2,408 research outputs found

    Wavelets as a variational basis of the XY model

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    We use Daubechies' orthonormal compact wavelets as a variational basis for the XYXY model in two and three dimensions. Assuming that the fluctuations of the wavelet coefficients are Gaussian and uncorrelated, minimization of the free energy yields the fluctuation strength of wavelet coefficients at different scales, from which observables can be computed. This model is able to describe the low-temperature phase and makes a prediction about the phase transition temperature.Comment: 3 pages, postscript. Contribution to the Lattice 93 workshop (Dallas, Texas, October 1993

    Fast quantum information transfer with superconducting flux qubits coupled to a cavity

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    We present a way to realize quantum information transfer with superconducting flux qubits coupled to a cavity. Because only resonant qubit-cavity interaction and resonant qubit-pulse interaction are applied, the information transfer can be performed much faster, when compared with the previous proposals. This proposal does not require adjustment of the qubit level spacings during the operation. Moreover, neither uniformity in the device parameters nor exact placement of qubits in the cavity is needed by this proposal.Comment: 6 pages, 3 figure

    A n-qubit controlled phase gate with superconducting quantum interference devices coupled to a resonator

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    We present a way to realize a nn-qubit controlled phase gate with superconducting quantum interference devices (SQUIDs) by coupling them to a superconducting resonator. In this proposal, the two logical states of a qubit are represented by the two lowest levels of a SQUID. An intermediate level of each SQUID is utilized to facilitate coherent control and manipulation of quantum states of the qubits. It is interesting to note that a nn-qubit controlled phase gate can be achieved with nn SQUIDs by successively applying a π/2\pi /2 Jaynes-Cummings pulse to each of the n1n-1 control SQUIDs before and after a π\pi Jaynes-Cummings pulse on the target SQUID.Comment: 9 pages, 4 figures, 1 table, RevTeX, Resubmitted to Phys. Rev.

    Observing workplace incivility towards women: The roles of target reactions, actor motives, and actor-target relationships

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    The current study conceptualized observer reactions to uncivil behavior towards women as an ethical behavior and examined three factors (target reaction, actor motive, and actor-target relationship) that influence these reactions. Two vignette studies with women and men undergraduate and graduate students in western Switzerland were conducted. Study 1 (N=148) was a written vignette study that assessed how the reaction of female targets to incivility and the motives of actors influenced observer reactions. Results showed that a female target's reaction influenced observers' evaluations of the harm caused by an uncivil incident, and that an actor's motive affected observers' assessments of the necessity to intervene. Study 2 (N=81) was a video vignette study that assessed the effects of the reactions by female targets to incivility and the relationship between the target and the actor on observer reactions.We found that female targets' reactions influenced observers' evaluations of harm and the perceived necessity to intervene. Furthermore, the effect of a female target's reaction on observers' evaluations of harm was moderated by the relationship between the actor and the target: a female target who laughed at the uncivil behavior was perceived as less harmed, when she and the actor had a personal relationship than when they had a professional relationship. When the female target reacted hurt or neutrally, actor-target relationship did not affect observers' evaluations of harm. We conclude by discussing the implications of our findings for theory and practice

    Feedback cooling of a cantilever's fundamental mode below 5 mK

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    We cool the fundamental mechanical mode of an ultrasoft silicon cantilever from a base temperature of 2.2 K to 2.9 +/- 0.3 mK using active optomechanical feedback. The lowest observed mode temperature is consistent with limits determined by the properties of the cantilever and by the measurement noise. For high feedback gain, the driven cantilever motion is found to suppress or "squash" the optical interferometer intensity noise below the shot noise level.Comment: 4 pages, 6 figure

    Nuclear spin relaxation induced by a mechanical resonator

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    We report on measurements of the spin lifetime of nuclear spins strongly coupled to a micromechanical cantilever as used in magnetic resonance force microscopy. We find that the rotating-frame correlation time of the statistical nuclear polarization is set by the magneto-mechanical noise originating from the thermal motion of the cantilever. Evidence is based on the effect of three parameters: (1) the magnetic field gradient (the coupling strength), (2) the Rabi frequency of the spins (the transition energy), and (3) the temperature of the low-frequency mechanical modes. Experimental results are compared to relaxation rates calculated from the spectral density of the magneto-mechanical noise.Comment: 4 pages, 4 figure

    The pattern of non-intercepted medication errors in a university affiliated teaching hospital

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    INTRODUCTION: The primary goal of reducing medication errors is to eliminate errors that reach the patient. We aimed to study the pattern of interception of medication errors along the medication use process. METHODS: We analysed reported medication incidents in a teaching hospital in 2006 to 2010. We used …published_or_final_versionThe 17th Medical Research Conference, The University of Hong Kong, Hong Kong, 14 January 2012. In Hong Kong Medical Journal, 2012, v. 18 suppl. 1, p. 44, abstract no. 6

    Enhanced heat capacity and a new temperature instability in superfluid He-4 in the presence of a constant heat flux near T-lambda

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    We present the first experimental evidence that the heat capacity of superfluid 4He, at temperatures very close to the lambda point Tλ, is enhanced by a constant heat flux Q. The heat capacity at constant Q, CQ, is predicted to diverge at a temperature Tc(Q)<Tλ at which superflow becomes unstable. In agreement with previous measurements, we find that dissipation enters our cell at a temperature, TDAS(Q), below the theoretical value, Tc(Q). We argue that TDAS(Q) can be accounted for by a temperature instability at the cell wall, and is therefore distinct from Tc(Q). The excess heat capacity we measure has the predicted scaling behavior as a function of T and Q, but it is much larger than predicted by current theory

    Symmetric-Asymmetric transition in mixtures of Bose-Einstein condensates

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    We propose a new kind of quantum phase transition in phase separated mixtures of Bose-Einstein condensates. In this transition, the distribution of the two components changes from a symmetric to an asymmetric shape. We discuss the nature of the phase transition, the role of interface tension and the phase diagram. The symmetric to asymmetric transition is the simplest quantum phase transition that one can imagine. Careful study of this problem should provide us new insight into this burgeoning field of discovery.Comment: 6 pages, 3 eps figure

    Similarity Analysis of Nonlinear Equations and Bases of Finite Wavelength Solitons

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    We introduce a generalized similarity analysis which grants a qualitative description of the localised solutions of any nonlinear differential equation. This procedure provides relations between amplitude, width, and velocity of the solutions, and it is shown to be useful in analysing nonlinear structures like solitons, dublets, triplets, compact supported solitons and other patterns. We also introduce kink-antikink compact solutions for a nonlinear-nonlinear dispersion equation, and we construct a basis of finite wavelength functions having self-similar properties.Comment: 18 pages Latex, 6 figures ep
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