10,309 research outputs found
Nested entangled states for distributed quantum channels
We find a coupling-strength configuration for a linear chain of N spins which
gives rise to simultaneous multiple Bell states. We suggest a way such an
interesting entanglement pattern can be used in order to distribute maximally
entangled channels to remote locations and generate multipartite entanglement
with a minimum-control approach. Our proposal thus provides a way to achieve
the core resources in distributed information processing. The schemes we
describe can be efficiently tested in chains of coupled cavities interacting
with three-level atoms.Comment: 4 pages, 2 figures, RevTeX
Quantum state transfer via temporal kicking of information
We propose a strategy for perfect state transfer in spin chains based on the
use of an unmodulated coupling Hamiltonian whose coefficients are explicitly
time dependent. We show that, if specific and non-demanding conditions are
satisfied by the temporal behavior of the coupling strengths, our model allows
perfect state transfer. The paradigma put forward by our proposal holds the
promises to set an alternative standard to the use of clever encoding and
coupling-strength engineering for perfect state transfer.Comment: 7 pages, 7 figures, RevTeX
Optimal path for a quantum teleportation protocol in entangled networks
Bellman's optimality principle has been of enormous importance in the
development of whole branches of applied mathematics, computer science, optimal
control theory, economics, decision making, and classical physics. Examples are
numerous: dynamic programming, Markov chains, stochastic dynamics, calculus of
variations, and the brachistochrone problem. Here we show that Bellman's
optimality principle is violated in a teleportation problem on a quantum
network. This implies that finding the optimal fidelity route for teleporting a
quantum state between two distant nodes on a quantum network with bi-partite
entanglement will be a tough problem and will require further investigation.Comment: 4 pages, 1 figure, RevTeX
Atmospheric Thermodynamic Profiling through the Use of a Micro-Pulse Raman Lidar System: Introducing the Compact Raman Lidar MARCO
It was for a long time believed that lidar systems based on the use of high-repetition micro-pulse lasers could be effectively used to only stimulate atmospheric elastic backscatter echoes, and thus were only exploited in elastic backscatter lidar systems. Their application to stimulate rotational and roto-vibrational Raman echoes, and consequently, their exploitation in atmospheric thermodynamic profiling, was considered not feasible based on the technical specifications possessed by these laser sources until a few years ago. However, recent technological advances in the design and development of micro-pulse lasers, presently achieving high UV average powers (1–5 W) and small divergences (0.3–0.5 mrad), in combination with the use of large aperture telescopes (0.3–0.4 m diameter primary mirrors), allow one to presently develop micro-pulse laser-based Raman lidars capable of measuring the vertical profiles of atmospheric thermodynamic parameters, namely water vapor and temperature, both in the daytime and night-time. This paper is aimed at demonstrating the feasibility of these measurements and at illustrating and discussing the high achievable performance level, with a specific focus on water vapor profile measurements. The technical solutions identified in the design of the lidar system and their technological implementation within the experimental setup of the lidar prototype are also carefully illustrated and discussed
Filamentation in Kerr media from pulsed Bessel beams
In contrast with filamentation of ultrashort laser pulses with standard Gaussian beams in Kerr media, three different types of Bessel filaments are obtained in air or in water by focusing ultrashort laser pulses with an axicon. We thoroughly investigate the different regimes and show that the beam reshapes as a nonlinear Bessel beam which establishes a conical energy flux from the low intensity tails toward the high intensity peak. This flux efficiently sustains a high contrast long-distance propagation and easily generates a continuous plasma channel in air
N=1 Matter from Fractional Branes
We study a bound state of fractional D3-branes localized inside the
world-volume of fractional D7-branes on the orbifold C^3/Z_2 x Z_2. We
determine the open string spectrum that leads to N=1 U(N1)xU(N2)xU(N3)xU(N4)
gauge theory with matter having the number of D7-branes as a flavor index. We
derive the linearized boundary action of the D7-brane on this orbifold using
the boundary state formalism and we discuss the tadpole cancellation. After
computing the asymptotic expression of the supergravity solution the anomalies
of the gauge theory are reproduced.Comment: LaTeX 20 pages, 1 figure, small changes and references adde
Perfect state transfer on a spin-chain without state initialization
We demonstrate that perfect state transfer can be achieved using an
engineered spin chain and clean local end-chain operations, without requiring
the initialization of the state of the medium nor fine tuning of
control-pulses. This considerably relaxes the prerequisites for obtaining
reliable transfer of quantum information across interacting-spin systems.
Moreover, it allows us to shed light on the interplay among purity,
entanglement and operations on a class of many-body systems potentially useful
for quantum information processing tasks.Comment: 5 pages, 1 figure, RevTeX
Hamiltonian Determination with Restricted Access in Transverse Field Ising Chain
We propose a method to evaluate parameters in the Hamiltonian of the Ising
chain under site-dependent transverse fields, with a proviso that we can
control and measure one of the edge spins only. We evaluate the eigenvalues of
the Hamiltonian and the time-evoultion operator exactly for a 3-spin chain,
from which we obtain the expectation values of of the first spin.
The parameters are found from the peak positions of the Fourier transform of
the expectation value. There are four assumptions in our method, which are mild
enough to be satisfied in many physical systems.Comment: 15pages, 4 figure
Development and validation of a clinical and computerised Decision Support System for Management of Hypertension (DSS-HTN) at a Primary Health Care (PHC) setting
Background: Hypertension remains the top global cause of disease burden. Decision support systems (DSS) could provide an adequate and cost-effective m
Project "Biodiversity MARE Tricase": a biodiversity inventory of the coastal area of Tricase (Ionian Sea, Italy) – Mollusca: Heterobranchia
The marine biodiversity of the Tricase coastal area (Ionian Sea, Italy) was investigated at the MARE Outpost (Avamposto MARE) between 2016 and 2017, with the help of citizen scientists and trained taxonomists. Among the most interesting groups encountered, heterobranch molluscs deserve a special mention. Altogether, 268 specimens were ascribed to this group and referred to 49 taxa. Notwithstanding the extensive literature on Mediterranean heterobranchs, two species proved to be new to the Italian coasts, the records of eight species represented their easternmost sightings in the Mediterranean Sea, and 13 taxa represented new records for the Ionian Sea. In addition, several feeding habits and phenological events were new to science. Although the European Union's Marine Strategy Framework Directive lists "Biodiversity is maintained" as the first descriptor in achieving "Good Environmental Status", our results highlighted the presence of conspicuous gaps in the knowledge of species distribution, taxonomy and ecology of heterobranch molluscs, indicating the necessity of even small-scale species checklists to understand biodiversity changes in worldwide biota
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