19,255 research outputs found

    Three-Way Entanglement and Three-Qubit Phase Gate Based on a Coherent Six-Level Atomic System

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    We analyze the nonlinear optical response of a six-level atomic system under a configuration of electromagnetically induced transparency. The giant fifth-order nonlinearity generated in such a system with a relatively large cross-phase modulation effect can produce efficient three-way entanglement and may be used for realizing a three-qubit quantum phase gate. We demonstrate that such phase gate can be transferred to a Toffoli gate, facilitating practical applications in quantum information and computation.Comment: 10 pages, 2 figure

    Wavelength-swept Tm-doped fiber laser operating in the two-micron wavelength band

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    A wavelength-swept thulium-doped silica fiber laser using an intracavity rotating slotted-disk wavelength scanning filter in combination with an intracavity solid etalon for passive control of temporal and spectral profiles is reported. The laser yielded a wavelength swept output in a step-wise fashion with each laser pulse separated from the previous pulse by a frequency interval equal to the free-spectral-range of the etalon and with an instantaneous linewidth of <0.05 nm. Scanning ranges from 1905 nm to 2049 nm for a cladding-pumping laser configuration, and from 1768 nm to 1956 nm for a core-pumping laser configuration were achieved at average output powers up to ~1 W

    An agent-based cognitive approach for healthcare process management

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    Proceedings of the IEEE International Conference on Cognitive Informatics, 2009, p. 441-447Healthcare organizations are facing the challenge of delivering high-quality services through effective process management. There have been frequent changes of clinical processes and increased interactions between different functional units. To facilitate the dynamic and interactive processes in healthcare organizations, an agent-based cognitive approach is presented in this study. The emphasis is placed on dynamic clinical and administrative process management, and knowledge building as the foundation for process management. The treatment of primary open angle glaucoma is used as an example to demonstrate the effectiveness of approach for healthcare process management. © 2009 IEEE.published_or_final_versio

    The UNAM-KIAS Catalog of Isolated Galaxies

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    A new catalog of isolated galaxies from The Sloan Digital Sky Survey (DR5) is presented. 1520 isolated galaxies were found in 1.4 steradians of sky. The selection criteria in this so called UNAM-KIAS catalog was implemented from a variation on the criteria developed by Karachentseva 1973 including full redshift information. Through an image processing pipeline that takes advantage from the high resolution (~ 0.4 ''/pix) and high dynamic range of the SDSS images, a uniform g band morphological classification for all these galaxies is presented. We identify 80% (SaSm) spirals (50% later than Sbc types) on one hand, and a scarce population of early-type E(6.5%) and S0(8%) galaxies amounting to 14.5% on the other hand. This magnitude-limited catalog is ~ 80% complete at 16.5, 15.6, 15.0, 14.6 and 14.4 magnitudes in the ugriz bands respectively. Some representative physical properties including SDSS magnitudes and color distributions, color-color diagrams, absolute magnitude-color, and concentration-color diagrams as a function of morphological type are presented. The UNAM-KIAS Morphological Atlas is also released along with this paper. For each galaxy of type later than Sa, a mosaic is presented that includes: (1) a g-band logarithmic image, (2) a g band filtered-enhanced image where a Gaussian kernel of various sizes was applied and (3) an RGB color image from the SDSS database. For E/S0/Sa galaxies, in addition to the images in (1), (2) and (3), plots of r band surface brightness and geometric profiles (ellipticity, Position Angle PA and A4/B4 coefficients of the Fourier series expansions of deviations of a pure ellipse) are provided...Comment: 40 pages, 17 figures and 3 table

    The UNAM-KIAS Catalog of Isolated Galaxies

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    A new catalog of isolated galaxies from The Sloan Digital Sky Survey (DR5) is presented. 1520 isolated galaxies were found in 1.4 steradians of sky. The selection criteria in this so called UNAM-KIAS catalog was implemented from a variation on the criteria developed by Karachentseva 1973 including full redshift information. Through an image processing pipeline that takes advantage from the high resolution (~ 0.4 ''/pix) and high dynamic range of the SDSS images, a uniform g band morphological classification for all these galaxies is presented. We identify 80% (SaSm) spirals (50% later than Sbc types) on one hand, and a scarce population of early-type E(6.5%) and S0(8%) galaxies amounting to 14.5% on the other hand. This magnitude-limited catalog is ~ 80% complete at 16.5, 15.6, 15.0, 14.6 and 14.4 magnitudes in the ugriz bands respectively. Some representative physical properties including SDSS magnitudes and color distributions, color-color diagrams, absolute magnitude-color, and concentration-color diagrams as a function of morphological type are presented. The UNAM-KIAS Morphological Atlas is also released along with this paper. For each galaxy of type later than Sa, a mosaic is presented that includes: (1) a g-band logarithmic image, (2) a g band filtered-enhanced image where a Gaussian kernel of various sizes was applied and (3) an RGB color image from the SDSS database. For E/S0/Sa galaxies, in addition to the images in (1), (2) and (3), plots of r band surface brightness and geometric profiles (ellipticity, Position Angle PA and A4/B4 coefficients of the Fourier series expansions of deviations of a pure ellipse) are provided...Comment: 40 pages, 17 figures and 3 table

    Neutral Gas Properties and Lyα\alpha Escape in Extreme Green Pea Galaxies

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    Mechanisms regulating the escape of Lyα\alpha photons and ionizing radiation remain poorly understood. To study these processes we analyze VLA 21cm observations of one Green Pea (GP), J160810+352809 (hereafter J1608), and HST COS spectra of 17 GP galaxies at z<0.2z<0.2. All are highly ionized: J1608 has the highest [O III] λ5007\lambda5007/[O II] λ3727\lambda3727 for star-forming galaxies in SDSS, and the 17 GPs have [O III]/[O II] ≄6.6\geq6.6. We set an upper limit on J1608's HI mass of log⁥MHI/M⊙=8.4\log M_{HI}/M_\odot=8.4, near or below average compared to similar mass dwarf galaxies. In the COS sample, eight GPs show Lyα\alpha absorption components, six of which also have Lyα\alpha emission. The HI column densities derived from Lyα\alpha absorption are high, log⁥NHI/\log N_{HI}/cm−2=19−21^{-2}=19-21, well above the LyC optically thick limit. Using low-ionization absorption lines, we measure covering fractions (f_{\mbox{cov}}) of 0.1−10.1-1, and find that f_{\mbox{cov}} strongly anti-correlates with Lyα\alpha escape fraction. Low covering fractions may facilitate Lyα\alpha and LyC escape through dense neutral regions. GPs with f_{\mbox{cov}}\sim1 all have low neutral gas velocities, while GPs with lower f_{\mbox{cov}}=0.2-0.6 have a larger range of velocities. Conventional mechanical feedback may help establish low f_{\mbox{cov}} in some cases, whereas other processes may be important for GPs with low velocities. Finally, we compare f_{\mbox{cov}} with proposed indicators of LyC escape. Ionizing photon escape likely depends on a combination of neutral gas geometry and kinematics, complicating the use of emission-line diagnostics for identifying LyC emitters.Comment: 21 pages, 11 figures, accepted for publication in Ap

    Inversion formula and Parsval theorem for complex continuous wavelet transforms studied by entangled state representation

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    In a preceding Letter (Opt. Lett. 32, 554 (2007)) we have proposed complex continuous wavelet transforms (CCWTs) and found Laguerre--Gaussian mother wavelets family. In this work we present the inversion formula and Parsval theorem for CCWT by virtue of the entangled state representation, which makes the CCWT theory complete. A new orthogonal property of mother wavelet in parameter space is revealed.Comment: 4 pages no figur

    The effects of Zn Impurity on the Properties of Doped Cuprates in the Normal State

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    We study the interplay of quantum impurity, and collective spinon and holon dynamics in Zn doped high-Tc_c cuprates in the normal state. The two-dimensional t-tâ€Č^{\prime}-J models with one and a small amount of Zn impurity are investigated within a numerical method based on the double-time Green function theory. We study the inhomogeneities of holon density and antiferromagnetic correlation background in cases with different Zn concentrations, and obtain that doped holes tend to assemble around the Zn impurity with their mobility being reduced. Therefore a bound state of holon is formed around the nonmagnetic Zn impurity with the effect helping Zn to introduce local antiferromagnetism around itself. The incommensurate peaks we obtained in the spin structure factor indicate that Zn impurities have effects on mixing the q=(π\pi, π\pi) and q=0 components in spin excitations.Comment: 5 pages, 3 figure

    High-order volterra model predictive control and its application to a nonlinear polymerisation process

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    Model Predictive Control (MPC) has recently found wide acceptance in the process industry, but the existing design and implementation methods are restricted to linear process models. A chemical process involves, however, severe nonlinearity which cannot be ignored in practice. This paper aims to solve this nonlinear control problem by extending MPC to nonlinear models. It develops an analytical framework for nonlinear model predictive control (NMPC), and also offers a third-order Volterra series based nonparametric nonlinear modelling technique for NMPC design which relieves practising engineers from the need for first deriving a physical-principles based model. An on-line realisation technique for implementing the NMPC is also developed. The NMPC is then applied to a Mitsubishi Chemicals polymerisation reaction process. The results show that this nonlinear MPC technique is feasible and very effective. It considerably outperforms linear and low-order Volterra model based methods. The advantages of the approach developed lie not only in control performance superior to existing NMPC methods, but also in relieving practising engineers from the need for deriving an analytical model and then converting it to a Volterra model through which the model can only be obtained up to the second order

    Analysis of Laser ARPES from Bi2_2Sr2_2CaCu2_2O8+ÎŽ_{8+\delta} in superconductive state: angle resolved self-energy and fluctuation spectrum

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    We analyze the ultra high resolution laser angle resolved photo-emission spectroscopy (ARPES) intensity from the slightly underdoped Bi2_2Sr2_2CaCu2_2O8+ÎŽ_{8+\delta} in the superconductive (SC) state. The momentum distribution curves (MDC) were fitted at each energy \w employing the SC Green's function along several cuts perpendicular to the Fermi surface with the tilt angle Ξ\theta with respect to the nodal cut. The clear observation of particle-hole mixing was utilized such that the complex self-energy as a function of ω\omega is directly obtained from the fitting. The obtained angle resolved self-energy is then used to deduce the Eliashberg function \alpha^2 F^{(+)}(\th,\w) in the diagonal channel by inverting the d-wave Eliashberg equation using the maximum entropy method. Besides a broad featureless spectrum up to the cutoff energy ωc\omega_c, the deduced α2F\alpha^2 F exhibits two peaks around 0.05 eV and 0.015 eV. The former and the broad feature are already present in the normal state, while the latter emerges only below TcT_c. Both peaks become enhanced as TT is lowered or the angle th⁥\th moves away from the nodal direction. The implication of these findings are discussed.Comment: 7 pages, 5 figures, summited to PR
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