1,026 research outputs found

    Simple scheme for implementing the Deutsch-Jozsa algorithm in thermal cavity

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    We present a simple scheme to implement the Deutsch-Jozsa algorithm based on two-atom interaction in a thermal cavity. The photon-number-dependent parts in the evolution operator are canceled with the strong resonant classical field added. As a result, our scheme is immune to thermal field, and does not require the cavity to remain in the vacuum state throughout the procedure. Besides, large detuning between the atoms and the cavity is not necessary neither, leading to potential speed up of quantum operation. Finally, we show by numerical simulation that the proposed scheme is equal to demonstrate the Deutsch-Jozsa algorithm with high fidelity.Comment: 7 pages, 4 figure

    Unification of Dark Matter and Dark Energy in a Modified Entropic Force Model

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    In Verlinde's entropic force scenario of gravity, Newton's laws and Einstein equations can be obtained from the first pinciples and general assumptions. However, the equipartition law of energy is invalid at very low temperatures. We show clearly that the threshold of the equipartition law of energy is related with horizon of the universe. Thus, a one-dimension Debye (ODD) model in the direction of radius of the modified entropic force (MEF) maybe suitable in description of the accelerated expanding universe. We present a Friedmann cosmic dynamical model in the ODD-MEF framework. We examine carefully constraints on the ODD-MEF model from the Union2 compilation of the Supernova Cosmology Project (SCP) collaboration, the data from the observation of the large-scale structure (LSS) and the cosmic microwave background (CMB), i.e. SNe Ia+LSS+CMB. The combined numerical analysis gives the best-fit value of the model parameters ζ109\zeta\simeq10^{-9} and Ωm0=0.224\Omega_{m0}=0.224, with χmin2=591.156\chi_{min}^2=591.156. The corresponding age of the universe agrees with the result of D. Spergel {\it et al.}\cite{Spergel2003} at 95% confidence level. The numerical result also yields an accelerated expanding universe without invoking any kind of dark energy. Taking ζ(2πωD/H0)\zeta(\equiv 2\pi \omega_D/H_0) as a running parameter associated with the structure scale rr, we obtain a possible unified scenario of the asymptotic flatness of the radial velocity dispersion of spiral galaxies, the accelerated expanding universe and the Pioneer 10/11 anomaly in the entropic force framework of Verlinde.Comment: 23 pages, 6 figure

    A Comparative Study of Patients’ Attitudes Toward Clinical Research in the United States and Urban and Rural China

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    As the number of clinical trials conducted in China increases, understanding Chinese attitudes toward clinical research is critical for designing effective and ethical studies. Two survey studies were conducted in 2012 and 2013 to compare patient attitudes toward clinical research and factors affecting research participation in the United States and urban and rural China. We surveyed 525 patients in 2012 (186 US, 186 urban, 153 rural China) and 690 patients in 2013 (412 US, 206 urban, 72 rural China). US patients were more likely to have no concerns regarding research participation than Chinese patients. Most common concerns of US patients were safety, privacy and confidentiality, and time required. Safety was a top concern for many Chinese. Chinese patients, particularly rural Chinese, were more concerned about the likelihood of self‐benefit, and receiving free medical care and financial incentive had greater influence on their participation. Being informed of the freedom to choose whether to participate or to leave a study was less important to Chinese patients. Our study provides important insights into Chinese patients' attitudes toward clinical research and the need to educate them about their rights. These findings help in designing cross‐cultural clinical studies that maximize enrollment while upholding Western ethical standards.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111170/1/cts12254.pd

    Characterization of an Ionization Readout Tile for nEXO

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    A new design for the anode of a time projection chamber, consisting of a charge-detecting "tile", is investigated for use in large scale liquid xenon detectors. The tile is produced by depositing 60 orthogonal metal charge-collecting strips, 3~mm wide, on a 10~\si{\cm} ×\times 10~\si{\cm} fused-silica wafer. These charge tiles may be employed by large detectors, such as the proposed tonne-scale nEXO experiment to search for neutrinoless double-beta decay. Modular by design, an array of tiles can cover a sizable area. The width of each strip is small compared to the size of the tile, so a Frisch grid is not required. A grid-less, tiled anode design is beneficial for an experiment such as nEXO, where a wire tensioning support structure and Frisch grid might contribute radioactive backgrounds and would have to be designed to accommodate cycling to cryogenic temperatures. The segmented anode also reduces some degeneracies in signal reconstruction that arise in large-area crossed-wire time projection chambers. A prototype tile was tested in a cell containing liquid xenon. Very good agreement is achieved between the measured ionization spectrum of a 207^{207}Bi source and simulations that include the microphysics of recombination in xenon and a detailed modeling of the electrostatic field of the detector. An energy resolution σ/E\sigma/E=5.5\% is observed at 570~\si{keV}, comparable to the best intrinsic ionization-only resolution reported in literature for liquid xenon at 936~V/\si{cm}.Comment: 18 pages, 13 figures, as publishe

    Measurements of J/psi decays into phi pi^0, phi eta, and phi eta^prime

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    Based on 5.8x10^7 J/psi events detected in BESII, the branching fractions of J/psi--> phi eta and phi eta^prime are measured for different eta and eta^prime decay modes. The results are significantly higher than previous measurements. An upper limit on B(J/psi--> phi pi^0) is also obtained.Comment: 9 pages, 10 figure

    First observation of ψ(2S)pnˉπ+c.c.\psi(2S) \to p \bar{n} \pi^- +c.c.

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    Using 14 million ψ(2S)\psi(2S) events collected with the Beijing Spectrometer (BESII) at the Beijing Electron-Positron Collider, the branching fractions of ψ(2S)\psi(2S) decays to pnˉπp \bar{n} \pi^- and pˉnπ+\bar{p} n \pi^+ and the branching fractions of the main background channels ψ(2S)pnˉππ0\psi(2S) \to p \bar{n} \pi^-\pi^0, ψ(2S)γχc0γpnˉπ\psi(2S) \to \gamma\chi_{c0} \to \gamma p \bar{n} \pi^-, ψ(2S)γχc2γpnˉπ\psi(2S) \to \gamma\chi_{c2} \to \gamma p \bar{n} \pi^-, and ψ(2S)γχcJγpnˉππ0\psi(2S) \to \gamma \chi_{cJ} \to \gamma p \bar{n} \pi^- \pi^0 are determined. The contributions of the NN^{\ast} resonances in ψ(2S)pnˉπ+c.c.\psi(2S) \to p \bar{n} \pi^- +c.c. are also discussed.Comment: 19 pages, 8 figures, add vertex requirement systematic erro

    Measurement of the branching fractions of psi(2S) -> 3(pi+pi-) and J/psi -> 2(pi+pi-)

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    Using data samples collected at sqrt(s) = 3.686GeV and 3.650GeV by the BESII detector at the BEPC, the branching fraction of psi(2S) -> 3(pi+pi-) is measured to be [4.83 +- 0.38(stat) +- 0.69(syst)] x 10^-4, and the relative branching fraction of J/psi -> 2(pi+pi-) to that of J/psi -> mu+mu- is measured to be [5.86 +- 0.19(stat) +- 0.39(syst)]% via psi(2S) -> (pi+pi-)J/psi, J/psi -> 2(pi+pi-). The electromagnetic form factor of 3(pi+pi-) is determined to be 0.21 +- 0.02 and 0.20 +- 0.01 at sqrt(s) = 3.686GeV and 3.650GeV, respectively.Comment: 17pages, 7 figures, submitted to Phys. Rev.
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