Spin and field squeezing in a spin-orbit coupled Bose-Einstein condensate

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Quantum waveguide theory of serial stub structures

The electronic behaviors in quantum wires with serial stubs are studied. A general theory of quantum waveguide based on transfer matrix method is developed and is used to treat periodic stub structures, serial stub structures with a defect stub, and Fibonacci stub structures. A number of interesting physical properties in connection with electronic transmission, energy spectra, and charge density distributions in these structures, are found theoretically. In particular, we find that whether there are periodicity and symmetry in the transmission and energy spectra depends on the commensurability of the length parameters. If one length ratio is incommensurate, then the transmission and energy spectra do not exhibit periodicity and symmetry even for periodic stub structures. In particular, the quasiperiodic behaviors are shown in Fibonacci stub structures proposed by us whenever the length parameters are commensurate. The experimental relevance is also addressed briefly. © 1999 American Institute of Physics.published_or_final_versio

Coupled optical interface modes in a Fibonacci dielectric superlattice

The coupled optical interface modes in a Fibonacci dielectric superlattice are studied. In the dielectric continuum approximation, the dispersion relation is found to have two bands of dual triadic Cantor structures, each being nonuniform scaling. For most of the eigenfrequencies, the amplitude profiles of electrostatic potential in this quasiperiodic structure are critical. Moreover, an invariant is analytically derived and is used to describe the general features of the frequency spectra and potential profiles.published_or_final_versio

Persistent currents in mesoscopic Fibonacci rings

In the framework of a tight-binding model, we study energy spectra and persistent currents in mesoscopic Fibonacci rings threaded by a magnetic flux. It is found that the flux-dependent electron eigenenergies E(Φ) in mesoscopic Fibonacci rings still form "bands" with respect to the flux Φ, but there is a scaling relation between the total "bandwidth" and the Fibonacci number. When the strength of the one-dimensional quasiperiodic potential increases, the persistent current decreases rapidly. Interestingly, for a generalized mixing model of mesoscopic Fibonacci rings, free-electron-like persistent current may appear if the number of electrons of the system takes a specific value.published_or_final_versio

Vibrations of beams and rods carrying a moving mass

We study the vibration of slender one-dimensional elastic structures (beams, cables, wires, rods) under the effect of a moving mass or load. We first consider the classical small- deflection (Euler-Bernoulli) beam case, where we look at tip vibrations of a cantilever as a model for a barreled launch system. Then we develop a theory for large deformations based on Cosserat rod theory. We illustrate the effect of moving loads on large-deformation structures with a few cable and arch problems. Large deformations are found to have a resonance detuning effect on the cable. For the arch we find different failure modes depending on its depth: a shallow arch fails by in-plane collapse, while a deep arch fails by sideways flopping. In both cases the speed of the traversing load is found to have a stabilising effect on the structure, with failure suppressed entirely at sufficiently high speed

Numerical Relaxation Approach for Solving the General Ginzburg-Landau Equations for Type-Ii Superconductors

Journals published by the American Physical Society can be found at http://journals.aps.org/A numerical relaxation approach for solving the general Ginzburg-Landau equations for type-II superconductors is developed. It is first applied to an isotropic type-II superconductor near H(c1) in order to establish the reliability and effectiveness of this approach. The strength of this approach should be in dealing with anisotropic and/or inhomogeneous systems. As an initial test of this strength, we have applied it to some anisotropic cases. Distributions of the superconducting order parameter and the local magnetic field, as well as the lower critical field for these cases, are presented

Flux Motion in Anisotropic Type-Ii Superconductors Near H(c2)

Journals published by the American Physical Society can be found at http://journals.aps.org/Flux motion in anisotropic type-II superconductors is studied in the framework of the time-dependent Ginzburg-Landau theory. Expressions for the flux-flow resistivity tensor (including all the longitudinal and Hall elements) are obtained for the case that the applied magnetic field H is parallel to one of the principal axes of the sample and H is near the upper critical field H(c2). A simple method is proposed for obtaining the anisotropy ratios from the H dependences of the longitudinal resistivities

Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

Out-Of-Plane Transverse Resistivity in High-T-C Superconductors as a Signature of Flow of Rigid Vortex Lines

Journals published by the American Physical Society can be found at http://journals.aps.org/When the transport current is applied parallel to the CuO2 layers, say, along the a axis, of a high-T-c superconductor, and the magnetic field B is in a direction which makes a polar angle theta with the c axis and an azimuthal angle phi with the ac plane, for the case of rigid flux lines, in addition to the usual longitudinal resistivity rho(perpendicular to), there should also exist an out-of-plane transverse resistivity rho(perpendicular to), which is of the same order of magnitude as rho(perpendicular to) and satisfies the relation rho(perpendicular to)/rho(parallel to) =tan theta cos phi in the high anisotropy limit and for theta being not very close to pi/2. For less rigid flux lines, reduction in rho(perpendicular to)rho(parallel to) from this prediction should be observed, and for a set of decoupled pancake vortices, rho(perpendicular to) should vanish entirely