168 research outputs found
Experimental implementation of a NMR entanglement witness
Entanglement witnesses (EW) allow the detection of entanglement in a quantum
system, from the measurement of some few observables. They do not require the
complete determination of the quantum state, which is regarded as a main
advantage. On this paper it is experimentally analyzed an entanglement witness
recently proposed in the context of Nuclear Magnetic Resonance (NMR)
experiments to test it in some Bell-diagonal states. We also propose some
optimal entanglement witness for Bell-diagonal states. The efficiency of the
two types of EW's are compared to a measure of entanglement with tomographic
cost, the generalized robustness of entanglement. It is used a GRAPE algorithm
to produce an entangled state which is out of the detection region of the EW
for Bell-diagonal states. Upon relaxation, the results show that there is a
region in which both EW fails, whereas the generalized robustness still shows
entanglement, but with the entanglement witness proposed here with a better
performance
Inter-Colony Comparison of Diving Behavior of an Arctic Top Predator: Implications for Warming in the Greenland Sea
The goal of this study was to assess how diverse oceanographic conditions and prey communities affect the foraging behavior of little auks Alle alle. The Greenland Sea is characterized by 3 distinct water masses: (1) the East Greenland Current (EGC), which carries Arctic waters southward; (2) the Sørkapp Current (SC), which originates in the Arctic Ocean but flows north along the west coast of Spitsbergen; and (3) the West Spitsbergen Current (WSC), which carries warm Atlantic-derived water north. Each of these 3 water masses is characterized by a distinct mesozooplankton community. Little auks breeding adjacent to the EGC have access to large, lipid-rich Calanus copepods, whereas those adjacent to the SC have medium sized prey, while those near the WSC are limited to even smaller, less profitable prey. We used time−depth recorders to compare the time allocation and diving behavior of little auks adjacent to each of these 3 water masses. We predicted that birds in the EGC would not have to forage as intensively as those in the SC or WSC. We found that little auks foraging in the EGC spent less time at sea, spent less time flying, dived less often, made fewer long, deep dives, and made fewer V-shaped searching dives. This indicates that the EGC provides a more favorable foraging environment than do the warmer water masses to the east. Comparing the foraging behavior of little auk populations confined to Arctic versus Atlantic-influenced waters can provide insight into the potential impacts of future warming in the Greenland Sea
Local channels preserving maximal entanglement or Schmidt number
Maximal entanglement and Schmidt number play an important role in various
quantum information tasks. In this paper, it is shown that a local channel
preserves maximal entanglement state(MES) or preserves pure states with Schmidt
number ( is a fixed integer) if and only if it is a local unitary
operation.Comment: 10 page
Radiative Correction to the Dirichlet Casimir Energy for Theory in Two Spatial Dimensions
In this paper, we calculate the next to the leading order Casimir energy for
real massive and massless scalar fields within theory,
confined between two parallel plates with the Dirichlet boundary condition in
two spatial dimensions. Our results are finite in both cases, in sharp contrast
to the infinite result reported previously for the massless case. In this paper
we use a renormalization procedure introduced earlier, which naturally
incorporates the boundary conditions. As a result our radiative correction term
is different from the previously calculated value. We further use a
regularization procedure which help us to obtain the finite results without
resorting to any analytic continuation techniques.Comment: 8 pages, 3 figure
Development and validation of an analytical method by UV spectrophotometry for the quantitative determination of the anti-neoplastic β-lapachone
A β-lapachona é uma ortonaftoquinona natural extraÃda de plantas da famÃlia Bignoniaceae,
como o Ipê Roxo (Tabebuia avellanedae Lor), árvore nativa do Brasil, ou sintetizada a partir de seu isômero
lapachol. A β-lapachona têm demonstrado uma série de ações farmacológicas incluindo antibacteriana,
antifúngica, tripanossomicida, antiviral e antineoplásica. Não há relatos na literatura de um método analÃtico
espectrofotométrico para a quantificação de β-lapachona. Assim, o presente trabalho descreve o desenvolvimento
de um método simples, econômico, rápido e preciso por espectrofotometria para a quantificação
deste fármaco. O método desenvolvido consiste na solubilização da β-lapachona em álcool etÃlico
com posterior diluição no sistema de solventes álcool etÃlico:água para quantificação em ultravioleta (λ =
256 nm). O método foi validado segundo parâmetros descritos pela International Conference on Harmonization
(Q2A/Q2B) e Agência Nacional de Vigilância Sanitária (ANVISA) RE 899/03. Os resultados da validação
mostram que o método é robusto, linear, sensÃvel, preciso e exato dentro dos parâmetros avaliados.Colegio de Farmacéuticos de la Provincia de Buenos Aire
Character of superposed states under deterministic LOCC
In this paper we investigate the effect of superposition of states on local
conversion of pure bipartite states under deterministic LOCC. We are able to
form a bridge between comparable and incomparable classes of states through the
linear superposition of states. For example, if we consider two pairs of
incomparable states, then their superposition may result into a comparable pair
of states. We investigate many such cases and provide some of the results in
tabular form. We also investigate the entanglement behavior of such classes of
states, specifically their monotone nature. Finally we provide some bounds of
different measures of entanglement based on the idea of comparability and
incomparability under deterministic LOCC.Comment: 9 pages, pdflatex, no figure, to appear in the journal Quantum
Information Processin
Vortex Line Fluctuations in Model High Temperature Superconductors
We carry out Monte Carlo simulations of the uniformly frustrated 3d XY model
as a model for vortex line fluctuations in a high Tc superconductor. A density
of vortex lines of f=1/25 is considered. We find two sharp phase transitions.
The low T phase is an ordered vortex line lattice. The high T normal phase is a
vortex line liquid with much entangling, cutting, and loop excitations. An
intermediate phase is found which is characterized as a vortex line liquid of
disentangled lines. In this phase, the system displays superconducting
properties in the direction parallel to the magnetic field, but normal behavior
in planes perpendicular to the magnetic field.Comment: 38 pages, LaTeX 15 figures (upon request to
[email protected]
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