Authors:Nicola Dalla Pozza, Matteo G. A. Paris Abstract: International Journal of Quantum Information, Volume 15, Issue 04, June 2017. We revisit the problem of finding the Naimark extension of a probability operator-valued measure (POVM), i.e. its implementation as a projective measurement in a larger Hilbert space. In particular, we suggest an iterative method to build the projective measurement from the sole requirements of orthogonality and positivity. Our method improves existing ones, as it may be employed also to extend POVMs containing elements with rank larger than one. It is also more effective in terms of computational steps. Citation: International Journal of Quantum Information PubDate: 2017-06-22T06:29:41Z DOI: 10.1142/S0219749917500290

Authors:Shahrokh Heidari, Mohammad Rasoul Pourarian, Reza Gheibi, Mosayeb Naseri, Monireh Houshmand Abstract: International Journal of Quantum Information, Ahead of Print. One of the most considering matters in the field of quantum information processing is quantum data hiding including quantum steganography and quantum watermarking. This field is an efficient tool for protecting any kind of digital data. In this paper, three quantum color images steganography algorithms are investigated based on Least Significant Bit (LSB). The first algorithm employs only one of the image’s channels to cover secret data. The second procedure is based on LSB XORing technique, and the last algorithm utilizes two channels to cover the color image for hiding secret quantum data. The performances of the proposed schemes are analyzed by using software simulations in MATLAB environment. The analysis of PSNR, BER and Histogram graphs indicate that the presented schemes exhibit acceptable performances and also theoretical analysis demonstrates that the networks complexity of the approaches scales squarely. Citation: International Journal of Quantum Information PubDate: 2017-08-01T08:36:12Z DOI: 10.1142/S0219749917500393

Authors:Lionel Tenemeza Kenfack, Martin Tchoffo, Georges Collince Fouokeng, Lukong Cornelius Fai Abstract: International Journal of Quantum Information, Ahead of Print. In the present paper, the joint effects of two kinds of classical environmental noises, without direct interaction among each other, on the dynamics of quantum correlations (QCs) of a three-qubit system coupled in independent environments is investigated. More precisely, we join the random telegraph noise (RTN) and the static noise (SN) and focus on the dynamics of entanglement and quantum discord (QD) when the qubits are initially prepared in the GHZ- and W-type states. The overall noise affecting the qubits is obtained by combining the RTN and SN in two different setups. The results show that the disorder of the environmental noise as well as its memory qualities and the purity of the initial state considered play a crucial role in the time evolution of the system in such a way that the dynamics of QCs can be controlled by varying them. In fact, we show that, depending on the initial state and noise regime considered, the rate of collapse of QCs may either decrease or increase with the increase of the degree of disorder of the SN, the switching rate of the RTN and the purity of the initial state. Citation: International Journal of Quantum Information PubDate: 2017-07-25T08:10:06Z DOI: 10.1142/S0219749917500381

Authors:Salvatore Lorenzo, Tony J. G. Apollaro, Andrea Trombettoni, Simone Paganelli Abstract: International Journal of Quantum Information, Ahead of Print. In this paper we discuss the implementation of 2-qubit quantum state transfer (QST) in inhomogeneous spin chains where the sender and the receiver blocks are coupled through the bulk channel via weak links. The fidelity and the typical timescale of the QST are discussed as a function of the parameters of the weak links. Given the possibility of implementing with cold atoms in optical lattices a variety of condensed matter systems, including spin systems, we also discuss the possible implementation of the discussed 2-qubit QST with cold gases with weak links, together with a discussion of the applications and limitations of the presented results. Citation: International Journal of Quantum Information PubDate: 2017-07-20T05:47:15Z DOI: 10.1142/S021974991750037X

Authors:Katarzyna Bolonek-Lasoń Abstract: International Journal of Quantum Information, Ahead of Print. The explicit construction is presented of two-player game satisfying: (i) symmetry with respect to the permutation of the players; (ii) the existence of upper bound on total payoff following from Bell inequality; (iii) the existence of unfair equilibrium with total payoff saturating the above bound. The quantum counterpart of the game is considered which possesses only fair equilibria and strategies outperforming the classical ones. Citation: International Journal of Quantum Information PubDate: 2017-07-13T03:16:45Z DOI: 10.1142/S0219749917500332

Authors:Feng-Ming Liu, Mei-Ling Jin Abstract: International Journal of Quantum Information, Ahead of Print. The research on information quantization is important in the field of information theory. As a result, based on the quantum theory, the information was quantified from the information receiving aspect in this report. First of all, several concepts were presented, such as the InfoBar, the Amount of Information and the Power of Information as well as the algorithm of the Power of Information. Then, according to the relationship between the InfoBar and the amount of Information, the wave equation was decided based on the receiving information, meanwhile, the equation of wave function was defined as well. Finally, via the numerical simulation, the received model results as well as the sample result were basically matched. Thus, the validity of the model can be proved. Citation: International Journal of Quantum Information PubDate: 2017-07-13T03:16:45Z DOI: 10.1142/S0219749917500368

Authors:Haozhen Situ, Ramón Alonso-Sanz, Lvzhou Li, Cai Zhang Abstract: International Journal of Quantum Information, Ahead of Print. Recently, the first conflicting interest quantum game based on the nonlocality property of quantum mechanics has been introduced in A. Pappa, N. Kumar, T. Lawson, M. Santha, S. Y. Zhang, E. Diamanti and I. Kerenidis, Phys. Rev. Lett. 114 (2015) 020401. Several quantum games of the same genre have also been proposed subsequently. However, these games are constructed from some well-known Bell inequalities, thus are quite abstract and lack of realistic interpretations. In the present paper, we modify the common interest land bidding game introduced in N. Brunner and N. Linden, Nat. Commun. 4 (2013) 2057, which is also based on nonlocality and can be understood as two companies collaborating in developing a project. The modified game has conflicting interest and reflects the free rider problem in economics. Then we show that it has a fair quantum solution that leads to better outcome. Finally, we study how several types of paradigmatic noise affect the outcome of this game. Citation: International Journal of Quantum Information PubDate: 2017-07-07T03:08:39Z DOI: 10.1142/S0219749917500344

Authors:Ihab H. Naeim, J. Batle, S. Abdalla, A. Farouk Abstract: International Journal of Quantum Information, Ahead of Print. We study the nonlocality dynamics for an eight-qubit model in cavity QED, where four atoms are confined in four different cavities, all of them initially prepared in the maximally correlated state of four qubits, which corresponds to the atomic degrees of freedom. The nonlocality evolution for the latter states will show that the corresponding maximal violation of a multipartite Bell inequality will experience revivals at precise times, defining, in analogy with entanglement, nonlocality sudden deaths, as well as nonlocality sudden rebirths. The present contribution paves the way to describe, by employing the nonlocality multipartite correlation measure, collective complex behavior displayed by slightly interacting cavity QED arrays. Citation: International Journal of Quantum Information PubDate: 2017-06-30T08:40:38Z DOI: 10.1142/S0219749917500356

Authors:M. Bendahane, M. El Atiki, A. Kassou-Ou-Ali Abstract: International Journal of Quantum Information, Ahead of Print. In this work, we study the wave particle duality and the Aharonov–Bohm effect in a Mach–Zehnder interferometer in a magnetic field which is in a superposition of two opposite directions. In addition, a “classical” experimental scheme is proposed which mimics such an interferometer. Citation: International Journal of Quantum Information PubDate: 2017-06-29T04:24:39Z DOI: 10.1142/S0219749917500320

Authors:C. Cruz Abstract: International Journal of Quantum Information, Ahead of Print. The characterization of quantum information quantifiers has attracted a considerable attention of the scientific community, since they are a useful tool to verify the presence of quantum correlations in a quantum system. In this context, in the present work we show a theoretical study of some quantifiers, such as entanglement witness, entanglement of formation, Bell’s inequality violation and geometric quantum discord as a function of the diffractive properties of neutron scattering. We provide one path toward identifying the presence of quantum correlations and quantum nonlocality in a molecular magnet as a Heisenberg spin-[math] dimer, by diffractive properties typically obtained via neutron scattering experiments. Citation: International Journal of Quantum Information PubDate: 2017-06-13T07:42:34Z DOI: 10.1142/S0219749917500319

Authors:Thiago Prudêncio Abstract: International Journal of Quantum Information, Ahead of Print. Generation of Aharonov–Bohm (AB) phase has achieved a state-of-the-art in mesoscopic systems with manipulation and control of the AB effect. The possibility of transfer information encoded in such systems to nonclassical states of light increases the possible scenarios where the information can be manipulated and transferred. In this paper, we propose a quantum transfer of the AB phase generated in a spintronic device, a topological spin transistor (TST), to an quantum optical device, a coherent state superposition in high-Q cavity and discuss optical and spin-optical superpositions in the presence of an AB phase. We demonstrate that the AB phase generated in the TST can be transferred to the coherent state superposition, considering the interaction with the spin state and the quantum optical manipulation of the coherent state superposition. We show that these cases provide examples of two-qubit states modulated by AB effect and that the phase parameter can be used to control the degree of rotation of the qubit state. We also show under a measurement on the spin basis, an optical one-qubit state that can be modulated by the AB effect. In these cases, we consider a dispersive interaction between a coherent state and a spin state with an acquired AB phase and also discuss a dissipative case where a given Lindblad equation is achieved and solved. Citation: International Journal of Quantum Information PubDate: 2017-06-12T08:08:56Z DOI: 10.1142/S0219749917500289

Authors:Frédéric Holweck, Metod Saniga Abstract: International Journal of Quantum Information, Ahead of Print. We investigate small geometric configurations that furnish observable-based proofs of the Kochen–Specker theorem. Assuming that each context consists of the same number of observables and each observable is shared by two contexts, it is proved that the most economical proofs are the famous Mermin–Peres square and the Mermin pentagram featuring, respectively, 9 and 10 observables, there being no proofs using less than 9 observables. We also propose a new proof with 14 observables forming a “magic” heptagram. On the other hand, some other prominent small-size finite geometries, like the Pasch configuration and the prism, are shown not to be contextual. Citation: International Journal of Quantum Information PubDate: 2017-06-12T08:08:54Z DOI: 10.1142/S0219749917500265

Authors:Kan He, Dahong Wei, Li Wang Abstract: International Journal of Quantum Information, Ahead of Print. In this paper, we extend existing variance-based sum uncertainty relations for pure states to those for mixed states by a mathematical approach. Furthermore, we show that the monotonicity of the standard deviation of observables induces a variance-based sum uncertainty relation. Finally, the multiobservable case is also discussed. Citation: International Journal of Quantum Information PubDate: 2017-06-07T06:27:18Z DOI: 10.1142/S0219749917500307

Authors:Liang Qiu, Fei Pan, Zhi Liu Abstract: International Journal of Quantum Information, Ahead of Print. We construct the tripartite Bell-type inequalities of product states for [math]-norm of coherence, relative entropy of coherence and skew information. We give examples of three-qubit entangled states that violate these inequalities. Particularly, the tripartite Bell-type inequality for relative entropy of coherence is always violated by the W class pure or mixed states as well as the GHZ class pure or mixed states, being used as entanglement witness. Citation: International Journal of Quantum Information PubDate: 2017-06-06T03:25:52Z DOI: 10.1142/S0219749917500253

Authors:W.-J. Wu, K. Yan, Y.-Q. Xie, Yinzhong Wu, Xiang Hao Abstract: International Journal of Quantum Information, Ahead of Print. We put forward a measure for evaluating quantum speed limit for arbitrary mixed states of open systems by means of trace distance. Compared with some present measures, it can provide an optimal bound to the speed of the evolution. The dynamical crossover from no speedup region to speedup region happens during the spontaneous decay of an atom. The evolution is characteristic of the alternating behavior between quantum acceleration and deceleration in the strong coupling case. Under the condition of detuning, the evolution can be initially accelerated and then decelerated to a normal process either in the weak or strong coupling regime. In accordance with the uncertainty relation, we demonstrate that the potential capacity for quantum speedup evolution is closely related to the energy feedback from the reservoir to the system. The negative decay rate for the evolution results in the speedup process where the photons previously emitted by the atom are reabsorbed at a later time. The values of the spontaneous decay rate become positive after a long enough time, which results in the evolution with no speedup potential. Citation: International Journal of Quantum Information PubDate: 2017-06-06T03:25:46Z DOI: 10.1142/S0219749917500277

Authors:Majid Haghparast, Neda Dousttalab Abstract: International Journal of Quantum Information, Ahead of Print. Multi-valued quantum operations have several advantages over binary operators. They decrease the number of essential data sending lines dramatically, which reduces the internal connections and thus can improve the circuit efficiency. In this paper, new reversible quaternary flip-flops are proposed which decrease the number of internal connectors and complexity of the circuits. So, the speed of circuits is increased. The implementation of synchronous sequential circuits requires memory elements. The proposed flip-flops need solely one memory element. Citation: International Journal of Quantum Information PubDate: 2017-05-23T01:00:04Z DOI: 10.1142/S0219749917500241

Authors:Hussein Abulkasim, Safwat Hamad, Amal Khalifa, Khalid El Bahnasy Abstract: International Journal of Quantum Information, Ahead of Print. Quantum secret sharing techniques allow two parties or more to securely share a key, while the same number of parties or less can efficiently deduce the secret key. In this paper, we propose an authenticated quantum secret sharing protocol, where a quantum dialogue protocol is adopted to authenticate the identity of the parties. The participants simultaneously authenticate the identity of each other based on parts of a prior shared key. Moreover, the whole prior shared key can be reused for deducing the secret data. Although the proposed scheme does not significantly improve the efficiency performance, it is more secure compared to some existing quantum secret sharing scheme due to the identity authentication process. In addition, the proposed scheme can stand against participant attack, man-in-the-middle attack, impersonation attack, Trojan-horse attack as well as information leaks. Citation: International Journal of Quantum Information PubDate: 2017-05-04T03:18:19Z DOI: 10.1142/S021974991750023X