66,231 research outputs found
Polarized entangled Bose-Einstein condensation
We consider a mixture of two distinct species of atoms of pseudospin-1/2 with
both intraspecies and Interspecies spin-exchange interactions, and find all the
ground stats in a general case of the parameters in the effective Hamiltonian.
In general, corresponding to the two species and two pseudo-spin states, there
are four orbital wave functions into which the atoms condense. We find that in
certain parameter regimes, the ground state is the so-called polarized
entangled Bose-Einstein condensation, i.e. in addition to condensation of
interspecies singlet pairs, there are unpaired atoms with spins polarized in
the same direction. The interspecies entanglement and polarization
significantly affect the generalized Gross-Pitaevskii equations governing the
four orbital wave functions into which the atoms condense, as an interesting
interplay between spin and orbital degrees of freedom.Comment: 14 pages, received by PRA on 27 October 201
Spin-polarized tunneling spectroscopic studies of the intrinsic heterogeneity and pseudogap phenomena in colossal magnetoresistive manganite La_{0.7}Ca_{0.3}MnO_{3}
Spatially resolved tunneling spectroscopic studies of colossal
magnetoresistive (CMR) manganite (LCMO) epitaxial
films on substrate are investigated as
functions of temperature, magnetic field and spin polarization by means of
scanning tunneling spectroscopy. Systematic surveys of the tunneling spectra
taken with Pt/Ir tips reveal spatial variations on the length scale of a few
hundred nanometers in the ferromagnetic state, which may be attributed to the
intrinsic heterogeneity of the manganites due to their tendency towards phase
separation. The electronic heterogeneity is found to decrease either with
increasing field at low temperatures or at temperatures above all magnetic
ordering temperatures. On the other hand, spectra taken with Cr-coated tips are
consistent with convoluted electronic properties of both LCMO and Cr. In
particular, for temperatures below the magnetic ordering temperatures of both
Cr and LCMO, the magnetic-field dependent tunneling spectra may be
quantitatively explained by the scenario of spin-polarized tunneling in a
spin-valve configuration. Moreover, a low-energy insulating energy gap eV commonly found in the tunneling conductance spectra of bulk metallic
LCMO at may be attributed to a surface ferromagnetic insulating (FI)
phase, as evidenced by its spin filtering effect at low temperatures and
vanishing gap value above the Curie temperature. Additionally, temperature
independent pseudogap (PG) phenomena existing primarily along the boundaries of
magnetic domains are observed in the zero-field tunneling spectra. The PG
becomes strongly suppressed by applied magnetic fields at low temperatures when
the tunneling spectra of LCMO become highly homogeneous. These findings suggest
that the occurrence PG is associated with the electronic heterogeneity of the
manganites.Comment: 15 pages, 15 figures. Published in Physical Review B. Corresponding
author: Nai-Chang Yeh (E-mail: [email protected]
Food Safety Knowledge and Practice Among Community in Sg. Pelek, Sepang, Selangor Darul Ehsan
Food safety is a basic requirement of food quality. It is an increasingly important public health issue to prevent and control food borne illnesses. A cross-sectional study was designed to determine level of knowledge and practice on food safety, to determine the association between knowledge and practice, and also to identify the association between socio-demographic factors and practice score of the population studied. This study was conducted among adult population in Taman Bahagia, Sungai Pelek, Sepang, Selangor Darul Ehsan. Data were collected using an interviewed structured questionnaire. A stratified random sampling was performed to obtain houses, followed by simple random sampling to select sample in the house. A total of 115 data sets were analysed using Statistical Package for Social Sciences (SPSS) version 20.0. Analysis showed that 35% of respondents have poor level of knowledge on food safety, whereas 27% of the respondents have poor level of practices on food safety. Multiple linear regression revealed that there are a significant association between education level (p<0.001), Adj b=2.57 (95% CI: 1.15, 3.99) and gender (p=0.048), Adj b=1.15 (95% CI: 0.01, 2.29) with practice score on food safety. Therefore, health promotion and education on the importance of practicing food safety at home should be focused to prevent further unwanted health effects
Generation of a High-Visibility Four-Photon Entangled State and Realization of a Four-Party Quantum Communication Complexity Scenario
We obtain a four-photon polarization-entangled state with a visibility as
high as (95.35\pm 0.45)% directly from a single down-conversion source. A
success probability of (81.54\pm 1.38)% is observed by applying this entangled
state to realize a four-party quantum communication complexity scenario (QCCS),
which comfortably surpass the classical limit of 50%. As a comparison, two
Einstein-Podolsky-Rosen (EPR) pairs are shown to implement the scenario with a
success probability of (73.89\pm 1.33)%. This four-photon state can be used to
fulfill decoherence-free quantum information processing and other advanced
quantum communication schemes.Comment: REVTEX 4.0, 4 pages, 4 figures, 1 tabl
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Source-specific Fine Particulate Using Spatiotemporal Concentration Fields Developed using Chemical Transport Modelling and Data Assimilation
Anderson Localization at the Subwavelength Scale and Loss Compensation for Surface-Plasmon Polaritons in Disordered Arrays of Metallic Nanowires
Using a random array of coupled metallic nanowires as a generic example of
disordered plasmonic systems, we demonstrate that the structural disorder
induces localization of light in these nanostructures at a deep-subwavelength
scale. The ab initio analysis is based on solving the complete set of 3D
Maxwell equations. We find that random variations of the radius of coupled
plasmonic nanowires are sufficient to induce the Anderson localization (AL) of
surface-plasmon polaritons (SPPs), the size of these trapped modes being
significantly smaller than the wavelength. Remarkably, the optical-gain
coefficient, needed to compensate losses in the plasmonic components of the
system, is much smaller than the loss coefficient of the metal, which is
obviously beneficial for the realization of the AL in plasmonic nanostructures.
The dynamics of excitation and propagation of the Anderson-localized SPPs are
addressed too.Comment: 5 pages, 4 figures, to appear in Phys. Rev.
The Droplet State and the Compressibility Anomaly in Dilute 2D Electron Systems
We investigate the space distribution of carrier density and the
compressibility of two-dimensional (2D) electron systems by using the local
density approximation. The strong correlation is simulated by the local
exchange and correlation energies. A slowly varied disorder potential is
applied to simulate the disorder effect. We show that the compressibility
anomaly observed in 2D systems which accompanies the metal-insulator transition
can be attributed to the formation of the droplet state due to disorder effect
at low carrier densities.Comment: 4 pages, 3 figure
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