Quantum walk on distinguishable non-interacting many-particles and indistinguishable two-particle

We present an investigation of many-particle quantum walks in systems of non-interacting distinguishable particles. Along with a redistribution of the many-particle density profile we show that the collective evolution of the many-particle system resembles the single-particle quantum walk evolution when the number of steps is greater than the number of particles in the system. For non-uniform initial states we show that the quantum walks can be effectively used to separate the basis states of the particle in position space and grouping like state together. We also discuss a two-particle quantum walk on a two- dimensional lattice and demonstrate an evolution leading to the localization of both particles at the center of the lattice. Finally we discuss the outcome of a quantum walk of two indistinguishable particles interacting at some point during the evolution.Comment: 8 pages, 7 figures, To appear in special issue: "quantum walks" to be published in Quantum Information Processin

Discrete-time quantum walks on one-dimensional lattices

In this paper, we study discrete-time quantum walks on one-dimensional lattices. We find that the coherent dynamics depends on the initial states and coin parameters. For infinite size of lattice, we derive an explicit expression for the return probability, which shows scaling behavior $P(0,t)\sim t^{-1}$ and does not depends on the initial states of the walk. In the long-time limit, the probability distribution shows various patterns, depending on the initial states, coin parameters and the lattice size. The average mixing time $M_{\epsilon}$ closes to the limiting probability in linear $N$ (size of the lattice) for large values of thresholds $\epsilon$. Finally, we introduce another kind of quantum walk on infinite or even-numbered size of lattices, and show that the walk is equivalent to the traditional quantum walk with symmetrical initial state and coin parameter.Comment: 17 pages research not

Quantum walks: a comprehensive review

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

Distribution and risk factors associated with Babesia spp. infection in hunting dogs from Southern Italy

Canine babesiosis is caused by haemoprotozoan organisms of the genus Babesia which are transmitted by the bite of a hard tick. The aim of this survey was to determine the prevalence and risk factors associated with Babesia species infections in hunting dogs from Southern Italy. Blood samples were collected from 1311 healthy dogs in the Napoli, Avellino and Salerno provinces of the Campania region of Southern Italy. Serological testing was performed using two enzyme-linked immunosorbent assays (ELISA), with one designed to detect B. canis and B. vogeli antibodies, and the other designed to detect B. gibsoni antibodies. Blood samples were also tested by quantitative real-time polymerase chain reaction (qPCR) assays for amplification of B. canis, B. vogeli and B. gibsoni DNA. The overall seroprevalence for B. canis/B. vogeli was 14.0%, compared to 0.2% for B. gibsoni. B. canis and B. vogeli PCR positive rates were 0.15% and 1.1%, respectively. B. gibsoni DNA was not amplified by qPCR. Male gender (OR 1.85), increased age (OR 1.01), long hair coat (OR 1.61) and living in Salerno province (OR 1.71) represented risk factors for B. canis/B. vogeli seroreactivity. Hunting dogs in Southern Italy are often exposed to B. canis/B. vogeli, however Babesia spp. infection was infrequently detected using qPCR. Further studies are needed to determine the extent to which Babesia spp. cause clinical disease in hunting dogs, and to evaluate the potential epidemiological relationships between hunting dogs and wild animal populations sharing the same area

Optimal strategies to infer the width of an infinite square well by performing measurements on the particle(s) contained in the well

We seek the optimal strategy to infer the width a of an infinite potential well by performing measurements on the particle(s) contained in the well. In particular, we address quantum estimation theory as the proper framework to formulate the problem and to determine the optimal quantum measurement, as well as to evaluate the ultimate bounds to precision. Our results show that in a static framework the best strategy is to measure position on a delocalized particle, corresponding to a width-independent quantum signal-to-noise ratio (QSNR), which increases with delocalisation. Upon considering time-evolution inside the well, we find that QSNR increases with time as t(2) (at least for small t). On the other hand, it decreases with a and thus time-evolution is a metrological resource only when the width is not too large compared to the available time evolution. Finally, we consider entangled particles in the well and observe super-additivity of the QSNR: it is the sum of the single-particle QSNRs, plus a positive definite term, which depends on their preparation and may increase with the number of entangled particles. Overall, entanglement represents a resource for the precise characterization of potential wells