entanglement distribution between distant parties is an essential component to most quantum communication protocols. Unfortunately, decoherence effects such as phase noise in optical fibres are known to demolish entanglement. Iterative (multistep) entanglement distillation protocols have long been proposed to overcome decoherence, but their probabilistic nature makes them inefficient since the success probability decays exponentially with the number of steps. Quantum memories have been contemplated to make entanglement distillation practical, but suitable quantum memories are not realised to date. Here, we present the theory for an efficient iterative entanglement distillation protocol without quantum memories and provide a proof-of-principle experimental demonstration. The scheme is applied to phase-diffused two-mode-squeezed states and proven to distil entanglement for up to three iteration steps. The data are indistinguishable from those that an efficient scheme using quantum memories would produce. Since our protocol includes the final measurement it is particularly promising for enhancing continuous-variable quantum key distribution.
Experimental quantum computing without entanglement.
Lanyon, B P; Barbieri, M; Almeida, M P; White, A G
2008-11-14
Deterministic quantum computation with one pure qubit (DQC1) is an efficient model of computation that uses highly mixed states. Unlike pure-state models, its power is not derived from the generation of a large amount of entanglement. Instead it has been proposed that other nonclassical correlations are responsible for the computational speedup, and that these can be captured by the quantum discord. In this Letter we implement DQC1 in an all-optical architecture, and experimentally observe the generated correlations. We find no entanglement, but large amounts of quantum discord-except in three cases where an efficient classical simulation is always possible. Our results show that even fully separable, highly mixed, states can contain intrinsically quantum mechanical correlations and that these could offer a valuable resource for quantum information technologies.
Entangled photons and quantum communication
International Nuclear Information System (INIS)
Yuan Zhensheng; Bao Xiaohui; Lu Chaoyang; Zhang Jun; Peng Chengzhi; Pan Jianwei
2010-01-01
This article reviews the progress of quantum communication that utilizes photonic entanglement. We start with a survey of various methods for generating entangled photons, followed by an introduction of the theoretical principles and the experimental implementations of quantum key distribution. We then move on to a discussion of more involved quantum communication protocols including quantum dense coding, teleportation and quantum communication complexity. After that, we review the progress in free-space quantum communication, decoherence-free subspace, and quantum repeater protocols which are essential ingredients for long-distance quantum communication. Practical realizations of quantum repeaters, which require an interface between photons and quantum memories, are discussed briefly. Finally, we draw concluding remarks considering the technical challenges, and put forward an outlook on further developments of this field.
Quantum steganography using prior entanglement
Energy Technology Data Exchange (ETDEWEB)
Mihara, Takashi, E-mail: mihara@toyo.jp
2015-06-05
Steganography is the hiding of secret information within innocent-looking information (e.g., text, audio, image, video, etc.). A quantum version of steganography is a method based on quantum physics. In this paper, we propose quantum steganography by combining quantum error-correcting codes with prior entanglement. In many steganographic techniques, embedding secret messages in error-correcting codes may cause damage to them if the embedded part is corrupted. However, our proposed steganography can separately create secret messages and the content of cover messages. The intrinsic form of the cover message does not have to be modified for embedding secret messages. - Highlights: • Our steganography combines quantum error-correcting codes with prior entanglement. • Our steganography can separately create secret messages and the content of cover messages. • Errors in cover messages do not have affect the recovery of secret messages. • We embed a secret message in the Steane code as an example of our steganography.
Quantum steganography using prior entanglement
International Nuclear Information System (INIS)
Mihara, Takashi
2015-01-01
Steganography is the hiding of secret information within innocent-looking information (e.g., text, audio, image, video, etc.). A quantum version of steganography is a method based on quantum physics. In this paper, we propose quantum steganography by combining quantum error-correcting codes with prior entanglement. In many steganographic techniques, embedding secret messages in error-correcting codes may cause damage to them if the embedded part is corrupted. However, our proposed steganography can separately create secret messages and the content of cover messages. The intrinsic form of the cover message does not have to be modified for embedding secret messages. - Highlights: • Our steganography combines quantum error-correcting codes with prior entanglement. • Our steganography can separately create secret messages and the content of cover messages. • Errors in cover messages do not have affect the recovery of secret messages. • We embed a secret message in the Steane code as an example of our steganography
On the entangled ergodic theorem
Eisner, T.; Kunszenti-kovács, D.
2013-01-01
We study the convergence of the so-called entangled ergodic averages 1 Nk !N n1,...,nk=1 T n!(m) m Am−1T n!(m−1) m−1 Am−2 . . . A1T n!(1) 1 , where k " m and ! : {1, . . . ,m} #{1, . . . , k} is a surjective map.We show that, on general Banach spaces and without any restriction on the partition !,
Quantifying entanglement of overlapping indistinguishable particles
Gittings, Joseph R.
This thesis develops the quantitative study of quantum entanglement in systems of identical particles. Understanding this topic is essential for the construction of quantum information processing devices involving identical particles. A brief overview of necessary concepts and methods, such as the density matrix, the entanglement in pure and mixed states of distinguishable particles, and some common applications of entanglement is given in the introduction. Some competing methods of calculating the entanglement in bipartite pure states of indistinguishable particles are examined. It is shown that only the 'site entropy' measure introduced by Zanardi satisfies all the criteria for a correct entanglement measure. A teleportation protocol which utilizes all the entanglement carried (in both the spin and space degrees of freedom) in a doubly- occupied molecular bonding orbital is presented. The output from an interferometer in a thought experiment described by Omar et al. is studied as an example to see whether entanglement can be separated into space-only, spin-only, and space-spin components. A similar exercise is performed for a doubly-occupied molecular bonding orbital. The relationship between these results and the application of superselection rules (SSRs) to the quantification of useful entanglement is discussed. A numerical method for estimating the entanglement of formation of a mixed state of arbitrary dimension by a conjugate gradient algorithm is described. The results of applying an implementation of the algorithm to both random and isotropic states of 2 qutrits (i.e. two three-dimensional systems) is described. Existing work on calculating entanglement between two sites in various spin systems is outlined. New methods for calculating the entanglement between two sites in various types of degenerate quantum gas - a Fermi gas, a Bose condensate, and a BCS superconductor - are described. The results of numerical studies of the entanglement in a normal metal
Is quantum entanglement invariant in special relativity?
Ahn, D.; Lee, H. J.; Hwang, S. W.; Kim, M. S.
2003-01-01
Quantum entanglements are of fundamental importance in quantum physics ranging from the quantum information processing to the physics of black hole. Here, we show that the quantum entanglement is not invariant in special relativity. This suggests that nearly all aspects of quantum information processing would be affected significantly when relativistic effects are considered because present schemes are based on the general assumption that entanglement is invariant. There should be additional ...
Entanglement and Quantum Logical Gates. Part I.
Freytes, H.; Giuntini, R.; Leporini, R.; Sergioli, G.
2015-12-01
Is it possible to give a logical characterization of entanglement and of entanglement-measures in terms of the probabilistic behavior of some gates? This question admits different (positive or negative) answers in the case of different systems of gates and in the case of different classes of density operators. In the first part of this article we investigate possible relations between entanglement-measures and the probabilistic behavior of quantum computational conjunctions.
Hybrid Long-Distance Entanglement Distribution Protocol
DEFF Research Database (Denmark)
Brask, J.B.; Rigas, I.; Polzik, E.S.
2010-01-01
We propose a hybrid (continuous-discrete variable) quantum repeater protocol for long-distance entanglement distribution. Starting from states created by single-photon detection, we show how entangled coherent state superpositions can be generated by means of homodyne detection. We show that near......-deterministic entanglement swapping with such states is possible using only linear optics and homodyne detectors, and we evaluate the performance of our protocol combining these elements....
Entanglement dynamics in random media
Menezes, G.; Svaiter, N. F.; Zarro, C. A. D.
2017-12-01
We study how the entanglement dynamics between two-level atoms is impacted by random fluctuations of the light cone. In our model the two-atom system is envisaged as an open system coupled with an electromagnetic field in the vacuum state. We employ the quantum master equation in the Born-Markov approximation in order to describe the completely positive time evolution of the atomic system. We restrict our investigations to the situation in which the atoms are coupled individually to two spatially separated cavities, one of which displays the emergence of light-cone fluctuations. In such a disordered cavity, we assume that the coefficients of the Klein-Gordon equation are random functions of the spatial coordinates. The disordered medium is modeled by a centered, stationary, and Gaussian process. We demonstrate that disorder has the effect of slowing down the entanglement decay. We conjecture that in a strong-disorder environment the mean life of entangled states can be enhanced in such a way as to almost completely suppress quantum nonlocal decoherence.
Entanglement as a Semantic Resource
Dalla Chiara, Maria Luisa; Giuntini, Roberto; Ledda, Antonio; Leporini, Roberto; Sergioli, Giuseppe
2010-10-01
The characteristic holistic features of the quantum theoretic formalism and the intriguing notion of entanglement can be applied to a field that is far from microphysics: logical semantics. Quantum computational logics are new forms of quantum logic that have been suggested by the theory of quantum logical gates in quantum computation. In the standard semantics of these logics, sentences denote quantum information quantities: systems of qubits ( quregisters) or, more generally, mixtures of quregisters ( qumixes), while logical connectives are interpreted as special quantum logical gates (which have a characteristic reversible and dynamic behavior). In this framework, states of knowledge may be entangled, in such a way that our information about the whole determines our information about the parts; and the procedure cannot be, generally, inverted. In spite of its appealing properties, the standard version of the quantum computational semantics is strongly “Hilbert-space dependent”. This certainly represents a shortcoming for all applications, where real and complex numbers do not generally play any significant role (as happens, for instance, in the case of natural and of artistic languages). We propose an abstract version of quantum computational semantics, where abstract qumixes, quregisters and registers are identified with some special objects (not necessarily living in a Hilbert space), while gates are reversible functions that transform qumixes into qumixes. In this framework, one can give an abstract definition of the notions of superposition and of entangled pieces of information, quite independently of any numerical values. We investigate three different forms of abstract holistic quantum computational logic.
A class of quantum gate entanglers
International Nuclear Information System (INIS)
Heydari, Hoshang
2010-01-01
We construct quantum gate entanglers for different classes of multipartite states based on the definition of W and GHZ concurrence classes. First, we review the basic construction of concurrence classes based on the orthogonal complement of a positive operator valued measure (POVM) on quantum phase. Then, we construct quantum gate entanglers for different classes of multi-qubit states. In particular, we show that these operators can entangle multipartite states if they satisfy some conditions for W and GHZ classes of states. Finally, we explicitly give the W class and GHZ classes of quantum gate entanglers for four-qubit states.
Entanglement property in matrix product spin systems
International Nuclear Information System (INIS)
Zhu Jingmin
2012-01-01
We study the entanglement property in matrix product spin-ring systems systemically by von Neumann entropy. We find that: (i) the Hilbert space dimension of one spin determines the upper limit of the maximal value of the entanglement entropy of one spin, while for multiparticle entanglement entropy, the upper limit of the maximal value depends on the dimension of the representation matrices. Based on the theory, we can realize the maximum of the entanglement entropy of any spin block by choosing the appropriate control parameter values. (ii) When the entanglement entropy of one spin takes its maximal value, the entanglement entropy of an asymptotically large spin block, i.e. the renormalization group fixed point, is not likely to take its maximal value, and so only the entanglement entropy S n of a spin block that varies with size n can fully characterize the spin-ring entanglement feature. Finally, we give the entanglement dynamics, i.e. the Hamiltonian of the matrix product system. (author)
Entanglement Equilibrium and the Einstein Equation.
Jacobson, Ted
2016-05-20
A link between the semiclassical Einstein equation and a maximal vacuum entanglement hypothesis is established. The hypothesis asserts that entanglement entropy in small geodesic balls is maximized at fixed volume in a locally maximally symmetric vacuum state of geometry and quantum fields. A qualitative argument suggests that the Einstein equation implies the validity of the hypothesis. A more precise argument shows that, for first-order variations of the local vacuum state of conformal quantum fields, the vacuum entanglement is stationary if and only if the Einstein equation holds. For nonconformal fields, the same conclusion follows modulo a conjecture about the variation of entanglement entropy.
Quantum entanglement in helium-like ions
Lin, Y.-C.; Ho, Y. K.
2012-06-01
Recently, there have been considerable interests to investigate quantum entanglement in two-electron atoms [1-3]. Here we investigate quantum entanglement for the ground and excited states of helium-like ions using correlated wave functions, concentrating on the particle-particle entanglement coming from the continuous spatial degrees of freedom. We use the two-electron wave functions constructed by employing B-spline basis to calculate the linear entropy of the reduced density matrix L=1-TrA(ρA^2 ) as a measure of the spatial entanglement. HereρA=TrB(| >AB ABDehesa et. al., J. Phys. B 45, 015504 (2012)
Quantum communication using a multiqubit entangled channel
Energy Technology Data Exchange (ETDEWEB)
Ghose, Shohini, E-mail: sghose@wlu.ca [Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario (Canada); Institute for Quantum Computing, University of Waterloo, Ontario (Canada); Hamel, Angele [Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario (Canada)
2015-12-31
We describe a protocol in which two senders each teleport a qubit to a receiver using a multiqubit entangled state. The multiqubit channel used for teleportation is genuinely 4-qubit entangled and is not equivalent to a product of maximally entangled Bell pairs under local unitary operations. We discuss a scenario in which both senders must participate for the qubits to be successfully teleported. Such an all-or-nothing scheme cannot be implemented with standard two-qubit entangled Bell pairs and can be useful for different communication and computing tasks.
Entanglement Swapping in the Presence of White and Color Noise
Dotsenko, Ivan S.; Korobka, R.
2018-02-01
The influence of white and color noise on the outcome of the entanglement swapping process is investigated in a four-qubit system. Critical degree of noise in initial state, that could destroy entanglement in a result state is presented. The entanglement characteristics, such as concurrence, tangle, etc. are compared. Results could be helpful for experiments regarding entanglement swapping as conditions for initial quantum entangled states, to obtain entangled result state.
Double and triple entanglement in a single neutron system
International Nuclear Information System (INIS)
Erdösi, D.
2015-01-01
Single-neutron interferometry is used in various experiments to study the foundations of quantum mechanics. The drawback of this technique, however, is that the contrast of neutron interferometers is very prone to disturbances, in particular, temperature variations. In order to achieve very low degrading of the contrast, we develop new devices to manipulate the neutron-s spin and energy in the interferometer. These devices open the door for quantum state generation with much higher fidelities than it has been possible so far in neutron interferometry. Spin rotators with time-dependent (radio-frequency (RF)) field change both spin and energy. We improve our RF spin-rotators for the interferometer by equipping them with miniature Helmholtz coils, which allows to adjust the energy shift due to each RF coil independently. This is essential for the generation of certain quantum states. This improvement is made possible by a new coil cooling method. Furthermore, we also develop new Larmor precession accelerators and decelerators that do not consume energy and hence do not produce heat at all. We demonstrate two applications of the new spin and energy manipulators by generating bi- and tripartite entanglement between the neutron's spin, energy and path degrees of freedom in the interferometer: we succeed in generating a Bell-like state and GHZ- and W-like states. For Bell state generation we also introduce a convenient spin preparation scheme that uses our Larmor precession manipulator. We achieve a considerably more significant violation of a Bell-like inequality than with the previous method, thus further confirming quantum contextuality. With our RF spin rotators we achieve for the GHZ- and W-like states fidelities between 95 and 99%. (author) [de
Design of a tripartite network for the prediction of drug targets
Kunimoto, Ryo; Bajorath, Jürgen
2018-02-01
Drug-target networks have aided in many target prediction studies aiming at drug repurposing or the analysis of side effects. Conventional drug-target networks are bipartite. They contain two different types of nodes representing drugs and targets, respectively, and edges indicating pairwise drug-target interactions. In this work, we introduce a tripartite network consisting of drugs, other bioactive compounds, and targets from different sources. On the basis of analog relationships captured in the network and so-called neighbor targets of drugs, new drug targets can be inferred. The tripartite network was found to have a stable structure and simulated network growth was accompanied by a steady increase in assortativity, reflecting increasing correlation between degrees of connected nodes leading to even network connectivity. Local drug environments in the tripartite network typically contained neighbor targets and revealed interesting drug-compound-target relationships for further analysis. Candidate targets were prioritized. The tripartite network design extends standard drug-target networks and provides additional opportunities for drug target prediction.
Toward a Tripartite Model of L2 Reading Strategy Use, Motivations, and Learner Beliefs
Matsumoto, Hiroyuki; Hiromori, Tomohito; Nakayama, Akira
2013-01-01
The present study proposes a tripartite model of L2 reading strategy use, reading motivations, and general learner beliefs by examining the relationships among them in an L2 context. Reading strategy instruction was performed for 360 first-year university students enrolled in a reading-based course, in expectation of affecting their motivations…
Fox, Jeremy K.; Halpern, Leslie F.; Ryan, Julie L.; Lowe, Kelly A.
2010-01-01
Although the tripartite model reliably distinguishes anxiety and depression in adolescents, it remains unclear how negative affectivity (NA) and positive affectivity (PA) influence developmental pathways to internalizing problems. Based on models which propose that affectivity shapes how youth react to stress, the present study attempted to…
Abrams, Katie; Meyers, Courtney; Irani, Tracy; Baker, Lauri
2010-01-01
Several land-grant institutions have adopted a name to encompass the teaching, research, and Extension components of the university, creating a brand identity for those public services. But, in the mind of stakeholders, has the connection between the tripartite mission and the brand name been made? The study reported here sought to determine…
Examination of evidence for collinear cluster tri-partition
Pyatkov, Yu. V.; Kamanin, D. V.; Alexandrov, A. A.; Alexandrova, I. A.; Goryainova, Z. I.; Malaza, V.; Mkaza, N.; Kuznetsova, E. A.; Strekalovsky, A. O.; Strekalovsky, O. V.; Zhuchko, V. E.
2017-12-01
Background: In a series of experiments at different time-of-flight spectrometers of heavy ions we have observed manifestations of a new at least ternary decay channel of low excited heavy nuclei. Due to specific features of the effect, it was called collinear cluster tri-partition (CCT). The obtained experimental results have initiated a number of theoretical articles dedicated to different aspects of the CCT. Special attention was paid to kinematics constraints and stability of collinearity. Purpose: To compare theoretical predictions with our experimental data, only partially published so far. To develop the model of one of the most populated CCT modes that gives rise to the so-called "Ni-bump." Method: The fission events under analysis form regular two-dimensional linear structures in the mass correlation distributions of the fission fragments. The structures were revealed both at a highly statistically reliable level but on the background substrate, and at the low statistics in almost noiseless distribution. The structures are bounded by the known magic fragments and were reproduced at different spectrometers. All this provides high reliability of our experimental findings. The model of the CCT proposed here is based on theoretical results, published recently, and the detailed analysis of all available experimental data. Results: Under our model, the CCT mode giving rise to the Ni bump occurs as a two-stage breakup of the initial three body chain like the nuclear configuration with an elongated central cluster. After the first scission at the touching point with one of the side clusters, the predominantly heavier one, the deformation energy of the central cluster allows the emission of up to four neutrons flying apart isotropically. The heavy side cluster and a dinuclear system, consisting of the light side cluster and the central one, relaxed to a less elongated shape, are accelerated in the mutual Coulomb field. The "tip" of the dinuclear system at the moment
Entangling mobility and interactions in social media.
Grabowicz, Przemyslaw A; Ramasco, José J; Gonçalves, Bruno; Eguíluz, Víctor M
2014-01-01
Daily interactions naturally define social circles. Individuals tend to be friends with the people they spend time with and they choose to spend time with their friends, inextricably entangling physical location and social relationships. As a result, it is possible to predict not only someone's location from their friends' locations but also friendship from spatial and temporal co-occurrence. While several models have been developed to separately describe mobility and the evolution of social networks, there is a lack of studies coupling social interactions and mobility. In this work, we introduce a model that bridges this gap by explicitly considering the feedback of mobility on the formation of social ties. Data coming from three online social networks (Twitter, Gowalla and Brightkite) is used for validation. Our model reproduces various topological and physical properties of the networks not captured by models uncoupling mobility and social interactions such as: i) the total size of the connected components, ii) the distance distribution between connected users, iii) the dependence of the reciprocity on the distance, iv) the variation of the social overlap and the clustering with the distance. Besides numerical simulations, a mean-field approach is also used to study analytically the main statistical features of the networks generated by a simplified version of our model. The robustness of the results to changes in the model parameters is explored, finding that a balance between friend visits and long-range random connections is essential to reproduce the geographical features of the empirical networks.
Entanglement in non-Hermitian quantum theory
Indian Academy of Sciences (India)
September 2009 physics pp. 485–498. Entanglement in non-Hermitian quantum theory. ARUN K PATI. Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005, India. E-mail: akpati@iopb.res.in. Abstract. Entanglement is one of the key features of quantum world that has no classical counterpart. This arises due to the ...
Two particle entanglement and its geometric duals
International Nuclear Information System (INIS)
Wasay, Muhammad Abdul; Bashir, Asma
2017-01-01
We show that for a system of two entangled particles, there is a dual description to the particle equations in terms of classical theory of conformally stretched spacetime. We also connect these entangled particle equations with Finsler geometry. We show that this duality translates strongly coupled quantum equations in the pilot-wave limit to weakly coupled geometric equations. (orig.)
Black holes as parts of entangled systems
Basini, G.; Capozziello, S.; Longo, G.
A possible link between EPR-type quantum phenomena and astrophysical objects like black holes, under a new general definition of entanglement, is established. A new approach, involving backward time evolution and topology changes, is presented bringing to a definition of the system black hole-worm hole-white hole as an entangled system.
Fisher metric, geometric entanglement, and spin networks
Chirco, Goffredo; Mele, Fabio M.; Oriti, Daniele; Vitale, Patrizia
2018-02-01
Starting from recent results on the geometric formulation of quantum mechanics, we propose a new information geometric characterization of entanglement for spin network states in the context of quantum gravity. For the simple case of a single-link fixed graph (Wilson line), we detail the construction of a Riemannian Fisher metric tensor and a symplectic structure on the graph Hilbert space, showing how these encode the whole information about separability and entanglement. In particular, the Fisher metric defines an entanglement monotone which provides a notion of distance among states in the Hilbert space. In the maximally entangled gauge-invariant case, the entanglement monotone is proportional to a power of the area of the surface dual to the link thus supporting a connection between entanglement and the (simplicial) geometric properties of spin network states. We further extend such analysis to the study of nonlocal correlations between two nonadjacent regions of a generic spin network graph characterized by the bipartite unfolding of an intertwiner state. Our analysis confirms the interpretation of spin network bonds as a result of entanglement and to regard the same spin network graph as an information graph, whose connectivity encodes, both at the local and nonlocal level, the quantum correlations among its parts. This gives a further connection between entanglement and geometry.
Entangled Light Emission From a Diode
International Nuclear Information System (INIS)
Stevenson, R. M.; Shields, A. J.; Salter, C. L.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A.
2011-01-01
Electrically-driven entangled photon generation is demonstrated for the first time using a single semiconductor quantum dot embedded in a light emitting diode structure. The entanglement fidelity is shown to be of sufficient quality for applications such as quantum key distribution.
Two particle entanglement and its geometric duals
Energy Technology Data Exchange (ETDEWEB)
Wasay, Muhammad Abdul [University of Agriculture, Department of Physics, Faisalabad (Pakistan); Quaid-i-Azam University Campus, National Centre for Physics, Islamabad (Pakistan); Bashir, Asma [University of Agriculture, Department of Physics, Faisalabad (Pakistan)
2017-12-15
We show that for a system of two entangled particles, there is a dual description to the particle equations in terms of classical theory of conformally stretched spacetime. We also connect these entangled particle equations with Finsler geometry. We show that this duality translates strongly coupled quantum equations in the pilot-wave limit to weakly coupled geometric equations. (orig.)
Detecting Multiparticle Entanglement of Dicke States
DEFF Research Database (Denmark)
Lücke, Bernd; Peise, Jan; Vitagliano, Giuseppe
2014-01-01
of entangled states, including Dicke states. Experimentally, we produce a Dicke-like state using spin dynamics in a Bose-Einstein condensate. Our criterion proves that it contains at least genuine 28-particle entanglement. We infer a generalized squeezing parameter of −11.4(5) dB....
Quantum entanglement and quantum computational algorithms
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 56; Issue 2-3. Quantum entanglement ... Arvind. Quantum information processing Volume 56 Issue 2-3 February-March 2001 pp 357-365 ... The existence of entangled quantum states gives extra power to quantum computers over their classical counterparts. Quantum ...
Quantum entanglement in polarization and space
Lee, Peter Sing Kin
2006-01-01
One of the most intriguing concepts of quantum mechanics is quantum entanglement. Two physical systems are said to be entangled with respect to a certain variable, if their individual outcomes of the variable are undetermined before measurement, but strictly correlated. Measurement of the variable
Entanglement in non-Hermitian quantum theory
Indian Academy of Sciences (India)
Abstract. Entanglement is one of the key features of quantum world that has no classical counterpart. This arises due to the linear superposition principle and the tensor product structure of the Hilbert space when we deal with multiparticle systems. In this paper, we will introduce the notion of entanglement for quantum ...
Rank-dependant factorization of entanglement evolution
International Nuclear Information System (INIS)
Siomau, Michael
2016-01-01
Highlights: • In some cases the complex entanglement evolution can be factorized on simple terms. • We suggest factorization equations for multiqubit entanglement evolution. • The factorization is solely defined by the rank of the final state density matrices. • The factorization is independent on the local noisy channels and initial pure states. - Abstract: The description of the entanglement evolution of a complex quantum system can be significantly simplified due to the symmetries of the initial state and the quantum channels, which simultaneously affect parts of the system. Using concurrence as the entanglement measure, we study the entanglement evolution of few qubit systems, when each of the qubits is affected by a local unital channel independently on the others. We found that for low-rank density matrices of the final quantum state, such complex entanglement dynamics can be completely described by a combination of independent factors representing the evolution of entanglement of the initial state, when just one of the qubits is affected by a local channel. We suggest necessary conditions for the rank of the density matrices to represent the entanglement evolution through the factors. Our finding is supported with analytical examples and numerical simulations.
Entanglement and the quantum brachistochrone problem
Borras, A.; Zander, C.; Plastino, A. R.; Casas, M.; Plastino, A.
2008-02-01
Entanglement is closely related to some fundamental features of the dynamics of composite quantum systems: quantum entanglement enhances the "speed" of evolution of certain quantum states, as measured by the time required to reach an orthogonal state. The concept of "speed" of quantum evolution constitutes an important ingredient in any attempt to determine the fundamental limits that basic physical laws impose on how fast a physical system can process or transmit information. Here we explore the relationship between entanglement and the speed of quantum evolution in the context of the quantum brachistochrone problem. Given an initial and a final state of a composite system we consider the amount of entanglement associated with the brachistochrone evolution between those states, showing that entanglement is an essential resource to achieve the alluded time-optimal quantum evolution.
Maximal Entanglement in High Energy Physics
Directory of Open Access Journals (Sweden)
Alba Cervera-Lierta, José I. Latorre, Juan Rojo, Luca Rottoli
2017-11-01
Full Text Available We analyze how maximal entanglement is generated at the fundamental level in QED by studying correlations between helicity states in tree-level scattering processes at high energy. We demonstrate that two mechanisms for the generation of maximal entanglement are at work: i $s$-channel processes where the virtual photon carries equal overlaps of the helicities of the final state particles, and ii the indistinguishable superposition between $t$- and $u$-channels. We then study whether requiring maximal entanglement constrains the coupling structure of QED and the weak interactions. In the case of photon-electron interactions unconstrained by gauge symmetry, we show how this requirement allows reproducing QED. For $Z$-mediated weak scattering, the maximal entanglement principle leads to non-trivial predictions for the value of the weak mixing angle $\\theta_W$. Our results are a first step towards understanding the connections between maximal entanglement and the fundamental symmetries of high-energy physics.
Entanglement creation in low-energy scattering
Energy Technology Data Exchange (ETDEWEB)
Weder, Ricardo [Institut National de Recherche en Informatique et en Automatique Paris-Rocquencourt, Projet POEMS, Domaine de Voluceau-Rocquencourt, BP 105, F-78153, Le Chesnay Cedex (France)
2011-12-15
We study the entanglement creation in the low-energy scattering of two particles in three dimensions, for a general class of interaction potentials that are not required to be spherically symmetric. The incoming asymptotic state, before the collision, is a product of two normalized Gaussian states. After the scattering, the particles are entangled. We take as a measure of the entanglement the purity of one of them. We provide a rigorous explicit computation, with error bound, of the leading order of the purity at low energy. The entanglement depends strongly on the difference of the masses. It takes its minimum when the masses are equal, and it increases rapidly with the difference of the masses. It is quite remarkable that the anisotropy of the potential gives no contribution to the leading order of the purity, in spite of the fact that entanglement is a second-order effect.
Superadditivity of distillable entanglement from quantum teleportation
Bandyopadhyay, Somshubhro; Roychowdhury, Vwani
2005-12-01
We show that the phenomenon of superadditivity of distillable entanglement observed in multipartite quantum systems results from the consideration of states created during the execution of the standard end-to-end quantum teleportation protocol [and a few additional local operations and classical communication (LOCC) steps] on a linear chain of singlets. Some of these intermediate states are tensor products of bound entangled (BE) states, and hence, by construction possess distillable entanglement, which can be unlocked by simply completing the rest of the LOCC operations required by the underlying teleportation protocol. We use this systematic approach to construct both new and known examples of superactivation of bound entanglement, and examples of activation of BE states using other BE states. A surprising outcome is the construction of noiseless quantum relay channels with no distillable entanglement between any two parties, except for that between the two end nodes.
Superadditivity of distillable entanglement from quantum teleportation
International Nuclear Information System (INIS)
Bandyopadhyay, Somshubhro; Roychowdhury, Vwani
2005-01-01
We show that the phenomenon of superadditivity of distillable entanglement observed in multipartite quantum systems results from the consideration of states created during the execution of the standard end-to-end quantum teleportation protocol [and a few additional local operations and classical communication (LOCC) steps] on a linear chain of singlets. Some of these intermediate states are tensor products of bound entangled (BE) states, and hence, by construction possess distillable entanglement, which can be unlocked by simply completing the rest of the LOCC operations required by the underlying teleportation protocol. We use this systematic approach to construct both new and known examples of superactivation of bound entanglement, and examples of activation of BE states using other BE states. A surprising outcome is the construction of noiseless quantum relay channels with no distillable entanglement between any two parties, except for that between the two end nodes
Deterministic dense coding with partially entangled states
Mozes, Shay; Oppenheim, Jonathan; Reznik, Benni
2005-01-01
The utilization of a d -level partially entangled state, shared by two parties wishing to communicate classical information without errors over a noiseless quantum channel, is discussed. We analytically construct deterministic dense coding schemes for certain classes of nonmaximally entangled states, and numerically obtain schemes in the general case. We study the dependency of the maximal alphabet size of such schemes on the partially entangled state shared by the two parties. Surprisingly, for d>2 it is possible to have deterministic dense coding with less than one ebit. In this case the number of alphabet letters that can be communicated by a single particle is between d and 2d . In general, we numerically find that the maximal alphabet size is any integer in the range [d,d2] with the possible exception of d2-1 . We also find that states with less entanglement can have a greater deterministic communication capacity than other more entangled states.
Optimized entanglement witnesses for Dicke states
Energy Technology Data Exchange (ETDEWEB)
Bergmann, Marcel; Guehne, Otfried [Naturwissenschaftlich-Technische Fakultaet, Universitaet Siegen, Department Physik, Walter-Flex-Strasse 3, D-57068 Siegen (Germany)
2013-07-01
Quantum entanglement is an important resource for applications in quantum information processing like quantum teleportation and cryptography. Moreover, the number of particles that can be entangled experimentally using polarized photons or ion traps has been significantly enlarged. Therefore, criteria to decide the question whether a given multi-particle state is entangled or not have to be improved. Our approach to this problem uses the notion of PPT mixtures which form an approximation to the set of bi-separable states. With this method, entanglement witnesses can be obtained in a natural manner via linear semi-definite programming. In our contribution, we will present analytical results for entanglement witnesses for Dicke states. This allows to overcome the limitations of convex optimization.
Kerr nonlinear coupler and entanglement
International Nuclear Information System (INIS)
Leonski, Wieslaw; Miranowicz, Adam
2004-01-01
We discuss a model comprising two coupled nonlinear oscillators (Kerr-like nonlinear coupler) with one of them pumped by an external coherent excitation. Applying the method of nonlinear quantum scissors we show that the quantum evolution of the coupler can be closed within a finite set of n-photon Fock states. Moreover, we show that the system is able to generate Bell-like states and, as a consequence, the coupler discussed behaves as a two-qubit system. We also analyse the effects of dissipation on entanglement of formation parametrized by concurrence
Entanglement fidelity of quantum memories
International Nuclear Information System (INIS)
Surmacz, K.; Nunn, J.; Waldermann, F. C.; Wang, Z.; Walmsley, I. A.; Jaksch, D.
2006-01-01
We introduce a figure of merit for a quantum memory which measures the preservation of entanglement between a qubit stored in and retrieved from the memory and an auxiliary qubit. We consider a general quantum memory system consisting of a medium of two level absorbers, with the qubit to be stored encoded in a single photon. We derive an analytic expression for our figure of merit taking into account Gaussian fluctuations in the Hamiltonian parameters, which, for example, model inhomogeneous broadening and storage time dephasing. Finally we specialize to the case of an atomic quantum memory where fluctuations arise predominantly from Doppler broadening and motional dephasing
Quantum Entanglement Growth under Random Unitary Dynamics
Directory of Open Access Journals (Sweden)
Adam Nahum
2017-07-01
Full Text Available Characterizing how entanglement grows with time in a many-body system, for example, after a quantum quench, is a key problem in nonequilibrium quantum physics. We study this problem for the case of random unitary dynamics, representing either Hamiltonian evolution with time-dependent noise or evolution by a random quantum circuit. Our results reveal a universal structure behind noisy entanglement growth, and also provide simple new heuristics for the “entanglement tsunami” in Hamiltonian systems without noise. In 1D, we show that noise causes the entanglement entropy across a cut to grow according to the celebrated Kardar-Parisi-Zhang (KPZ equation. The mean entanglement grows linearly in time, while fluctuations grow like (time^{1/3} and are spatially correlated over a distance ∝(time^{2/3}. We derive KPZ universal behavior in three complementary ways, by mapping random entanglement growth to (i a stochastic model of a growing surface, (ii a “minimal cut” picture, reminiscent of the Ryu-Takayanagi formula in holography, and (iii a hydrodynamic problem involving the dynamical spreading of operators. We demonstrate KPZ universality in 1D numerically using simulations of random unitary circuits. Importantly, the leading-order time dependence of the entropy is deterministic even in the presence of noise, allowing us to propose a simple coarse grained minimal cut picture for the entanglement growth of generic Hamiltonians, even without noise, in arbitrary dimensionality. We clarify the meaning of the “velocity” of entanglement growth in the 1D entanglement tsunami. We show that in higher dimensions, noisy entanglement evolution maps to the well-studied problem of pinning of a membrane or domain wall by disorder.
Gain maximization in a probabilistic entanglement protocol
di Lorenzo, Antonio; Esteves de Queiroz, Johnny Hebert
Entanglement is a resource. We can therefore define gain as a monotonic function of entanglement G (E) . If a pair with entanglement E is produced with probability P, the net gain is N = PG (E) - (1 - P) C , where C is the cost of a failed attempt. We study a protocol where a pair of quantum systems is produced in a maximally entangled state ρm with probability Pm, while it is produced in a partially entangled state ρp with the complementary probability 1 -Pm . We mix a fraction w of the partially entangled pairs with the maximally entangled ones, i.e. we take the state to be ρ = (ρm + wUlocρpUloc+) / (1 + w) , where Uloc is an appropriate unitary local operation designed to maximize the entanglement of ρ. This procedure on one hand reduces the entanglement E, and hence the gain, but on the other hand it increases the probability of success to P =Pm + w (1 -Pm) , therefore the net gain N may increase. There may be hence, a priori, an optimal value for w, the fraction of failed attempts that we mix in. We show that, in the hypothesis of a linear gain G (E) = E , even assuming a vanishing cost C -> 0 , the net gain N is increasing with w, therefore the best strategy is to always mix the partially entangled states. Work supported by CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico, proc. 311288/2014-6, and by FAPEMIG, Fundação de Amparo à Pesquisa de Minas Gerais, proc. IC-FAPEMIG2016-0269 and PPM-00607-16.
Entanglement of pinnipeds at Marion Island | Hofmeyr | African ...
African Journals Online (AJOL)
During the period April 1991–March 1996, 10 entangled Antarctic fur seals Arctocephalus gazella, 28 entangled Subantarctic fur seals A. tropicalis and one entangled southern elephant seal Mirounga leonina were observed at Marion Island, Southern Ocean. Entanglement of fur seals was estimated at between 0.01 and ...
PhD thesis: Multipartite entanglement and quantum algorithms
Alsina, Daniel
2017-01-01
PhD thesis dealing with various aspects of multipartite entanglement, such as entanglement measures, absolutely maximally entangled states, bell inequalities, entanglement spectrum and quantum frustration. Also some quantum algorithms run with the IBM quantum computer are covered, together with others applied to adiabatic quantum computation and quantum thermodynamics.
Entangling capabilities of symmetric two-qubit gates
Indian Academy of Sciences (India)
states from some suitably chosen initial separable states in terms of their entangling power. Keywords. Quantum entanglement; SU(3) generators; entangling power. PACS No. 03.65.Ud. 1. Introduction. In the last few years, there has been considerable increase in experimental activity aiming to create entangled quantum ...
Entanglement fidelity of the standard quantum teleportation channel
Energy Technology Data Exchange (ETDEWEB)
Li, Gang; Ye, Ming-Yong, E-mail: myye@fjnu.edu.cn; Lin, Xiu-Min
2013-09-16
We consider the standard quantum teleportation protocol where a general bipartite state is used as entanglement resource. We use the entanglement fidelity to describe how well the standard quantum teleportation channel transmits quantum entanglement and give a simple expression for the entanglement fidelity when it is averaged on all input states.
Quantum entanglement of baby universes
International Nuclear Information System (INIS)
Aganagic, Mina; Okuda, Takuya; Ooguri, Hirosi
2007-01-01
We study quantum entanglements of baby universes which appear in non-perturbative corrections to the OSV formula for the entropy of extremal black holes in type IIA string theory compactified on the local Calabi-Yau manifold defined as a rank 2 vector bundle over an arbitrary genus G Riemann surface. This generalizes the result for G=1 in hep-th/0504221. Non-perturbative terms can be organized into a sum over contributions from baby universes, and the total wave-function is their coherent superposition in the third quantized Hilbert space. We find that half of the universes preserve one set of supercharges while the other half preserve a different set, making the total universe stable but non-BPS. The parent universe generates baby universes by brane/anti-brane pair creation, and baby universes are correlated by conservation of non-normalizable D-brane charges under the process. There are no other source of entanglement of baby universes, and all possible states are superposed with the equal weight
Linearity of holographic entanglement entropy
Energy Technology Data Exchange (ETDEWEB)
Almheiri, Ahmed [Stanford Institute for Theoretical Physics, Department of Physics,Stanford University, Stanford, CA 94305 (United States); Dong, Xi [School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Swingle, Brian [Stanford Institute for Theoretical Physics, Department of Physics,Stanford University, Stanford, CA 94305 (United States)
2017-02-14
We consider the question of whether the leading contribution to the entanglement entropy in holographic CFTs is truly given by the expectation value of a linear operator as is suggested by the Ryu-Takayanagi formula. We investigate this property by computing the entanglement entropy, via the replica trick, in states dual to superpositions of macroscopically distinct geometries and find it consistent with evaluating the expectation value of the area operator within such states. However, we find that this fails once the number of semi-classical states in the superposition grows exponentially in the central charge of the CFT. Moreover, in certain such scenarios we find that the choice of surface on which to evaluate the area operator depends on the density matrix of the entire CFT. This nonlinearity is enforced in the bulk via the homology prescription of Ryu-Takayanagi. We thus conclude that the homology constraint is not a linear property in the CFT. We also discuss the existence of ‘entropy operators’ in general systems with a large number of degrees of freedom.
Cloning the entanglement of a pair of quantum bits
International Nuclear Information System (INIS)
Lamoureux, Louis-Philippe; Navez, Patrick; Cerf, Nicolas J.; Fiurasek, Jaromir
2004-01-01
It is shown that any quantum operation that perfectly clones the entanglement of all maximally entangled qubit pairs cannot preserve separability. This 'entanglement no-cloning' principle naturally suggests that some approximate cloning of entanglement is nevertheless allowed by quantum mechanics. We investigate a separability-preserving optimal cloning machine that duplicates all maximally entangled states of two qubits, resulting in 0.285 bits of entanglement per clone, while a local cloning machine only yields 0.060 bits of entanglement per clone
Quantum Entanglement: Separability, Measure, Fidelity of Teleportation, and Distillation
Directory of Open Access Journals (Sweden)
Ming Li
2010-01-01
Full Text Available Quantum entanglement plays crucial roles in quantum information processing. Quantum entangled states have become the key ingredient in the rapidly expanding field of quantum information science. Although the nonclassical nature of entanglement has been recognized for many years, considerable efforts have been taken to understand and characterize its properties recently. In this review, we introduce some recent results in the theory of quantum entanglement. In particular separability criteria based on the Bloch representation, covariance matrix, normal form and entanglement witness, lower bounds, subadditivity property of concurrence and tangle, fully entangled fraction related to the optimal fidelity of quantum teleportation, and entanglement distillation will be discussed in detail.
Gauge field entanglement in Kitaev's honeycomb model
Dóra, Balázs; Moessner, Roderich
2018-01-01
A spin fractionalizes into matter and gauge fermions in Kitaev's spin liquid on the honeycomb lattice. This follows from a Jordan-Wigner mapping to fermions, allowing for the construction of a minimal entropy ground-state wave function on the cylinder. We use this to calculate the entanglement entropy by choosing several distinct partitionings. First, by partitioning an infinite cylinder into two, the -ln2 topological entanglement entropy is reconfirmed. Second, the reduced density matrix of the gauge sector on the full cylinder is obtained after tracing out the matter degrees of freedom. This allows for evaluating the gauge entanglement Hamiltonian, which contains infinitely long-range correlations along the symmetry axis of the cylinder. The matter-gauge entanglement entropy is (Ny-1 )ln2 , with Ny the circumference of the cylinder. Third, the rules for calculating the gauge sector entanglement of any partition are determined. Rather small correctly chosen gauge partitions can still account for the topological entanglement entropy in spite of long-range correlations in the gauge entanglement Hamiltonian.
The geometry of entanglement and Grover's algorithm
International Nuclear Information System (INIS)
Iwai, Toshihiro; Hayashi, Naoki; Mizobe, Kimitake
2008-01-01
A measure of entanglement with respect to a bipartite partition of n-qubit has been defined and studied from the viewpoint of Riemannian geometry (Iwai 2007 J. Phys. A: Math. Theor. 40 12161). This paper has two aims. One is to study further the geometry of entanglement, and the other is to investigate Grover's search algorithms, both the original and the fixed-point ones, in reference with entanglement. As the distance between the maximally entangled states and the separable states is known already in the previous paper, this paper determines the set of maximally entangled states nearest to a typical separable state which is used as an initial state in Grover's search algorithms, and to find geodesic segments which realize the above-mentioned distance. As for Grover's algorithms, it is already known that while the initial and the target states are separable, the algorithms generate sequences of entangled states. This fact is confirmed also in the entanglement measure proposed in the previous paper, and then a split Grover algorithm is proposed which generates sequences of separable states only with respect to the bipartite partition
Dynamics of pairwise entanglement between two Tavis-Cummings atoms
International Nuclear Information System (INIS)
Guo Jinliang; Song Heshan
2008-01-01
We investigate the time evolution of pairwise entanglement between two Tavis-Cummings atoms for various entangled initial states, including pure and mixed states. We find that the phenomenon of entanglement sudden death behaviors is distinct in the evolution of entanglement for different initial states. What deserves mentioning here is that the initial portion of the excited state in the initial state is responsible for the sudden death of entanglement, and the degree of this effect also depends on the initial states
Entanglement measurement with discrete multiple-coin quantum walks
International Nuclear Information System (INIS)
Endrejat, J; Buettner, H
2005-01-01
Within a special multi-coin quantum walk scheme, we analyse the effect of the entanglement of the initial coin state. For states with a special entanglement structure, it is shown that this entanglement can be measured with the mean value of the walk, which depends on the i-concurrence of the initial coin state. Further, the entanglement evolution is investigated and it is shown that the symmetry of the probability distribution is reflected by the symmetry of the entanglement distribution
Controlling entanglement by direct quantum feedback
Carvalho, A. R. R.; Reid, A. J. S.; Hope, J. J.
2008-07-01
We discuss the generation of entanglement between electronic states of two atoms in a cavity using direct quantum feedback schemes. We compare the effects of different control Hamiltonians and detection processes in the performance of entanglement production and show that the quantum-jump-based feedback proposed by Carvalho and Hope [Phys. Rev. A 76, 010301(R) (2007)] can protect highly entangled states against decoherence. We provide analytical results that explain the robustness of jump feedback, and also analyze the perspectives of experimental implementation by scrutinizing the effects of imperfections and approximations in our model.
Entanglement rate for Gaussian continuous variable beams
Jiao Deng, Zhi; Habraken, Steven J. M.; Marquardt, Florian
2016-06-01
We derive a general expression that quantifies the total entanglement production rate in continuous variable systems, where a source emits two entangled Gaussian beams with arbitrary correlators. This expression is especially useful for situations where the source emits an arbitrary frequency spectrum, e.g. when cavities are involved. To exemplify its meaning and potential, we apply it to a four-mode optomechanical setup that enables the simultaneous up- and down-conversion of photons from a drive laser into entangled photon pairs. This setup is efficient in that both the drive and the optomechanical up- and down-conversion can be fully resonant.
Quantum entanglement and fixed-point bifurcations
International Nuclear Information System (INIS)
Hines, Andrew P.; McKenzie, Ross H.; Milburn, G.J.
2005-01-01
How does the classical phase-space structure for a composite system relate to the entanglement characteristics of the corresponding quantum system? We demonstrate how the entanglement in nonlinear bipartite systems can be associated with a fixed-point bifurcation in the classical dynamics. Using the example of coupled giant spins we show that when a fixed point undergoes a supercritical pitchfork bifurcation, the corresponding quantum state--the ground state--achieves its maximum amount of entanglement near the critical point. We conjecture that this will be a generic feature of systems whose classical limit exhibits such a bifurcation
Entangled spin clusters: some special features
Tribedi, Amit; Bose, Indrani
2006-01-01
In this paper, we study three specific aspects of entanglement in small spin clusters. We first study the effect of inhomogeneous exchange coupling strength on the entanglement properties of the S=1/2 antiferromagnetic linear chain tetramer compound NaCuAsO_{4}. The entanglement gap temperature, T_{E}, is found to have a non-monotonic dependence on the value of $\\alpha$, the exchange coupling inhomogeneity parameter. We next determine the variation of T_{E} as a function of S for a spin dimer...
Maximally entangled mixed states and conditional entropies
International Nuclear Information System (INIS)
Batle, J.; Casas, M.; Plastino, A.; Plastino, A.R.
2005-01-01
The maximally entangled mixed states of Munro et al. [Phys. Rev. A 64, 030302 (2001)] are shown to exhibit interesting features vis a vis conditional entropic measures. The same happens with the Ishizaka and Hiroshima states [Phys. Rev. A 62, 022310 (2000)], whose entanglement degree cannot be increased by acting on them with logic gates. Special types of entangled states that do not violate classical entropic inequalities are seen to exist in the space of two qubits. Special meaning can be assigned to the Munro et al. special participation ratio of 1.8
Entanglement and disorder: a mean field approach
Energy Technology Data Exchange (ETDEWEB)
Pasquale, Ferdinando de [Dipartimento di Fisica, Universita di Roma La Sapienza, Piazzale A Moro 2, 00185 Roma (Italy); Giorgi, Gian Luca, E-mail: ferdinando.depasquale@roma1.infn.i, E-mail: gianluca@ifisc.uib-csic.e [Institute for Cross-Disciplinary Physics and Complex Systems, IFISC (CSIC-UIB), Campus Universitat Illes Balears, E-07122 Palma de Mallorca (Spain)
2010-09-01
The entanglement of symmetric mean-field (MF) ground states is studied for systems of finite size. While a bare MF approximation amounts to considering factorized states, the symmetrization allows one to restore an amount of entanglement, which survives if finite systems are considered. For the isotropic XY model in the presence of a random transverse field, we calculated the one-site entanglement entropy, which is zero both for vanishing and maximum disorder and reaches a maximum for an intermediate value of disorder.
Spacetime entanglement with f(R) gravity
Energy Technology Data Exchange (ETDEWEB)
Pourhasan, Razieh [Perimeter Institute for Theoretical Physics,31 Caroline St. N., Waterloo, ON, N2L 2Y5 (Canada); Department of Physics & Astronomy, University of Waterloo,200 University Ave. W., Waterloo, ON, N2L 3G1 (Canada)
2014-06-03
We study the entanglement entropy of a general region in a theory of induced gravity using holographic calculations. In particular we use holographic entanglement entropy prescription of Ryu-Takayanagi in the context of the Randall-Sundrum 2 model while considering general f(R) gravity in the bulk. Showing the leading term is given by the usual Bekenstein-Hawking formula, we confirm the conjecture by Bianchi and Myers for this theory. Moreover, we calculate the first subleading term to entanglement entropy and show they agree with the Wald entropy up to extrinsic curvature terms.
Detecting Kondo Entanglement by Electron Conductance
Yoo, Gwangsu; Lee, S.-S. B.; Sim, H.-S.
2018-04-01
Quantum entanglement between an impurity spin and electrons nearby is a key property of the single-channel Kondo effects. We show that the entanglement can be detected by measuring electron conductance through a double quantum dot in an orbital Kondo regime. We derive a relation between the entanglement and the conductance, when the SU(2) spin symmetry of the regime is weakly broken. The relation reflects the universal form of many-body states near the Kondo fixed point. Using it, the spatial distribution of the entanglement—hence, the Kondo cloud—can be detected, with breaking of the symmetry spatially nonuniformly by electrical means.
Evolution of entanglement under echo dynamics
International Nuclear Information System (INIS)
Prosen, Tomaz; Znidaric, Marko; Seligman, Thomas H.
2003-01-01
Echo dynamics and fidelity are often used to discuss stability in quantum-information processing and quantum chaos. Yet fidelity yields no information about entanglement, the characteristic property of quantum mechanics. We study the evolution of entanglement in echo dynamics. We find qualitatively different behavior between integrable and chaotic systems on one hand and between random and coherent initial states for integrable systems on the other. For the latter the evolution of entanglement is given by a classical time scale. Analytic results are illustrated numerically in a Jaynes-Cummings model
Entanglement of a Single Spin-1 Object: An Example of Ubiquitous Entanglement
Binicioglu, Sinem; Can, M. Ali; Klyachko, Alexander A.; Shumovsky, Alexander S.
2006-01-01
Using a single spin-1 object as an example, we discuss a recent approach to quantum entanglement. The key idea of the approach consists in presetting of basic observables in the very definition of quantum system. Specification of basic observables defines the dynamic symmetry of the system. Entangled states of the system are then interpreted as states with maximal amount of uncertainty of all basic observables. The approach gives purely physical picture of entanglement. In particular, it sepa...
Entanglement entropy with a time-dependent Hamiltonian
Sivaramakrishnan, Allic
2018-03-01
The time evolution of entanglement tracks how information propagates in interacting quantum systems. We study entanglement entropy in CFT2 with a time-dependent Hamiltonian. We perturb by operators with time-dependent source functions and use the replica trick to calculate higher-order corrections to entanglement entropy. At first order, we compute the correction due to a metric perturbation in AdS3/CFT2 and find agreement on both sides of the duality. Past first order, we find evidence of a universal structure of entanglement propagation to all orders. The central feature is that interactions entangle unentangled excitations. Entanglement propagates according to "entanglement diagrams," proposed structures that are motivated by accessory spacetime diagrams for real-time perturbation theory. To illustrate the mechanisms involved, we compute higher-order corrections to free fermion entanglement entropy. We identify an unentangled operator, one which does not change the entanglement entropy to any order. Then, we introduce an interaction and find it changes entanglement entropy by entangling the unentangled excitations. The entanglement propagates in line with our conjecture. We compute several entanglement diagrams. We provide tools to simplify the computation of loop entanglement diagrams, which probe UV effects in entanglement propagation in CFT and holography.
Tripartite nonlocality for an open Dirac system in the background of Schwarzschild space–time
Ding, Zhi-Yong; Shi, Jia-Dong; Wu, Tao; He, Juan
2017-12-01
In this paper, the behavior of the tripartite nonlocality for a Dirac system in the background of Schwarzschild space–time is studied. It is shown that the nonlocality of the ultimate physical accessible state always decreases as the Hawking effect increases monotonically, which is independent of the number of particles located near the event horizon. Besides, the more particles there are located near the event horizon, the more difficult the violation of the Svetlichny inequality becomes. Furthermore, we investigate the property of these particles suffering from a non-Markovian environment, and derive that the nonlocality decreases quickly with the increasing decoherence time accompanied by damping revivals. To preserve tripartite nonlocality in the non-Markovian environment, we propose a scheme by means of prior weak measurement and post measurement reversal. It is worth noticing that the effect is better for larger measurement strengths, while it induces smaller success probability.
Attachment, the tripartite influence model, and the development of body dissatisfaction.
Hardit, Saroj K; Hannum, James W
2012-09-01
The tripartite model of influence proposes that three primary core sources of influence-parents, peers and media-contribute to the development of body dissatisfaction and disordered eating. In the current study, this model was examined in a sample of 205 undergraduate women. This study added to previous research by investigating mother and father criticism separately and by examining the potential moderating effects of parental attachment in the pathway to body dissatisfaction. Results indicated partial support for the tripartite model of influence. Sociocultural influences (media) were found to be a significant predictor of body dissatisfaction, but not parental or peer criticism. Anxious attachment was found to be a significant moderator on the effects of sociocultural attitudes in body dissatisfaction. Limitations and future research implications are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.
THE PARTICIPATE TRIPARTITE OF GEOGRAPHIC INFORMATION SCIENCE VIA OPEN SOURCE SOFTWARE EDUCATION
Directory of Open Access Journals (Sweden)
Teerawong Laosuwan
2012-11-01
Full Text Available This article describes educational experiences in an advanced graduate GIScience courses together with propose specific tripartite (teachers, researchers, and practitioners contributions. By combining high-quality interoperable data between past and present monitored time using expert software conjointly developed by tripartite cooperation, new designs and applications with a complex thematic topographic map were successfully developed through an intensive work. Conceptual frameworks and practical topics of the application can be different from student to student depending on metadata, geo-referencing, digitizing and topology building, and spatial interpolation and spatial analysis. Former students can work on data they have been introduced into the GIS, taking care of every detail about data, metadata, data models, formats, file relationships, etc. The experience can be easily adapted to other courses in the university over Thailand.
Entropic Entanglement: Information Prison Break
Directory of Open Access Journals (Sweden)
Alexander Y. Yosifov
2017-01-01
Full Text Available We argue that certain nonviolent local quantum field theory (LQFT modification considered at the global horizon (r=2M of a static spherically symmetric black hole can lead to adiabatic leakage of quantum information in the form of Hawking particles. The source of the modification is (i smooth at r=2M and (ii rapidly vanishing at r≫2M. Furthermore, we restore the unitary evolution by introducing extra quanta which departs slightly from the generic Hawking emission without changing the experience of an infalling observer (no drama. Also, we suggest that a possible interpretation of the Bekenstein-Hawking bound as entanglement entropy may yield a nonsingular dynamical horizon behavior described by black hole thermodynamics. Hence, by treating gravity as a field theory and considering its coupling to the matter fields in the Minkowski vacuum, we derive the conjectured fluctuations of the background geometry of a black hole.
DEFF Research Database (Denmark)
Rehm, Matthias; Rodil, Kasper
2016-01-01
In this paper we investigate the notion of intangible cultural heritage as a driver for smart city learning applications. To this end, we shortly explore the notion of intangible heritage before presenting the tripartite digitization model that was originally developed for indigenous cultural...... heritage but can equally be applied to the smart city context. We then discuss parts of the model making use of a specific case study aiming at re-creating places in the city....
Upon Further Reflection: More on the History, Tripartite Role, and Challenges of the Professoriate
Jeffrey R. Mueller
2015-01-01
This paper expands on the role of the professor by detailing the origins of the profession, adding some of the unique contributions of North American universities as well as some of the best practice recommendations to the unique tripartite role of the professor. It describes current challenges to the profession including the ever-controversial student rating of professors. It continues with the significance of empowerment to the role of the professor. It concludes with a predictive prescrip...
Directory of Open Access Journals (Sweden)
Ning Ma
2015-11-01
Full Text Available Purpose: In forest insurance market, there are three main participants including the insurance company, the forest farmer and the government. As different participant has different benefit object, there will be a complex and dynamic game relationship among all participants. The purpose of this paper is to make the game relationship among all participants in forest insurance market clear, and then to put forward some policy suggestions on the implementation of forest insurance from the view of game theory. Design/methodology/approach: Firstly, the static game model between the insurance company and the forest farmer is set up. According to the result of static game model, it’s difficult to implement forest insurance without government. Secondly, the tripartite dynamic game model among the government, the insurance company and the forest farmer is proposed, and the equilibrium solution of tripartite dynamic game model is acquired. Finally, the behavioral characteristics of all participants are analyzed according to the equilibrium solution of tripartite dynamic game model. Findings: the government’s allowance will be an important positive factor to implement forest insurance. The loss of the insurance company, which the lower insurance premium brings, can be compensated by the allowance from the government. The more the government provides allowance, the more actively the insurance company will implement forest insurance at a low insurance premium. In this situation, the forest farmer will be more likely to purchase the forest insurance, then the scope of forest insurance implementation will expend. Originality/value: There is a complex and dynamic game relationship among all participants in forest insurance market. Based on the tripartite dynamic game model, to make the game relationship between each participant clear is conducive to the implementation of forest insurance market in China.
Tri-partite complex for axonal transport drug delivery achieves pharmacological effect
Directory of Open Access Journals (Sweden)
Frederickson Martyn
2010-01-01
Full Text Available Abstract Background Targeted delivery of pharmaceutical agents into selected populations of CNS (Central Nervous System neurons is an extremely compelling goal. Currently, systemic methods are generally used for delivery of pain medications, anti-virals for treatment of dermatomal infections, anti-spasmodics, and neuroprotectants. Systemic side effects or undesirable effects on parts of the CNS that are not involved in the pathology limit efficacy and limit clinical utility for many classes of pharmaceuticals. Axonal transport from the periphery offers a possible selective route, but there has been little progress towards design of agents that can accomplish targeted delivery via this intraneural route. To achieve this goal, we developed a tripartite molecular construction concept involving an axonal transport facilitator molecule, a polymer linker, and a large number of drug molecules conjugated to the linker, then sought to evaluate its neurobiology and pharmacological behavior. Results We developed chemical synthesis methodologies for assembling these tripartite complexes using a variety of axonal transport facilitators including nerve growth factor, wheat germ agglutinin, and synthetic facilitators derived from phage display work. Loading of up to 100 drug molecules per complex was achieved. Conjugation methods were used that allowed the drugs to be released in active form inside the cell body after transport. Intramuscular and intradermal injection proved effective for introducing pharmacologically effective doses into selected populations of CNS neurons. Pharmacological efficacy with gabapentin in a paw withdrawal latency model revealed a ten fold increase in half life and a 300 fold decrease in necessary dose relative to systemic administration for gabapentin when the drug was delivered by axonal transport using the tripartite vehicle. Conclusion Specific targeting of selected subpopulations of CNS neurons for drug delivery by axonal
Characterization of a novel tripartite nuclear localization sequence in the EGFR family.
Hsu, Sheng-Chieh; Hung, Mien-Chie
2007-04-06
Aberrant expression of epidermal growth factor receptor (EGFR) is present in many human tumors. Several reports have shown that EGFR is translocated into the nucleus during liver regeneration and in several types of cells and tissues such as placenta and thyroid. Nuclear EGFR is associated with transcription, DNA synthesis, and DNA repair activity and serves as a prognostic marker in breast carcinoma and oropharyngeal squamous cell cancer. However, the nuclear localization sequence (NLS) of EGFR has not been extensively examined. In this study, we have shown that the juxtamembrane region of EGFR harbors a putative NLS with three clusters of basic amino acids (RRRHIVRKRTLRR (amino acids 645-657)) that mediates the nuclear localization of EGFR. We found that this newly characterized tripartite NLS is conserved among the EGFR family members (EGFR, ErbB2, ErbB3, and ErbB4) and is able to move each to the nucleus. Further, this tripartite NLS could also mediate the nuclear localization of other known cytoplasmic proteins such as pyruvate kinase. We have demonstrated that mutating one of the three basic amino acid clusters (R or K --> A) leads to significant impairment of the nuclear localization of EGFR and that of a green fluorescent protein-pyruvate kinase-NLS reporter protein. Our results show that this tripartite NLS is distinct from the traditional mono- and bipartite NLS and reveal a mechanism that could account for the nuclear localization of membrane receptors.
Su, Zhaofeng; Li, Lvzhou; Ling, Jie
2018-04-01
Nonlocality is an important resource for quantum information processing. Genuine tripartite nonlocality, which is sufficiently confirmed by the violation of Svetlichny inequality, is a kind of more precious resource than the standard one. The genuine tripartite nonlocality is usually quantified by the amount of maximal violation of Svetlichny inequality. The problem of detecting and quantifying the genuine tripartite nonlocality of quantum states is of practical significance but still open for the case of general three-qubit quantum states. In this paper, we quantitatively investigate the genuine nonlocality of three-qubit states, which not only include pure states but also include mixed states. Firstly, we derive a simplified formula for the genuine nonlocality of a general three-qubit state, which is a function of the corresponding three correlation matrices. Secondly, we develop three properties of the genuine nonlocality which can help us to analyze the genuine nonlocality of complex states and understand the nature of quantum nonlocality. Further, we get analytical results of genuine nonlocality for two classes of three-qubit states which have special correlation matrices. In particular, the genuine nonlocality of generalized three-qubit GHZ states, which is derived by Ghose et al. (Phys. Rev. Lett. 102, 250404, 2009), and that of three-qubit GHZ-symmetric states, which is derived by Paul et al. (Phys. Rev. A 94, 032101, 2016), can be easily derived by applying the strategy and properties developed in this paper.
Convex Optimization over Classes of Multiparticle Entanglement
Shang, Jiangwei; Gühne, Otfried
2018-02-01
A well-known strategy to characterize multiparticle entanglement utilizes the notion of stochastic local operations and classical communication (SLOCC), but characterizing the resulting entanglement classes is difficult. Given a multiparticle quantum state, we first show that Gilbert's algorithm can be adapted to prove separability or membership in a certain entanglement class. We then present two algorithms for convex optimization over SLOCC classes. The first algorithm uses a simple gradient approach, while the other one employs the accelerated projected-gradient method. For demonstration, the algorithms are applied to the likelihood-ratio test using experimental data on bound entanglement of a noisy four-photon Smolin state [Phys. Rev. Lett. 105, 130501 (2010), 10.1103/PhysRevLett.105.130501].
Machine learning spatial geometry from entanglement features
You, Yi-Zhuang; Yang, Zhao; Qi, Xiao-Liang
2018-02-01
Motivated by the close relations of the renormalization group with both the holography duality and the deep learning, we propose that the holographic geometry can emerge from deep learning the entanglement feature of a quantum many-body state. We develop a concrete algorithm, call the entanglement feature learning (EFL), based on the random tensor network (RTN) model for the tensor network holography. We show that each RTN can be mapped to a Boltzmann machine, trained by the entanglement entropies over all subregions of a given quantum many-body state. The goal is to construct the optimal RTN that best reproduce the entanglement feature. The RTN geometry can then be interpreted as the emergent holographic geometry. We demonstrate the EFL algorithm on a 1D free fermion system and observe the emergence of the hyperbolic geometry (AdS3 spatial geometry) as we tune the fermion system towards the gapless critical point (CFT2 point).
Concurrent remote entanglement with continuous variables
Zalys-Geller, E.; Narla, A.; Shankar, S.; Hatridge, M.; Silveri, M.; Sliwa, K. M.; Mundhada, S. O.; Girvin, S. M.; Devoret, M. H.
A necessary ingredient for large scale quantum information processing is the ability to entangle distant qubits on demand. In the field of superconducting quantum information, this process can be achieved by entangling stationary superconducting qubits with flying coherent states of microwave light, which are then co-amplified by a Josephson Parametric Converter (JPC). The JPC also serves as a which-path information eraser, causing the probabilistic continuous measurement process to concurrently entangle the qubits. We discuss the sensitivity of the experiment to the loss of quantum information during the flight of the coherent states, as well as strategies to improve which-path information erasure and reduce information loss to the degree required for entanglement generation. Work supported by ARO, AFOSR, NSF, and YINQE.
Entanglement entropy of magnetic electron stars
Energy Technology Data Exchange (ETDEWEB)
Albash, Tameem; Johnson, Clifford V.; MacDonald, Scott [Department of Physics and Astronomy, University of Southern California,920 Bloom Walk, Los Angeles, CA (United States)
2015-09-24
We study the behavior of the entanglement entropy in (2+1)-dimensional strongly coupled theories via the AdS/CFT correspondence. We consider theories at a finite charge density with a magnetic field, with their holographic dual being Einstein-Maxwell-Dilaton theory in four dimensional anti-de Sitter gravity. Restricting to black hole and electron star solutions at zero temperature in the presence of a background magnetic field, we compute their holographic entanglement entropy using the Ryu-Takayanagi prescription for both strip and disk geometries. In the case of the electric or magnetic zero temperature black holes, we are able to confirm that the entanglement entropy is invariant under electric-magnetic duality. In the case of the electron star with a finite magnetic field, for the strip geometry, we find a discontinuity in the first derivative of the entanglement entropy as the strip width is increased.
Criticality and entanglement in random quantum systems
International Nuclear Information System (INIS)
Refael, G; Moore, J E
2009-01-01
We review studies of entanglement entropy in systems with quenched randomness, concentrating on universal behavior at strongly random quantum critical points. The disorder-averaged entanglement entropy provides insight into the quantum criticality of these systems and an understanding of their relationship to non-random ('pure') quantum criticality. The entanglement near many such critical points in one dimension shows a logarithmic divergence in subsystem size, similar to that in the pure case but with a different universal coefficient. Such universal coefficients are examples of universal critical amplitudes in a random system. Possible measurements are reviewed along with the one-particle entanglement scaling at certain Anderson localization transitions. We also comment briefly on higher dimensions and challenges for the future.
Projected entangled pair states: status and prospects
Energy Technology Data Exchange (ETDEWEB)
Verstraete, Frank [Universitaet Wien (Austria)
2008-07-01
We report on the progress made to extend the density matrix renormalization group to higher dimensions, discuss the underlying theory of projected entangled pair states (PEPS) and illustrate its potential on the hand of a few examples.
On quantum entanglement and quantum communication
International Nuclear Information System (INIS)
Zukowski, Marek
2009-01-01
This article presents a talk given at 23rd International Conference on Theoretical Physics (Ustron, 2008). A new version of Bell's theorem is presented, with inequalities based on four assumptions: realism, locality and ''free will'' and ''principle of rotational symmetry of physical laws''. The new Bell-type inequalities are derived using a simple geometrical intuition. The assumptions behind Bell's theorem are discussed. A critique of overinterpretations of violations of Bell inequalities is given. Further on, a new criterion for entanglement is presented, based on simple geometrical ideas. This leads to a new class of entanglement identifiers, which is richer than entanglement witnesses. Finally a link between Bell's theorem and communication complexity problems will be shown. It covers also realizations, which do not involve entanglement (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
On the entanglement entropy for gauge theories
International Nuclear Information System (INIS)
Ghosh, Sudip; Soni, Ronak M; Trivedi, Sandip P.
2015-01-01
We propose a definition for the entanglement entropy of a gauge theory on a spatial lattice. Our definition applies to any subset of links in the lattice, and is valid for both Abelian and Non-Abelian gauge theories. For ℤ N and U(1) theories, without matter, our definition agrees with a particular case of the definition given by Casini, Huerta and Rosabal. We also argue that in general, both for Abelian and Non-Abelian theories, our definition agrees with the entanglement entropy calculated using a definition of the replica trick. Our definition, however, does not agree with some standard ways to measure entanglement, like the number of Bell pairs which can be produced by entanglement distillation.
Entanglement degradation in depolarizing light scattering
International Nuclear Information System (INIS)
Aiello, A.; Woerdman, J.P.
2005-01-01
Full text: In the classical regime, when a beam of light is scattered by a medium, it may emerge partially or completely depolarized depending on the optical properties of the medium. Correspondingly, in the quantum regime, when an entangled two-photon pair is scattered, the classical depolarization may result in an entanglement degradation. Here, relations between photon scattering, entanglement and multi-mode detection are investigated. We establish a general framework in which one- and two-photon elastic scattering processes can be discussed, and we focus on the study of the intrinsic entanglement degradation caused by a multi-mode detection. We show that any multi-mode scattered state cannot maximally violate the Bell-CHSH inequality because of the momentum spread. The results presented here have general validity and can be applied to both deterministic and random scattering processes. (author)
Multipartite secret key distillation and bound entanglement
International Nuclear Information System (INIS)
Augusiak, Remigiusz; Horodecki, Pawel
2009-01-01
Recently it has been shown that quantum cryptography beyond pure entanglement distillation is possible and a paradigm for the associated protocols has been established. Here we systematically generalize the whole paradigm to the multipartite scenario. We provide constructions of new classes of multipartite bound entangled states, i.e., those with underlying twisted Greenberger-Horne-Zeilinger (GHZ) structure and nonzero distillable cryptographic key. We quantitatively estimate the key from below with the help of the privacy squeezing technique.
Thermal entanglement properties of small spin clusters
Bose, Indrani; Tribedi, Amit
2005-01-01
Exchange interactions in spin systems can give rise to quantum entanglement in the ground and thermal states of the systems. In this paper, we consider a spin tetramer, with spins of magnitude 1/2, in which the spins interact via nearest-neighbour, diagonal and four-spin interactions of strength J1, J2 and K respectively. The ground and thermal state entanglement properties of the tetramer are calculated analytically in the various limiting cases. Signatures of quantum phase transition (QPT) ...
Entanglement of Indistinguishable Particles and its Quantification
Sokoli, Florian; Kümmerer, Burkhard
2015-01-01
We introduce geometric measures of entanglement for indistinguishable particles, which apply to mixed states, multipartite systems, and arbitrary dimensions. They are based on generalized (i.e., not necessarily finite) norms on the set of quantum states and lead to the first necessary and sufficient computational separability criterion in this general setting. The coherent approach developed in the paper allows us to compare, in particular, entanglement for fermionic and distinguishable parti...
Symmetric states: Their nonlocality and entanglement
Energy Technology Data Exchange (ETDEWEB)
Wang, Zizhu; Markham, Damian [CNRS LTCI, Département Informatique et Réseaux, Telecom ParisTech, 23 avenue d' Italie, CS 51327, 75214 Paris CEDEX 13 (France)
2014-12-04
The nonlocality of permutation symmetric states of qubits is shown via an extension of the Hardy paradox and the extension of the associated inequality. This is achieved by using the Majorana representation, which is also a powerful tool in the study of entanglement properties of symmetric states. Through the Majorana representation, different nonlocal properties can be linked to different entanglement properties of a state, which is useful in determining the usefulness of different states in different quantum information processing tasks.
Holographic QCD, entanglement entropy, and critical temperature
Ali-Akbari, M.; Lezgi, M.
2017-10-01
Based on gauge-gravity duality, by using holographic entanglement entropy, we have done a phenomenological study to probe the confinement-deconfinement phase transition in the holographic model resembling quantum chromodynamics with two massless flavors and three colors. Our outcomes are in perfect agreement with the expected results, qualitatively and quantitatively. We find out that the (holographic) entanglement entropy is a reliable order parameter for probing the phase transition.
Effects of dipole—dipole interaction on entanglement transfer
International Nuclear Information System (INIS)
Guo Hong; Xiong Hengna
2008-01-01
A system consisting of two different atoms interacting with a two-mode vacuum, where each atom is resonant only with one cavity mode, is considered. The effects of dipole—dipole (dd) interaction between two atoms on the atom-atom entanglement and mode-mode entanglement are investigated. For a weak dd interaction, when the atoms are initially separable, the entanglement between them can be induced by the dd interaction, and the entanglement transfer between the atoms and the modes occurs efficiently; when the atoms are initially entangled, the entanglement transfer is almost not influenced by the dd interaction. However, for a strong dd interaction, it is difficult to transfer the entanglement from the atoms to the modes, but the atom-atom entanglement can be maintained when the atoms are initially entangled
Global Dirac bispinor entanglement under Lorentz boosts
Bittencourt, Victor A. S. V.; Bernardini, Alex E.; Blasone, Massimo
2018-03-01
The effects of Lorentz boosts on the quantum entanglement encoded by a pair of massive spin-1/2 particles are described according to the Lorentz covariant structure described by Dirac bispinors. The quantum system considered incorporates four degrees of freedom: two of them related to the bispinor intrinsic parity and the other two related to the bispinor spin projection, i.e., the Dirac particle helicity. Because of the natural multipartite structure involved, the Meyer-Wallach global measure of entanglement is preliminarily used for computing global quantum correlations, while the entanglement separately encoded by spin degrees of freedom is measured through the negativity of the reduced two-particle spin-spin state. A general framework to compute the changes on quantum entanglement induced by a boost is developed and then specialized to describe three particular antisymmetric two-particle states. According to the results obtained, two-particle spin-spin entanglement cannot be created by the action of a Lorentz boost in a spin-spin separable antisymmetric state. On the other hand, the maximal spin-spin entanglement encoded by antisymmetric superpositions is degraded by Lorentz boosts driven by high-speed frame transformations. Finally, the effects of boosts on chiral states are shown to exhibit interesting invariance properties, which can only be obtained through such a Lorentz covariant formulation of the problem.
Fiber transport of spatially entangled photons
Löffler, W.; Eliel, E. R.; Woerdman, J. P.; Euser, T. G.; Scharrer, M.; Russell, P.
2012-03-01
High-dimensional entangled photons pairs are interesting for quantum information and cryptography: Compared to the well-known 2D polarization case, the stronger non-local quantum correlations could improve noise resistance or security, and the larger amount of information per photon increases the available bandwidth. One implementation is to use entanglement in the spatial degree of freedom of twin photons created by spontaneous parametric down-conversion, which is equivalent to orbital angular momentum entanglement, this has been proven to be an excellent model system. The use of optical fiber technology for distribution of such photons has only very recently been practically demonstrated and is of fundamental and applied interest. It poses a big challenge compared to the established time and frequency domain methods: For spatially entangled photons, fiber transport requires the use of multimode fibers, and mode coupling and intermodal dispersion therein must be minimized not to destroy the spatial quantum correlations. We demonstrate that these shortcomings of conventional multimode fibers can be overcome by using a hollow-core photonic crystal fiber, which follows the paradigm to mimic free-space transport as good as possible, and are able to confirm entanglement of the fiber-transported photons. Fiber transport of spatially entangled photons is largely unexplored yet, therefore we discuss the main complications, the interplay of intermodal dispersion and mode mixing, the influence of external stress and core deformations, and consider the pros and cons of various fiber types.
Entanglement entropy and nonabelian gauge symmetry
International Nuclear Information System (INIS)
Donnelly, William
2014-01-01
Entanglement entropy has proven to be an extremely useful concept in quantum field theory. Gauge theories are of particular interest, but for these systems the entanglement entropy is not clearly defined because the physical Hilbert space does not factor as a tensor product according to regions of space. Here we review a definition of entanglement entropy that applies to abelian and nonabelian lattice gauge theories. This entanglement entropy is obtained by embedding the physical Hilbert space into a product of Hilbert spaces associated to regions with boundary. The latter Hilbert spaces include degrees of freedom on the entangling surface that transform like surface charges under the gauge symmetry. These degrees of freedom are shown to contribute to the entanglement entropy, and the form of this contribution is determined by the gauge symmetry. We test our definition using the example of two-dimensional Yang–Mills theory, and find that it agrees with the thermal entropy in de Sitter space, and with the results of the Euclidean replica trick. We discuss the possible implications of this result for more complicated gauge theories, including quantum gravity. (paper)
First law of entanglement rates from holography
O'Bannon, Andy; Probst, Jonas; Rodgers, Ronnie; Uhlemann, Christoph F.
2017-09-01
For a perturbation of the state of a conformal field theory (CFT), the response of the entanglement entropy is governed by the so-called "first law" of entanglement entropy, in which the change in entanglement entropy is proportional to the change in energy. Whether such a first law holds for other types of perturbations, such as a change to the CFT Lagrangian, remains an open question. We use holography to study the evolution in time t of entanglement entropy for a CFT driven by a t -linear source for a conserved U (1 ) current or marginal scalar operator. We find that although the usual first law of entanglement entropy may be violated, a first law for the rates of change of entanglement entropy and energy still holds. More generally, we prove that this first law for rates holds in holography for any asymptotically (d +1 )-dimensional anti-de Sitter metric perturbation whose t dependence first appears at order zd in the Fefferman-Graham expansion about the boundary at z =0 .
Remarks on entanglement entropy in string theory
Balasubramanian, Vijay; Parrikar, Onkar
2018-03-01
Entanglement entropy for spatial subregions is difficult to define in string theory because of the extended nature of strings. Here we propose a definition for bosonic open strings using the framework of string field theory. The key difference (compared to ordinary quantum field theory) is that the subregion is chosen inside a Cauchy surface in the "space of open string configurations." We first present a simple calculation of this entanglement entropy in free light-cone string field theory, ignoring subtleties related to the factorization of the Hilbert space. We reproduce the answer expected from an effective field theory point of view, namely a sum over the one-loop entanglement entropies corresponding to all the particle-excitations of the string, and further show that the full string theory regulates ultraviolet divergences in the entanglement entropy. We then revisit the question of factorization of the Hilbert space by analyzing the covariant phase-space associated with a subregion in Witten's covariant string field theory. We show that the pure gauge (i.e., BRST exact) modes in the string field become dynamical at the entanglement cut. Thus, a proper definition of the entropy must involve an extended Hilbert space, with new stringy edge modes localized at the entanglement cut.
Entanglement entropy and nonabelian gauge symmetry
Donnelly, William
2014-11-01
Entanglement entropy has proven to be an extremely useful concept in quantum field theory. Gauge theories are of particular interest, but for these systems the entanglement entropy is not clearly defined because the physical Hilbert space does not factor as a tensor product according to regions of space. Here we review a definition of entanglement entropy that applies to abelian and nonabelian lattice gauge theories. This entanglement entropy is obtained by embedding the physical Hilbert space into a product of Hilbert spaces associated to regions with boundary. The latter Hilbert spaces include degrees of freedom on the entangling surface that transform like surface charges under the gauge symmetry. These degrees of freedom are shown to contribute to the entanglement entropy, and the form of this contribution is determined by the gauge symmetry. We test our definition using the example of two-dimensional Yang-Mills theory, and find that it agrees with the thermal entropy in de Sitter space, and with the results of the Euclidean replica trick. We discuss the possible implications of this result for more complicated gauge theories, including quantum gravity.
Entanglement and the shareability of quantum states
Doherty, Andrew C.
2014-10-01
This brief review discusses the problem of determining whether a given quantum state is separable or entangled. I describe an established approach to this problem that is based on the monogamy of entanglement, which is the observation that a pair of quantum systems that are strongly entangled must be uncorrelated with the rest of the world. Unentangled states on the other hand involve correlations that can be shared with many other parties. Checking whether a given quantum state is shareable involves constructing certain symmetric quantum state extensions and I discuss how to do this using a class of optimizations known as semidefinite programs. An attractive feature of this approach is that it generates explicit entanglement witnesses that can be measured to demonstrate the entanglement experimentally. In recent years analysis of this approach has greatly increased our understanding of the complexity of determining whether a given quantum state is entangled and this review aims to give a unified discussion of these developments. Specifically, I describe how to use finite quantum de Finetti theorems to prove that highly shareable states are nearly separable and use these results to understand the computational complexity of the problem. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘50 years of Bell’s theorem’.
Interuniversal entanglement in a cyclic multiverse
Robles-Pérez, Salvador; Balcerzak, Adam; Dąbrowski, Mariusz P.; Krämer, Manuel
2017-04-01
We study scenarios of parallel cyclic multiverses which allow for a different evolution of the physical constants, while having the same geometry. These universes are classically disconnected, but quantum-mechanically entangled. Applying the thermodynamics of entanglement, we calculate the temperature and the entropy of entanglement. It emerges that the entropy of entanglement is large at big bang and big crunch singularities of the parallel universes as well as at the maxima of the expansion of these universes. The latter seems to confirm earlier studies that quantum effects are strong at turning points of the evolution of the universe performed in the context of the timeless nature of the Wheeler-DeWitt equation and decoherence. On the other hand, the entropy of entanglement at big rip singularities is going to zero despite its presumably quantum nature. This may be an effect of total dissociation of the universe structures into infinitely separated patches violating the null energy condition. However, the temperature of entanglement is large/infinite at every classically singular point and at maximum expansion and seems to be a better measure of quantumness.
Hamid, Arian Zad
2016-12-01
We analytically investigate Multiple Quantum (MQ) NMR dynamics in a mixed-three-spin (1/2,1,1/2) system with XXX Heisenberg model at the front of an external homogeneous magnetic field B. A single-ion anisotropy property ζ is considered for the spin-1. The intensities dependence of MQ NMR coherences on their orders (zeroth and second orders) for two pairs of spins (1,1/2) and (1/2,1/2) of the favorite tripartite system are obtained. It is also investigated dynamics of the pairwise quantum entanglement for the bipartite (sub)systems (1,1/2) and (1/2,1/2) permanently coupled by, respectively, coupling constants J}1 and J}2, by means of concurrence and fidelity. Then, some straightforward comparisons are done between these quantities and the intensities of MQ NMR coherences and ultimately some interesting results are reported. We also show that the time evolution of MQ coherences based on the reduced density matrix of the pair spins (1,1/2) is closely connected with the dynamics of the pairwise entanglement. Finally, we prove that one can introduce MQ coherence of the zeroth order corresponds to the pair spins (1,1/2) as an entanglement witness at some special time intervals.
Hybrid entanglement concentration assisted with single coherent state
International Nuclear Information System (INIS)
Guo Rui; Zhou Lan; Sheng Yu-Bo; Gu Shi-Pu; Wang Xing-Fu
2016-01-01
Hybrid entangled state (HES) is a new type of entanglement, which combines the advantages of an entangled polarization state and an entangled coherent state. HES is widely discussed in the applications of quantum communication and computation. In this paper, we propose three entanglement concentration protocols (ECPs) for Bell-type HES, W-type HES, and cluster-type HES, respectively. After performing these ECPs, we can obtain the maximally entangled HES with some success probability. All the ECPs exploit the single coherent state to complete the concentration. These protocols are based on the linear optics, which are feasible in future experiments. (paper)
Entanglement-assisted quantum MDS codes constructed from negacyclic codes
Chen, Jianzhang; Huang, Yuanyuan; Feng, Chunhui; Chen, Riqing
2017-12-01
Recently, entanglement-assisted quantum codes have been constructed from cyclic codes by some scholars. However, how to determine the number of shared pairs required to construct entanglement-assisted quantum codes is not an easy work. In this paper, we propose a decomposition of the defining set of negacyclic codes. Based on this method, four families of entanglement-assisted quantum codes constructed in this paper satisfy the entanglement-assisted quantum Singleton bound, where the minimum distance satisfies q+1 ≤ d≤ n+2/2. Furthermore, we construct two families of entanglement-assisted quantum codes with maximal entanglement.
Becomings: Narrative Entanglements and Microsociology
Directory of Open Access Journals (Sweden)
Maria Tamboukou
2015-01-01
Full Text Available In this article, I look back in an art/research experiment of convening an exhibition of women artists and inviting them to a round-table discussion in the context of a sociological conference. The artists who took part in this event had been previously interviewed for a feminist research project, entitled "In the Fold Between Life and Art, a Genealogy of Women Artists". The conference exhibition gave the artists the opportunity to appear to an academic audience and present their work while the round-table discussion created a forum for a narrative event where all women were invited to recount stories of becoming an artist. In looking at this event I want to explore questions around the possibilities and limitations of narratives in microsociological inquiries. In following trails of ARENDT's theorisation of stories, I explore connections and tensions between social, political and cultural entanglements in narrative research. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1501193
Minimizing the loss of entanglement under dimensional reduction
Petersen, V.; Madsen, L. B.; Mølmer, K.
2004-05-01
We investigate the possibility of transforming, under local operations and classical communication, a general bipartite quantum state on a d A x d B tensor-product space into a final state in 2 x 2 dimensions, while maintaining as much entanglement as possible. For pure states, we prove that Nielsen’s theorem provides the optimal protocol, and we present quantitative results on the degree of entanglement before and after the dimensional reduction. For mixed states, we identify a protocol that we argue is optimal for isotropic and Werner states. In the literature, it has been conjectured that some Werner states are bound entangled and in support of this conjecture our protocol gives final states without entanglement for this class of states. For all other entangled Werner states and for all entangled isotropic states some degree of free entanglement is maintained. In this sense, our protocol may be used to discriminate between bound and free entanglement.
Entanglement dynamics of a pure bipartite system in dissipative environments
Energy Technology Data Exchange (ETDEWEB)
Tahira, Rabia; Ikram, Manzoor; Azim, Tasnim; Suhail Zubairy, M [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)
2008-10-28
We investigate the phenomenon of sudden death of entanglement in a bipartite system subjected to dissipative environments with arbitrary initial pure entangled state between two atoms. We find that in a vacuum reservoir the presence of the state where both atoms are in excited states is a necessary condition for the sudden death of entanglement. Otherwise entanglement remains for an infinite time and decays asymptotically with the decay of individual qubits. For pure 2-qubit entangled states in a thermal environment, we observe that the sudden death of entanglement always happens. The sudden death time of the entangled states is related to the temperature of the reservoir and the initial preparation of the entangled states.
Entanglement dynamics of a pure bipartite system in dissipative environments
International Nuclear Information System (INIS)
Tahira, Rabia; Ikram, Manzoor; Azim, Tasnim; Suhail Zubairy, M
2008-01-01
We investigate the phenomenon of sudden death of entanglement in a bipartite system subjected to dissipative environments with arbitrary initial pure entangled state between two atoms. We find that in a vacuum reservoir the presence of the state where both atoms are in excited states is a necessary condition for the sudden death of entanglement. Otherwise entanglement remains for an infinite time and decays asymptotically with the decay of individual qubits. For pure 2-qubit entangled states in a thermal environment, we observe that the sudden death of entanglement always happens. The sudden death time of the entangled states is related to the temperature of the reservoir and the initial preparation of the entangled states.
Influence of parameters entanglement on the quantum algorithms
Directory of Open Access Journals (Sweden)
Alexey V. Kasarkin
2012-05-01
Full Text Available The article we consider the influence of parameters entanglement on the quantum algorithms, in particular influence of partial entanglement for quantum teleportation. The simulation results presented in chart form.
Entanglement transitions induced by large deviations
Bhosale, Udaysinh T.
2017-12-01
The probability of large deviations of the smallest Schmidt eigenvalue for random pure states of bipartite systems, denoted as A and B , is computed analytically using a Coulomb gas method. It is shown that this probability, for large N , goes as exp[-β N2Φ (ζ ) ] , where the parameter β is the Dyson index of the ensemble, ζ is the large deviation parameter, while the rate function Φ (ζ ) is calculated exactly. Corresponding equilibrium Coulomb charge density is derived for its large deviations. Effects of the large deviations of the extreme (largest and smallest) Schmidt eigenvalues on the bipartite entanglement are studied using the von Neumann entropy. Effect of these deviations is also studied on the entanglement between subsystems 1 and 2, obtained by further partitioning the subsystem A , using the properties of the density matrix's partial transpose ρ12Γ. The density of states of ρ12Γ is found to be close to the Wigner's semicircle law with these large deviations. The entanglement properties are captured very well by a simple random matrix model for the partial transpose. The model predicts the entanglement transition across a critical large deviation parameter ζ . Log negativity is used to quantify the entanglement between subsystems 1 and 2. Analytical formulas for it are derived using the simple model. Numerical simulations are in excellent agreement with the analytical results.
Multipartite entangled states in particle mixing
International Nuclear Information System (INIS)
Blasone, M.; Dell'Anno, F.; De Siena, S.; Di Mauro, M.; Illuminati, F.
2008-01-01
In the physics of flavor mixing, the flavor states are given by superpositions of mass eigenstates. By using the occupation number to define a multiqubit space, the flavor states can be interpreted as multipartite mode-entangled states. By exploiting a suitable global measure of entanglement, based on the entropies related to all possible bipartitions of the system, we analyze the correlation properties of such states in the instances of three- and four-flavor mixing. Depending on the mixing parameters, and, in particular, on the values taken by the free phases, responsible for the CP-violation, entanglement concentrates in certain bipartitions. We quantify in detail the amount and the distribution of entanglement in the physically relevant cases of flavor mixing in quark and neutrino systems. By using the wave packet description for localized particles, we use the global measure of entanglement, suitably adapted for the instance of multipartite mixed states, to analyze the decoherence, induced by the free evolution dynamics, on the quantum correlations of stationary neutrino beams. We define a decoherence length as the distance associated with the vanishing of the coherent interference effects among massive neutrino states. We investigate the role of the CP-violating phase in the decoherence process.
[Discussion on quantum entanglement theory and acupuncture].
Wang, Jun; Wu, Bin; Chen, Sheng
2017-11-12
The quantum entanglement is a new discovery of modern physics and has drawn a widely attention in the world. After learning the quantum entanglement, the authors have found that many characteristics of quantum are reflected in TCM, acupuncture theory and clinical practice. For example, the quantum entanglement phenomenon is mutually verified with the holism, yinyang doctrine, the theory of primary, secondary, root and knot in TCM, etc. It can be applied to interpret the clinical situations which is difficult to be explained in clinical practice, such as the instant effect of acupuncture, multi-point stimulation in one disorder and the points with specific effects. On the basis of the discovery above, the quantum entanglement theory achieved the mutual treatment among the relatives in acupuncture clinical practice and the therapeutic effects were significant. The results suggest that the coupling relationship in quantum entanglement presents between the diseases and the acupoints in the direct relative. The authors believe that the discovery in this study contributes to the exploration on the approaches to the acupuncture treatment in clinical practice and enrich the ideas on the disease prevention.
Broadband waveguide quantum memory for entangled photons.
Saglamyurek, Erhan; Sinclair, Neil; Jin, Jeongwan; Slater, Joshua A; Oblak, Daniel; Bussières, Félix; George, Mathew; Ricken, Raimund; Sohler, Wolfgang; Tittel, Wolfgang
2011-01-27
The reversible transfer of quantum states of light into and out of matter constitutes an important building block for future applications of quantum communication: it will allow the synchronization of quantum information, and the construction of quantum repeaters and quantum networks. Much effort has been devoted to the development of such quantum memories, the key property of which is the preservation of entanglement during storage. Here we report the reversible transfer of photon-photon entanglement into entanglement between a photon and a collective atomic excitation in a solid-state device. Towards this end, we employ a thulium-doped lithium niobate waveguide in conjunction with a photon-echo quantum memory protocol, and increase the spectral acceptance from the current maximum of 100 megahertz to 5 gigahertz. We assess the entanglement-preserving nature of our storage device through Bell inequality violations and by comparing the amount of entanglement contained in the detected photon pairs before and after the reversible transfer. These measurements show, within statistical error, a perfect mapping process. Our broadband quantum memory complements the family of robust, integrated lithium niobate devices. It simplifies frequency-matching of light with matter interfaces in advanced applications of quantum communication, bringing fully quantum-enabled networks a step closer.
Quantum entanglement and geometry of determinantal varieties
International Nuclear Information System (INIS)
Chen Hao
2006-01-01
Quantum entanglement was first recognized as a feature of quantum mechanics in the famous paper of Einstein, Podolsky, and Rosen. Recently it has been realized that quantum entanglement is a key ingredient in quantum computation, quantum communication, and quantum cryptography. In this paper, we introduce algebraic sets, which are determinantal varieties in the complex projective spaces or the products of complex projective spaces, for the mixed states on bipartite or multipartite quantum systems as their invariants under local unitary transformations. These invariants are naturally arised from the physical consideration of measuring mixed states by separable pure states. Our construction has applications in the following important topics in quantum information theory: (1) separability criterion, it is proved that the algebraic sets must be a union of the linear subspaces if the mixed states are separable; (2) simulation of Hamiltonians, it is proved that the simulation of semipositive Hamiltonians of the same rank implies the projective isomorphisms of the corresponding algebraic sets; (3) construction of bound entangled mixed states, examples of the entangled mixed states which are invariant under partial transpositions (thus PPT bound entanglement) are constructed systematically from our new separability criterion
Aspects of entanglement entropy for gauge theories
International Nuclear Information System (INIS)
Soni, Ronak M.; Trivedi, Sandip P.
2016-01-01
A definition for the entanglement entropy in a gauge theory was given recently in arXiv:1501.02593. Working on a spatial lattice, it involves embedding the physical state in an extended Hilbert space obtained by taking the tensor product of the Hilbert space of states on each link of the lattice. This extended Hilbert space admits a tensor product decomposition by definition and allows a density matrix and entanglement entropy for the set of links of interest to be defined. Here, we continue the study of this extended Hilbert space definition with particular emphasis on the case of Non-Abelian gauge theories. We extend the electric centre definition of Casini, Huerta and Rosabal to the Non-Abelian case and find that it differs in an important term. We also find that the entanglement entropy does not agree with the maximum number of Bell pairs that can be extracted by the processes of entanglement distillation or dilution, and give protocols which achieve the maximum bound. Finally, we compute the topological entanglement entropy which follows from the extended Hilbert space definition and show that it correctly reproduces the total quantum dimension in a class of Toric code models based on Non-Abelian discrete groups.
Initial conditions and entanglement sudden death
International Nuclear Information System (INIS)
Qian, Xiao-Feng; Eberly, J.H.
2012-01-01
We report results bearing on the behavior of non-local decoherence and its potential for being managed or even controlled. The decoherence process known as entanglement sudden death (ESD) can drive prepared entanglement to zero at the same time that local coherences and fidelity remain non-zero. For a generic ESD-susceptible Bell superposition state, we provide rules restricting the occurrence and timing of ESD, amounting to management tools over a continuous variation of initial conditions. These depend on only three parameters: initial purity, entanglement and excitation. Knowledge or control of initial phases is not needed. -- Highlights: ► We study the possibility of managing disentanglement through initial conditions. ► The initial parameters are the amount of entanglement, excitation, and purity. ► Entanglement sudden death (ESD) free and ESD susceptible phases are identified. ► ESD onset time is also presented in the ESD susceptible phase. ► Our results may guide experiments to prepare ESD free or delayed ESD states.
Applications of quantum entanglement in space
International Nuclear Information System (INIS)
Ursin, R.; Aspelmeyer, M.; Jennewein, T.; Zeilinger, A.
2005-01-01
Full text: Quantum entanglement is at the heart of quantum physics. At the same time it is the basis for novel quantum communication schemes, such as quantum cryptography over long distances. Bringing quantum entanglement to the space environment will open a new range of fundamental physics experiments, and will provide unique opportunities for quantum communication applications over long distances. We proposed tests of quantum communication in space, whereby an entangled photon Source is placed onboard the ISS, and two entangled photons are transmitted via a simultaneous down link and received at two distant ground stations. Furthermore, performing a series of consecutive single down links with separate ground stations will enable a test of establishing quantum cryptography even on a global scale. This Space-QUEST proposal was submitted within ESA's OA-2004 and was rated as 'outstanding' because of both, a novel and imaginative scientific content and for technological applications of quantum cryptography respectively. We intend to explore the possibilities to send, receive and manipulate single entangled photon pairs using telescopes, reflectors and high-power lasers over a distance of some tens of kilometers up to 100 kilometers experimentally. A distance of approx. 10 kilometer would already correspond to one atmospheric equivalent and would thus imply the feasibility of installing a ground to satellite link. We are already collaborating with European Space Agency ESA, to investigate and outline the accommodation of a quantum communication terminal in existing optical terminals for satellite communication. (author)
... often, it could be a sign of a balance problem. Balance problems can make you feel unsteady. You may ... related injuries, such as a hip fracture. Some balance problems are due to problems in the inner ...
Entanglement is not very useful for estimating multiple phases
International Nuclear Information System (INIS)
Ballester, Manuel A.
2004-01-01
The problem of the estimation of multiple phases (or of commuting unitaries) is considered. This is a submodel of the estimation of a completely unknown unitary operation where it has been shown in recent works that there are considerable improvements by using entangled input states and entangled measurements. Here it is shown that, when estimating commuting unitaries, there is practically no advantage in using entangled input states or entangled measurements
Entanglement entropy from surface terms in general relativity
Bhattacharyya, Arpan; Sinha, Aninda
2013-01-01
Entanglement entropy in local quantum field theories is typically ultraviolet divergent due to short distance effects in the neighbourhood of the entangling region. In the context of gauge/gravity duality, we show that surface terms in general relativity are able to capture this entanglement entropy. In particular, we demonstrate that for 1+1 dimensional CFTs at finite temperature whose gravity dual is the BTZ black hole, the Gibbons-Hawking-York term precisely reproduces the entanglement ent...
Nodal-line entanglement entropy: Generalized Widom formula from entanglement Hamiltonians
Pretko, Michael
2017-06-01
A system of fermions forming a Fermi surface exhibits a large degree of quantum entanglement, even in the absence of interactions. In particular, the usual case of a codimension one Fermi surface leads to a logarithmic violation of the area law for entanglement entropy as dictated by the Widom formula. We here generalize this formula to the case of arbitrary codimension, which is of particular interest for nodal lines in three dimensions. We first re-derive the standard Widom formula by calculating an entanglement Hamiltonian for Fermi-surface systems, obtained by repurposing a trick commonly applied to relativistic theories. The entanglement Hamiltonian will take a local form in terms of a low-energy patch theory for the Fermi surface, although it is nonlocal with respect to the microscopic fermions. This entanglement Hamiltonian can then be used to derive the entanglement entropy, yielding a result in agreement with the Widom formula. The method is then generalized to arbitrary codimension. For nodal lines, the area law is obeyed, and the magnitude of the coefficient for a particular partition is nonuniversal. However, the coefficient has a universal dependence on the shape and orientation of the nodal line relative to the partitioning surface. By comparing the relative magnitude of the area law for different partitioning cuts, entanglement entropy can be used as a tool for diagnosing the presence and shape of a nodal line in a ground-state wave function.
Ferrer, Rebecca A; Klein, William M P; Persoskie, Alexander; Avishai-Yitshak, Aya; Sheeran, Paschal
2016-10-01
Although risk perception is a key predictor in health behavior theories, current conceptions of risk comprise only one (deliberative) or two (deliberative vs. affective/experiential) dimensions. This research tested a tripartite model that distinguishes among deliberative, affective, and experiential components of risk perception. In two studies, and in relation to three common diseases (cancer, heart disease, diabetes), we used confirmatory factor analyses to examine the factor structure of the tripartite risk perception (TRIRISK) model and compared the fit of the TRIRISK model to dual-factor and single-factor models. In a third study, we assessed concurrent validity by examining the impact of cancer diagnosis on (a) levels of deliberative, affective, and experiential risk perception, and (b) the strength of relations among risk components, and tested predictive validity by assessing relations with behavioral intentions to prevent cancer. The tripartite factor structure was supported, producing better model fit across diseases (studies 1 and 2). Inter-correlations among the components were significantly smaller among participants who had been diagnosed with cancer, suggesting that affected populations make finer-grained distinctions among risk perceptions (study 3). Moreover, all three risk perception components predicted unique variance in intentions to engage in preventive behavior (study 3). The TRIRISK model offers both a novel conceptualization of health-related risk perceptions, and new measures that enhance predictive validity beyond that engendered by unidimensional and bidimensional models. The present findings have implications for the ways in which risk perceptions are targeted in health behavior change interventions, health communications, and decision aids.
Directory of Open Access Journals (Sweden)
Christine Ritlop
Full Text Available BACKGROUND: Group II introns are RNA enzymes that splice themselves from pre-mRNA transcripts. Most bacterial group II introns harbour an open reading frame (ORF, coding for a protein with reverse transcriptase, maturase and occasionally DNA binding and endonuclease activities. Some ORF-containing group II introns were shown to be mobile retroelements that invade new DNA target sites. From an evolutionary perspective, group II introns are hypothesized to be the ancestors of the spliceosome-dependent nuclear introns and the small nuclear RNAs (snRNAs--U1, U2, U4, U5 and U6 that are important functional elements of the spliceosome machinery. The ability of some group II introns fragmented in two or three pieces to assemble and undergo splicing in trans supports the theory that spliceosomal snRNAs evolved from portions of group II introns. METHODOLOGY/PRINCIPAL FINDINGS: We used a transposon-based genetic screen to explore the ability of the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis to be fragmented into three pieces in vivo. Trans-splicing tripartite variants of Ll.LtrB were selected using a highly efficient and sensitive trans-splicing/conjugation screen. We report that numerous fragmentation sites located throughout Ll.LtrB support tripartite trans-splicing, showing that this intron is remarkably tolerant to fragmentation. CONCLUSIONS/SIGNIFICANCE: This work unveils the great versatility of group II intron fragments to assemble and accurately trans-splice their flanking exons in vivo. The selected introns represent the first evidence of functional tripartite group II introns in bacteria and provide experimental support for the proposed evolutionary relationship between group II introns and snRNAs.
Scaturo, Douglas J
2010-01-01
One problem in conceptualizing the various explanatory factors in psychotherapy has been the lack of a common theoretical language by which to construe these various aspects of treatment. This article integrates a broad range of theoretical contributions within the wider context of a learning theory perspective of essential psychotherapeutic processes. A tripartite model of psychotherapy is outlined that incorporates the contributions of the emotional learning that takes place in the therapeutic alliance, the cognitive aspects of the therapist's technical interventions that are intended to accelerate change, and the behavioral elements of relearning that take place in the patient's world beyond the consulting room.
Panov, A A
2013-01-01
Contrary to members of the suborder Polyphaga; ground beetles have been found to possess tripartite mushroom bodies, which are poorly developed in members of basal taxa and maximally elaborated in evolutionarily advanced groups. Nevertheless, they do not reach the developmental stage, which has been previously found in particular families of beetles. It has been pointed out that anew formation of the Kenyon cells occurs during at least the first months of adult life, and inactive neuroblasts are found even in one-year-old beetles. It has been suggested that there is a relation between the Kenyon cell number and development of the centers of Kenyon cell new-formation.
New Results in Studying of the Collinear Cluster Tripartition of the $^{252}$Cf Nucleus
Pyatkov, Yu V; Trzaska, W; Yamaletdinov, S R; Sokol, E A; Tjukavkin, A N; Aleksandrov, A A; Aleksandrova, I A; Denisov, S V; Krajnov, V P; Khlebnikov, S Yu; Kuzmina, T E; Kuznetsova, E A; Mitrofanov, S V; Penionzhkevich, Yu E; Ryabov, Yu; Tishchenko, V G; Florko, B V
2004-01-01
New experimental results confirming collinear cluster tripartition mode in ^{252}Cf (sf) have been obtained at the modified FOBOS spectrometer. Some events have been detected with the low total mass of fission fragments, which turned out to be by 30-40 % smaller than the initial mass of the fissioning nuclei. The group of these rare events gated by the large neutron multiplicity measured revealed the specific rectangular-shaped structures in the mass distribution of the coincident collinear fragments bounded by the magic mass numbers.
Transformation of bipartite non-maximally entangled states into a ...
Indian Academy of Sciences (India)
[6], quantum cryptography [7] and so on. The preparation of entangled state becomes more and more important in quantum infor- mation processing. One knows that bipartite entanglement can be generated through a variety of solutions [8–10]. A maximally entangled state of two qubits is called a Bell state. For atomic qubits ...
Tractable Quantification of Entanglement for Multipartite Pure States
International Nuclear Information System (INIS)
Nian-Quan, Jiang; Yu-Jian, Wang; Yi-Zhuang, Zheng; Gen-Chang, Cai
2008-01-01
We present kth-order entanglement measure and global kth-order entanglement measure for multipartite pure states, and extend Bennett's measure of partial entropy for bipartite pure states to a multipartite case. These measures are computable and can effectively classify and quantify the entanglement of multipartite pure states. (general)
Drivers and annual estimates of marine wildlife entanglement rates
McIntosh, R.R.; Kirkwood, Roger; Sutherland, D.R.; Dann, Peter
2015-01-01
Methods of calculating wildlife entanglement rates are not standardised between studies and often ignore the influence of observer effort, confounding comparisons. From 1997-2013 we identified 359 entangled Australian fur seals at Seal Rocks, south-eastern Australia. Most entanglement materials
Fast Entanglement Establishment via Local Dynamics for Quantum Repeater Networks
Gyongyosi, Laszlo; Imre, Sandor
Quantum entanglement is a necessity for future quantum communication networks, quantum internet, and long-distance quantum key distribution. The current approaches of entanglement distribution require high-delay entanglement transmission, entanglement swapping to extend the range of entanglement, high-cost entanglement purification, and long-lived quantum memories. We introduce a fundamental protocol for establishing entanglement in quantum communication networks. The proposed scheme does not require entanglement transmission between the nodes, high-cost entanglement swapping, entanglement purification, or long-lived quantum memories. The protocol reliably establishes a maximally entangled system between the remote nodes via dynamics generated by local Hamiltonians. The method eliminates the main drawbacks of current schemes allowing fast entanglement establishment with a minimized delay. Our solution provides a fundamental method for future long-distance quantum key distribution, quantum repeater networks, quantum internet, and quantum-networking protocols. This work was partially supported by the GOP-1.1.1-11-2012-0092 project sponsored by the EU and European Structural Fund, by the Hungarian Scientific Research Fund - OTKA K-112125, and by the COST Action MP1006.
Entanglement between particle partitions in itinerant many-particle states
Haque, M.; Zozulya, O.S.; Schoutens, K.
2009-01-01
We review 'particle-partitioning entanglement' for itinerant many-particle systems. This is defined as the entanglement between two subsets of particles making up the system. We identify generic features and mechanisms of particle entanglement that are valid over whole classes of itinerant quantum
Entanglement generation secure against general attacks
Pirker, Alexander; Dunjko, Vedran; Dür, Wolfgang; Briegel, Hans J.
2017-11-01
We present a security proof for establishing private entanglement by means of recurrence-type entanglement distillation protocols over noisy quantum channels. We consider protocols where the local devices are imperfect, and show that nonetheless a confidential quantum channel can be established, and used to e.g. perform distributed quantum computation in a secure manner. While our results are not fully device independent (which we argue to be unachievable in settings with quantum outputs), our proof holds for arbitrary channel noise and noisy local operations, and even in the case where the eavesdropper learns the noise. Our approach relies on non-trivial properties of distillation protocols which are used in conjunction with de-Finetti and post-selection-type techniques to reduce a general quantum attack in a non-asymptotic scenario to an i.i.d. setting. As a side result, we also provide entanglement distillation protocols for non-i.i.d. input states.
A new approach to entangling neutral atoms.
Energy Technology Data Exchange (ETDEWEB)
Lee, Jongmin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Deutsch, Ivan H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Biedermann, Grant W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-11-01
Our team has developed a new approach to entangling neutral atoms with a Rydberg-dressed interaction. Entangling neutral atoms is an essential key of quantum technologies such as quantum computation, many-body quantum simulation, and high-precision atomic sensors . The demonstrated Rydberg-dressed protocol involves adiabatically imposing a light shift on the ground state by coupling an excited Rydberg state with a tuned laser field. Using this technique, we have demonstrated a strong and tunable dipole - dipole interaction between two individually trapped atoms with energy shifts of order 1 MHz, which has been challenging to achieve in other protocols . During this program, we experimentally demonstrated Bell-state entanglement and the isomorphism to the Jaynes - Cumming model of a Rydberg-dressed two-atom system. Our theoretical calculations of a CPHASE quantum logic gate and arbitrary Dicke state quantum control in this system encourage further work.
Heralded amplification of path entangled quantum states
Monteiro, F.; Verbanis, E.; Caprara Vivoli, V.; Martin, A.; Gisin, N.; Zbinden, H.; Thew, R. T.
2017-06-01
Device-independent quantum key distribution (DI-QKD) represents one of the most fascinating challenges in quantum communication, exploiting concepts of fundamental physics, namely Bell tests of nonlocality, to ensure the security of a communication link. This requires the loophole-free violation of a Bell inequality, which is intrinsically difficult due to losses in fibre optic transmission channels. Heralded photon amplification (HPA) is a teleportation-based protocol that has been proposed as a means to overcome transmission loss for DI-QKD. Here we demonstrate HPA for path entangled states and characterise the entanglement before and after loss by exploiting a recently developed displacement-based detection scheme. We demonstrate that by exploiting HPA we are able to reliably maintain high fidelity entangled states over loss-equivalent distances of more than 50 km.
Holographic entanglement entropy of surface defects
Energy Technology Data Exchange (ETDEWEB)
Gentle, Simon A.; Gutperle, Michael; Marasinou, Chrysostomos [Department of Physics and Astronomy, University of California,Los Angeles, CA 90095 (United States)
2016-04-12
We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in N=4 supersymmetric Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena http://dx.doi.org/10.1007/JHEP05(2014)025 to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussed.
Holographic entanglement entropy of surface defects
Gentle, Simon A.; Gutperle, Michael; Marasinou, Chrysostomos
2016-04-01
We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in N=4 supersymmetric Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena [1] to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussed.
Entangled Networks, Synchronization, and Optimal Network Topology
Donetti, Luca; Hurtado, Pablo I.; Muñoz, Miguel A.
2005-10-01
A new family of graphs, entangled networks, with optimal properties in many respects, is introduced. By definition, their topology is such that it optimizes synchronizability for many dynamical processes. These networks are shown to have an extremely homogeneous structure: degree, node distance, betweenness, and loop distributions are all very narrow. Also, they are characterized by a very interwoven (entangled) structure with short average distances, large loops, and no well-defined community structure. This family of nets exhibits an excellent performance with respect to other flow properties such as robustness against errors and attacks, minimal first-passage time of random walks, efficient communication, etc. These remarkable features convert entangled networks in a useful concept, optimal or almost optimal in many senses, and with plenty of potential applications in computer science or neuroscience.
Spin Entanglement Witness for Quantum Gravity
Bose, Sougato; Mazumdar, Anupam; Morley, Gavin W.; Ulbricht, Hendrik; Toroš, Marko; Paternostro, Mauro; Geraci, Andrew A.; Barker, Peter F.; Kim, M. S.; Milburn, Gerard
2017-12-01
Understanding gravity in the framework of quantum mechanics is one of the great challenges in modern physics. However, the lack of empirical evidence has lead to a debate on whether gravity is a quantum entity. Despite varied proposed probes for quantum gravity, it is fair to say that there are no feasible ideas yet to test its quantum coherent behavior directly in a laboratory experiment. Here, we introduce an idea for such a test based on the principle that two objects cannot be entangled without a quantum mediator. We show that despite the weakness of gravity, the phase evolution induced by the gravitational interaction of two micron size test masses in adjacent matter-wave interferometers can detectably entangle them even when they are placed far apart enough to keep Casimir-Polder forces at bay. We provide a prescription for witnessing this entanglement, which certifies gravity as a quantum coherent mediator, through simple spin correlation measurements.
Comb entanglement in quantum spin chains
International Nuclear Information System (INIS)
Keating, J. P.; Mezzadri, F.; Novaes, M.
2006-01-01
Bipartite entanglement in the ground state of a chain of N quantum spins can be quantified either by computing pairwise concurrence or by dividing the chain into two complementary subsystems. In the latter case the smaller subsystem is usually a single spin or a block of adjacent spins and the entanglement differentiates between critical and noncritical regimes. Here we extend this approach by considering a more general setting: our smaller subsystem S A consists of a comb of L spins, spaced p sites apart. Our results are thus not restricted to a simple area law, but contain nonlocal information, parametrized by the spacing p. For the XX model we calculate the von Neumann entropy analytically when N→∞ and investigate its dependence on L and p. We find that an external magnetic field induces an unexpected length scale for entanglement in this case
Probing renormalization group flows using entanglement entropy
International Nuclear Information System (INIS)
Liu, Hong; Mezei, Márk
2014-01-01
In this paper we continue the study of renormalized entanglement entropy introduced in http://dx.doi.org/10.1007/JHEP04(2013)162. In particular, we investigate its behavior near an IR fixed point using holographic duality. We develop techniques which, for any static holographic geometry, enable us to extract the large radius expansion of the entanglement entropy for a spherical region. We show that for both a sphere and a strip, the approach of the renormalized entanglement entropy to the IR fixed point value contains a contribution that depends on the whole RG trajectory. Such a contribution is dominant, when the leading irrelevant operator is sufficiently irrelevant. For a spherical region such terms can be anticipated from a geometric expansion, while for a strip whether these terms have geometric origins remains to be seen
Holographic entanglement entropy of surface defects
International Nuclear Information System (INIS)
Gentle, Simon A.; Gutperle, Michael; Marasinou, Chrysostomos
2016-01-01
We calculate the holographic entanglement entropy in type IIB supergravity solutions that are dual to half-BPS disorder-type surface defects in N=4 supersymmetric Yang-Mills theory. The entanglement entropy is calculated for a ball-shaped region bisected by a surface defect. Using the bubbling supergravity solutions we also compute the expectation value of the defect operator. Combining our result with the previously-calculated one-point function of the stress tensor in the presence of the defect, we adapt the calculation of Lewkowycz and Maldacena http://dx.doi.org/10.1007/JHEP05(2014)025 to obtain a second expression for the entanglement entropy. Our two expressions agree up to an additional term, whose possible origin and significance is discussed.
Efficient Multiparticle Entanglement via Asymmetric Rydberg Blockade
DEFF Research Database (Denmark)
Saffman, Mark; Mølmer, Klaus
2009-01-01
We present an efficient method for producing N particle entangled states using Rydberg blockade interactions. Optical excitation of Rydberg states that interact weakly, yet have a strong coupling to a second control state is used to achieve state dependent qubit rotations in small ensembles. On t....... On the basis of quantitative calculations, we predict that an entangled quantum superposition state of eight atoms can be produced with a fidelity of 84% in cold Rb atoms.......We present an efficient method for producing N particle entangled states using Rydberg blockade interactions. Optical excitation of Rydberg states that interact weakly, yet have a strong coupling to a second control state is used to achieve state dependent qubit rotations in small ensembles...
Entanglement production in quantum decision making
International Nuclear Information System (INIS)
Yukalov, V. I.; Sornette, D.
2010-01-01
The quantum decision theory introduced recently is formulated as a quantum theory of measurement. It describes prospect states represented by complex vectors of a Hilbert space over a prospect lattice. The prospect operators, acting in this space, form an involutive bijective algebra. A measure is defined for quantifying the entanglement produced by the action of prospect operators. This measure characterizes the level of complexity of prospects involved in decision making. An explicit expression is found for the maximal entanglement produced by the operators of multimode prospects.
Entangled solitons and stochastic Q-bits
International Nuclear Information System (INIS)
Rybakov, Yu.P.; Kamalov, T.F.
2007-01-01
Stochastic realization of the wave function in quantum mechanics with the inclusion of soliton representation of extended particles is discussed. Two-solitons configurations are used for constructing entangled states in generalized quantum mechanics dealing with extended particles, endowed with nontrivial spin S. Entangled solitons construction being introduced in the nonlinear spinor field model, the Einstein-Podolsky-Rosen (EPR) correlation is calculated and shown to coincide with the quantum mechanical one for the 1/2-spin particles. The concept of stochastic q-bits is used for quantum computing modelling
Entanglement of bosonic modes in symmetric graphs
International Nuclear Information System (INIS)
Asoudeh, M.; Karimipour, V.
2005-01-01
The ground and thermal states of a quadratic Hamiltonian representing the interaction of bosonic modes or particles are always Gaussian states. We investigate the entanglement properties of these states for the case where the interactions are represented by harmonic forces acting along the edges of symmetric graphs - i.e., one-, two-, and three-dimensional rectangular lattices, mean-field clusters, and platonic solids. We determine the entanglement of formation (EOF) as a function of the interaction strength, calculate the maximum EOF in each case, and compare these values with the bounds found previously for quadratic Hamiltonians
Continuous variable entanglement by radiation pressure
Energy Technology Data Exchange (ETDEWEB)
Pirandola, Stefano; Mancini, Stefano; Vitali, David; Tombesi, Paolo [INFM, Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy)
2003-08-01
We show that when an intense and quasi-monochromatic laser field is incident on a single vibrating and perfectly reflecting mirror in free space, radiation pressure realizes an effective coupling between a mirror vibrational mode and the first two optical sidebands of the incident field. The two reflected sidebands are in fact entangled by the optomechanical interaction and the resulting continuous variable entanglement proves to be robust against the thermal noise acting on the vibrational mode. If the duration of the incident laser pulse is appropriately chosen, the resulting state of the two sideband modes becomes an exact two-mode squeezed state.
Robust entanglement under multipartite correlated dephasing
Energy Technology Data Exchange (ETDEWEB)
Carnio, Edoardo [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Physikalisches Institut, Albert-Ludwigs-Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg (Germany); Gessner, Manuel [Physikalisches Institut, Albert-Ludwigs-Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg (Germany); Buchleitner, Andreas [Physikalisches Institut, Albert-Ludwigs-Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg (Germany); Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universitaet Freiburg, Albertstrasse 19, 79104 Freiburg (Germany)
2015-07-01
We derive an analytical description for the dephasing process undergone by a system on non-interacting atomic qubits, immersed in a uniform, fluctuating magnetic field. The dephasing process is correlated, as the noise source is common to all the particles and induces an effective atom-atom interaction on them. This correlated nature allows to specify field orientations that preserve any degree of atomic entanglement for all times, and families of states with entanglement properties that are time-invariant for arbitrary field orientations. Our formalism applies to arbitrary spectral distributions of the fluctuations.
Cord entanglement in monoamniotic twin pregnancies
DEFF Research Database (Denmark)
Lyndrup, J; Schouenborg, Lars Øland
1987-01-01
Monoamniotic twin pregnancy involves a heavy risk of fatal umbilical cord entanglement. Two cases are reported. In the first case, both twins were found dead in the 36th week, and the monoamnionicity was recognized at birth. In the second case, the monoamnionicity was discovered during an ultraso...... an ultrasound examination, and cord entanglement was suspected in the 35th week on the basis of a non-stress test (NST) with variable decelerations. Cesarean section was performed and two healthy children were delivered....
Multipartite monogamous relations for entanglement and discord
Ferreira, Jonhy S. S.; Filenga, Daví; Cornelio, Marcio F.; Fanchini, Felipe F.
2018-01-01
The distribution of quantum correlations in multipartite systems plays a significant role in several aspects of quantum information theory. While it is well known that these quantum correlations cannot be freely distributed, the way that they are shared in a multipartite system is an open problem even for a small set of qubits. Based on monogamylike relations between entanglement and discord for n -partite systems, we show how these correlations are distributed in general, determining distinct equalities and inequalities to the quantum discord and the entanglement of formation for arbitrary multipartite pure states.
Quantum entangling power of adiabatically connected Hamiltonians
International Nuclear Information System (INIS)
Hamma, Alioscia; Zanardi, Paolo
2004-01-01
The space of quantum Hamiltonians has a natural partition in classes of operators that can be adiabatically deformed into each other. We consider parametric families of Hamiltonians acting on a bipartite quantum state space. When the different Hamiltonians in the family fall in the same adiabatic class, one can manipulate entanglement by moving through energy eigenstates corresponding to different values of the control parameters. We introduce an associated notion of adiabatic entangling power. This novel measure is analyzed for general dxd quantum systems, and specific two-qubit examples are studied
Witnessing Multipartite Entanglement by Detecting Asymmetry
Directory of Open Access Journals (Sweden)
Davide Girolami
2017-03-01
Full Text Available The characterization of quantum coherence in the context of quantum information theory and its interplay with quantum correlations is currently subject of intense study. Coherence in a Hamiltonian eigenbasis yields asymmetry, the ability of a quantum system to break a dynamical symmetry generated by the Hamiltonian. We here propose an experimental strategy to witness multipartite entanglement in many-body systems by evaluating the asymmetry with respect to an additive Hamiltonian. We test our scheme by simulating asymmetry and entanglement detection in a three-qubit Greenberger–Horne–Zeilinger (GHZ diagonal state.
Separability criteria and method of measurement for entanglement
Mohd, Siti Munirah; Idrus, Bahari; Mukhtar, Muriati
2014-06-01
Quantum computers have the potentials to solve certain problems faster than classical computers. In quantum computer, entanglement is one of the elements beside superposition. Recently, with the advent of quantum information theory, entanglement has become an important resource for Quantum Information and Computation. The purpose of this paper is to discuss the separability criteria and method of measurement for entanglement. This paper is aimed at viewing the method that has been proposed in previous works in bipartite and multipartite entanglement. The outcome of this paper is to classify the different method that used to measure entanglement for bipartite and multipartite cases including the advantage and disadvantage of each method.
Separability criteria and method of measurement for entanglement
Energy Technology Data Exchange (ETDEWEB)
Mohd, Siti Munirah; Idrus, Bahari; Mukhtar, Muriati [Industrial Computing Research Group, Faculty of Information Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)
2014-06-19
Quantum computers have the potentials to solve certain problems faster than classical computers. In quantum computer, entanglement is one of the elements beside superposition. Recently, with the advent of quantum information theory, entanglement has become an important resource for Quantum Information and Computation. The purpose of this paper is to discuss the separability criteria and method of measurement for entanglement. This paper is aimed at viewing the method that has been proposed in previous works in bipartite and multipartite entanglement. The outcome of this paper is to classify the different method that used to measure entanglement for bipartite and multipartite cases including the advantage and disadvantage of each method.
Separability criteria and method of measurement for entanglement
International Nuclear Information System (INIS)
Mohd, Siti Munirah; Idrus, Bahari; Mukhtar, Muriati
2014-01-01
Quantum computers have the potentials to solve certain problems faster than classical computers. In quantum computer, entanglement is one of the elements beside superposition. Recently, with the advent of quantum information theory, entanglement has become an important resource for Quantum Information and Computation. The purpose of this paper is to discuss the separability criteria and method of measurement for entanglement. This paper is aimed at viewing the method that has been proposed in previous works in bipartite and multipartite entanglement. The outcome of this paper is to classify the different method that used to measure entanglement for bipartite and multipartite cases including the advantage and disadvantage of each method
Sudden entanglement death, and ways to avoid it
International Nuclear Information System (INIS)
Eberly, J.H.; Ting Yu
2005-01-01
We report that non-communicating but entangled qubit pairs are almost universally liable to sudden entanglement death. In the presence of minor and purely local environmental noises their mixed-state entanglement may abruptly become zero long before the noises are able to destroy the local qubit coherence. Despite the inability of unitary transformations to alter entanglement, for example of Werner states, unitary transformations have been found to delay or defeat the sudden death event. These results upset the conventional understanding that entanglement lifetime can be estimated from qubit lifetime. This is not even approximately or qualitatively true. (author)
How a single photon can mediate entanglement between two others
Energy Technology Data Exchange (ETDEWEB)
Lima Bernardo, Bertúlio de, E-mail: bertulio.fisica@gmail.com
2016-10-15
We describe a novel quantum information protocol, which probabilistically entangles two distant photons that have never interacted. Different from the entanglement swapping protocol, which requires two pairs of maximally entangled photons as the input states, as well as a Bell-state measurement (BSM), the present scheme only requires three photons: two to be entangled and another to mediate the correlation, and no BSM, in a process that we call “entanglement mediation”. Furthermore, in analyzing the paths of the photons in our arrangement, we conclude that one of them, the mediator, exchanges information with the two others simultaneously, which seems to be a new quantum-mechanical feature.
Tripartite conferences on radiation protection: Canada, United Kingdom, United States (1949-1953)
International Nuclear Information System (INIS)
Taylor, L.S.
1984-08-01
As a result of largely informal contacts between scientists from the United States, Canada, and United Kingdom, it became evident to their governments that, to insure compatible protection practices, closer technical cooperation must be established. This led to a two-day conference between representatives of the three governments at Chalk River, Ontario in September 1949; it was the first of what became known as the Tripartite Conferences. The initial talks led quickly to agreement on the new NCRP proposals for a basic permissible dose for the exposure of workers to external sources of radiation. A second meeting in Harwell, England, during the summer of 1950 reached tentative agreement on the outstanding problems. The third and last Tripartite Conference took place at Harriman, New York, in early spring 1953. This meeting produced the final recommendations, insofar as they involved agreements between the three countries, for new protection standards. Questions regarding the proceedings of the conferences and interpretations of their findings have arisen over the succeeding years; even as recently as 1983. Continued interest and consequent inquiries emphasized the desirability of providing more permanent documentation of those very important conferences. This author, a member of the United States delegation to all three conferences, came into possession of most of the working papers and final reports, hence he has felt the obligation to assemble this material for both technical and historical reference. This report compromises mainly of a brief discussion of the conferences themselves, with some background information leading up to their organization
Leveraging tagging and rating for recommendation: RMF meets weighted diffusion on tripartite graphs
Li, Jianguo; Tang, Yong; Chen, Jiemin
2017-10-01
Recommender systems (RSs) have been a widely exploited approach to solving the information overload problem. However, the performance is still limited due to the extreme sparsity of the rating data. With the popularity of Web 2.0, the social tagging system provides more external information to improve recommendation accuracy. Although some existing approaches combine the matrix factorization models with the tag co-occurrence and context of tags, they neglect the issue of tag sparsity that would also result in inaccurate recommendations. Consequently, in this paper, we propose a novel hybrid collaborative filtering model named WUDiff_RMF, which improves regularized matrix factorization (RMF) model by integrating Weighted User-Diffusion-based CF algorithm(WUDiff) that obtains the information of similar users from the weighted tripartite user-item-tag graph. This model aims to capture the degree correlation of the user-item-tag tripartite network to enhance the performance of recommendation. Experiments conducted on four real-world datasets demonstrate that our approach significantly performs better than already widely used methods in the accuracy of recommendation. Moreover, results show that WUDiff_RMF can alleviate the data sparsity, especially in the circumstance that users have made few ratings and few tags.
A unique tripartite collision tumor of the esophagus: A case report.
Schizas, Dimitrios; Michalinos, Adamantios; Alexandrou, Paraskevi; Moris, Demetrios; Baliou, Evangelia; Tsilimigras, Diamantis; Throupis, Theodore; Liakakos, Theodore
2017-12-01
We report a unique case of a tripartite esophageal collision tumor consisting of three separate histologic types. Therapeutic dilemmas on the proper treatment of those rare neoplasms remain unanswered considering both proper surgical therapy and adjuvant therapy. In this paper, we report a unique case of a patient with a tripartite esophageal collision tumor consisting of a small cell carcinoma, an adenocarcinoma of medium differentiation and a signet ring cell carcinoma. Diagnosis is difficult as clinical presentation of the patient was undistinguishable from other, commoner tumor types. The patient's diagnostic and therapeutic course along with available data on the collisions tumor's biological behavior and treatment are briefly discussed. Esophagectomy is the best treatment options for these patients. Unique nature of this tumor demands aggresive oncologic treatment. Collision tumors are rare neoplasms consisting of distinct cell populations developing in juxtaposition to one another without any areas of intermingling. Various cell types can be found. However, collision neoplasms of the esophagus combining adenomatous and neuroendocrine components are exceedingly rare, with only 5 cases described to date in the literature. Given their rarity, limited information is available on their tumorigenesis, biological behavior and clinical course. In general, these tumors are aggressive neoplasms and significantly affect patient treatment and prognosis.
The role of the tripartite glutamatergic synapse in the pathophysiology of Alzheimer's disease.
Rudy, Carolyn C; Hunsberger, Holly C; Weitzner, Daniel S; Reed, Miranda N
2015-03-01
Alzheimer's disease (AD) is the most common form of dementia in individuals over 65 years of age and is characterized by accumulation of beta-amyloid (Aβ) and tau. Both Aβ and tau alter synaptic plasticity, leading to synapse loss, neural network dysfunction, and eventually neuron loss. However, the exact mechanism by which these proteins cause neurodegeneration is still not clear. A growing body of evidence suggests perturbations in the glutamatergic tripartite synapse, comprised of a presynaptic terminal, a postsynaptic spine, and an astrocytic process, may underlie the pathogenic mechanisms of AD. Glutamate is the primary excitatory neurotransmitter in the brain and plays an important role in learning and memory, but alterations in glutamatergic signaling can lead to excitotoxicity. This review discusses the ways in which both beta-amyloid (Aβ) and tau act alone and in concert to perturb synaptic functioning of the tripartite synapse, including alterations in glutamate release, astrocytic uptake, and receptor signaling. Particular emphasis is given to the role of N-methyl-D-aspartate (NMDA) as a possible convergence point for Aβ and tau toxicity.
Mining Symptom-Herb Patterns from Patient Records Using Tripartite Graph.
Chen, Jinpeng; Poon, Josiah; Poon, Simon K; Xu, Ling; Sze, Daniel M Y
2015-01-01
Unlike the western medical approach where a drug is prescribed against specific symptoms of patients, traditional Chinese medicine (TCM) treatment has a unique step, which is called syndrome differentiation (SD). It is argued that SD is considered as patient classification because prior to the selection of the most appropriate formula from a set of relevant formulae for personalization, a practitioner has to label a patient belonging to a particular class (syndrome) first. Hence, to detect the patterns between herbs and symptoms via syndrome is a challenging problem; finding these patterns can help prepare a prescription that contributes to the efficacy of a treatment. In order to highlight this unique triangular relationship of symptom, syndrome, and herb, we propose a novel three-step mining approach. It first starts with the construction of a heterogeneous tripartite information network, which carries richer information. The second step is to systematically extract path-based topological features from this tripartite network. Finally, an unsupervised method is used to learn the best parameters associated with different features in deciding the symptom-herb relationships. Experiments have been carried out on four real-world patient records (Insomnia, Diabetes, Infertility, and Tourette syndrome) with comprehensive measurements. Interesting and insightful experimental results are noted and discussed.
Entangling two transportable neutral atoms via local spin exchange.
Kaufman, A M; Lester, B J; Foss-Feig, M; Wall, M L; Rey, A M; Regal, C A
2015-11-12
To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.
Entanglement of purification: from spin chains to holography
Nguyen, Phuc; Devakul, Trithep; Halbasch, Matthew G.; Zaletel, Michael P.; Swingle, Brian
2018-01-01
Purification is a powerful technique in quantum physics whereby a mixed quantum state is extended to a pure state on a larger system. This process is not unique, and in systems composed of many degrees of freedom, one natural purification is the one with minimal entanglement. Here we study the entropy of the minimally entangled purification, called the entanglement of purification, in three model systems: an Ising spin chain, conformal field theories holographically dual to Einstein gravity, and random stabilizer tensor networks. We conjecture values for the entanglement of purification in all these models, and we support our conjectures with a variety of numerical and analytical results. We find that such minimally entangled purifications have a number of applications, from enhancing entanglement-based tensor network methods for describing mixed states to elucidating novel aspects of the emergence of geometry from entanglement in the AdS/CFT correspondence.
Remote information concentration and multipartite entanglement in multilevel systems
Energy Technology Data Exchange (ETDEWEB)
Wang Xinwen; Zhang Dengyu; Tang Shiqing; Xie Lijun [Department of Physics and Electronic Information, Hengyang Normal University, Hengyang 421008 (China); Yang Guojian [Department of Physics, Beijing Normal University, Beijing 100875 (China)
2011-10-15
Remote information concentration (RIC) in d-level systems (qudits) is studied. It is shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations. The entangled channel can be different types of genuine multipartite pure entangled states which are inequivalent under local operations and classical communication. The entangled channel can also be a mixed entangled state, even a bound entangled state which has a similar form to the Smolin state, but has different features from the Smolin state. A common feature of all these pure and mixed entangled states is found; i.e., they have d{sup 2} common commuting stabilizers. The differences of qudit-RIC and qubit-RIC (d=2) are also analyzed.
Silicon photonic processor of two-qubit entangling quantum logic
Santagati, R.; Silverstone, J. W.; Strain, M. J.; Sorel, M.; Miki, S.; Yamashita, T.; Fujiwara, M.; Sasaki, M.; Terai, H.; Tanner, M. G.; Natarajan, C. M.; Hadfield, R. H.; O'Brien, J. L.; Thompson, M. G.
2017-11-01
Entanglement is a fundamental property of quantum mechanics, and is a primary resource in quantum information systems. Its manipulation remains a central challenge in the development of quantum technology. In this work, we demonstrate a device which can generate, manipulate, and analyse two-qubit entangled states, using miniature and mass-manufacturable silicon photonics. By combining four photon-pair sources with a reconfigurable six-mode interferometer, embedding a switchable entangling gate, we generate two-qubit entangled states, manipulate their entanglement, and analyse them, all in the same silicon chip. Using quantum state tomography, we show how our source can produce a range of entangled and separable states, and how our switchable controlled-Z gate operates on them, entangling them or making them separable depending on its configuration.
Quantum entanglement in two-electron atomic models
Energy Technology Data Exchange (ETDEWEB)
Manzano, D; Plastino, A R; Dehesa, J S [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, Granada E-18071 (Spain); Koga, T, E-mail: arplastino@ugr.e [Applied Chemistry Research Unit, Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido 050-8585 (Japan)
2010-07-09
We explore the main entanglement properties exhibited by the eigenfunctions of two exactly soluble two-electron models, the Crandall atom and the Hooke atom, and compare them with the entanglement features of helium-like systems. We compute the amount of entanglement associated with the wavefunctions corresponding to the fundamental and first few excited states of these models. We investigate the dependence of the entanglement on the parameters of the models and on the quantum numbers of the eigenstates. It is found that the amount of entanglement of the system tends to increase with energy in both models. In addition, we study the entanglement of a few states of helium-like systems, which we compute using high-quality Kinoshita-like eigenfunctions. The dependence of the entanglement of helium-like atoms on the nuclear charge and on energy is found to be consistent with the trends observed in the previous two model systems.
Entanglement in non-Hermitian quantum theory
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics; Volume 73; Issue 3. Entanglement in non-Hermitian quantum theory. Arun K Pati ... This arises due to the linear superposition principle and the tensor product structure of the Hilbert space when we deal with multiparticle systems. In this paper, we will introduce the notion of ...
Entanglement production in quantized chaotic systems
Indian Academy of Sciences (India)
we have also considered the effect of different coupling strengths on entanglement production. Most of the earlier studies have considered the effect of chaos on en- tanglement production for the case of initially pure state of the overall system. A basic assumption of these studies is that the initial state of the overall system is.
Entanglement versus negative domains of Wigner functions
DEFF Research Database (Denmark)
Dahl, Jens Peder; Mack, H.; Wolf, A.
2006-01-01
We show that s waves, that is wave functions that only depend on a hyperradius, are entangled if and only if the corresponding Wigner functions exhibit negative domains. We illustrate this feature using a special class of s waves which allows us to perform the calculations analytically. This clas...
Quantum entanglement helps in improving economic efficiency
International Nuclear Information System (INIS)
Du Jiangfeng; Ju Chenyong; Li Hui
2005-01-01
We propose an economic regulation approach based on quantum game theory for the government to reduce the abuses of oligopolistic competition. Theoretical analysis shows that this approach can help government improve the economic efficiency of the oligopolistic market, and help prevent monopoly due to incorrect information. These advantages are completely attributed to the quantum entanglement, a unique quantum mechanical character
Entanglement and the power of one qubit
International Nuclear Information System (INIS)
Datta, Animesh; Flammia, Steven T.; Caves, Carlton M.
2005-01-01
The 'power of one qubit' refers to a computational model that has access to only one pure bit of quantum information, along with n qubits in the totally mixed state. This model, though not as powerful as a pure-state quantum computer, is capable of performing some computational tasks exponentially faster than any known classical algorithm. One such task is to estimate with fixed accuracy the normalized trace of a unitary operator that can be implemented efficiently in a quantum circuit. We show that circuits of this type generally lead to entangled states, and we investigate the amount of entanglement possible in such circuits, as measured by the multiplicative negativity. We show that the multiplicative negativity is bounded by a constant, independent of n, for all bipartite divisions of the n+1 qubits, and so becomes, when n is large, a vanishingly small fraction of the maximum possible multiplicative negativity for roughly equal divisions. This suggests that the global nature of entanglement is a more important resource for quantum computation than the magnitude of the entanglement
Entanglement production in quantized chaotic systems
Indian Academy of Sciences (India)
eigenangles of UT , is Wigner distributed which is typical of any quantized chaotic systems [7,8]. Therefore, it is quite reasonable to expect that the statistical bound on entanglement can be estimated by random matrix modeling. The two RDMs, corresponding to two subsystems, have the structures A†A and AA†, where A is.
Entanglement spectroscopy on a quantum computer
Johri, Sonika; Steiger, Damian S.; Troyer, Matthias
2017-11-01
We present a quantum algorithm to compute the entanglement spectrum of arbitrary quantum states. The interesting universal part of the entanglement spectrum is typically contained in the largest eigenvalues of the density matrix which can be obtained from the lower Renyi entropies through the Newton-Girard method. Obtaining the p largest eigenvalues (λ1>λ2⋯>λp ) requires a parallel circuit depth of O [p (λ1/λp) p] and O [p log(N )] qubits where up to p copies of the quantum state defined on a Hilbert space of size N are needed as the input. We validate this procedure for the entanglement spectrum of the topologically ordered Laughlin wave function corresponding to the quantum Hall state at filling factor ν =1 /3 . Our scaling analysis exposes the tradeoffs between time and number of qubits for obtaining the entanglement spectrum in the thermodynamic limit using finite-size digital quantum computers. We also illustrate the utility of the second Renyi entropy in predicting a topological phase transition and in extracting the localization length in a many-body localized system.
Black Hole Entanglement and Quantum Error Correction
Verlinde, E.; Verlinde, H.
2013-01-01
It was recently argued in [1] that black hole complementarity strains the basic rules of quantum information theory, such as monogamy of entanglement. Motivated by this argument, we develop a practical framework for describing black hole evaporation via unitary time evolution, based on a holographic
Higher spin entanglement entropy from CFT
International Nuclear Information System (INIS)
Datta, Shouvik; David, Justin R.; Ferlaino, Michael; Kumar, S. Prem
2014-01-01
We consider free fermion and free boson CFTs in two dimensions, deformed by a chemical potential μ for the spin-three current. For the CFT on the infinite spatial line, we calculate the finite temperature entanglement entropy of a single interval perturbatively to second order in μ in each of the theories. We find that the result in each case is given by the same non-trivial function of temperature and interval length. Remarkably, we further obtain the same formula using a recent Wilson line proposal for the holographic entanglement entropy, in holomorphically factorized form, associated to the spin-three black hole in SL(3,ℝ)×SL(3,ℝ) Chern-Simons theory. Our result suggests that the order μ 2 correction to the entanglement entropy may be universal for W-algebra CFTs with spin-three chemical potential, and constitutes a check of the holographic entanglement entropy proposal for higher spin theories of gravity in AdS 3 .
Microscopic wormholes and the geometry of entanglement
Energy Technology Data Exchange (ETDEWEB)
Lobo, Francisco S.N. [Centro de Astronomia e Astrofisica da Universidade de Lisboa, Lisbon (Portugal); Olmo, Gonzalo J. [Centro Mixto Universidad de Valencia-CSIC, Universidad de Valencia, Departamento de Fisica Teorica y IFIC, Valencia (Spain); Rubiera-Garcia, D. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba (Brazil)
2014-06-15
It has recently been suggested that Einstein-Rosen (ER) bridges can be interpreted as maximally entangled states of two black holes that form a complex Einstein-Podolsky-Rosen (EPR) pair. This relationship has been dubbed as the ER = EPR correlation. In this work, we consider the latter conjecture in the context of quadratic Palatini theory. An important result, which stems from the underlying assumptions as regards the geometry on which the theory is constructed, is the fact that all the charged solutions of the quadratic Palatini theory possess a wormhole structure. Our results show that spacetime may have a foam like microstructure with wormholes generated by fluctuations of the quantum vacuum. This involves the spontaneous creation/annihilation of entangled particle-antiparticle pairs, existing in a maximally entangled state connected by a nontraversable wormhole. Since the particles are produced from the vacuum and therefore exist in a singlet state, they are necessarily entangled with one another. This gives further support to the ER = EPR claim. (orig.)
Probabilistic entanglement transformation by local overlap modification
Energy Technology Data Exchange (ETDEWEB)
Roa, Luis, E-mail: lroa@udec.cl [Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); Ladrón de Guevara, M.L. [Departamento de Física, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Jara-Figueroa, C. [Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción (Chile); González-Céspedes, E. [Departamento de Física, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile)
2013-01-03
We present a strategy to transform the entanglement of two qubits under a local unitary-reduction process. Such procedure modifies the overlap between two pure states involved in a specific representation of the initial bipartite pure state. We study the scopes of the proposal and present a concrete scheme of experimental realization by using cold ions confined in linear Paul traps.
Quantum information and entanglement transfer for qutrits
International Nuclear Information System (INIS)
Delgado, A.; Saavedra, C.; Retamal, J.C.
2007-01-01
We propose a scheme for the transfer of quantum information among distant qutrits. We apply this scheme to the distribution of entanglement of qutrits states among distant nodes and to the generation of multipartite antisymmetric states. We also discuss applications to quantum secret sharing
Quantum entanglement and teleportation using statistical correlations
Indian Academy of Sciences (India)
Administrator
Dedicated to the memory of the late Professor S K Rangarajan. *For correspondence. Quantum entanglement and teleportation using statistical correlations. †. ATUL KUMAR and MANGALA SUNDER KRISHNAN*. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 e-mail: mangal@iitm.ac.in.
Remote quantum entanglement between two micromechanical oscillators.
Riedinger, Ralf; Wallucks, Andreas; Marinković, Igor; Löschnauer, Clemens; Aspelmeyer, Markus; Hong, Sungkun; Gröblacher, Simon
2018-04-01
Entanglement, an essential feature of quantum theory that allows for inseparable quantum correlations to be shared between distant parties, is a crucial resource for quantum networks 1 . Of particular importance is the ability to distribute entanglement between remote objects that can also serve as quantum memories. This has been previously realized using systems such as warm 2,3 and cold atomic vapours 4,5 , individual atoms 6 and ions 7,8 , and defects in solid-state systems 9-11 . Practical communication applications require a combination of several advantageous features, such as a particular operating wavelength, high bandwidth and long memory lifetimes. Here we introduce a purely micromachined solid-state platform in the form of chip-based optomechanical resonators made of nanostructured silicon beams. We create and demonstrate entanglement between two micromechanical oscillators across two chips that are separated by 20 centimetres . The entangled quantum state is distributed by an optical field at a designed wavelength near 1,550 nanometres. Therefore, our system can be directly incorporated in a realistic fibre-optic quantum network operating in the conventional optical telecommunication band. Our results are an important step towards the development of large-area quantum networks based on silicon photonics.
Stress Relaxation in Entangled Polymer Melts
DEFF Research Database (Denmark)
Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf
2010-01-01
We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t...
Holographic entanglement entropy and gravitational anomalies
Castro, A.; Detournay, S.; Iqbal, N.; Perlmutter, E.
2014-01-01
We study entanglement entropy in two-dimensional conformal field theories with a gravitational anomaly. In theories with gravity duals, this anomaly is holographically represented by a gravitational Chern-Simons term in the bulk action. We show that the anomaly broadens the Ryu-Takayanagi minimal
Cord entanglement in monoamniotic twin pregnancies
DEFF Research Database (Denmark)
Lyndrup, J; Schouenborg, Lars Øland
1987-01-01
Monoamniotic twin pregnancy involves a heavy risk of fatal umbilical cord entanglement. Two cases are reported. In the first case, both twins were found dead in the 36th week, and the monoamnionicity was recognized at birth. In the second case, the monoamnionicity was discovered during...
Entanglement entropy in free quantum field theory
International Nuclear Information System (INIS)
Casini, H; Huerta, M
2009-01-01
In this paper, we first introduce the general methods to calculate the entanglement entropy for free fields, within the Euclidean and the real-time formalisms. Then, we describe the particular examples which have been worked out explicitly in two, three and more dimensions.
Entanglement production in quantized chaotic systems
Indian Academy of Sciences (India)
Quantum chaos is a subject whose major goal is to identify and to investigate different quantum signatures of classical chaos. Here we study entanglement production in coupled chaotic systems as a possible quantum indicator of classical chaos. We use coupled kicked tops as a model for our extensive numerical studies.
Entanglement in Solid-State Nanostructures
Bodoky, F.
2009-01-01
The goal of this thesis is to investigate theoretically the generation and behaviour of multipartite entanglement for solid-state nanosystems, in particular electron spin quantum bits (so-called 'qubits') in quantum dots. A quantum dot is a tiny potential well where a single electron can be trapped.
Dissipative preparation of entanglement in optical cavities
DEFF Research Database (Denmark)
Kastoryano, Michael James; Reiter, Florentin; Sørensen, Anders Søndberg
2011-01-01
We propose a novel scheme for the preparation of a maximally entangled state of two atoms in an optical cavity. Starting from an arbitrary initial state, a singlet state is prepared as the unique fixed point of a dissipative quantum dynamical process. In our scheme, cavity decay is no longer...
Testing nonlocal realism with entangled coherent states
International Nuclear Information System (INIS)
Paternostro, Mauro; Jeong, Hyunseok
2010-01-01
We investigate the violation of nonlocal realism using entangled coherent states (ECSs) under nonlinear operations and homodyne measurements. We address recently proposed Leggett-type inequalities, including a class of optimized incompatibility inequalities proposed by Branciard et al. [Nature Phys. 4, 681 (2008)], and thoroughly assess the effects of detection inefficiency.
Quantum entanglement and teleportation using statistical correlations
Indian Academy of Sciences (India)
Administrator
Abstract. A study of quantum teleportation using two and three-particle correlated density matrix is presented. A criterion based on standard quantum statistical correlations employed in the many-body virial expansion is used to determine the extent of entanglement for a 2N-particle system. A relation between the probability ...
Evolution and Survival of Quantum Entanglement
2015-05-06
violation procedure applicable to continuous variable states. Another connection to experimental work (done by the Rio de Janeiro team of Davidovich and...interpretation of numerical calculations. Expressions for individual collapse and revival signals of both population and entanglement were obtained
Entangled exciton states in quantum dot molecules
Bayer, Manfred
2002-03-01
Currently there is strong interest in quantum information processing(See, for example, The Physics of Quantum Information, eds. D. Bouwmeester, A. Ekert and A. Zeilinger (Springer, Berlin, 2000).) in a solid state environment. Many approaches mimic atomic physics concepts in which semiconductor quantum dots are implemented as artificial atoms. An essential building block of a quantum processor is a gate which entangles the states of two quantum bits. Recently a pair of vertically aligned quantum dots has been suggested as optically driven quantum gate(P. Hawrylak, S. Fafard, and Z. R. Wasilewski, Cond. Matter News 7, 16 (1999).)(M. Bayer, P. Hawrylak, K. Hinzer, S. Fafard, M. Korkusinski, Z.R. Wasilewski, O. Stern, and A. Forchel, Science 291, 451 (2001).): The quantum bits are individual carriers either on dot zero or dot one. The different dot indices play the same role as a "spin", therefore we call them "isospin". Quantum mechanical tunneling between the dots rotates the isospin and leads to superposition of these states. The quantum gate is built when two different particles, an electron and a hole, are created optically. The two particles form entangled isospin states. Here we present spectrocsopic studies of single self-assembled InAs/GaAs quantum dot molecules that support the feasibility of this proposal. The evolution of the excitonic recombination spectrum with varying separation between the dots allows us to demonstrate coherent tunneling of carriers across the separating barrier and the formation of entangled exciton states: Due to the coupling between the dots the exciton states show a splitting that increases with decreasing barrier width. For barrier widths below 5 nm it exceeds the thermal energy at room temperature. For a given barrier width, we find only small variations of the tunneling induced splitting demonstrating a good homogeneity within a molecule ensemble. The entanglement may be controlled by application of electromagnetic field. For
Entanglement consumption of instantaneous nonlocal quantum measurements
International Nuclear Information System (INIS)
Clark, S R; Jaksch, D; Connor, A J; Popescu, S
2010-01-01
Relativistic causality has dramatic consequences on the measurability of nonlocal variables and poses the fundamental question of whether it is physically meaningful to speak about the value of nonlocal variables at a particular time. Recent work has shown that by weakening the role of the measurement in preparing eigenstates of the variable, it is in fact possible to measure all nonlocal observables instantaneously by exploiting entanglement. However, for these measurement schemes to succeed with certainty, an infinite amount of entanglement must be distributed initially and all this entanglement is necessarily consumed. In this work, we sharpen the characterization of instantaneous nonlocal measurements by explicitly devising schemes in which only a finite amount of the initially distributed entanglement is ever utilized. This enables us to determine an upper bound to the average consumption for the most general cases of nonlocal measurements. This includes the tasks of state verification, where the measurement verifies if the system is in a given state, and verification measurements of a general set of eigenstates of an observable. Despite its finiteness, the growth of entanglement consumption is found to display an extremely unfavourable exponential of an exponential scaling with either the number of qubits needed to contain the Schmidt rank of the target state or the total number of qubits in the system for an operator measurement. This scaling is seen to be a consequence of the combination of the generic exponential scaling of unitary decompositions combined with the highly recursive structure of our scheme required to overcome the no-signalling constraint of relativistic causality.
Wegener, Charlotte; Tanggaard, Lene
2013-01-01
This article investigates the innovation concept in two key welfare areas where the demands for innovation are substantial, namely vocational education and elder care. On the basis of ethnographic fieldwork and interviews on the collaboration between an educational institution and elder care services, the article develops a tripartite empirical…
Strupp, Hans H.; Hadley, Suzanne W.
1978-01-01
Society, the patient, and the mental health professional each define ideal mental health from a different vantage point. A truly adequate picture of an individual's mental health is possible only if these three facets of a tripartite model of functioning are evaluated and integrated. (Author/SJL)
Dalton, B. J.; Goold, J.; Garraway, B. M.; Reid, M. D.
2017-02-01
These two accompanying papers are concerned with entanglement for systems of identical massive bosons and the relationship to spin squeezing and other quantum correlation effects. The main focus is on two mode entanglement, but multi-mode entanglement is also considered. The bosons may be atoms or molecules as in cold quantum gases. The previous paper I dealt with the general features of quantum entanglement and its specific definition in the case of systems of identical bosons. Entanglement is a property shared between two (or more) quantum sub-systems. In defining entanglement for systems of identical massive particles, it was concluded that the single particle states or modes are the most appropriate choice for sub-systems that are distinguishable, that the general quantum states must comply both with the symmetrization principle and the super-selection rules (SSR) that forbid quantum superpositions of states with differing total particle number (global SSR compliance). Further, it was concluded that (in the separable states) quantum superpositions of sub-system states with differing sub-system particle number (local SSR compliance) also do not occur. The present paper II determines possible tests for entanglement based on the treatment of entanglement set out in paper I. Several inequalities involving variances and mean values of operators have been previously proposed as tests for entanglement between two sub-systems. These inequalities generally involve mode annihilation and creation operators and include the inequalities that define spin squeezing. In this paper, spin squeezing criteria for two mode systems are examined, and spin squeezing is also considered for principle spin operator components where the covariance matrix is diagonal. The proof, which is based on our SSR compliant approach shows that the presence of spin squeezing in any one of the spin components requires entanglement of the relevant pair of modes. A simple Bloch vector test for
... Past Issues Special Section: Focus on Communication Balancing Acts Past Issues / Fall 2008 Table of Contents For ... scientific research on hearing, balance, smell, taste, voice, speech, and language—common elements in how we perceive ...
Jackson, Ben; Dimmock, James A; Taylor, Ian M; Hagger, Martin S
2012-11-01
Within supervised rehabilitation programs, Lent and Lopez (2002) proposed that clients and therapists develop a "tripartite" network of efficacy beliefs, comprising their confidence in their own ability, their confidence in the other person's ability, and their estimation of the other person's confidence in them. To date, researchers have yet to explore the potential relational outcomes associated with this model in rehabilitation contexts. In Study 1, we recruited 170 exercise clients (Mage = 63.73, SD = 6.46) who were enrolled in a one-to-one aerobic exercise program with a therapist as a result of a lower-limb musculoskeletal disorder. Clients reported their tripartite efficacy beliefs and perceptions about the quality of their relationship with their therapist, and respective therapists rated each client's engagement in his or her exercise program. In Study 2, we recruited 68 separate exercise clients (Mage = 65.93, SD = 5.80) along with their therapists (n = 68, Mage = 31.89, SD = 4.79) from the same program, to examine whether individuals' efficacy perceptions were related to their own and/or the other person's relationship quality perceptions. In Study 1, each of the tripartite efficacy constructs displayed positive direct effects with respect to clients' relationship quality appraisals, as well as indirect effects in relation to program engagement. Actor-partner interdependence modeling in Study 2 demonstrated that clients and therapists reported more adaptive relationship perceptions when they themselves held strong tripartite efficacy beliefs (i.e., actor effects), and that clients viewed their relationship in a more positive light when their therapist was highly confident in the client's ability (i.e., partner effect). These findings underscore the potential utility of the tripartite efficacy framework in relation to motivational and relational processes within supervised exercise programs. PsycINFO Database Record (c) 2012 APA, all rights reserved
Towards an Urbanism of Entanglement
DEFF Research Database (Denmark)
Tietjen, Anne
2009-01-01
This PhD thesis examines the concept of the urban site in relation to polarised spatial development in Denmark. At the core of this research project is a design based investigation that tests site based approaches in two study areas in East and North Jutland. Together with - and directly related...... to the design study - an investigation of the theoretical and methodological foundations of contemporary urban design practice is undertaken. The phenomenon of polarisation is a pertinent starting point to identify challenges and potentials of contemporary urban design. Polarised spatial development reflects...... of spatial equality throughout Denmark to an ideal of balanced development. This shift dates back to the 1980s but has gained new topicality in light of increased spatial inequality. Current Danish spatial policy targets the two large city regions around Copenhagen and in East Jutland as the engines...
Radiation protection and radiation safety: CERN and its host states to sign a tripartite agreement.
2010-01-01
On 15 November CERN and its Host States will sign a tripartite agreement that replaces the existing bilateral agreements in matters of radiation protection and radiation safety at CERN. It will provide, for the first time, a single forum where the three parties will discuss how maximum overall safety can best be achieved in the specific CERN context. CERN has always maintained close collaboration with its Host States in matters of safety. “The aim of this collaboration is especially to ensure best practice in the field of radiation protection and the safe operation of CERN’s facilities”, explains Ralf Trant, Head of the Occupational Health & Safety and Environmental Protection (HSE) Unit. Until today, CERN’s collaboration with its Host States was carried out under two sets of bilateral agreements: depending on which side of the French-Swiss border they were being carried out on, a different framework applied to the same activities. This approach has b...
Joya, Wajid; Khan, Salman; Khalid Khan, M.; Alam, Sher
2017-05-01
The behavior of bipartite quantum discord (BQD) and tripartite quantum discord (TQD) in the Heisenberg XXZ spins chain is investigated with the increasing size of the system using the approach of the quantum renormalization group method. Analytical relations for both BQD and TQD are obtained and the results are checked through numerical optimization. In the thermodynamics limit, both types of discord exhibit quantum phase transition (QPT). The boundary of QPT links the phases of saturated discord and zero discord. The first derivative of both discords becomes discontinuous at the critical point, which corresponds to the second-order phase transition. Qualitatively identical, the amount of saturated BQD strongly depends on the relative positions of spins inside a block. TQD can be a better candidate than BQD both for analyzing QPT and implementing quantum information tasks. The scaling behavior in the vicinity of the critical point is discussed.
Tylka, Tracy L
2011-06-01
Although muscularity and body fat concerns are central to conceptualizing men's body image, they have not been examined together within existing structural models. This study refined the tripartite influence model (Thompson, Heinberg, Altabe, & Tantleff-Dunn, 1999) by including dual body image pathways (muscularity and body fat dissatisfaction) to engagement in muscular enhancement and disordered eating behaviors, respectively, and added dating partners as a source of social influence. Latent variable structural equation modeling analyses supported this quadripartite model in 473 undergraduate men. Nonsignificant paths were trimmed and two unanticipated paths were added. Muscularity dissatisfaction and body fat dissatisfaction represented dual body image pathways to men's engagement in muscularity enhancement behaviors and disordered eating behaviors, respectively. Pressures to be mesomorphic from friends, family, media, and dating partners made unique contributions to the model. Internalization of the mesomorphic ideal, muscularity dissatisfaction, and body fat dissatisfaction played key meditational roles within the model. Copyright © 2011 Elsevier Ltd. All rights reserved.
Valenza, Gaetano; Tedesco, Luciano; Lanata, Antonio; De Rossi, Danilo; Scilingo, Enzo Pasquale
2013-01-01
In this paper a novel and efficient computational implementation of a Spiking Neuron-Astrocyte Network (SNAN) is reported. Neurons are modeled according to the Izhikevich formulation and the neuron-astrocyte interactions are intended as tripartite synapsis and modeled with the previously proposed nonlinear transistor-like model. Concerning the learning rules, the original spike-timing dependent plasticity is used for the neural part of the SNAN whereas an ad-hoc rule is proposed for the astrocyte part. SNAN performances are compared with a standard spiking neural network (SNN) and evaluated using the polychronization concept, i.e., number of co-existing groups that spontaneously generate patterns of polychronous activity. The astrocyte-neuron ratio is the biologically inspired value of 1.5. The proposed SNAN shows higher number of polychronous groups than SNN, remarkably achieved for the whole duration of simulation (24 hours).
Li, Jia-Jia; Du, Meng-Meng; Wang, Rong; Lei, Jin-Zhi; Wu, Ying
Astrocytes have important functions in the central nervous system (CNS) and are significant in our understanding of the neuronal network. Astrocytes modulate neuronal firings at both single cell level of tripartite synapses and the neuron-glial network level. Astrocytes release adenosine triphosphate (ATP) and glutamate into the neuron-glial network. These gliotransmitters diffuse over the network to form long distance signals to regulate neuron firings. In this paper, we study a neuron-glial network model that includes a diffusion of astrocytic ATP and glutamate to investigate how long distance diffusion of the gliotransmitters affects the information processing in a neuronal network. We find that gliotransmitters diffusion can compensate for the failure of information processing of interneuron network firings induced by defectively coupled synapses. Moreover, we find that calcium waves in astrocyte network and firings in interneuron network are both sensitive to the glutamate diffusion rate and feedback intensities of astrocytes on interneurons.
Antarctic fellfield response to climate change: a tripartite synthesis of experimental data.
Kennedy, Andrew D
1996-07-01
This paper explores the biological consequences of climate change by integrating the results of a tripartite investigation involving fumarole, field manipulation and laboratory incubation experiments. The geographical region for this research is the maritime Antarctic. Under contemporary climate conditions, the lithosols in this region support only a sparse cryptogamic flora of limited taxonomic diversity and low structural complexity. However, the existence in geothermal areas of temperate species (e.g. Campylopus introflexus, Marchantia polymorpha, Philonotis acicularis) growing outside their normal biogeographical range suggests that elevated temperature and humidity may alter the trajectory of community development towards Magellanic or Patagonian composition. Productivity is also likely to increase, as indicated by significantly greater vegetative biomass recorded beneath climate-ameliorating soil covers than in controls. Barren fellfield soil samples transplanted to the laboratory and incubated at temperatures of 2-25°C show rapid development of moss, algae and lichen propagules in the range 15-25°C. A variety of species develop that have not been recorded in the field. The presence of exotic taxa indicates the existence of a dormant propagule bank in maritime Antarctic soils and suggests that no significant delay is likely to occur between the onset of climate warming and community development: instead, rapid establishment of those species favoured by the new climate conditions will yield a distinct founder effect, with increasing above- and below-ground biomass stimulating biogeochemical cycling. It is argued that the combined results of this synthesis identify generic responses to climate change arising from the importance at high latitudes of low temperature and water availability as limiting factors: subject to other growth resources being non-limiting, a more consistent stimulatory response to climate change may be expected than in temperate or
Irina, Insarova; Dyakov, Max; Ptushenko, Vasiliy; Shtaer, Oksana
Lichens are symbiotic organisms consisting of at least two genetic different partners: a heterotrophic fungus (mycobiont) and a phototrophic alga or cyanobacterium (photobiont). Lichens are ubiquitous at global scale. These symbiotic organisms represent the dominant type of “vegetation” at 8 - 10% of land (Larson, 1987). Abiotic stress’ resistance is notable for lichens among all eukaryotes. Lichens are often called “extremophiles” for their ability to acclimate the most severe environmental conditions. These features allow regarding lichens as a group of organisms which is potentially able to keep viability under open space conditions and to survive within Mars-like atmosphere types. The research presented was carried out in the network of spacecraft Bion-1 experiments involving the investigation of physiological and ultrastructural changes in biological objects survivable under open space conditions. Similar researches were already conducted on bipartite lichen species. The most attention was paid to the influence of UV and other space radiation types on lichen viability in those works. Thus we have taken tripartite lichen Peltigera aphthosa as a main research object and temperature fluctuations from extremely high to extremely low values in accordance to solar and umbral orbit sides - for the main extreme environmental factors. These factors were the less studied in previous works. During the research the influence of incubation under anaerobic conditions, multi-time effects of high and low temperatures and their interchange on respiratory metabolism, photosynthetic apparatus condition and the ultrastructure of P. aphthosa thalli was assessed. The data obtained demonstrate that activity either mycobiont or photobiont in tripartite lichen Peltigera aphthosa keep near unchanged under influence of all stress factors explored on dry thalli.
Directory of Open Access Journals (Sweden)
Jansa Jan
2009-06-01
Full Text Available Abstract Background Like other species of the Phaseoleae tribe, common bean (Phaseolus vulgaris L. has the potential to establish symbiosis with rhizobia and to fix the atmospheric dinitrogen (N2 for its N nutrition. Common bean has also the potential to establish symbiosis with arbuscular mycorrhizal fungi (AMF that improves the uptake of low mobile nutrients such as phosphorus, from the soil. Both rhizobial and mycorrhizal symbioses can act synergistically in benefits on plant. Results The tripartite symbiosis of common bean with rhizobia and arbuscular mycorrhizal fungi (AMF was assessed in hydroaeroponic culture with common bean (Phaseolus vulgaris L., by comparing the effects of three fungi spp. on growth, nodulation and mycorrhization of the roots under sufficient versus deficient P supplies, after transfer from initial sand culture. Although Glomus intraradices Schenck & Smith colonized intensely the roots of common bean in both sand and hydroaeroponic cultures, Gigaspora rosea Nicolson & Schenck only established well under sand culture conditions, and no root-colonization was found with Acaulospora mellea Spain & Schenck under either culture conditions. Interestingly, mycorrhization by Glomus was also obtained by contact with mycorrhized Stylosanthes guianensis (Aubl. sw in sand culture under deficient P before transfer into hydroaeroponic culture. The effect of bean genotype on both rhizobial and mycorrhizal symbioses with Glomus was subsequently assessed with the common bean recombinant inbreed line 7, 28, 83, 115 and 147, and the cultivar Flamingo. Significant differences among colonization and nodulation of the roots and growth among genotypes were found. Conclusion The hydroaeroponic culture is a valuable tool for further scrutinizing the physiological interactions and nutrient partitioning within the tripartite symbiosis.
A tripartite clustering analysis on microRNA, gene and disease model.
Shen, Chengcheng; Liu, Ying
2012-02-01
Alteration of gene expression in response to regulatory molecules or mutations could lead to different diseases. MicroRNAs (miRNAs) have been discovered to be involved in regulation of gene expression and a wide variety of diseases. In a tripartite biological network of human miRNAs, their predicted target genes and the diseases caused by altered expressions of these genes, valuable knowledge about the pathogenicity of miRNAs, involved genes and related disease classes can be revealed by co-clustering miRNAs, target genes and diseases simultaneously. Tripartite co-clustering can lead to more informative results than traditional co-clustering with only two kinds of members and pass the hidden relational information along the relation chain by considering multi-type members. Here we report a spectral co-clustering algorithm for k-partite graph to find clusters with heterogeneous members. We use the method to explore the potential relationships among miRNAs, genes and diseases. The clusters obtained from the algorithm have significantly higher density than randomly selected clusters, which means members in the same cluster are more likely to have common connections. Results also show that miRNAs in the same family based on the hairpin sequences tend to belong to the same cluster. We also validate the clustering results by checking the correlation of enriched gene functions and disease classes in the same cluster. Finally, widely studied miR-17-92 and its paralogs are analyzed as a case study to reveal that genes and diseases co-clustered with the miRNAs are in accordance with current research findings.
Wendling, Carolin C; Piecyk, Agnes; Refardt, Dominik; Chibani, Cynthia; Hertel, Robert; Liesegang, Heiko; Bunk, Boyke; Overmann, Jörg; Roth, Olivia
2017-04-11
Evolutionary shifts in bacterial virulence are often associated with a third biological player, for instance temperate phages, that can act as hyperparasites. By integrating as prophages into the bacterial genome they can contribute accessory genes, which can enhance the fitness of their prokaryotic carrier (lysogenic conversion). Hyperparasitic influence in tripartite biotic interactions has so far been largely neglected in empirical host-parasite studies due to their inherent complexity. Here we experimentally address whether bacterial resistance to phages and bacterial harm to eukaryotic hosts is linked using a natural tri-partite system with bacteria of the genus Vibrio, temperate vibriophages and the pipefish Syngnathus typhle. We induced prophages from all bacterial isolates and constructed a three-fold replicated, fully reciprocal 75 × 75 phage-bacteria infection matrix. According to their resistance to phages, bacteria could be grouped into three distinct categories: highly susceptible (HS-bacteria), intermediate susceptible (IS-bacteria), and resistant (R-bacteria). We experimentally challenged pipefish with three selected bacterial isolates from each of the three categories and determined the amount of viable Vibrio counts from infected pipefish and the expression of pipefish immune genes. While the amount of viable Vibrio counts did not differ between bacterial groups, we observed a significant difference in relative gene expression between pipefish infected with phage susceptible and phage resistant bacteria. These findings suggest that bacteria with a phage-susceptible phenotype are more harmful against a eukaryotic host, and support the importance of hyperparasitism and the need for an integrative view across more than two levels when studying host-parasite evolution.
Viaña, John Noel M; Gilbert, Frederic
2018-01-01
Memory dysfunction and cognitive impairments due to Alzheimer's disease can affect the selfhood and identity of afflicted individuals, causing distress to both people with Alzheimer's disease and their caregivers. Recently, a number of case studies and clinical trials have been conducted to determine the potential of deep brain stimulation as a therapeutic modality for people with Alzheimer's disease. Some of these studies have shown that deep brain stimulation could induce flashbacks and stabilize or even improve memory. However, deep brain stimulation itself has also been attributed as a potential threat to identity and selfhood, especially when procedure-related adverse events arise. We anticipate potential effects of deep brain stimulation for people with Alzheimer's disease on selfhood, reconciling information from medical reports, psychological, and sociological investigations on the impacts of deep brain stimulation or Alzheimer's disease on selfhood. A tripartite model of the self that extends the scope of Rom Harré's and Steve Sabat's social constructionist framework was used. In this model, potential effects of deep brain stimulation for Alzheimer's disease on Self 1 or singularity through use of first-person indexicals, and gestures of self-reference, attribution, and recognition; Self 2 or past and present attributes, knowledge of these characteristics, and continuity of narrative identity; and Self 3 or the relational and social self are explored. The ethical implications of potential effects of deep brain stimulation for Alzheimer's disease on the tripartite self are then highlighted, focusing on adapting informed consent procedures and care provided throughout the trial to account for both positive and negative plausible effects on Self 1, Self 2, and Self 3.
Quantum load balancing in ad hoc networks
Hasanpour, M.; Shariat, S.; Barnaghi, P.; Hoseinitabatabaei, S. A.; Vahid, S.; Tafazolli, R.
2017-06-01
This paper presents a novel approach in targeting load balancing in ad hoc networks utilizing the properties of quantum game theory. This approach benefits from the instantaneous and information-less capability of entangled particles to synchronize the load balancing strategies in ad hoc networks. The quantum load balancing (QLB) algorithm proposed by this work is implemented on top of OLSR as the baseline routing protocol; its performance is analyzed against the baseline OLSR, and considerable gain is reported regarding some of the main QoS metrics such as delay and jitter. Furthermore, it is shown that QLB algorithm supports a solid stability gain in terms of throughput which stands a proof of concept for the load balancing properties of the proposed theory.
Asymptotic properties of entanglement polytopes for large number of qubits
Maciążek, Tomasz; Sawicki, Adam
2018-02-01
Entanglement polytopes have been recently proposed as a way of witnessing the stochastic local operations and classical communication (SLOCC) multipartite entanglement classes using single particle information. We present first asymptotic results concerning the feasibility of this approach for a large number of qubits. In particular, we show that entanglement polytopes of the L-qubit system accumulate in the distance O(\\frac{1}{\\sqrt{L}}) from the point corresponding to the maximally mixed reduced one-qubit density matrices. This implies existence of a possibly large region where many entanglement polytopes overlap, i.e. where the witnessing power of entanglement polytopes is weak. Moreover, we argue that the witnessing power cannot be strengthened by any entanglement distillation protocol, as for large L the required purity is above current capability.
Entanglement and thermodynamics after a quantum quench in integrable systems
Alba, Vincenzo; Calabrese, Pasquale
2017-07-01
Entanglement and entropy are key concepts standing at the foundations of quantum and statistical mechanics. Recently, the study of quantum quenches revealed that these concepts are intricately intertwined. Although the unitary time evolution ensuing from a pure state maintains the system at zero entropy, local properties at long times are captured by a statistical ensemble with nonzero thermodynamic entropy, which is the entanglement accumulated during the dynamics. Therefore, understanding the entanglement evolution unveils how thermodynamics emerges in isolated systems. Alas, an exact computation of the entanglement dynamics was available so far only for noninteracting systems, whereas it was deemed unfeasible for interacting ones. Here, we show that the standard quasiparticle picture of the entanglement evolution, complemented with integrability-based knowledge of the steady state and its excitations, leads to a complete understanding of the entanglement dynamics in the space-time scaling limit. We thoroughly check our result for the paradigmatic Heisenberg chain.
Deterministically entangling multiple remote quantum memories inside an optical cavity
Yan, Zhihui; Liu, Yanhong; Yan, Jieli; Jia, Xiaojun
2018-01-01
Quantum memory for the nonclassical state of light and entanglement among multiple remote quantum nodes hold promise for a large-scale quantum network, however, continuous-variable (CV) memory efficiency and entangled degree are limited due to imperfect implementation. Here we propose a scheme to deterministically entangle multiple distant atomic ensembles based on CV cavity-enhanced quantum memory. The memory efficiency can be improved with the help of cavity-enhanced electromagnetically induced transparency dynamics. A high degree of entanglement among multiple atomic ensembles can be obtained by mapping the quantum state from multiple entangled optical modes into a collection of atomic spin waves inside optical cavities. Besides being of interest in terms of unconditional entanglement among multiple macroscopic objects, our scheme paves the way towards the practical application of quantum networks.
Two-point entanglement near a quantum phase transition
International Nuclear Information System (INIS)
Chen, Han-Dong
2007-01-01
In this work, we study the two-point entanglement S(i, j), which measures the entanglement between two separated degrees of freedom (ij) and the rest of system, near a quantum phase transition. Away from the critical point, S(i, j) saturates with a characteristic length scale ξ E , as the distance |i - j| increases. The entanglement length ξ E agrees with the correlation length. The universality and finite size scaling of entanglement are demonstrated in a class of exactly solvable one-dimensional spin model. By connecting the two-point entanglement to correlation functions in the long range limit, we argue that the prediction power of a two-point entanglement is universal as long as the two involved points are separated far enough
Entanglement entropy and differential entropy for massive flavors
International Nuclear Information System (INIS)
Jones, Peter A.R.; Taylor, Marika
2015-01-01
In this paper we compute the holographic entanglement entropy for massive flavors in the D3-D7 system, for arbitrary mass and various entangling region geometries. We show that the universal terms in the entanglement entropy exactly match those computed in the dual theory using conformal perturbation theory. We derive holographically the universal terms in the entanglement entropy for a CFT perturbed by a relevant operator, up to second order in the coupling; our results are valid for any entangling region geometry. We present a new method for computing the entanglement entropy of any top-down brane probe system using Kaluza-Klein holography and illustrate our results with massive flavors at finite density. Finally we discuss the differential entropy for brane probe systems, emphasising that the differential entropy captures only the effective lower-dimensional Einstein metric rather than the ten-dimensional geometry.
Quantum key distribution with an entangled light emitting diode
Energy Technology Data Exchange (ETDEWEB)
Dzurnak, B.; Stevenson, R. M.; Nilsson, J.; Dynes, J. F.; Yuan, Z. L.; Skiba-Szymanska, J.; Shields, A. J. [Toshiba Research Europe Limited, 208 Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Farrer, I.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)
2015-12-28
Measurements performed on entangled photon pairs shared between two parties can allow unique quantum cryptographic keys to be formed, creating secure links between users. An advantage of using such entangled photon links is that they can be adapted to propagate entanglement to end users of quantum networks with only untrusted nodes. However, demonstrations of quantum key distribution with entangled photons have so far relied on sources optically excited with lasers. Here, we realize a quantum cryptography system based on an electrically driven entangled-light-emitting diode. Measurement bases are passively chosen and we show formation of an error-free quantum key. Our measurements also simultaneously reveal Bell's parameter for the detected light, which exceeds the threshold for quantum entanglement.
Renormalization group flow of entanglement entropy to thermal entropy
Kim, Ki-Seok; Park, Chanyong
2017-05-01
Utilizing the holographic technique, we investigate how the entanglement entropy evolves along the renormalization group flow. After introducing a new generalized temperature which satisfies the thermodynamicslike law even in the IR regime, we find that the renormalized entropy and the generalized temperature in the IR limit approach the thermal entropy and thermodynamic temperature of a real thermal system. This result implies that the microscopic quantum entanglement entropy in the IR region leads to the thermodynamic relation up to small quantum corrections caused by the quantum entanglement near the entangling surface. Intriguingly, this IR feature of the entanglement entropy universally happens regardless of the detail of the dual field theory and the shape of the entangling surface. We check this IR universality with a most general geometry called the hyperscaling violation geometry which is dual to a relativistic nonconformal field theory.
Entanglement entropy and differential entropy for massive flavors
Energy Technology Data Exchange (ETDEWEB)
Jones, Peter A.R. [Physics and Astronomy and STAG Research Centre, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom); Taylor, Marika [Mathematical Sciences and STAG Research Centre, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom)
2015-08-04
In this paper we compute the holographic entanglement entropy for massive flavors in the D3-D7 system, for arbitrary mass and various entangling region geometries. We show that the universal terms in the entanglement entropy exactly match those computed in the dual theory using conformal perturbation theory. We derive holographically the universal terms in the entanglement entropy for a CFT perturbed by a relevant operator, up to second order in the coupling; our results are valid for any entangling region geometry. We present a new method for computing the entanglement entropy of any top-down brane probe system using Kaluza-Klein holography and illustrate our results with massive flavors at finite density. Finally we discuss the differential entropy for brane probe systems, emphasising that the differential entropy captures only the effective lower-dimensional Einstein metric rather than the ten-dimensional geometry.
Experimental observation of entanglement duality for identical particles
International Nuclear Information System (INIS)
Ma, J-J; Yuan, X-X; Zu, C; Chang, X-Y; Hou, P-Y; Duan, L-M
2014-01-01
It was shown recently that entanglement of identical particles has a feature called dualism (Bose and Home 2013 Phys. Rev. Lett. 110 140404), which is fundamentally connected with quantum indistinguishability. Here we report an experiment that observes the entanglement duality for the first time with two identical photons, which manifest polarization entanglement when labeled by different paths or path entanglement when labeled by polarization states. By adjusting the mismatch in frequency or arrival time of the entangled photons, we tune the photon indistinguishability from the quantum to the classical limit and observe that the entanglement duality disappears under the emergence of classical distinguishability, confirming it as a characteristic feature of quantum indistinguishable particles. (paper)
Entanglement Evolution of Three-Qubit States under Local Decoherence
International Nuclear Information System (INIS)
Ma Xiaosan; Liu Gaosheng; Wang Anmin
2010-01-01
By using negativity as entanglement measure, we have investigated the effect of local decoherence from a non-Markovian environment on the time evolution of entanglement of three-qubit states including the GHZ state, the W state, and the Werner state. From the results, we find that the entanglement dynamics depends not only on the coupling strengths but also on the specific states of concern. Specifically, the entanglement takes different behaviors under weak or strong coupling and it varies with the quantum states under study. The entanglement of the GHZ state and the Werner state can be destroyed completely by the local decoherence, while the entanglement of the W state can survive through the local decoherence partially. (general)
Statistical bounds on the dynamical production of entanglement
International Nuclear Information System (INIS)
Abreu, Romulo F.; Vallejos, Raul O.
2007-01-01
We present a random-matrix analysis of the entangling power of a unitary operator as a function of the number of times it is iterated. We consider unitaries belonging to the circular ensembles of random matrices [the circular unitary (CUE) or circular orthogonal ensemble] applied to random (real or complex) nonentangled states. We verify numerically that the average entangling power is a monotonically decreasing function of time. The same behavior is observed for the 'operator entanglement' - an alternative measure of the entangling strength of a unitary operator. On the analytical side we calculate the CUE operator entanglement and asymptotic values for the entangling power. We also provide a theoretical explanation of the time dependence in the CUE cases
Entanglement is Necessary for Emergent Classicality in All Physical Theories.
Richens, Jonathan G; Selby, John H; Al-Safi, Sabri W
2017-08-25
One of the most striking features of quantum theory is the existence of entangled states, responsible for Einstein's so called "spooky action at a distance." These states emerge from the mathematical formalism of quantum theory, but to date we do not have a clear idea of the physical principles that give rise to entanglement. Why does nature have entangled states? Would any theory superseding classical theory have entangled states, or is quantum theory special? One important feature of quantum theory is that it has a classical limit, recovering classical theory through the process of decoherence. We show that any theory with a classical limit must contain entangled states, thus establishing entanglement as an inevitable feature of any theory superseding classical theory.
Entanglement dynamics in itinerant fermionic and bosonic systems
Pillarishetty, Durganandini
2017-04-01
The concept of quantum entanglement of identical particles is fundamental in a wide variety of quantum information contexts involving composite quantum systems. However, the role played by particle indistinguishabilty in entanglement determination is being still debated. In this work, we study, theoretically, the entanglement dynamics in some itinerant bosonic and fermionic systems. We show that the dynamical behaviour of particle entanglement and spatial or mode entanglement are in general different. We also discuss the effect of fermionic and bosonic statistics on the dynamical behaviour. We suggest that the different dynamical behaviour can be used to distinguish between particle and mode entanglement in identical particle systems and discuss possible experimental realizations for such studies. I acknowledge financial support from DST, India through research Grant.
Atomic focusing by quantum fields: Entanglement properties
Energy Technology Data Exchange (ETDEWEB)
Paz, I.G. da [Departamento de Física, Universidade Federal do Piauí, Campus Ministro Petrônio Portela, CEP 64049-550, Teresina, PI (Brazil); Frazão, H.M. [Universidade Federal do Piauí, Campus Profa. Cinobelina Elvas, CEP 64900-000, Bom Jesus, PI (Brazil); Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil); Nemes, M.C. [Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil); Peixoto de Faria, J.G. [Departamento de Física e Matemática, Centro Federal de Educação Tecnológica de Minas Gerais, Av. Amazonas 7675, Belo Horizonte, MG 30510-000 (Brazil)
2014-04-01
The coherent manipulation of the atomic matter waves is of great interest both in science and technology. In order to study how an atom optic device alters the coherence of an atomic beam, we consider the quantum lens proposed by Averbukh et al. [1] to show the discrete nature of the electromagnetic field. We extend the analysis of this quantum lens to the study of another essentially quantum property present in the focusing process, i.e., the atom–field entanglement, and show how the initial atomic coherence and purity are affected by the entanglement. The dynamics of this process is obtained in closed form. We calculate the beam quality factor and the trace of the square of the reduced density matrix as a function of the average photon number in order to analyze the coherence and purity of the atomic beam during the focusing process.
Entanglement witnesses: construction, analysis and classification
International Nuclear Information System (INIS)
Chruściński, Dariusz; Sarbicki, Gniewomir
2014-01-01
From the physical point of view entanglement witnesses (EWs) define a universal tool for analysis and classification of quantum entangled states. From the mathematical perspective bipartite EWs provide highly non-trivial generalization of positive operators and establish elegant correspondence with the theory of positive maps in matrix algebras. We concentrate on theoretical analysis of various important notions like decomposability, atomicity, optimality, extremality and exposedness. Several methods of construction are provided as well. Our discussion is illustrated by many examples enabling the reader to see the intricate structure of these objects. It is shown that the theory of EWs finds elegant geometric formulation in terms of convex cones and related geometric structures. (topical review)
Entanglement entropy in three dimensional gravity
Energy Technology Data Exchange (ETDEWEB)
Maxfield, Henry [Centre for Particle Theory & Department of Mathematical Sciences, Durham University,South Road, Durham DH1 3LE (United Kingdom)
2015-04-07
The Ryu-Takayanagi (RT) and covariant Hubeny-Rangamani-Takayanagi (HRT) proposals relate entanglement entropy in CFTs with holographic duals to the areas of minimal or extremal surfaces in the bulk geometry. We show how, in three dimensional pure gravity, the relevant regulated geodesic lengths can be obtained by writing a spacetime as a quotient of AdS{sub 3}, with the problem reduced to a simple purely algebraic calculation. We explain how this works in both Lorentzian and Euclidean formalisms, before illustrating its use to obtain novel results in a number of examples, including rotating BTZ, the ℝℙ{sup 2} geon, and several wormhole geometries. This includes spatial and temporal dependence of single-interval entanglement entropy, despite these symmetries being broken only behind an event horizon. We also discuss considerations allowing HRT to be derived from analytic continuation of Euclidean computations in certain contexts, and a related class of complexified extremal surfaces.
Energy transmission using recyclable quantum entanglement
Ye, Ming-Yong; Lin, Xiu-Min
2016-07-01
It is known that faster-than-light (FTL) transmission of energy could be achieved if the transmission were considered in the framework of non-relativistic classical mechanics. Here we show that FTL transmission of energy could also be achieved if the transmission were considered in the framework of non-relativistic quantum mechanics. In our transmission protocol a two-spin Heisenberg model is considered and the energy is transmitted by two successive local unitary operations on the initially entangled spins. Our protocol does not mean that FTL transmission can be achieved in reality when the theory of relativity is considered, but it shows that quantum entanglement can be used in a recyclable way in energy transmission.
Stress Relaxation in Entangled Polymer Melts
DEFF Research Database (Denmark)
Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf
2010-01-01
We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t......We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements...... excellent agreement for the Likhtman-McLeish theory using the double reptation approximation for constraint release, if we remove the contribution of high-frequency modes to contour length fluctuations of the primitive chain....
Quantum entanglement and neutron scattering experiments
International Nuclear Information System (INIS)
Cowley, R A
2003-01-01
It is shown that quantum entanglement in condensed matter can be observed with scattering experiments if the energy resolution of the experiments enables a clear separation between the elastic scattering and the scattering from the excitations in the system. These conditions are not satisfied in recent deep inelastic neutron scattering experiments from hydrogen-containing systems that have been interpreted as showing the existence of quantum entanglement for short times in, for example, water at room temperature. It is shown that the theory put forward to explain these experiments is inconsistent with the first-moment sum rule for the Van Hove scattering function and we suggest that the theory is incorrect. The experiments were performed using the unique EVS spectrometer at ISIS and suggestions are made about how the data and their interpretation should be re-examined
Entanglement detection with bounded reference frames
International Nuclear Information System (INIS)
Costa, Fabio; Brukner, Caslav; Harrigan, Nicholas; Rudolph, Terry
2009-01-01
Quantum experiments usually assume the existence of perfect, classical reference frames (RFs), which allow for the specification of measurement settings (e.g. orientation of the Stern-Gerlach magnet in spin measurements) with arbitrary precision. If the RFs are 'bounded' (i.e. quantum systems themselves, having a finite number of degrees of freedom), only limited precision can be attained. Using spin coherent states as bounded RFs, we have found the minimum size needed for them to violate local realism for entangled spin systems. For composite systems of spin 1/2 particles, RFs of very small size are sufficient for the violation; however, to see this violation for macroscopic entangled spins, the size of the RF must be at least quadratically larger than that of the spins. The unavailability of such RFs gives a possible explanation for the non-observance of violation of local realism in everyday experience.
Spectroscopy by frequency entangled photon pairs
Yabushita, Atsushi; Kobayashi, Takayoshi
2003-01-01
Quantum spectroscopy was performed using the frequency-entangled broadband photon pairs generated by spontaneous parametric down-conversion. An absorptive sample was placed in front of the idler photon detector, and the frequency of signal photons was resolved by a diffraction grating. The absorption spectrum of the sample was measured by counting the coincidences, and the result is in agreement with the one measured by a conventional spectrophotometer with a classical light source.
Quantum Communication Using Macroscopic Phase Entangled States
2015-12-10
U.S. Army RDECOM, Aviation & Missile Research, Development & Engineering Center Name of Contractor: University of Maryland at Baltimore County...Principal Investigator: Dr. James Franson Business Address: 1000 Hilltop Circle, Baltimore , MD 21250 Phone number: 410-455-8115 Effective date...distribution with entanglement witnessing”, Physical Review A, v. 89, 012315 (2014). • David Simon, Gregg Jaeger, and Alexander Sergienko ’’Quantum
Deformed Fredkin spin chain with extensive entanglement
Salberger, Olof; Udagawa, Takuma; Zhang, Zhao; Katsura, Hosho; Klich, Israel; Korepin, Vladimir
2017-06-01
We introduce a new spin chain which is a deformation of the Fredkin spin chain and has a phase transition between bounded and extensive entanglement entropy scaling. In this chain, spins have a local interaction of three nearest neighbors. The Hamiltonian is frustration-free and its ground state can be described analytically as a weighted superposition of Dyck paths that depends on a deformation parameter t. In the purely spin 1/2 case, whenever t\
Nonlocality and entanglement in qubit systems
Energy Technology Data Exchange (ETDEWEB)
Batle, J [Departament de Fisica, Universitat de les Illes Balears, 07122 Palma de Mallorca (Spain); Casas, M, E-mail: vdfsjbv4@uib.es [Departament de Fisica and IFISC-CSIC, Universitat de les Illes Balears, 07122 Palma de Mallorca (Spain)
2011-11-04
Nonlocality and quantum entanglement constitute two special aspects of the quantum correlations existing in quantum systems, which are of paramount importance in quantum-information theory. Traditionally, they have been regarded as identical (equivalent, in fact, for pure two qubit states, that is, Gisin's Theorem), yet they constitute different resources. Describing nonlocality by means of the violation of several Bell inequalities, we obtain by direct optimization those states of two qubits that maximally violate a Bell inequality, in terms of their degree of mixture as measured by either their participation ratio R = 1/Tr({rho}{sup 2}) or their maximum eigenvalue {lambda}{sub max}. This optimum value is obtained as well, which coincides with previous results. Comparison with entanglement is performed too. An example of an application is given in the XY model. In this novel approximation, we also concentrate on the nonlocality for linear combinations of pure states of two qubits, providing a closed form for their maximal nonlocality measure. The case of Bell diagonal mixed states of two qubits is also extensively studied. Special attention concerning the connection between nonlocality and entanglement for mixed states of two qubits is paid to the so-called maximally entangled mixed states. Additional aspects for the case of two qubits are also described in detail. Since we deal with qubit systems, we will perform an analogous study for three qubits, employing similar tools. Relation between distillability and nonlocality is explored quantitatively for the whole space of states of three qubits. We finally extend our analysis to four-qubit systems, where nonlocality for generalized Greenberger-Horne-Zeilinger states of arbitrary number of parties is computed. (paper)
Localization and Entanglement in Relativistic Quantum Physics
Yngvason, Jakob
2014-01-01
The combination of quantum theory and special relativity leads to structures that differ in several respects from non-relativistic quantum mechanics of particles. These differences are quite familiar to practitioners of Algebraic Quantum Field Theory but less well known outside this community. The paper is intended as a concise survey of some selected aspects of relativistic quantum physics, in particular regarding localization and entanglement.
Muon-fluorine entanglement in fluoropolymers.
Lancaster, T; Pratt, F L; Blundell, S J; McKenzie, I; Assender, H E
2009-08-26
We present the results of muon spin relaxation measurements on the fluoropolymers polytetrafluoroethylene (PTFE), poly(vinylidene fluoride) (PVDF) and poly(vinyl fluoride) (PVF). Entanglement between the muon spin and the spins of the fluorine nuclei in the polymers allows us to identify the different muon stopping states that occur in each of these materials and provides a method of probing the local environment of the muon and the dynamics of the polymer chains.
Teleporting entanglement during black hole evaporation
International Nuclear Information System (INIS)
Brustein, Ram; Medved, A.J.M.
2016-01-01
The unitary evaporation of a black hole (BH) in an initially pure state must lead to the eventual purification of the emitted radiation. It follows that the late radiation has to be entangled with the early radiation and, as a consequence, the entanglement among the Hawking pair partners has to decrease continuously from maximal to vanishing during the BH’s life span. Starting from the basic premise that both the horizon radius and the center of mass of a finite-mass BH are fluctuating quantum mechanically, we show how this process is realized. First, it is shown that the horizon fluctuations induce a small amount of variance in the total linear momentum of each created pair. This is in contrast to the case of an infinitely massive BH, for which the total momentum of the produced pair vanishes exactly on account of momentum conservation. This variance leads to a random recoil of the BH during each emission and, as a result, the center of mass of the BH undergoes a quantum random walk. Consequently, the uncertainty in its momentum grows as the square root of the number of emissions. We then show that this uncertainty controls the amount of deviation from maximal entanglement of the produced pairs and that this deviation is determined by the ratio of the cumulative number of emitted particles to the initial BH entropy. Thus, the interplay between the horizon and center-of-mass fluctuations provides a mechanism for teleporting entanglement from the pair partners to the BH and the emitted radiation.
Entanglement and Quantum Computation: An Overview
Energy Technology Data Exchange (ETDEWEB)
Perez, R.B.
2000-06-27
This report presents a selective compilation of basic facts from the fields of particle entanglement and quantum information processing prepared for those non-experts in these fields that may have interest in an area of physics showing counterintuitive, ''spooky'' (Einstein's words) behavior. In fact, quantum information processing could, in the near future, provide a new technology to sustain the benefits to the U.S. economy due to advanced computer technology.
Entanglement entropy in causal set theory
Sorkin, Rafael D.; Yazdi, Yasaman K.
2018-04-01
Entanglement entropy is now widely accepted as having deep connections with quantum gravity. It is therefore desirable to understand it in the context of causal sets, especially since they provide in a natural manner the UV cutoff needed to render entanglement entropy finite. Formulating a notion of entanglement entropy in a causal set is not straightforward because the type of canonical hypersurface-data on which its definition typically relies is not available. Instead, we appeal to the more global expression given in Sorkin (2012 (arXiv:1205.2953)) which, for a Gaussian scalar field, expresses the entropy of a spacetime region in terms of the field’s correlation function within that region (its ‘Wightman function’ W(x, x') ). Carrying this formula over to the causal set, one obtains an entropy which is both finite and of a Lorentz invariant nature. We evaluate this global entropy-expression numerically for certain regions (primarily order-intervals or ‘causal diamonds’) within causal sets of 1 + 1 dimensions. For the causal-set counterpart of the entanglement entropy, we obtain, in the first instance, a result that follows a (spacetime) volume law instead of the expected (spatial) area law. We find, however, that one obtains an area law if one truncates the commutator function (‘Pauli–Jordan operator’) and the Wightman function by projecting out the eigenmodes of the Pauli–Jordan operator whose eigenvalues are too close to zero according to a geometrical criterion which we describe more fully below. In connection with these results and the questions they raise, we also study the ‘entropy of coarse-graining’ generated by thinning out the causal set, and we compare it with what one obtains by similarly thinning out a chain of harmonic oscillators, finding the same, ‘universal’ behaviour in both cases.
Teleporting entanglement during black hole evaporation
Energy Technology Data Exchange (ETDEWEB)
Brustein, Ram [Department of Physics, Ben-Gurion University,Beer-Sheva 84105 (Israel); Medved, A.J.M. [Department of Physics & Electronics, Rhodes University,Grahamstown 6140 (South Africa); National Institute for Theoretical Physics (NITheP),Western Cape 7602 (South Africa)
2016-10-06
The unitary evaporation of a black hole (BH) in an initially pure state must lead to the eventual purification of the emitted radiation. It follows that the late radiation has to be entangled with the early radiation and, as a consequence, the entanglement among the Hawking pair partners has to decrease continuously from maximal to vanishing during the BH’s life span. Starting from the basic premise that both the horizon radius and the center of mass of a finite-mass BH are fluctuating quantum mechanically, we show how this process is realized. First, it is shown that the horizon fluctuations induce a small amount of variance in the total linear momentum of each created pair. This is in contrast to the case of an infinitely massive BH, for which the total momentum of the produced pair vanishes exactly on account of momentum conservation. This variance leads to a random recoil of the BH during each emission and, as a result, the center of mass of the BH undergoes a quantum random walk. Consequently, the uncertainty in its momentum grows as the square root of the number of emissions. We then show that this uncertainty controls the amount of deviation from maximal entanglement of the produced pairs and that this deviation is determined by the ratio of the cumulative number of emitted particles to the initial BH entropy. Thus, the interplay between the horizon and center-of-mass fluctuations provides a mechanism for teleporting entanglement from the pair partners to the BH and the emitted radiation.
Effect of photonic band gap on entanglement dynamics of qubits
Wu, Jing-Nuo; Hsieh, Wen-Feng; Cheng, Szu-Cheng
2012-01-01
We study how the environment of photonic band gap (PBG) materials affects entanglement dynamics of qubits. Entanglement between the single qubit and the PBG environment is investigated through the von Neumann entropy while that for two initially entangled qubits in this PBG reservoir is through concurrence. Dynamics of these measurements are solved in use of the fractional calculus which has been shown appropriate for the systems with non-Markovian dynamics. Entropy dynamics of the single qub...
Quantum Conditional Cloning of Continuous Variable Entangled States
Liu, K.; Gao, J. R.
2014-12-01
We extend the technique of conditional preparation to a quantum cloning machine, and present a protocol of 1 -> 2 conditional cloning of squeezed state and entanglement states. It is shown that the entanglement degree of the cloned entangled states can be well preserved even when the fidelity between the input and output states is beyond the limit of 4/9. This scheme is practicable since only the linear elements of beam splitters, homodyne detections, optical modulations and electrical trigger system, are involved.
Entanglement of Generalized Two-Mode Binomial States and Teleportation
International Nuclear Information System (INIS)
Wang Dongmei; Yu Youhong
2009-01-01
The entanglement of the generalized two-mode binomial states in the phase damping channel is studied by making use of the relative entropy of the entanglement. It is shown that the factors of q and p play the crucial roles in control the relative entropy of the entanglement. Furthermore, we propose a scheme of teleporting an unknown state via the generalized two-mode binomial states, and calculate the mean fidelity of the scheme. (general)
Generalised squeezing and information theory approach to quantum entanglement
Vourdas, A.
1993-01-01
It is shown that the usual one- and two-mode squeezing are based on reducible representations of the SU(1,1) group. Generalized squeezing is introduced with the use of different SU(1,1) rotations on each irreducible sector. Two-mode squeezing entangles the modes and information theory methods are used to study this entanglement. The entanglement of three modes is also studied with the use of the strong subadditivity property of the entropy.
Sustainable Entangled State of Two Qutrits Under Laser Irradiation
Directory of Open Access Journals (Sweden)
Biryukov A.А.
2015-01-01
Full Text Available We study the evolution of quantum entanglement in the model of two identical qubits interacting with a single-mode laser field. The density matrix and Peres-Horodecki parameter are calculated within the frameworks of path-integral formalism. The quantum entanglement measure is shown to be strongly dependent upon the phase difference between the laser radiation acting on each cubit. This observation may offer the possibility of quantum entanglement stationary control by varying the distance between the qubits.
Entanglement from dissipation and holographic interpretation
Cantcheff, M. Botta; Gadelha, Alexandre L.; Marchioro, Dáfni F. Z.; Nedel, Daniel Luiz
2018-02-01
In this work we study a dissipative field theory where the dissipation process is manifestly related to dynamical entanglement and put it in the holographic context. Such endeavour is realized by further development of a canonical approach to study quantum dissipation, which consists of doubling the degrees of freedom of the original system by defining an auxiliary one. A time dependent entanglement entropy for the vacumm state is calculated and a geometrical interpretation of the auxiliary system and the entropy is given in the context of the AdS/CFT correspondence using the Ryu-Takayanagi formula. We show that the dissipative dynamics is controlled by the entanglement entropy and there are two distinct stages: in the early times the holographic interpretation requires some deviation from classical General Relativity; in the later times the quantum system is described as a wormhole, a solution of the Einstein's equations near to a maximally extended black hole with two asymptotically AdS boundaries. We focus our holographic analysis in this regime, and suggest a mechanism similar to teleportation protocol to exchange (quantum) information between the two CFTs on the boundaries (see Maldacena et al. in Fortschr Phys 65(5):1700034, arXiv:1704.05333 [hep-th], 2017).
Coupled harmonic oscillators and their quantum entanglement
Makarov, Dmitry N.
2018-04-01
A system of two coupled quantum harmonic oscillators with the Hamiltonian H ̂=1/2 (1/m1p̂1 2+1/m2p̂2 2+A x12+B x22+C x1x2) can be found in many applications of quantum and nonlinear physics, molecular chemistry, and biophysics. The stationary wave function of such a system is known, but its use for the analysis of quantum entanglement is complicated because of the complexity of computing the Schmidt modes. Moreover, there is no exact analytical solution to the nonstationary Schrodinger equation H ̂Ψ =i ℏ ∂/Ψ ∂ t and Schmidt modes for such a dynamic system. In this paper we find a solution to the nonstationary Schrodinger equation; we also find in an analytical form a solution to the Schmidt mode for both stationary and dynamic problems. On the basis of the Schmidt modes, the quantum entanglement of the system under consideration is analyzed. It is shown that for certain parameters of the system, quantum entanglement can be very large.
Entangled identities and psychotropic substance use.
Gibson, Barry; Acquah, Sam; Robinson, Peter G
2004-07-01
This paper reports the findings of a grounded theory study investigating drug users' concerns and experiences of their oral health. The aim of this paper is to demonstrate how the findings relate to various strands of literature which focus on processes and discourses of recovery from problematic drug use (biographical reconstruction), the chronic illness literature (biographical disruption), public/private discourses and the myth of addiction. Data were collected from four focus groups containing a total of 25 participants, and 15 in-depth interviews. Participants were recruited from drug detoxification programmes (27), recovery units following detoxification (9) and a drug rehabilitation unit (4). Data analysis revealed that the core concern of drug users' was talking about the 'entangled' nature of their identity whilst they were on drugs. Such 'entangled identities' emerged through what appeared to be a gradual sedimentation process of drug-using habits and routines that replaced those of the everyday self. Other concerns were distancing one's self from the drug using self (involving expressions of disgust) and recovery processes (disentangling). The paper discusses each of these core problems in the light of the literature on the recovery from drug use, the chronic illness literature and the myth of addiction. It concludes by briefly reflecting on problematic psychotropic substance use as another form of biographical disruption formed on the basis of a dialectic between private discourses of the entangled self and public discourses of addiction. It suggests that further work should be conducted in these areas.
Effect of weak measurement on entanglement distribution over noisy channels.
Wang, Xin-Wen; Yu, Sixia; Zhang, Deng-Yu; Oh, C H
2016-03-03
Being able to implement effective entanglement distribution in noisy environments is a key step towards practical quantum communication, and long-term efforts have been made on the development of it. Recently, it has been found that the null-result weak measurement (NRWM) can be used to enhance probabilistically the entanglement of a single copy of amplitude-damped entangled state. This paper investigates remote distributions of bipartite and multipartite entangled states in the amplitudedamping environment by combining NRWMs and entanglement distillation protocols (EDPs). We show that the NRWM has no positive effect on the distribution of bipartite maximally entangled states and multipartite Greenberger-Horne-Zeilinger states, although it is able to increase the amount of entanglement of each source state (noisy entangled state) of EDPs with a certain probability. However, we find that the NRWM would contribute to remote distributions of multipartite W states. We demonstrate that the NRWM can not only reduce the fidelity thresholds for distillability of decohered W states, but also raise the distillation efficiencies of W states. Our results suggest a new idea for quantifying the ability of a local filtering operation in protecting entanglement from decoherence.
Cosmological implications of quantum entanglement in the multiverse
Directory of Open Access Journals (Sweden)
Sugumi Kanno
2015-12-01
Full Text Available We explore the cosmological implications of quantum entanglement between two causally disconnected universes in the multiverse. We first consider two causally separated de Sitter spaces with a state which is initially entangled. We derive the reduced density matrix of our universe and compute the spectrum of vacuum fluctuations. We then consider the same system with an initially non-entangled state. We find that due to quantum interference scale dependent modulations may enter the spectrum for the case of initially non-entangled state. This gives rise to the possibility that the existence of causally disconnected universes may be experimentally tested by analyzing correlators in detail.
Cosmological implications of quantum entanglement in the multiverse
Energy Technology Data Exchange (ETDEWEB)
Kanno, Sugumi, E-mail: sugumi.kanno@ehu.es [Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao (Spain)
2015-12-17
We explore the cosmological implications of quantum entanglement between two causally disconnected universes in the multiverse. We first consider two causally separated de Sitter spaces with a state which is initially entangled. We derive the reduced density matrix of our universe and compute the spectrum of vacuum fluctuations. We then consider the same system with an initially non-entangled state. We find that due to quantum interference scale dependent modulations may enter the spectrum for the case of initially non-entangled state. This gives rise to the possibility that the existence of causally disconnected universes may be experimentally tested by analyzing correlators in detail.
Universal entanglement timescale for Rényi entropies
Cresswell, Jesse C.
2018-02-01
Recently it was shown that the growth of entanglement in an initially separable state, as measured by the purity of subsystems, can be characterized by a timescale that takes a universal form for any Hamiltonian. We show that the same timescale governs the growth of entanglement for all Rényi entropies. Since the family of Rényi entropies completely characterizes the entanglement of a pure bipartite state, our timescale is a universal feature of bipartite entanglement. The timescale depends only on the interaction Hamiltonian and the initial state.
Entanglement entropy evolution under double-trace deformation
Energy Technology Data Exchange (ETDEWEB)
Song, Yushu [College of Physical Science and Technology, Hebei University, Baoding (China)
2017-12-15
In this paper, we study the bulk entanglement entropy evolution in conical BTZ black bole background using the heat kernel method. This is motivated by exploring the new examples where the quantum correction of the entanglement entropy gives the leading contribution. We find that in the large black hole limit the bulk entanglement entropy decreases under the double-trace deformation which is consistent with the holographic c theorem and in the small black hole limit the bulk entanglement entropy increases under the deformation. We also discuss the minimal area correction. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Multipartite entanglement via the Mayer-Vietoris theorem
Patrascu, Andrei T.
2017-10-01
The connection between entanglement and topology manifests itself in the form of the ER-EPR duality. This statement however refers to the maximally entangled states only. In this article I study the multipartite entanglement and the way in which it relates to the topological interpretation of the ER-EPR duality. The 2 dimensional genus 1 torus will be generalised to a n-dimensional general torus, where the information about the multipartite entanglement will be encoded in the higher inclusion maps of the Mayer-Vietorist sequence.
Optomechanical entanglement via non-degenerate parametric interactions
International Nuclear Information System (INIS)
Ahmed, Rizwan; Qamar, Shahid
2017-01-01
We present a scheme for the optomechanical entanglement between a micro-mechanical mirror and the field inside a bimodal cavity system using a non-degenerate optical parametric amplifier (NOPA). Our results show that the introduction of NOPA makes the entanglement stronger or more robust against the mean number of average thermal phonons and cavity decay. Interestingly, macroscopic entanglement depends upon the choice of the phase associated with classical field driving NOPA. We also consider the effects of input laser power on optomechanical entanglement. (paper)
Extended tensor products and generalization of the notion of entanglement
Khrennikov, Andrei; Rosinger, Elemer E.
2012-03-01
Motivated by the novel applications of the mathematical formalism of quantum theory and its generalizations in cognitive science, psychology, social and political sciences, and economics, we extend the notion of the tensor product and entanglement. We also study the relation between conventional entanglement of complex qubits and our generalized entanglement. Our construction can also be used to describe entanglement in the framework of non-Archimedean physics. It is also possible to construct tensor products of non-Archimedean (e.g., p-adic) and complex Hilbert spaces.
Distillability Sudden Birth of Entanglement for Qutrit-Qutrit Systems
International Nuclear Information System (INIS)
Huang Jiang; Ali Mazhar
2014-01-01
We report the sudden appearance of distillability between two statistically independent reservoirs modelled as qutrit-qutrit systems. This feature of bipartite quantum systems is different from the previously observed phenomenon of entanglement sudden birth. It is found that the states of reservoirs first become bound entangled, thus exhibiting entanglement sudden birth, consequently followed by the sudden birth of distillability, and it is shown that whenever distillability is lost abruptly from principal system, it also necessarily appears abruptly among reservoirs' degrees of freedom. This surprising observation reflects yet another peculiarity of dynamical aspects of quantum entanglement
Entanglement distribution by an arbitrarily inept delivery service
International Nuclear Information System (INIS)
Jones, S.J.; Wiseman, H.M.; Pope, D.T.
2005-01-01
We consider the scenario where a company C manufactures in bulk pure entangled pairs of particles, each pair intended for a distinct pair of distant customers. Unfortunately, its delivery service is inept - the probability that any given customer pair receives its intended particles is S set-membership sign [0,1], and the customers cannot detect whether an error has occurred. Remarkably, no matter how small S is, it is still possible for C to distribute entanglement by starting with nonmaximally entangled pairs. We determine the maximum entanglement distributable for a given S, and also determine the ability of the parties to perform nonlocal tasks with the qubits they receive
Jiao, Yong; Wakakuwa, Eyuri; Ogawa, Tomohiro
2018-02-01
We consider asymptotic convertibility of an arbitrary sequence of bipartite pure states into another by local operations and classical communication (LOCC). We adopt an information-spectrum approach to address cases where each element of the sequences is not necessarily a tensor power of a bipartite pure state. We derive necessary and sufficient conditions for the LOCC convertibility of one sequence to another in terms of spectral entropy rates of entanglement of the sequences. Based on these results, we also provide simple proofs for previously known results on the optimal rates of entanglement concentration and dilution of general sequences of bipartite pure states.
Entanglement patterns in mutually unbiased basis sets
Energy Technology Data Exchange (ETDEWEB)
Lawrence, Jay [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States) and The James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States)
2011-08-15
A few simply stated rules govern the entanglement patterns that can occur in mutually unbiased basis sets (MUBs) and constrain the combinations of such patterns that can coexist in full complements of MUBs. We consider Hilbert spaces of prime power dimensions (D=p{sup N}), as realized by systems of N prime-state particles, where full complements of D+1 MUBs are known to exist, and we assume only that MUBs are eigenbases of generalized Pauli operators, without using any particular construction. The general rules include the following: (1) In any MUB, a given particle appears either in a pure state or totally entangled and (2) in any full MUB complement, each particle is pure in (p+1) bases (not necessarily the same ones) and totally entangled in the remaining (p{sup N}-p). It follows that the maximum number of product bases is p+1 and, when this number is realized, all remaining (p{sup N}-p) bases in the complement are characterized by the total entanglement of every particle. This ''standard distribution'' is inescapable for two-particle systems (of any p), where only product and generalized Bell bases are admissible MUB types. This and the following results generalize previous results for qubits [Phys. Rev. A 65. 032320 (2002); Phys. Rev. A 72, 062310 (2005)] and qutrits [Phys. Rev. A 70, 012302 (2004)], drawing particularly upon [Phys. Rev. A 72, 062310 (2005)]. With three particles there are three MUB types, and these may be combined in (p+2) different ways to form full complements. With N=4, there are 6 MUB types for p=2, but new MUB types become possible with larger p, and these are essential to realizing full complements. With this example, we argue that new MUB types that show new entanglement patterns should enter with every step in N and, also, when N is a prime plus 1, at a critical p value, p=N-1. Such MUBs should play critical roles in filling complements.
DEFF Research Database (Denmark)
Walther-Hansen, Mads
2016-01-01
This paper explores the concept of balance in music production and examines the role of conceptual metaphors in reasoning about audio editing. Balance may be the most central concept in record production, however, the way we cognitively understand and respond meaningfully to a mix requiring balance...... is not thoroughly understood. In this paper I treat balance as a metaphor that we use to reason about several different actions in music production, such as adjusting levels, editing the frequency spectrum or the spatiality of the recording. This study is based on an exploration of a linguistic corpus of sound...
International Nuclear Information System (INIS)
Girard, J.; Ribrag, M.; Signarbieux, C.
A multidimensional experiment on the tripartition process has been planned at Grenoble's High Flux Reactor in order to measure in correlation the masses velocities, directions of the two fragments and the alpha-particle [fr
Part of being an Active, More Powerful You means finding balance in your daily life: taking on the Must-dos and finding time for some Should Dos and Want-to-Dos. Sometimes, emotions and commitments can come into play and upset the balance.
Brus, D.J.
2015-01-01
In balanced sampling a linear relation between the soil property of interest and one or more covariates with known means is exploited in selecting the sampling locations. Recent developments make this sampling design attractive for statistical soil surveys. This paper introduces balanced sampling
Spin–spin entanglement in moving frames: Properties of negativity
Indian Academy of Sciences (India)
In the present article, we use negativity to investigate the entanglement between two massive particles in the spin degrees of freedom, as seen by moving observers. Assuming that the occurrence of spin-momentum states is determined by Gaussian probability distributions, we show that the degree of entanglement ...
Four-qubit entanglement classification from string theory.
Borsten, L; Dahanayake, D; Duff, M J; Marrani, A; Rubens, W
2010-09-03
We invoke the black-hole-qubit correspondence to derive the classification of four-qubit entanglement. The U-duality orbits resulting from timelike reduction of string theory from D=4 to D=3 yield 31 entanglement families, which reduce to nine up to permutation of the four qubits.
Path-entangled photon sources on nonlinear chips
Directory of Open Access Journals (Sweden)
Alexander S. Solntsev
2017-11-01
Full Text Available Photon entanglement has a range of applications from secure communication to the tests of quantum mechanics. Utilizing optical nonlinearity for the generation of entangled photons remains the most widely used approach due to its quality and simplicity. The on-chip integration of entangled light sources has enabled the increase of complexity and enhancement of stability compared to bulk optical implementations. Entanglement over different optical paths is uniquely suited for photonic chips, since waveguides are typically optimized for particular wavelength and polarization, making polarization- and frequency-entanglement less practical. In this review we focus on the latest developments in the field of on-chip nonlinear path-entangled photon sources. We provide a review of recent implementations and compare various approaches to tunability, including thermo-optical, electro-optical and all-optical tuning. We also discuss a range of important technical issues, in particular the on-chip separation of the pump and generated entangled photons. Finally, we review different quality control methods, including on-chip quantum tomography and recently discovered classical-quantum analogy that allows to characterize entangled photon sources by performing simple nonlinear measurements in the classical regime.
Entanglement between noncomplementary parts of many-body systems
International Nuclear Information System (INIS)
Wichterich, Hannu Christian
2011-01-01
This thesis investigates the structure and behaviour of entanglement, the purely quantum mechanical part of correlations, in many-body systems, employing both numerical and analytical techniques at the interface of condensed matter theory and quantum information theory. Entanglement can be seen as a precious resource which, for example, enables the noiseless and instant transmission of quantum information, provided the communicating parties share a sufficient ''amount'' of it. Furthermore, measures of entanglement of a quantum mechanical state are perceived as useful probes of collective properties of many-body systems. For instance, certain measures are capable of detecting and classifying ground-state phases and, particularly, transition (or critical) points separating such phases. Chapters 2 and 3 focus on entanglement in many-body systems and its use as a potential resource for communication protocols. They address the questions of how a substantial amount of entanglement can be established between distant subsystems, and how efficiently this entanglement could be ''harvested'' by way of measurements. The subsequent chapters 4 and 5 are devoted to universality of entanglement between large collections of particles undergoing a quantum phase transition, where, despite the enormous complexity of these systems, collective properties including entanglement no longer depend crucially on the microscopic details. (orig.)
Entanglement entropy after selective measurements in quantum chains
International Nuclear Information System (INIS)
Najafi, Khadijeh; Rajabpour, M.A.
2016-01-01
We study bipartite post measurement entanglement entropy after selective measurements in quantum chains. We first study the quantity for the critical systems that can be described by conformal field theories. We find a connection between post measurement entanglement entropy and the Casimir energy of floating objects. Then we provide formulas for the post measurement entanglement entropy for open and finite temperature systems. We also comment on the Affleck-Ludwig boundary entropy in the context of the post measurement entanglement entropy. Finally, we also provide some formulas regarding modular hamiltonians and entanglement spectrum in the after measurement systems. After through discussion regarding CFT systems we also provide some predictions regarding massive field theories. We then discuss a generic method to calculate the post measurement entanglement entropy in the free fermion systems. Using the method we study the post measurement entanglement entropy in the XY spin chain. We check numerically the CFT and the massive field theory results in the transverse field Ising chain and the XX model. In particular, we study the post meaurement entanglement entropy in the infinite, periodic and open critical transverse field Ising chain and the critical XX model. The effect of the temperature and the gap is also discussed in these models.
Entanglement dynamics in critical random quantum Ising chain with perturbations
Huang, Yichen
2017-05-01
We simulate the entanglement dynamics in a critical random quantum Ising chain with generic perturbations using the time-evolving block decimation algorithm. Starting from a product state, we observe super-logarithmic growth of entanglement entropy with time. The numerical result is consistent with the analytical prediction of Vosk and Altman using a real-space renormalization group technique.
Entanglement of two ground state neutral atoms using Rydberg blockade
DEFF Research Database (Denmark)
Miroshnychenko, Yevhen; Browaeys, Antoine; Evellin, Charles
2011-01-01
We report on our recent progress in trapping and manipulation of internal states of single neutral rubidium atoms in optical tweezers. We demonstrate the creation of an entangled state between two ground state atoms trapped in separate tweezers using the effect of Rydberg blockade. The quality...... of the entanglement is measured using global rotations of the internal states of both atoms....
Entanglement entropy after selective measurements in quantum chains
Energy Technology Data Exchange (ETDEWEB)
Najafi, Khadijeh [Department of Physics, Georgetown University,37th and O Sts. NW, Washington, DC 20057 (United States); Rajabpour, M.A. [Instituto de Física, Universidade Federal Fluminense,Av. Gal. Milton Tavares de Souza s/n, Gragoatá, 24210-346, Niterói, RJ (Brazil)
2016-12-22
We study bipartite post measurement entanglement entropy after selective measurements in quantum chains. We first study the quantity for the critical systems that can be described by conformal field theories. We find a connection between post measurement entanglement entropy and the Casimir energy of floating objects. Then we provide formulas for the post measurement entanglement entropy for open and finite temperature systems. We also comment on the Affleck-Ludwig boundary entropy in the context of the post measurement entanglement entropy. Finally, we also provide some formulas regarding modular hamiltonians and entanglement spectrum in the after measurement systems. After through discussion regarding CFT systems we also provide some predictions regarding massive field theories. We then discuss a generic method to calculate the post measurement entanglement entropy in the free fermion systems. Using the method we study the post measurement entanglement entropy in the XY spin chain. We check numerically the CFT and the massive field theory results in the transverse field Ising chain and the XX model. In particular, we study the post meaurement entanglement entropy in the infinite, periodic and open critical transverse field Ising chain and the critical XX model. The effect of the temperature and the gap is also discussed in these models.
An entanglement concentration protocol for cluster states using ...
Indian Academy of Sciences (India)
Permanent link: http://www.ias.ac.in/article/fulltext/pram/086/05/0973-0983 ... The purpose of this paper is a proposal on entanglement concentration protocol forcluster states. The protocol ... We also make a comparative numerical study of the residual entanglement left out after the execution of each step of the protocol.
Spin–spin entanglement in moving frames: Properties of negativity
Indian Academy of Sciences (India)
disadvantages, have been proposed. These proposals include the entanglement of forma- tion (concurrence) [17,18], entanglement of distillation .... the y-axis, normal to the direction of the boost; the x-axis (the normalization of eq. (7) is based on this assumption). For the state of eq. (8), the partially transposed density.
Dark Entangled Steady States of Interacting Rydberg Atoms
DEFF Research Database (Denmark)
Dasari, Durga; Mølmer, Klaus
2013-01-01
their short-lived excited states lead to rapid, dissipative formation of an entangled steady state. We show that for a wide range of physical parameters, this entangled state is formed on a time scale given by the strengths of coherent Raman and Rabi fields applied to the atoms, while it is only weakly...
Complete hierarchies of efficient approximations to problems in entanglement theory
International Nuclear Information System (INIS)
Eisert, Jens; Hyllus, Philipp; Guehne, Otfried; Curty, Marcos
2004-01-01
We investigate several problems in entanglement theory from the perspective of convex optimization. This list of problems comprises (A) the decision whether a state is multiparty entangled, (B) the minimization of expectation values of entanglement witnesses with respect to pure product states, (C) the closely related evaluation of the geometric measure of entanglement to quantify pure multiparty entanglement, (D) the test whether states are multiparty entangled on the basis of witnesses based on second moments and on the basis of linear entropic criteria, and (E) the evaluation of instances of maximal output purities of quantum channels. We show that these problems can be formulated as certain optimization problems: as polynomially constrained problems employing polynomials of degree 3 or less. We then apply very recently established known methods from the theory of semidefinite relaxations to the formulated optimization problems. By this construction we arrive at a hierarchy of efficiently solvable approximations to the solution, approximating the exact solution as closely as desired, in a way that is asymptotically complete. For example, this results in a hierarchy of efficiently decidable sufficient criteria for multiparticle entanglement, such that every entangled state will necessarily be detected in some step of the hierarchy. Finally, we present numerical examples to demonstrate the practical accessibility of this approach
Continuous variable entanglement distillation of non-Gaussian states
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Dong, Ruifang; Heersink, Joel
2009-01-01
We experimentally demonstrate distillation of continuous variable entangled light that has undergone non-Gaussian attenuation loss. The continuous variable entanglement is generated with optical fibers and sent through a lossy channel, where the transmission is varying in time. By employing simple...
Heralded generation of a micro-macro entangled state
DEFF Research Database (Denmark)
Andersen, Ulrik Lund; Neergaard-Nielsen, Jonas Schou
2013-01-01
Using different optical setups based on squeezed state and photon subtraction we show how optical entanglement between a macroscopic and a microscopic state-the so-called Schro¨dinger cat state or micro-macro state-can be generated. The entangled state is heralded and is thus produced a priori...
Self-healing of quantum entanglement after an obstruction
CSIR Research Space (South Africa)
McLaren, M
2014-02-01
Full Text Available Quantum entanglement between photon pairs is fragile and can easily be masked by losses in transmission path and noise in the detection system. When observing the quantum entanglement between the spatial states of photon pairs produced by parametric...
Joshanloo, Mohsen
2017-09-04
The tripartite model of mental well-being offers a comprehensive account of the nature of mental well-being. According to this model, mental well-being is composed of three distinct yet related dimensions of subjective (hedonic), psychological and social well-being. The present study investigated the structural and discriminant validity of the three well-being factors. A large American sample (N = 2732) was used. Data were analyzed using both Confirmatory Factor Analysis (CFA) and Exploratory Structural Equation Modeling (ESEM). It was found that the well-being variables loaded on three separate factors, indicating that the tripartite model was consistent with the data. Discriminant validity was further evidenced by moderate correlations between the latent factors, and differential relationships with the Big Five personality traits. ESEM proved to be a more appropriate approach for analyzing the data given the presence of cross-loadings. These results support adequate structural and discriminant validity for the dimensions of the tripartite model.
Martinuz, Alfonso; Zewdu, Getaneh; Ludwig, Nicole; Grundler, Florian; Sikora, Richard A; Schouten, Alexander
2015-04-01
The research demonstrated that Arabidopsis can be used as a model system for studying plant-nematode-endophyte tripartite interactions; thus, opening new possibilities for further characterizing the molecular mechanisms behind these interactions. Arabidopsis has been established as an important model system for studying plant biology and plant-microbe interactions. We show that this plant can also be used for studying the tripartite interactions among plants, the root-knot nematode Meloidogyne incognita and a beneficial endophytic isolate of Fusarium oxysporum, strain Fo162. In various plant species, Fo162 can systemically reduce M. incognita infection development and fecundity. Here it is shown that Fo162 can also colonize A. thaliana roots without causing disease symptoms, thus behaving as a typical endophyte. As observed for other plants, this endophyte could not migrate from the roots into the shoots and leaves. Direct inoculation of the leaves also did not result in colonization of the plant. A significant increase in plant fresh weight, root length and average root diameter was observed, suggesting the promotion of plant growth by the endophyte. The inoculation of A. thaliana with F. oxysporum strain Fo162 also resulted in a significant reduction in the number of M. incognita juveniles infecting the roots and ultimately the number of galls produced. This was also observed in a split-root experiment, in which the endophyte and nematode were spatially separated. The usefulness of Arabidopsis opens new possibilities for further dissecting complex tripartite interactions at the molecular and biochemical level.
Quantum entanglement for systems of identical bosons: I. General features
International Nuclear Information System (INIS)
Dalton, B J; Goold, J; Garraway, B M; Reid, M D
2017-01-01
These two accompanying papers are concerned with two mode entanglement for systems of identical massive bosons and the relationship to spin squeezing and other quantum correlation effects. Entanglement is a key quantum feature of composite systems in which the probabilities for joint measurements on the composite sub-systems are no longer determined from measurement probabilities on the separate sub-systems. There are many aspects of entanglement that can be studied. This two-part review focuses on the meaning of entanglement, the quantum paradoxes associated with entangled states, and the important tests that allow an experimentalist to determine whether a quantum state—in particular, one for massive bosons is entangled. An overall outcome of the review is to distinguish criteria (and hence experiments) for entanglement that fully utilize the symmetrization principle and the super-selection rules that can be applied to bosonic massive particles. In the first paper (I), the background is given for the meaning of entanglement in the context of systems of identical particles. For such systems, the requirement is that the relevant quantum density operators must satisfy the symmetrization principle and that global and local super-selection rules prohibit states in which there are coherences between differing particle numbers. The justification for these requirements is fully discussed. In the second quantization approach that is used, both the system and the sub-systems are modes (or sets of modes) rather than particles, particles being associated with different occupancies of the modes. The definition of entangled states is based on first defining the non-entangled states—after specifying which modes constitute the sub-systems. This work mainly focuses on the two mode entanglement for massive bosons, but is put in the context of tests of local hidden variable theories, where one may not be able to make the above restrictions. The review provides the detailed