224,577 research outputs found

    Vortex description of the fractionalized phase in exciton bose condensate

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    As a sequel to the previous work [Phys. Rev. B 72, 235104 (2005)] we present a vortex description of the fractionalized phase in exciton bose condensate. Magnetic flux line and monopole of the 3+1D emergent U(1) gauge theory are identified in the exciton picture. A bundle of vortex/anti-vortex pairs of all flavors of excitons corresponds to the magnetic flux line and a point at which the vortices and anti-vortices recombine is identified as magnetic monopole. This completes the magnetic sector of the low energy excitation in the fractionalized phase.Comment: 8 pages, 6 figures; clarification made in introductio

    Polarization effects in microcoil resonators

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    Optical microcoil resonators (OMRs), formed by coiling a micron-diameter fibre around a rod as shown in Figure 1a, provide a unique resonator geometry in which light can evanescently couple between adjacent turns to produce high Q resonances. Furthermore, OMRs fabricated from a pigtailed fibre taper offer much lower coupling losses than cavity resonators. Applications in fields such as fluidic and temperature sensing have already been investigated, and the small fibre diameter and effective modal area indicate that OMRs are a promising platform for studying nonlinear interactions. A detailed understanding of OMR optical characteristics is crucial for further development, but theoretical studies have thus far neglected any polarization dependency. In this work, the influence of the fibre’s birefringence on the polarization of propagating light was studied by numerically solving polarization dependant coupled mode equations. The resulting transmission and dispersion properties are discussed for different degrees of fibre twist (Figure 1b). In addition to the linear behaviour, the nonlinear regime was explored, by incorporating a Kerr term, and found to be strongly enhanced around resonances

    Acoustic suspension system

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    An acoustic levitation system is described, with single acoustic source and a small reflector to stably levitate a small object while the object is processed as by coating or heating it. The system includes a concave acoustic source which has locations on opposite sides of its axis that vibrate towards and away from a focal point to generate a converging acoustic field. A small reflector is located near the focal point, and preferably slightly beyond it, to create an intense acoustic field that stably supports a small object near the reflector. The reflector is located about one-half wavelength from the focal point and is concavely curved to a radius of curvature (L) of about one-half the wavelength, to stably support an object one-quarter wavelength (N) from the reflector

    Time-Dependent Variational Approach to the Non-Abelian Pure Gauge Theory

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    The time-dependent variational approach to the pure Yang-Mills gauge theory, especially a color su(3) gauge theory, is formulated in the functional Schroedinger picture with a Gaussian wave functional approximation. The equations of motion for the quantum gauge fields are formulated in the Liouville-von Neumann form. This variational approach is applied in order to derive the transport coefficients, such as the shear viscosity, for the pure gluonic matter by using the linear response theory. As a result, the contribution to the shear viscosity from the quantum gluons is zero up to the lowest order of the coupling g in the quantum gluonic matter.Comment: 19 pages, no figures, using PTPTeX.cl

    Development of a Cone Penetrometer for Measuring Spectral Characteristics of Soils in Situ

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    A patent was recently granted to the U.S. Army for an adaptation of a soil cone penetrometer that can be used to measure the spectral characteristics (fluorescence or reflectance) of soils adjacent to the penetrometer rod. The system can use a variety of light sources and spectral analytical equipment. A laser induced fluorescence measuring system has proven to be of immediate use in mapping the distribution of oil contaminated soil at waste disposal and oil storage areas. The fiber optic adaptation coupled with a cone penetrometer permits optical characteristics of the in-situ soil to be measured rapidly, safely, and inexpensively. The fiber optic cone penetrometer can be used to gather spectral data to a depth of approximately 25 to 30 m even in dense sands or stiff clays and can investigate 300 m of soil per day. Typical detection limits for oil contamination in sand is on the order of several hundred parts per million
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