1,171 research outputs found
Universality of optimal measurements
We present optimal and minimal measurements on identical copies of an unknown
state of a qubit when the quality of measuring strategies is quantified with
the gain of information (Kullback of probability distributions). We also show
that the maximal gain of information occurs, among isotropic priors, when the
state is known to be pure. Universality of optimal measurements follows from
our results: using the fidelity or the gain of information, two different
figures of merits, leads to exactly the same conclusions. We finally
investigate the optimal capacity of copies of an unknown state as a quantum
channel of information.Comment: Revtex, 5 pages, no figure
Importance of Treatment Process on the Analysis of Penicillins in Milk Samples by Capillary Electrophoresis
Use Dosimetry Virtual Tool for Security Studies Physics and Nuclear
AbstractThe objective of this work is to develop a virtual detection tool of radioactive sources, such as to facilitate and assist the training and nuclear security planning. To accomplish this tool was created a virtual model of the Nuclear Engineering Institute (IEN) with virtual characters (avatars), able to move and interact with the environment, radiation detectors (fixed and portable) and sources radioactive. A tool developed enabled the simulation where individuals who were carrying radioactive sources were identified through the detectors installed at strategic points in the virtual environment. Furthermore, it was possible to detect and locate sources for handling portable detectors, operated by the characters within the virtual environment. The results showed a radiation detection system before the continuous profile radioactive sources, making it possible to evaluate the dose rate at any position of the virtual environment. So this work could help in both the security agents training and in the evaluation of the radiological safety of a nuclear site
Strong subadditivity inequality for quantum entropies and four-particle entanglement
Strong subadditivity inequality for a three-particle composite system is an
important inequality in quantum information theory which can be studied via a
four-particle entangled state. We use two three-level atoms in
configuration interacting with a two-mode cavity and the Raman adiabatic
passage technique for the production of the four-particle entangled state.
Using this four-particle entanglement, we study for the first time various
aspects of the strong subadditivity inequality.Comment: 5 pages, 3 figures, RevTeX4, submitted to PR
An EST-based analysis identifies new genes and reveals distinctive gene expression features of Coffea arabica and Coffea canephora
Background: Coffee is one of the world’s most important crops; it is consumed worldwide and plays a significant
role in the economy of producing countries. Coffea arabica and C. canephora are responsible for 70 and 30% of
commercial production, respectively. C. arabica is an allotetraploid from a recent hybridization of the diploid
species, C. canephora and C. eugenioides. C. arabica has lower genetic diversity and results in a higher quality
beverage than C. canephora. Research initiatives have been launched to produce genomic and transcriptomic data
about Coffea spp. as a strategy to improve breeding efficiency.
Results: Assembling the expressed sequence tags (ESTs) of C. arabica and C. canephora produced by the
Brazilian Coffee Genome Project and the Nestlé-Cornell Consortium revealed 32,007 clusters of C. arabica and
16,665 clusters of C. canephora. We detected different GC3 profiles between these species that are related to
their genome structure and mating system. BLAST analysis revealed similarities between coffee and grape (Vitis
vinifera) genes. Using KA/KS analysis, we identified coffee genes under purifying and positive selection. Protein
domain and gene ontology analyses suggested differences between Coffea spp. data, mainly in relation to
complex sugar synthases and nucleotide binding proteins. OrthoMCL was used to identify specific and prevalent
coffee protein families when compared to five other plant species. Among the interesting families annotated
are new cystatins, glycine-rich proteins and RALF-like peptides. Hierarchical clustering was used to
independently group C. arabica and C. canephora expression clusters according to expression data extracted
from EST libraries, resulting in the identification of differentially expressed genes. Based on these results, we
emphasize gene annotation and discuss plant defenses, abiotic stress and cup quality-related functional
categories.
Conclusion: We present the first comprehensive genome-wide transcript profile study of C. arabica and C.
canephora, which can be freely assessed by the scientific community at http://www.lge.ibi.unicamp.br/
coffea. Our data reveal the presence of species-specific/prevalent genes in coffee that may help to explain
particular characteristics of these two crops. The identification of differentially expressed transcripts offers a
starting point for the correlation between gene expression profiles and Coffea spp. developmental traits,
providing valuable insights for coffee breeding and biotechnology, especially concerning sugar metabolism
and stress tolerance
Dynamics of Entanglement in One-Dimensional Spin Systems
We study the dynamics of quantum correlations in a class of exactly solvable
Ising-type models. We analyze in particular the time evolution of initial Bell
states created in a fully polarized background and on the ground state. We find
that the pairwise entanglement propagates with a velocity proportional to the
reduced interaction for all the four Bell states. Singlet-like states are
favored during the propagation, in the sense that triplet-like states change
their character during the propagation under certain circumstances.
Characteristic for the anisotropic models is the instantaneous creation of
pairwise entanglement from a fully polarized state; furthermore, the
propagation of pairwise entanglement is suppressed in favor of a creation of
different types of entanglement. The ``entanglement wave'' evolving from a Bell
state on the ground state turns out to be very localized in space-time. Further
support to a recently formulated conjecture on entanglement sharing is given.Comment: 25 pages, 21 figures; revte
Separability and entanglement in 2x3xN composite quantum systems
The separability and entanglement of quantum mixed states in \Cb^2 \otimes
\Cb^3 \otimes \Cb^N composite quantum systems are investigated. It is shown
that all quantum states with positive partial transposes and rank
are separable.Comment: Latex, 15 page
Extraction methods and availability of micronutrients for wheat under a no-till system with a surface application of lime
Entanglement Sharing in the Two-Atom Tavis-Cummings Model
Individual members of an ensemble of identical systems coupled to a common
probe can become entangled with one another, even when they do not interact
directly. We investigate how this type of multipartite entanglement is
generated in the context of a system consisting of two two-level atoms
resonantly coupled to a single mode of the electromagnetic field. The dynamical
evolution is studied in terms of the entanglements in the different bipartite
partitions of the system, as quantified by the I-tangle. We also propose a
generalization of the so-called residual tangle that quantifies the inherent
three-body correlations in our tripartite system. This enables us to completely
characterize the phenomenon of entanglement sharing in the case of the two-atom
Tavis-Cummings model, a system of both theoretical and experimental interest.Comment: 11 pages, 4 figures, submitted to PRA, v3 contains corrections to
small error
Dynamic heterogeneities in the out-of-equilibrium dynamics of simple spherical spin models
The response of spherical two-spin interaction models, the spherical
ferromagnet (s-FM) and the spherical Sherrington-Kirkpatrick (s-SK) model, is
calculated for the protocol of the so-called nonresonant hole burning
experiment (NHB) for temperatures below the respective critical temperatures.
It is shown that it is possible to select dynamic features in the
out-of-equilibrium dynamics of both models, one of the hallmarks of dynamic
heterogeneities. The behavior of the s-SK model and the s-FM in three
dimensions is very similar, showing dynamic heterogeneities in the long time
behavior, i.e. in the aging regime. The appearence of dynamic heterogeneities
in the s-SK model explicitly demonstrates that these are not necessarily
related to {\it spatial} heterogeneities. For the s-FM it is shown that the
nature of the dynamic heterogeneities changes as a function of dimensionality.
With incresing dimension the frequency selectivity of the NHB diminishes and
the dynamics in the mean-field limit of the s-FM model becomes homogeneous.Comment: 16 pages, 8 figure
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