Distinguishing multi-partite states by local measurements

We analyze the distinguishability norm on the states of a multi-partite system, defined by local measurements. Concretely, we show that the norm associated to a tensor product of sufficiently symmetric measurements is essentially equivalent to a multi-partite generalisation of the non-commutative 2-norm (aka Hilbert-Schmidt norm): in comparing the two, the constants of domination depend only on the number of parties but not on the Hilbert spaces dimensions. We discuss implications of this result on the corresponding norms for the class of all measurements implementable by local operations and classical communication (LOCC), and in particular on the leading order optimality of multi-party data hiding schemes.Comment: 18 pages, 6 figures, 1 unreferenced referenc

Atom trapping and two-dimensional Bose-Einstein condensates in field-induced adiabatic potentials

We discuss a method to create two-dimensional traps as well as atomic shell, or bubble, states for a Bose-Einstein condensate initially prepared in a conventional magnetic trap. The scheme relies on the use of time-dependent, radio frequency-induced adiabatic potentials. These are shown to form a versatile and robust tool to generate novel trapping potentials. Our shell states take the form of thin, highly stable matter-wave bubbles and can serve as stepping-stones to prepare atoms in highly-excited trap eigenstates or to study `collapse and revival phenomena'. Their creation requires gravitational effects to be compensated by applying additional optical dipole potentials. However, in our scheme gravitation can also be exploited to provide a route to two-dimensional atom trapping. We demonstrate the loading process for such a trap and examine experimental conditions under which a 2D condensate may be prepared.Comment: 16 pages, 10 figure

Scattering of light and atoms in a Fermi-Dirac gas with BCS pairing

We theoretically study the optical properties of a Fermi-Dirac gas in the presence of a superfluid state. We calculate the leading quantum-statistical corrections to the standard column density result of the electric susceptibility. We also consider the Bragg diffraction of atoms by means of light-stimulated transitions of photons between two intersecting laser beams. Bardeen-Cooper-Schrieffer pairing between atoms in different internal levels magnifies incoherent scattering processes. The absorption linewidth of a Fermi-Dirac gas is broadened and shifted. Bardeen-Cooper-Schrieffer pairing introduces a collisional local-field shift that may dramatically dominate the Lorentz-Lorenz shift. For the case of the Bragg spectroscopy the static structure function may be significantly increased due to superfluidity in the nearforward scattering.Comment: 13 pages, 6 figures; to appear in PR

A Measurement of Time-Averaged Aerosol Optical Depth using Air-Showers Observed in Stereo by HiRes

Air fluorescence measurements of cosmic ray energy must be corrected for attenuation of the atmosphere. In this paper we show that the air-showers themselves can yield a measurement of the aerosol attenuation in terms of optical depth, time-averaged over extended periods. Although the technique lacks statistical power to make the critical hourly measurements that only specialized active instruments can achieve, we note the technique does not depend on absolute calibration of the detector hardware, and requires no additional equipment beyond the fluorescence detectors that observe the air showers. This paper describes the technique, and presents results based on analysis of 1258 air-showers observed in stereo by the High Resolution Fly's Eye over a four year span.Comment: 7 pages, 3 figures, accepted for publication by Astroparticle Physics Journa

Measurement of Aerosols at the Pierre Auger Observatory

The air fluorescence detectors (FDs) of the Pierre Auger Observatory are vital for the determination of the air shower energy scale. To compensate for variations in atmospheric conditions that affect the energy measurement, the Observatory operates an array of monitoring instruments to record hourly atmospheric conditions across the detector site, an area exceeding 3,000 square km. This paper presents results from four instruments used to characterize the aerosol component of the atmosphere: the Central Laser Facility (CLF), which provides the FDs with calibrated laser shots; the scanning backscatter lidars, which operate at three FD sites; the Aerosol Phase Function monitors (APFs), which measure the aerosol scattering cross section at two FD locations; and the Horizontal Attenuation Monitor (HAM), which measures the wavelength dependence of aerosol attenuation.Comment: Contribution to the 30th International Cosmic Ray Conference, Merida Mexico, July 2007; 4 pages, 4 figure

Generation and evolution of vortex-antivortex pairs in Bose-Einstein condensates

We propose a method for generating and controlling a spatially separated vortex--antivortex pair in a Bose-Einstein condensate trapped in a toroidal potential. Our simulations of the time dependent Gross-Pitaevskii equation show that in toroidal condensates vortex dynamics are different from the dynamics in the homogeneous case. Our numerical results agree well with analytical calculations using the image method. Our proposal offers an effective example of coherent generation and control of vortex dynamics in atomic condensates.Comment: 4 pages, 2 figure

Dark soliton states of Bose-Einstein condensates in anisotropic traps

Dark soliton states of Bose-Einstein condensates in harmonic traps are studied both analytically and computationally by the direct solution of the Gross-Pitaevskii equation in three dimensions. The ground and self-consistent excited states are found numerically by relaxation in imaginary time. The energy of a stationary soliton in a harmonic trap is shown to be independent of density and geometry for large numbers of atoms. Large amplitude field modulation at a frequency resonant with the energy of a dark soliton is found to give rise to a state with multiple vortices. The Bogoliubov excitation spectrum of the soliton state contains complex frequencies, which disappear for sufficiently small numbers of atoms or large transverse confinement. The relationship between these complex modes and the snake instability is investigated numerically by propagation in real time.Comment: 11 pages, 8 embedded figures (two in color

SRAO CO Observation of 11 Supernova Remnants in l = 70 to 190 deg

We present the results of 12CO J = 1-0 line observations of eleven Galactic supernova remnants (SNRs) obtained using the Seoul Radio Astronomy Observatory (SRAO) 6-m radio telescope. The observation was made as a part of the SRAO CO survey of SNRs between l = 70 and 190 deg, which is intended to identify SNRs interacting with molecular clouds. The mapping areas for the individual SNRs are determined to cover their full extent in the radio continuum. We used halfbeam grid spacing (60") for 9 SNRs and full-beam grid spacing (120") for the rest. We detected CO emission towards most of the remnants. In six SNRs, molecular clouds showed a good spatial relation with their radio morphology, although no direct evidence for the interaction was detected. Two SNRs are particularly interesting: G85.4+0.7, where there is a filamentary molecular cloud along the radio shell, and 3C434.1, where a large molecular cloud appears to block the western half of the remnant. We briefly summarize the results obtained for individual SNRs.Comment: Accepted for publication in Astrophysics & Space Science. 12 pages, 12 figures, and 3 table

Complex relationships among personality traits, job characteristics, and work behaviors

The aim of the study was to investigate the additive, mediating, and moderating effects of personality traits and job characteristics on work behaviors. Job applicants (N = 161) completed personality questionnaires measuring extraversion, neuroticism, achievement motivation, and experience seeking. One and a half years later, supervisors rated the applicants' job performance, and the job incumbents completed questionnaires about skill variety, autonomy, and feedback, work stress, job satisfaction, work self-efficacy, and propensity to leave. LISREL was used to test 15 hypotheses. Perceived feedback mediated the relationship between achievement motivation and job performance. Extraversion predicted work self-efficacy and job satisfaction. Work stress mediated the relationship between neuroticism and job satisfaction. Job satisfaction and experience seeking were related to propensity to leave. Autonomy, skill variety, and feedback were related to job satisfaction

The Vega debris disc: A view from Herschel

We present five band imaging of the Vega debris disc obtained using the Herschel Space Observatory. These data span a wavelength range of 70-500 mu m with full-width half-maximum angular resolutions of 5.6-36.9 ''. The disc is well resolved in all bands, with the ring structure visible at 70 and 160 mu m. Radial profiles of the disc surface brightness are produced, and a disc radius of 11 '' (similar to 85AU) is determined. The disc is seen to have a smooth structure thoughout the entire wavelength range, suggesting that the disc is in a steady state, rather than being an ephemeral structure caused by the recent collision of two large planetesimals