Scalable solid-state quantum computation in decoherence-free subspaces with trapped ions

We propose a decoherence-free subspaces (DFS) scheme to realize scalable quantum computation with trapped ions. The spin-dependent Coulomb interaction is exploited, and the universal set of unconventional geometric quantum gates is achieved in encoded subspaces that are immune from decoherence by collective dephasing. The scalability of the scheme for the ion array system is demonstrated, either by an adiabatic way of switching on and off the interactions, or by a fast gate scheme with comprehensive DFS encoding and noise decoupling techniques.Comment: 4 pages, 1 figur

The multitask theory of state enterprise reform: Empirical evidence from China

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Recovery of multiple parameters in subdiffusion from one lateral boundary measurement

This work is concerned with numerically recovering multiple parameters simultaneously in the subdiffusion model from one single lateral measurement on a part of the boundary, while in an incompletely known medium. We prove that the boundary measurement corresponding to a fairly general boundary excitation uniquely determines the order of the fractional derivative and the polygonal support of the diffusion coefficient, without knowing either the initial condition or the source. The uniqueness analysis further inspires the development of a robust numerical algorithm for recovering the fractional order and diffusion coefficient. The proposed algorithm combines small-time asymptotic expansion, analytic continuation of the solution and the level set method. We present extensive numerical experiments to illustrate the feasibility of the simultaneous recovery. In addition, we discuss the uniqueness of recovering general diffusion and potential coefficients from one single partial boundary measurement, when the boundary excitation is more specialized

Study on the insecticidal activity compounds of the essential oil from Syzygium aromaticum against stored grain insect pests

Insect pests are a major cause of damage in stored grain around the world. To control the stored grain insects, synthetic insecticides have been used extensively for many years, resulting in insect populations that are resistant to insecticides. Consequently there is an interest to find alternatives to chemical pesticides. The essential oil from Syzygium aromaticum (clove oil) has a number of bioactive compounds. The chemical constituents of the clove oil were analyzed by GC-MS, and 9 of 18 compounds were identified. The main compound (83%) was 2-methoxy-4-(2-propenyl)-phenol the second most common compound (12%) was trans-caryophyllene. These two pure compounds and clove oil were tested for toxicity and repellency against Rhyzopertha dominica, Sitophilus oryzae and Tribolium castaneum. The pure compounds were tested at the dosages found in clove oil. The mortality from 2-methoxy-4-(2-propenyl)-phenol was not significantly different from clove oil, suggesting that the activity of clove oil was solely due to this major compound. The repellency results were more complex. 2-methoxy-4-(2-propenyl)-phenol was more repellant than clove oil. Trans-caryophyllene was less toxic and less repellant than both clove oil and 2-methoxy-4-(2-propenyl)- phenol. The potential for these compounds to be used to control stored product insects is discussed. Keywords: Essential oils, Syzygium aromaticum, Clove oil, Insecticidal activity compounds, Stored grain insect

A frequency domain based approach to on-line system identification.

This thesis addresses the problem of identifying the dynamics of a linear system in the frequency domain. An alogrithm operating on the Fast Fourier Transform (FFT) of blocks of signals is developed and its performance evaluated through computer simulations. Several properties are tested, in particular, its convergence and its capabilities of identifying the frequency response of the unknown system.http://archive.org/details/frequencydomainb00chaoLieutenant, R.O.C. NavyApproved for public release; distribution is unlimited

A Numerical Method Based On Element Free Galerkin Method For Lower Bound Limit Analysis

Summary A solution procedure for lower bound limit analysis is presented making use of the element free Galerkin (EFG) method rather than of the traditional numerical methods such as finite element method and boundary element method. A reduced basis technique is adopted to solve the mathematical programming iteratively in a sequence of reduced self-equilibrium stress subspaces with very low dimensions. Numerical example in this paper shows that it is feasible and efficient to solve the problems of limit analysis by using the EFG method

Rewritable nanoscale oxide photodetector

Nanophotonic devices seek to generate, guide, and/or detect light using structures whose nanoscale dimensions are closely tied to their functionality. Semiconducting nanowires, grown with tailored optoelectronic properties, have been successfully placed into devices for a variety of applications. However, the integration of photonic nanostructures with electronic circuitry has always been one of the most challenging aspects of device development. Here we report the development of rewritable nanoscale photodetectors created at the interface between LaAlO3 and SrTiO3. Nanowire junctions with characteristic dimensions 2-3 nm are created using a reversible AFM writing technique. These nanoscale devices exhibit a remarkably high gain for their size, in part because of the large electric fields produced in the gap region. The photoconductive response is gate-tunable and spans the visible-to-near-infrared regime. The ability to integrate rewritable nanoscale photodetectors with nanowires and transistors in a single materials platform foreshadows new families of integrated optoelectronic devices and applications.Comment: 5 pages, 5 figures. Supplementary Information 7 pages, 9 figure