5,116 research outputs found

    Quantum harmonic oscillator state synthesis and analysis

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    Experiments are described in which a single, harmonically bound, beryllium ion in a Paul trap is put into Fock, thermal, coherent, squeezed, and Schroedinger cat states. Experimental determinations of the density matrix and the Wigner function are described. A simple calculation of the decoherence of a superposition of coherent states due to an external electric field is given.Comment: 13 pages, LaTeX2e, special style file spie.sty included, 11 eps figures included using epsfig, graphicx, subfigure, floatflt macros. To appear in Proc. Conf. on Atom Optics, San Jose, CA, Feb. 1997, edited by M. G. Prentiss and W. D. Phillips, SPIE Proc. # 299

    Universal and deterministic manipulation of the quantum state of harmonic oscillators: a route to unitary gates for Fock State qubits

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    We present a simple quantum circuit that allows for the universal and deterministic manipulation of the quantum state of confined harmonic oscillators. The scheme is based on the selective interactions of the referred oscillator with an auxiliary three-level system and a classical external driving source, and enables any unitary operations on Fock states, two-by-two. One circuit is equivalent to a single qubit unitary logical gate on Fock states qubits. Sequences of similar protocols allow for complete, deterministic and state-independent manipulation of the harmonic oscillator quantum state.Comment: 4 pages, 4 figure

    The Georgia Records Act and Its Implementation

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    Body size changes in passerine birds introduced to New Zealand from the UK

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    One feature of global geographic variation in avian body sizes is that they are larger on isolated islands than on continental regions. Therefore, this study aims to assess whether there have been changes in body size following successful establishment for seven passerine bird species (blackbird Turdus merula, song thrush T. philomelos, house sparrow Passer domesticus, chaffinch Fringilla coelebs, greenfinch Chloris chloris, goldfinch Carduelis carduelis, yellowhammer Emberiza citrinella) introduced from the continental islands of the UK to the more isolated oceanic landmass of New Zealand in the middle of the nineteenth century. Measures of tarsus length were taken from individuals from contemporary UK and New Zealand populations of these species, and from historical specimens collected around the time that individuals were translocated from the UK to New Zealand. Analysis of Variance was used to test for size differences between contemporary UK and New Zealand populations, and between historical UK and contemporary UK and New Zealand populations. Historical UK populations have longer tarsi, on average, than 12 (7 UK and 5 New Zealand) of the 14 contemporary populations. Significant decreases in tarsus length relative to the historical populations have occurred in the UK for blackbird, chaffinch and greenfinch, and in the New Zealand blackbird population. Contemporary New Zealand house sparrows have significantly longer tarsi, on average, than both historical and contemporary UK populations. Exposure to novel environments may be expected to lead to changes in the morphology and other traits of exotic species, but changes have also occurred in the native range. In fact, contrary to expectations, the most common differences we found were between contemporary and historical UK populations. Consideration of contemporary populations alone would underestimate the true scale of morphological change in these species over time, which may be due to phenotypic plasticity or genetic adaptation to environmental changes experienced by all populations in the last 150 years

    Planar Ion Trap Geometry for Microfabrication

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    We describe a novel high aspect ratio radiofrequency linear ion trap geometry that is amenable to modern microfabrication techniques. The ion trap electrode structure consists of a pair of stacked conducting cantilevers resulting in confining fields that take the form of fringe fields from parallel plate capacitors. The confining potentials are modeled both analytically and numerically. This ion trap geometry may form the basis for large scale quantum computers or parallel quadrupole mass spectrometers. PACS: 39.25.+k, 03.67.Lx, 07.75.+h, 07.10+CmComment: 14 pages, 16 figure

    Complexities of Technology Integration in the Elementary Classroom Context: A Structural Equation Model Study

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    Effectively integrating technology into classroom instruction presents teachers with several dilemmas about their understanding of how students learn, their approach to designing learning activities, and their conceptualization of their role as teachers (Windschitl, 2002). Using the Technological Pedagogical Content Knowledge (TPACK) model (Koehler & Mishra, 2005, 2009; Mishra & Koehler, 2006) as the conceptual model undergirding the research, this study was designed to build evidence towards establishing the validity and reliability of a measurement instrument employed to assess the technological, pedagogical, and content knowledge teachers utilize, as well as gain an understanding of how this knowledge is affected by teacher beliefs about technology use in classroom practice. Three contextual factors were also investigated, namely leadership support for technology, teaching self-efficacy, and traditional beliefs about children. Structural equation modeling (SEM) was selected for analyzing data gathered in this research design. The relationships among four latent factors and three latent variables were examined using measurement models to determine a final structural model. Results (N = 75) suggest that the TPACK-deep scale has potential as a measure of teachers’ beliefs about their technological, pedagogical, and content knowledge. The findings yielded by the present exploratory study pertain to Design, Exertion, Ethics, and Proficiency—which are considered the four factors of the TPACK-deep scale (Kabakci-Yurdakul et al., 2012). Furthermore, this study’s findings indicate positive predictive relationships between leadership support for technology and teachers’ beliefs about using technology in their classrooms. While positive predictive relationships between teachers’ teaching self-efficacy and their beliefs about technology integration in classroom practice were found, no statistically significant association between teachers’ beliefs about using technology and their traditional beliefs about children could be established for three (Design, Exertion, Ethics) of the four TPACK-deep factors under investigation
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