1,321 research outputs found

    A Note on 1-Edge Balance Index Set

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    A graph labeling is an assignment of integers to the vertices or edges or both, subject to certain conditions. Varieties of graph labeling have been investigated by many authors [2], [3] [5] and they serve as useful models for broad range of applications

    Enhancement of Geometric Phase by Frustration of Decoherence: A Parrondo like Effect

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    Geometric phase plays an important role in evolution of pure or mixed quantum states. However, when a system undergoes decoherence the development of geometric phase may be inhibited. Here, we show that when a quantum system interacts with two competing environments there can be enhancement of geometric phase. This effect is akin to Parrondo like effect on the geometric phase which results from quantum frustration of decoherence. Our result suggests that the mechanism of two competing decoherence can be useful in fault-tolerant holonomic quantum computation.Comment: 5 pages, 3 figures, Published versio

    On pseudo-hyperk\"ahler prepotentials

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    An explicit surjection from a set of (locally defined) unconstrained holomorphic functions on a certain submanifold of (Sp_1(C) \times C^{4n}) onto the set HK_{p,q} of local isometry classes of real analytic pseudo-hyperk\"ahler metrics of signature (4p,4q) in dimension 4n is constructed. The holomorphic functions, called prepotentials, are analogues of K\"ahler potentials for K\"ahler metrics and provide a complete parameterisation of HK_{p,q}. In particular, there exists a bijection between HK_{p,q} and the set of equivalence classes of prepotentials. This affords the explicit construction of pseudo-hyperk\"ahler metrics from specified prepotentials. The construction generalises one due to Galperin, Ivanov, Ogievetsky and Sokatchev. Their work is given a coordinate-free formulation and complete, self-contained proofs are provided. An appendix provides a vital tool for this construction: a reformulation of real analytic G-structures in terms of holomorphic frame fields on complex manifolds.Comment: 53 pages; v2: minor amendments to Def.4.1 and Theorem 4.5; a paragraph inserted in the proof of the latter; V3: minor changes; V4: minor changes/ typos corrected for journal versio

    Generic quantum walk using a coin-embedded shift operator

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    The study of quantum walk processes has been widely divided into two standard variants, the discrete-time quantum walk (DTQW) and the continuous-time quantum walk (CTQW). The connection between the two variants has been established by considering the limiting value of the coin operation parameter in the DTQW, and the coin degree of freedom was shown to be unnecessary [26]. But the coin degree of freedom is an additional resource which can be exploited to control the dynamics of the QW process. In this paper we present a generic quantum walk model using a quantum coin-embedded unitary shift operation UCU_{C}. The standard version of the DTQW and the CTQW can be conveniently retrieved from this generic model, retaining the features of the coin degree of freedom in both variants.Comment: 5 pages, 1 figure, Publishe

    Disordered quantum walk-induced localization of a Bose-Einstein condensate

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    We present an approach to induce localization of a Bose-Einstein condensate in a one-dimensional lattice under the influence of unitary quantum walk evolution using disordered quantum coin operation. We introduce a discrete-time quantum walk model in which the interference effect is modified to diffuse or strongly localize the probability distribution of the particle by assigning a different set of coin parameters picked randomly for each step of the walk, respectively. Spatial localization of the particle/state is explained by comparing the variance of the probability distribution of the quantum walk in position space using disordered coin operation to that of the walk using an identical coin operation for each step. Due to the high degree of control over quantum coin operation and most of the system parameters, ultracold atoms in an optical lattice offer opportunities to implement a disordered quantum walk that is unitary and induces localization. Here we present a scheme to use a Bose-Einstein condensate that can be evolved to the superposition of its internal states in an optical lattice and control the dynamics of atoms to observe localization. This approach can be adopted to any other physical system in which controlled disordered quantum walk can be implemented.Comment: 6 pages, 4 figures, published versio

    Optimizing the discrete time quantum walk using a SU(2) coin

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    We present a generalized version of the discrete time quantum walk, using the SU(2) operation as the quantum coin. By varying the coin parameters, the quantum walk can be optimized for maximum variance subject to the functional form σ2N2\sigma^2 \approx N^2 and the probability distribution in the position space can be biased. We also discuss the variation in measurement entropy with the variation of the parameters in the SU(2) coin. Exploiting this we show how quantum walk can be optimized for improving mixing time in an nn-cycle and for quantum walk search.Comment: 6 pages, 6 figure

    Quantumness of noisy quantum walks: a comparison between measurement-induced disturbance and quantum discord

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    Noisy quantum walks are studied from the perspective of comparing their quantumness as defined by two popular measures, measurement-induced disturbance (MID) and quantum discord (QD). While the former has an operational definition, unlike the latter, it also tends to overestimate non-classicality because of a lack of optimization over local measurements. Applied to quantum walks, we find that MID, while acting as a loose upper bound on QD, still tends to reflect correctly the trends in the behavior of the latter. However, there are regimes where its behavior is not indicative of non-classicality: in particular, we find an instance where MID increases with the application of noise, where we expect a reduction of quantumness.Comment: 5 pages with 4 figures, Published Versio

    Generation of hyperentangled states and two-dimensional quantum walks using JJ- (qq)- plates and polarization beamsplitters

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    A single photon can be made to entangle simultaneously in its different internal degrees of freedom (DoF) -- polarization, orbital angular momentum (OAM), and frequency -- as well as in its external DoF -- path. Such entanglement in multiple DoF is known as hyperentanglement and provide additional advantage for quantum information processing. We propose a passive optical setup using qq-plates and polarization beamsplitters to hyperentangle an incoming single photon in polarization, OAM, and path DoF. By mapping polarization DoF to a two-dimensional coin state, and path and OAM DoF to two spatial dimensions, xx and yy, we present a scheme for realization of two-dimensional discrete-time quantum walk using only polarization beamsplitters and qq-plates ensuing the generation of hyperentangled states. The amount of hyperentanglement generated is quantified by measuring the entanglement negativity between any two DoF. We further show the hyperentanglement generation can be controlled by using an additional coin operation or by replacing the qq-plate with a JJ-plate.Comment: A new appendix has been included, where Jones matrices are realized using JJ-plates and variable waveplate

    Decoherence on a two-dimensional quantum walk using four- and two-state particle

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    We study the decoherence effects originating from state flipping and depolarization for two-dimensional discrete-time quantum walks using four-state and two-state particles. By quantifying the quantum correlations between the particle and position degree of freedom and between the two spatial (xyx-y) degrees of freedom using measurement induced disturbance (MID), we show that the two schemes using a two-state particle are more robust against decoherence than the Grover walk, which uses a four-state particle. We also show that the symmetries which hold for two-state quantum walks breakdown for the Grover walk, adding to the various other advantages of using two-state particles over four-state particles.Comment: 12 pages, 16 figures, In Press, J. Phys. A: Math. Theor. (2013

    Assessing an Information Systems Master\u27s Curriculum Program: Revisiting the ACM\u27s MSIS 2006 Model Curriculum

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    The field of Information systems continues to change dynamically with the painful impact for reacting to those changes felt by both undergraduate and masters’ level programs. The purpose of this paper is to report the results of a comparative selfstudy of one MSIS program as a measure to assess its competitiveness among a set of other comparable, competitive and aspirant masters’ programs. The focus of the study is determine the viability of one specific master’s curriculum used currently to prepare students for professional careers in information systems in order to meet the marketplace challenges created by the ever-evolving information systems business needs. The fundamental methodology used in this study is based on that which was employed in a previous study conducted to assess the ‘fit’ of 86 MSIS programs with the MSIS 2000 Model Curriculum (Vijayaraman, et.al.) Findings will be presented that reflect shared learning objectives, curriculum content, currency, and relevancy necessary to assess whether changes to the current curriculum are necessary to establish a more competitive position among the three categories of comparable, competitive and aspirant university MSIS programs. One benefit that resulted from this initiative is the recognition that there has been relatively little research directed at assessing the overall direction of current MSIS programs and the need to revisit the need for a new MSIS model curriculum. The last endorsed MSIS model curriculum was published in 2006 (Gorgone, et.al. 2006), almost 10 years ago. It is the hope of presenting the results of this study that a discussion can begin to address the challenge of maintaining a viable MSIS curriculum that meets the current and future demands of the business communit
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