Efficient electronic entanglement concentration assisted with single mobile electron

We present an efficient entanglement concentration protocol (ECP) for mobile electrons with charge detection. This protocol is quite different from other ECPs for one can obtain a maximally entangled pair from a pair of less-entangled state and a single mobile electron with a certain probability. With the help of charge detection, it can be repeated to reach a higher success probability. It also does not need to know the coefficient of the original less-entangled states. All these advantages may make this protocol useful in current distributed quantum information processing.Comment: 6pages, 3figure

A GPU-based finite-size pencil beam algorithm with 3D-density correction for radiotherapy dose calculation

Targeting at the development of an accurate and efficient dose calculation engine for online adaptive radiotherapy, we have implemented a finite size pencil beam (FSPB) algorithm with a 3D-density correction method on GPU. This new GPU-based dose engine is built on our previously published ultrafast FSPB computational framework [Gu et al. Phys. Med. Biol. 54 6287-97, 2009]. Dosimetric evaluations against Monte Carlo dose calculations are conducted on 10 IMRT treatment plans (5 head-and-neck cases and 5 lung cases). For all cases, there is improvement with the 3D-density correction over the conventional FSPB algorithm and for most cases the improvement is significant. Regarding the efficiency, because of the appropriate arrangement of memory access and the usage of GPU intrinsic functions, the dose calculation for an IMRT plan can be accomplished well within 1 second (except for one case) with this new GPU-based FSPB algorithm. Compared to the previous GPU-based FSPB algorithm without 3D-density correction, this new algorithm, though slightly sacrificing the computational efficiency (~5-15% lower), has significantly improved the dose calculation accuracy, making it more suitable for online IMRT replanning

Robust linear dependence of thermal conductance on radial strain in carbon nanotubes

Nanotubes have recently been experimentally demonstrated to be perfect phonon waveguides. To explore the underlying physics, we present atomic scale calculations of thermal transport in carbon nanotubes under radial strain using the nonequilibrium Green’s function method. It is found that the thermal conductance exhibits a robust linear response behavior to radial strain over the whole elastic range. A detailed analysis of phonon transmission reveals that an elastic radial strain can be viewed as a perturbation of the transport of most of the low-frequency phonons. This is attributed to the unique bonding configuration of nanotubes, which can be well preserved even under severe deformation. Such a structural response to deformation, which is rare in other systems, explains the robust thermal transport in nanotubes against severe radial deformation

Evolutionary design of a full-envelope full-authority flight control system for an unstable high-performance aircraft

The use of an evolutionary algorithm in the framework of H1 control theory is being considered as a means for synthesizing controller gains that minimize a weighted combination of the infinite norm of the sensitivity function (for disturbance attenuation requirements) and complementary sensitivity function (for robust stability requirements) at the same time. The case study deals with a complete full-authority longitudinal control system for an unstable high-performance jet aircraft featuring (i) a stability and control augmentation system and (ii) autopilot functions (speed and altitude hold). Constraints on closed-loop response are enforced, that representing typical requirements on airplane handling qualities, that makes the control law synthesis process more demanding. Gain scheduling is required, in order to obtain satisfactory performance over the whole flight envelope, so that the synthesis is performed at different reference trim conditions, for several values of the dynamic pressure, used as the scheduling parameter. Nonetheless, the dynamic behaviour of the aircraft may exhibit significant variations when flying at different altitudes, even for the same value of the dynamic pressure, so that a trade-off is required between different feasible controllers synthesized at different altitudes for a given equivalent airspeed. A multiobjective search is thus considered for the determination of the best suited solution to be introduced in the scheduling of the control law. The obtained results are then tested on a longitudinal non-linear model of the aircraft

Detrended fluctuation analysis for fractals and multifractals in higher dimensions

One-dimensional detrended fluctuation analysis (1D DFA) and multifractal detrended fluctuation analysis (1D MF-DFA) are widely used in the scaling analysis of fractal and multifractal time series because of being accurate and easy to implement. In this paper we generalize the one-dimensional DFA and MF-DFA to higher-dimensional versions. The generalization works well when tested with synthetic surfaces including fractional Brownian surfaces and multifractal surfaces. The two-dimensional MF-DFA is also adopted to analyze two images from nature and experiment and nice scaling laws are unraveled.Comment: 7 Revtex pages inluding 11 eps figure

Terahertz Hall Measurements On Optimally Doped Single Crystal Bi-2212

The infrared Hall angle in optimally doped single crystal $\rm Bi_2 Sr_2 Ca Cu_2 O_{8+x}$ was measured from 3.05 to 21.75 meV as a continuous function of temperature from 25 to 300\,K. In the normal state, the temperature dependence of the real part of the cotangent of the infrared Hall angle obeys the same power law as dc measurements. The measured Hall frequency $\rm \omega_H$ is significantly larger than the expected value based upon ARPES data analyzed in terms of the relaxation time approximation. This discrepancy as well as the temperature dependence of $\rm Re(\cot{\theta_H})$ and $\omega_H$ is well described by a Fermi liquid theory in which current vertex corrections produced by electron-magnon scattering are included.Comment: 10 pages, 2 figure

Static displacements and chemical correlations in alloys

Recent experiments in metallic solid solutions have revealed interesting correlations between static pair-displacements and the ordering behavior of these alloys. This paper discusses a simple theoretical model which successfully explains these observations and which provides a natural framework for analyzing experimental measurements of pair-displacements and chemical correlations in solid solutions. The utility and scope of this model is demonstrated by analyzing results of experiments on $Ni-Fe$ and $Cr-Fe$ alloys and results of simulations of $Cu-Au$ and $Cu-Ag$ alloys.Comment: 12 page