5,823 research outputs found
Entanglement generation in spatially separated systems using quantum walk
We present a novel scheme to generate entanglement between two spatially
separated systems. The scheme makes use of spatial entanglement generated by a
single-particle quantum walk which is used to entangle two spatially separated,
not necessarily correlated, systems. This scheme can be used to entangle any
two systems which can interact with the spatial modes entangled during the
quantum walk evolution. A notable feature is that we can control the quantum
walk dynamics and its ability to localize leads to a substantial control and
improvement in the entanglement output.Comment: 9 pages, 5 figure
Dead Time Compensation for High-Flux Ranging
Dead time effects have been considered a major limitation for fast data
acquisition in various time-correlated single photon counting applications,
since a commonly adopted approach for dead time mitigation is to operate in the
low-flux regime where dead time effects can be ignored. Through the application
of lidar ranging, this work explores the empirical distribution of detection
times in the presence of dead time and demonstrates that an accurate
statistical model can result in reduced ranging error with shorter data
acquisition time when operating in the high-flux regime. Specifically, we show
that the empirical distribution of detection times converges to the stationary
distribution of a Markov chain. Depth estimation can then be performed by
passing the empirical distribution through a filter matched to the stationary
distribution. Moreover, based on the Markov chain model, we formulate the
recovery of arrival distribution from detection distribution as a nonlinear
inverse problem and solve it via provably convergent mathematical optimization.
By comparing per-detection Fisher information for depth estimation from high-
and low-flux detection time distributions, we provide an analytical basis for
possible improvement of ranging performance resulting from the presence of dead
time. Finally, we demonstrate the effectiveness of our formulation and
algorithm via simulations of lidar ranging.Comment: Revision with added estimation results, references, and figures, and
modified appendice
Nuclear Matter in Intense Magnetic Field and Weak Processes
We study the effect of magnetic field on the dominant neutrino emission
processes in neutron stars.The processes are first calculated for the case when
the magnetic field does not exceed the critical value to confine electrons to
the lowest Landau state.We then consider the more important case of intense
magnetic field to evaluate the direct URCA and the neutronisation processes. In
order to estimate the effect we derive the composition of cold nuclear matter
at high densities and in beta equilibrium, a situation appropriate for neutron
stars. The hadronic interactions are incorporated through the exchange of
scalar and vector mesons in the frame work of relativistic mean field theory.
In addition the effects of anomalous magnetic moments of nucleons are also
considered.Comment: 29 pages (LaTeX) including 7 figure
Spice bioactives in edible packaging
Edible packaging received significant attention in recent years. The main advantage of edible packaging over synthetic packaging is that they are environment friendly. The material used in edible packaging (lipids, polysaccharides, proteins) is generally recognized as safe and it acts as a barrier to gases, light and moisture. Spices have been traditionally used for its medicinal value. Spice extract or its essential oil possesses various bioactive compounds which are known for their antioxidant and antimicrobial property. Incorporation of spice extract or its essential oil into edible packaging exerts antimicrobial activity against the food pathogens thus preventing food spoilage and enhances the shelf-life and also increases the nutritional value of the final product. Antioxidant properties of spices retard the lipid oxidation. Dietary allergy and intolerance are also associated with packaging material and spices. Because of the high cost of film-forming material, scaling-up of edible packaging has remained a problem
Young stellar population and ongoing star formation in the HII complex Sh2-252
In this paper an extensive survey of the star forming complex Sh2-252 has
been undertaken with an aim to explore its hidden young stellar population as
well as to understand the structure and star formation history. This complex is
composed of five embedded clusters associated with the sub-regions A, C, E, NGC
2175s and Teu 136. Using 2MASS-NIR and Spitzer-IRAC, MIPS photometry we
identified 577 young stellar objects (YSOs), of which, 163 are Class I, 400 are
Class II and 14 are transition disk YSOs. Spatial distribution of the candidate
YSOs shows that they are mostly clustered around the sub-regions in the western
half of the complex, suggesting enhanced star formation activity towards its
west. Using the spectral energy distribution and optical colour-magnitude
diagram based age analyses, we derived probable evolutionary status of the
sub-regions of Sh2-252. Our analysis shows that the region A is the youngest (~
0.5 Myr), the regions B, C and E are of similar evolutionary stage (~ 1-2 Myr)
and the clusters NGC 2175s and Teu 136 are slightly evolved (~ 2-3 Myr).
Morphology of the region in the 1.1 mm map shows a semi-circular shaped
molecular shell composed of several clumps and YSOs bordering the western
ionization front of Sh2-252. Our analyses suggest that next generation star
formation is currently under way along this border and that possibly
fragmentation of the matter collected during the expansion of the HII region as
one of the major processes responsible for such stars. We observed the densest
concentration of YSOs (mostly Class I, ~ 0.5 Myr) at the western outskirts of
the complex, within a molecular clump associated with water and methanol masers
and we suggest that it is indeed a site of cluster formation at a very early
evolutionary stage, sandwiched between the two relatively evolved CHII regions
A and B.Comment: 19 pages, 13 figures, Accepted for publication in MNRA
Hybrid Stars
Recently there have been important developments in the determination of
neutron star masses which put severe constraints on the composition and
equation of state (EOS) of the neutron star matter. Here we study the effect of
quark and nuclear matter mixed phase on mass radius relationship of neutron
stars employing recent models from two classes of EOS's and discuss their
implications.Comment: 3 pages LaTeX including 2 figures, macros included, Talk presented at
the IX International Symposium on Particles, Strings and Cosmology
(PASCOS'03), TIFR, Mumbai, India, January 3-8,2003. To appear in their
proceeding
Search for TeV -rays from H1426+428 during 2004-07 with the TACTIC telescope
The BL Lac object H1426+428 () is an established source of TeV
-rays and detections of these photons from this object also have
important implications for estimating the Extragalactic Background Light (EBL)
in addition to the understanding of the particle acceleration and -ray
production mechanisms in the AGN jets. We have observed this source for about
244h in 2004, 2006 and 2007 with the TACTIC -ray telescope located at
Mt. Abu, India. Detailed analysis of these data do not indicate the presence of
any statistically significant TeV -ray signal from the source
direction. Accordingly, we have placed an upper limit of
on the integrated
-ray flux at 3 significance level.Comment: 11 pages, 5 figures accepted for publication in Journal of Physics G:
Nuclear and Particle Physic
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