4,688 research outputs found

    A "fair sampling" perspective on an apparent violation of duality

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    In the event in which a quantum mechanical particle can pass from an initial state to a final state along two possible paths, the duality principle states that "the simultaneous observation of wave and particle behavior is prohibited". [M. O. Scully, B.-G. Englert, and H. Walther. Nature, 351:111-116, 1991.] emphasized the importance of additional degrees of freedom in the context of complementarity. In this paper, we show how the consequences of duality change when allowing for biased sampling, that is, postselected measurements on specific degrees of freedom of the environment of the two-path state. Our work contributes to the explanation of previous experimental apparent violations of duality [R. Menzel, D. Puhlmann, A. Heuer, and W. P. Schleich. Proc. Natl. Acad. Sci., 109(24):9314-9319, 2012.] and opens up the way for novel experimental tests of duality.Comment: 10 pages, 8 figure

    Ethical Decision Making of Future Mexican Managers

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    A study to measure ethical decision making of Mexican business students compared to their US counterparts. Results suggest that Mexican students’ ethical decision-making frameworks differ from those documented by Keller et al. (2007) in their study of US students. Mexican students were not found to be highly religious, but subscribed more to utilitarian, deontological and hermeneutical frameworks for their ethical values. It is suggested that multinational firms doing business in Mexico might want to schedule ethics training of managers and to have a set of standards that employees can follow

    Fourier transforming a trapped Bose-Einstein condensate by waiting a quarter of the trap period: simulation and applications

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    We investigate the property of isotropic harmonic traps to Fourier transform a weakly interacting Bose–Einstein condensate (BEC) every quarter of a trap period. We solve the Gross–Pitaevskii equation numerically to investigate the time evolution of interacting BECs in the context of the Fourier transform, and we suggest potential applications

    Angular two-photon interference and angular two-qubit states

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    Using angular-position-orbital-angular-momentum entangled photons, we study angular two-photon interference in a scheme in which entangled photons are made to pass through apertures in the form of double angular slits, and using this scheme, we demonstrate an entangled two-qubit state that is based on the angular-position correlations of entangled photons. The entanglement of the two-qubit state is quantified in terms of concurrence. These results provide an additional means for preparing entangled quantum states for use in quantum information protocols

    The Performance and Calibration of the CRAFT Fly's Eye Fast Radio Burst Survey

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    Since January 2017, the Commensal Real-time ASKAP Fast Transients survey (CRAFT) has been utilising commissioning antennas of the Australian SKA Pathfinder (ASKAP) to survey for fast radio bursts (FRBs) in fly's eye mode. This is the first extensive astronomical survey using phased array feeds (PAFs), and a total of 20 FRBs have been reported. Here we present a calculation of the sensitivity and total exposure of this survey, using the pulsars B1641-45 (J1644-4559) and B0833-45 (J0835-4510, i.e.\ Vela) as calibrators. The design of the survey allows us to benchmark effects due to PAF beamshape, antenna-dependent system noise, radio-frequency interference, and fluctuations during commissioning on timescales from one hour to a year. Observation time, solid-angle, and search efficiency are calculated as a function of FRB fluence threshold. Using this metric, effective survey exposures and sensitivities are calculated as a function of the source counts distribution. The implied FRB rate is significantly lower than the 3737\,sky1^{-1}\,day1^{-1} calculated using nominal exposures and sensitivities for this same sample by \citet{craft_nature}. At the Euclidean power-law index of 1.5-1.5, the rate is 10.71.8+2.7(sys)±3(stat)10.7_{-1.8}^{+2.7}\,{\rm (sys)} \, \pm \, 3\,{\rm (stat)}\,sky1^{-1}\,day1^{-1} above a threshold of 57±6(sys)57\pm6\,{\rm (sys)}\,Jy\,ms, while for the best-fit index for this sample of 2.1-2.1, it is 16.61.5+1.9(sys)±4.7(stat)16.6_{-1.5}^{+1.9} \,{\rm (sys)}\, \pm 4.7\,{\rm (stat)}\,sky1^{-1}\,day1^{-1} above a threshold of 41.6±1.5(sys)41.6\pm1.5\,{\rm (sys)}\,Jy\,ms. This strongly suggests that these calculations be performed for other FRB-hunting experiments, allowing meaningful comparisons to be made between them.Comment: 21 pages, 15 figures, 2 tables, accepted for publication in PAS

    Unitary relations in time-dependent harmonic oscillators

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    For a harmonic oscillator with time-dependent (positive) mass and frequency, an unitary operator is shown to transform the quantum states of the system to those of a harmonic oscillator system of unit mass and time-dependent frequency, as well as operators. For a driven harmonic oscillator, it is also shown that, there are unitary transformations which give the driven system from the system of same mass and frequency without driving force. The transformation for a driven oscillator depends on the solution of classical equation of motion of the driven system. These transformations, thus, give a simple way of finding exact wave functions of a driven harmonic oscillator system, provided the quantum states of the corresponding system of unit mass are given.Comment: Submitted to J. Phys.

    The Excitation of Extended Red Emission: New Constraints on its Carrier From HST Observations of NGC 7023

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    The carrier of the dust-associated photoluminescence process causing the extended red emission (ERE) in many dusty interstellar environments remains unidentified. Several competing models are more or less able to match the observed broad, unstructured ERE band. We now constrain the character of the ERE carrier further by determining the wavelengths of the radiation that initiates the ERE. Using the imaging capabilities of the Hubble Space Telescope, we have resolved the width of narrow ERE filaments appearing on the surfaces of externally illuminated molecular clouds in the bright reflection nebula NGC 7023 and compared them with the depth of penetration of radiation of known wavelengths into the same cloud surfaces. We identify photons with wavelengths shortward of 118 nm as the source of ERE initiation, not to be confused with ERE excitation, however. There are strong indications from the well-studied ERE in the Red Rectangle nebula and in the high-|b| Galactic cirrus that the photon flux with wavelengths shortward of 118 nm is too small to actually excite the observed ERE, even with 100% quantum efficiency. We conclude, therefore, that ERE excitation results from a two-step process. While none of the previously proposed ERE models can match these new constraints, we note that under interstellar conditions most polycyclic aromatic hydrocarbon (PAH) molecules are ionized to the di-cation stage by photons with E > 10.5 eV and that the electronic energy level structure of PAH di-cations is consistent with fluorescence in the wavelength band of the ERE. Therefore, PAH di-cations deserve further study as potential carriers of the ERE. (abridged)Comment: Accepted for Publication in the Ap
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