13,825 research outputs found

    Topological Crystalline Bose Insulator in Two Dimensions via Entanglement Spectrum

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    Strongly correlated analogues of topological insulators have been explored in systems with purely on-site symmetries, such as time-reversal or charge conservation. Here, we use recently developed tensor network tools to study a quantum state of interacting bosons which is featureless in the bulk, but distinguished from an atomic insulator in that it exhibits entanglement which is protected by its spatial symmetries. These properties are encoded in a model many-body wavefunction that describes a fully symmetric insulator of bosons on the honeycomb lattice at half filling per site. While the resulting integer unit cell filling allows the state to bypass `no-go' theorems that trigger fractionalization at fractional filling, it nevertheless has nontrivial entanglement, protected by symmetry. We demonstrate this by computing the boundary entanglement spectra, finding a gapless entanglement edge described by a conformal field theory as well as degeneracies protected by the non-trivial action of combined charge-conservation and spatial symmetries on the edge. Here, the tight-binding representation of the space group symmetries plays a particular role in allowing certain entanglement cuts that are not allowed on other lattices of the same symmetry, suggesting that the lattice representation can serve as an additional symmetry ingredient in protecting an interacting topological phase. Our results extend to a related insulating state of electrons, with short-ranged entanglement and no band insulator analogue.Comment: 18 pages, 13 figures Added additional reference

    Single Photon Source with Individualized Single Photon Certifications

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    As currently implemented, single-photon sources cannot be made to produce single photons with high probability, while simultaneously suppressing the probability of yielding two or more photons. Because of this, single photon sources cannot really produce single photons on demand. We describe a multiplexed system that allows the probabilities of producing one and more photons to be adjusted independently, enabling a much better approximation of a source of single photons on demand. The scheme uses a heralded photon source based on parametric downconversion, but by effectively breaking the trigger detector area into multiple regions, we are able to extract more information about a heralded photon than is possible with a conventional arrangement. This scheme allows photons to be produced along with a quantitative ``certification'' that they are single photons. Some of the single-photon certifications can be significantly better than what is possible with conventional downconversion sources (using a unified trigger detector region), as well as being better than faint laser sources. With such a source of more tightly certified single photons, it should be possible to improve the maximum secure bit rate possible over a quantum cryptographic link. We present an analysis of the relative merits of this method over the conventional arrangement.Comment: 11 pages, 5 figures, SPIE Free-Space Laser Communication and Laser Imaging II. To appear in the proceeding of SPIE Free-Space Laser Communication and Laser Imaging II, vol 482

    CRIMES AND OFFENSES Bail Jumping: Redefine Offenses

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    The Act expands the crime of misdemeanor bail jumping to include defendants charged with or convicted any misdemeanor who fail to appear as directed. In addition, the Act creates the new offense of out-of-state bail jumping and provides notice procedures applicable to felony, misdemeanor, and out-of-state bail jumping

    CRIMINAL PROCEDURE Death Penalty Cases: Provide for Review of Pretrial Proceedings

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    The Act provides for discretionary review by the Georgia Supreme Court of all pretrial proceedings in death penalty cases. In addition, the Act sets forth procedures to be followed in ordering and conducting such a review

    CRIMINAL PROCEDURE Death Penalty Cases: Provide for Review of Pretrial Proceedings

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    The Act provides for discretionary review by the Georgia Supreme Court of all pretrial proceedings in death penalty cases. In addition, the Act sets forth procedures to be followed in ordering and conducting such a review

    CRIMES AND OFFENSES State-Wide Probation Act: Revise Certain Provisions

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    The Act revises the State-Wide Probation Act by creating a maximum period for probation and suspended sentences, setting standards for the revocation of such sentences, and limiting the amount of time that can be revoked, depending on the offense that constitutes the violation

    CRIMES AND OFFENSES State-Wide Probation Act: Revise Certain Provisions

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    The Act revises the State-Wide Probation Act by creating a maximum period for probation and suspended sentences, setting standards for the revocation of such sentences, and limiting the amount of time that can be revoked, depending on the offense that constitutes the violation

    Photon counting compressive depth mapping

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    We demonstrate a compressed sensing, photon counting lidar system based on the single-pixel camera. Our technique recovers both depth and intensity maps from a single under-sampled set of incoherent, linear projections of a scene of interest at ultra-low light levels around 0.5 picowatts. Only two-dimensional reconstructions are required to image a three-dimensional scene. We demonstrate intensity imaging and depth mapping at 256 x 256 pixel transverse resolution with acquisition times as short as 3 seconds. We also show novelty filtering, reconstructing only the difference between two instances of a scene. Finally, we acquire 32 x 32 pixel real-time video for three-dimensional object tracking at 14 frames-per-second.Comment: 16 pages, 8 figure

    Literature Review on Modeling of Density Difference Pumping Strategy for Geothermal Applications

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    The utilization of geothermal ground heat sources has been demonstrated at both large and small scales across the world. However, methods of extraction of the hot working fluids are often a source of energy inefficiency and high capital expense. Current techniques to extract geothermal fluids rely on mechanically and electrically driven down-hole components that require maintenance on a regular basis. In providing a solution, one approach that reduces complexity, decreases maintenance, and allows access to fluids at greater depth is an airlift approach. The airlift approach relies on injection of gas at a depth within a geothermal well to lift the working fluid to the surface using a density difference pumping strategy. This literature review focuses on existing methods and approaches to modeling the system throughout three scales: a microscale, intermediate scale, and macroscale. The microscale focuses on modeling considerations near the sparger head during bubble formation. The intermediate scale focuses on modeling techniques for characterizing bubble coalescing and gas hold-up. The macroscale focuses on modeling approaches over large length scales using a drift- flux model. Because of the varying phenomena experienced within the well, specifically complex bubble behavior and gas hold-up, it was a consensus amongst the literature to require a combination of in-depth experimental testing in combination with simulations to properly capture airlift flow rates. This literature review provides a review of modeling approaches that could be used to design a geothermal airlift system. Overall, the airlift system has the potential future application for power generation, district heating, and residential heating/cooling in geographic regions previously not considered based on existing technologies. The computational tools are currently available but it will require in-depth study of geothermal fluids under two-phase flow regimes
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