2,476 research outputs found

    Rotational Cooling of Polar Molecules by Stark-tuned Cavity Resonance

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    A general scheme for rotational cooling of diatomic heteronuclear molecules is proposed. It uses a superconducting microwave cavity to enhance the spontaneous decay via Purcell effect. Rotational cooling can be induced by sequentially tuning each rotational transition to cavity resonance, starting from the highest transition level to the lowest using an electric field. Electrostatic multipoles can be used to provide large confinement volume with essentially homogeneous background electric field.Comment: 10 pages, 6 figure

    Vortex Matter Transition in Bi2{}_2Sr2{}_2CaCu2{}_2O8+y{}_{8+y} under Tilted Fields

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    Vortex phase diagram under tilted fields from the cc axis in Bi2{}_2Sr2{}_2CaCu2{}_2O8+y{}_{8+y} is studied by local magnetization hysteresis measurements using Hall probes. When the field is applied at large angles from the cc axis, an anomaly (HpH_p^\ast) other than the well-known peak effect (HpH_p) are found at fields below HpH_p. The angular dependence of the field HpH_p^\ast is nonmonotonic and clearly different from that of HpH_p and depends on the oxygen content of the crystal. The results suggest existence of a vortex matter transition under tilted fields. Possible mechanisms of the transition are discussed.Comment: Revtex, 4 pages, some corrections are adde

    Modeling the lasing spectra of InAs/InP Quantum dash lasers

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98746/1/ApplPhysLett_98_101105.pd

    Pressure Dependence of the Irreversibility Line in Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta}:Role of Anisotropy in Flux-Line Formation

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    One of the important problems of high-temperature superconductivity is to understand and ultimately to control fluxoid motion. We present the results of a new technique for measuring the pressure dependence of the transition to superconductivity in a diamond anvil cell. By measuring the third harmonic of the {\it ac} susceptibility, we determine the onset of irreversible flux motion. This enables us to study the effects of pressure on flux motion. The application of pressure changes interplanar spacing, and hence the interplanar coupling, without significantly disturbing the intraplanar superconductivity. Thus we are able to separate the effects of coupling from other properties that might affect the flux motion. Our results directly show the relationship between lattice spacing, effective- mass anisotropy, and the irreversibility line in Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta}. Our results also demonstrate that an application of 2.5 GPa pressure causes a dramatic increase in interplanar coupling.Comment: 4 pages, 4 figure

    Biologically Inspired Monocular Vision Based Navigation and Mapping in GPS-Denied Environments

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    This paper presents an in-depth theoretical study of bio-vision inspired feature extraction and depth perception method integrated with vision-based simultaneous localization and mapping (SLAM). We incorporate the key functions of developed visual cortex in several advanced species, including humans, for depth perception and pattern recognition. Our navigation strategy assumes GPS-denied manmade environment consisting of orthogonal walls, corridors and doors. By exploiting the architectural features of the indoors, we introduce a method for gathering useful landmarks from a monocular camera for SLAM use, with absolute range information without using active ranging sensors. Experimental results show that the system is only limited by the capabilities of the camera and the availability of good corners. The proposed methods are experimentally validated by our self-contained MAV inside a conventional building

    Possible new vortex matter phases in BSCCO

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    The vortex matter phase diagram of BSCCO crystals is analyzed by investigating vortex penetration through the surface barrier in the presence of a transport current. The strength of the effective surface barrier, its nonlinearity, and asymmetry are used to identify a possible new ordered phase above the first-order transition. This technique also allows sensitive determination of the depinning temperature. The solid phase below the first-order transition is apparently subdivided into two phases by a vertical line extending from the multicritical point.Comment: 11 pages, 3 figures, accepted for publication in PR
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