Penetration of the Interplanetary Magnetic Field B(sub y) into Earth's Plasma Sheet

There has been considerable recent interest in the relationship between the cross-tail magnetic field component B(sub y) and tail dynamics. The purpose of this paper is to give an overall description of the penetration of the interplanetary magnetic field (IMF) B(sub y) into the near-Earth plasma sheet. We show that plasma sheet B(sub y) may be generated by the differential shear motion of field lines and enhanced by flux tube compression. The latter mechanism leads to a B(sub y) analogue of the pressure-balance inconsistency as flux tubes move from the far tail toward the Earth. The growth of B(sub y), however, may be limited by the dawn-dusk asymmetry in the shear velocity as a result of plasma sheet tilting. B(sub y) penetration into the plasma sheet implies field-aligned currents flowing between hemispheres. These currents together with the IMF B(sub y) related mantle field-aligned currents effectively shield the lobe from the IMF B(sub y)

Atom capture by nanotube and scaling anomaly

The existence of bound state of the polarizable neutral atom in the inverse square potential created by the electric field of single walled charged carbon nanotube (SWNT) is shown to be theoretically possible. The consideration of inequivalent boundary conditions due to self-adjoint extensions lead to this nontrivial bound state solution. It is also shown that the scaling anomaly is responsible for the existence of bound state. Binding of the polarizable atoms in the coupling constant interval \eta^2\in[0,1) may be responsible for the smearing of the edge of steps in quantized conductance, which has not been considered so far in literature.Comment: Accepted in Int.J.Theor.Phy

Vortex stability of interacting Bose-Einstein condensates confined in anisotropic harmonic traps

Vortex states of weakly-interacting Bose-Einstein condensates confined in three-dimensional rotating harmonic traps are investigated numerically at zero temperature. The ground state in the rotating frame is obtained by propagating the Gross-Pitaevskii equation for the condensate in imaginary time. The total energies between states with and without a vortex are compared, yielding critical rotation frequencies that depend on the anisotropy of the trap and the number of atoms. Vortices displaced from the center of nonrotating traps are found to have long lifetimes for sufficiently large numbers of atoms. The relationship between vortex stability and bound core states is explored.Comment: 5 pages, 2 embedded figures, revtex. To appear in Phys. Rev. Let

Transparent Anomalous Dispersion and Superluminal Light Pulse Propagation at a Negative Group Velocity

Anomalous dispersion cannot occur in a transparent passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, both theoretically and experimentally, that transparent linear anomalous dispersion can occur when a gain doublet is present. Therefore, a superluminal light pulse propagation can be observed even at a negative group velocity through a transparent medium with almost no pulse distortion. Consequently, a {\it negative transit time} is experimentally observed resulting in the peak of the incident light pulse to exit the medium even before entering it. This counterintuitive effect is a direct result of the {\it rephasing} process owing to the wave nature of light and is not at odds with either causality or Einstein's theory of special relativity.Comment: 12 journal pages, 9 figure

Complete quantum teleportation with a Kerr nonlinearity

We present a scheme for the quantum teleportation of the polarization state of a photon employing a cross-Kerr medium. The experimental feasibility of the scheme is discussed and we show that, using the recently demonstrated ultraslow light propagation in cold atomic media, our proposal can be realized with presently available technology.Comment: 4 pages, revtex, 1 eps figur

Sensitivities of Low Energy Reactor Neutrino Experiments

The low energy part of the reactor neutrino spectra has not been experimentally measured. Its uncertainties limit the sensitivities in certain reactor neutrino experiments. The origin of these uncertainties are discussed, and the effects on measurements of neutrino interactions with electrons and nuclei are studied. Comparisons are made with existing results. In particular, the discrepancies between previous measurements with Standard Model expectations can be explained by an under-estimation of the low energy reactor neutrino spectra. To optimize the experimental sensitivities, measurements for \nuebar-e cross-sections should focus on events with large ($>$1.5 MeV) recoil energy while those for neutrino magnetic moment searches should be based on events $<$100 keV. The merits and attainable accuracies for neutrino-electron scattering experiments using artificial neutrino sources are discussed.Comment: 25 pages, 9 figure

Quantum non-demolition (QND) modulation of quantum interference

We propose an experiment where quantum interference between two different paths is modulated by means of a QND measurement on one or both the arm of the interferometer. The QND measurement is achieved in a Kerr cell. We illustrate a scheme for the realisation of this experiment and some further developments.Comment: accepted for publicatio

Three-dimensional coherent X-ray diffraction imaging of a ceramic nanofoam: determination of structural deformation mechanisms

Ultra-low density polymers, metals, and ceramic nanofoams are valued for their high strength-to-weight ratio, high surface area and insulating properties ascribed to their structural geometry. We obtain the labrynthine internal structure of a tantalum oxide nanofoam by X-ray diffractive imaging. Finite element analysis from the structure reveals mechanical properties consistent with bulk samples and with a diffusion limited cluster aggregation model, while excess mass on the nodes discounts the dangling fragments hypothesis of percolation theory.Comment: 8 pages, 5 figures, 30 reference

Steep anomalous dispersion in coherently prepared Rb vapor

Steep dispersion of opposite signs in driven degenerate two-level atomic transitions have been predicted and observed on the D2 line of 87Rb in an optically thin vapor cell. The intensity dependence of the anomalous dispersion has been studied. The maximum observed value of anomalous dispersion [dn/dnu ~= -6x10^{-11}Hz^{-1}] corresponds to anegative group velocity V_g ~= -c/23000.Comment: 4 pages, 4 figure