Realizing quantum controlled phase-flip gate through quantum dot in silicon slow-light photonic crystal waveguide

We propose a scheme to realize controlled phase gate between two single photons through a single quantum dot in slow-light silicon photonic crystal waveguide. Enhanced Purcell factor and beta factor lead to high gate fidelity over broadband frequencies compared to cavity-assisted system. The excellent physical integration of this silicon photonic crystal waveguide system provides tremendous potential for large-scale quantum information processing.Comment: 9 pages, 3 figure

Linear scaling computation of the Fock matrix. IX. Parallel computation of the Coulomb matrix

We present parallelization of a quantum-chemical tree-code [J. Chem. Phys. {\bf 106}, 5526 (1997)] for linear scaling computation of the Coulomb matrix. Equal time partition [J. Chem. Phys. {\bf 118}, 9128 (2003)] is used to load balance computation of the Coulomb matrix. Equal time partition is a measurement based algorithm for domain decomposition that exploits small variation of the density between self-consistent-field cycles to achieve load balance. Efficiency of the equal time partition is illustrated by several tests involving both finite and periodic systems. It is found that equal time partition is able to deliver 91 -- 98 % efficiency with 128 processors in the most time consuming part of the Coulomb matrix calculation. The current parallel quantum chemical tree code is able to deliver 63 -- 81% overall efficiency on 128 processors with fine grained parallelism (less than two heavy atoms per processor).Comment: 7 pages, 6 figure

A comparative study between x-rays and gamma-rays irradiation on electrical characteristics of bipolar junction transistors (BJTS)

Irradiation impact of gamma rays and X-rays on bipolar junction transistors (BJTs) in terms of electronic excitation due to transfer of energy and subsequent ionization, as well as energy transfer to atomic nuclei is studied using in-situ method. Comparison is made on the electrical characteristics of the devices under test (DUT) for various collecting current at two different operating mode. Both temporary and permanent damages in DUTs are found to be induced by energy transfer from the irradiation by gamma-rays and X-rays, depending upon total dose absorbed and current drive. Increased probability of recombination, due to creation of electron–hole pairs at the base region is found to be the most significant radiation damage in BJTs, as it leads to decrease in electron flux reaching the collector region

Cryogenic spectroscopy of ultra-low density colloidal lead chalcogenide quantum dots on chip-scale optical cavities towards single quantum dot near-infrared cavity QED

We present evidence of cavity quantum electrodynamics from a sparse density of strongly quantum-confined Pb-chalcogenide nanocrystals (between 1 and 10) approaching single-dot levels on moderately high-Q mesoscopic silicon optical cavities. Operating at important near-infrared (1500-nm) wavelengths, large enhancements are observed from devices and strong modifications of the QD emission are achieved. Saturation spectroscopy of coupled QDs is observed at 77K, highlighting the modified nanocrystal dynamics for quantum information processing.Comment: * new additional figures and text * 10 pages, 5 figure

Temperature-tuning of near-infrared monodisperse quantum dot solids at 1.5 um for controllable Forster energy transfer

We present the first time-resolved cryogenic observations of Forster energy transfer in large, monodisperse lead sulphide quantum dots with ground state transitions near 1.5 um (0.83 eV), in environments from 160 K to room temperature. The observed temperature-dependent dipole-dipole transfer rate occurs in the range of (30-50 ns)^(-1), measured with our confocal single-photon counting setup at 1.5 um wavelengths. By temperature-tuning the dots, 94% efficiency of resonant energy transfer can be achieved for donor dots. The resonant transfer rates match well with proposed theoretical models

The prevalence of insomnia in the general population in China: A meta-analysis

This is the first meta-analysis of the pooled prevalence of insomnia in the general population of China. A systematic literature search was conducted via the following databases: PubMed, PsycINFO, EMBASE and Chinese databases (China National Knowledge Interne (CNKI), WanFang Data and SinoMed). Statistical analyses were performed using the Comprehensive Meta-Analysis program. A total of 17 studies with 115,988 participants met the inclusion criteria for the analysis. The pooled prevalence of insomnia in China was 15.0% (95% Confidence interval [CI]: 12.1%-18.5%). No significant difference was found in the prevalence between genders or across time period. The pooled prevalence of insomnia in population with a mean age of 43.7 years and older (11.6%; 95% CI: 7.5%-17.6%) was significantly lower than in those with a mean age younger than 43.7 years (20.4%; 95% CI: 14.2%-28.2%). The prevalence of insomnia was significantly affected by the type of assessment tools (Q = 14.1, P = 0.001). The general population prevalence of insomnia in China is lower than those reported in Western countries but similar to those in Asian countries. Younger Chinese adults appear to suffer from more insomnia than older adults

Revealing copper contamination at the Penang industrial area by using Malaysian mussel watch approach.

Concentrations of Cd, Cu, Ni, Fe, Pb and Zn were determined in the four different parts of soft tissues and shells of Perna viridis collected from 6 geographical sites in the Straits of Malacca in 2005. All the 6 metal concentrations except for Cu were considered low and comparable to those reported in the literature. The Cu concentrations found in the Penang population was found to be extremely elevated and exceeding the ranges for most reported studies as well as safety guidelines, which may be derived from a variety of industrial activities at Penang industrial area. Therefore, the consumption of mussels collected from the intertidal water adjacent to Penang Industrial Area should be given a special caution since human consumption on the mussels could pose toxicological risk of Cu. The present study showed that the Penang coastal water was receiving industrial effluents as a point source of Cu pollution as indicated by the elevated concentration of Cu in the different soft tissues of P. viridis

Modelling Evaporation and Evapotranspiration under Temperature Change in Malaysia

Temperature change has a direct effect on hydrology through its link with evapotranspiration. The potential impact of temperature change on the evapotranspiration is assessed; using a modelling approach based on a few physical weather measurements. Methods to estimate free-surface evaporation E and potential evapotranspiration ETp ' without any model calibration p~parameters, for monthly time series are presented. The model results are calculated by using observed average historic (1980-97) meteorological data and compared with USBR Class-A black pan evaporation data (1971-97) from the Muda Agricultural Development Authority, Malaysia. The long-term monthly averaged daily estimates of Ep for different months were compared with measured pan evaporation. Results of this simulation showed an accuracy of more than 95% with the observed pan evaporation data and thus, would be used for ET estimation. All the model equations containing temperature terms were set dependent of temperature. The correlation between mean monthly relative humidity and temperature was also made to investigate the sensitivity of ETp ' The ETp time series is perturbed by varying monthly temperature from 21"C to 41"C, with O.2"C increment to investigate the sensitivity of that series. Results from the perturbations showed that the temperature has significant effects on ET for each month.

Spectrum of Sizes for Perfect Deletion-Correcting Codes

One peculiarity with deletion-correcting codes is that perfect $t$-deletion-correcting codes of the same length over the same alphabet can have different numbers of codewords, because the balls of radius $t$ with respect to the Levenshte\u{\i}n distance may be of different sizes. There is interest, therefore, in determining all possible sizes of a perfect $t$-deletion-correcting code, given the length $n$ and the alphabet size~$q$. In this paper, we determine completely the spectrum of possible sizes for perfect $q$-ary 1-deletion-correcting codes of length three for all $q$, and perfect $q$-ary 2-deletion-correcting codes of length four for almost all $q$, leaving only a small finite number of cases in doubt.Comment: 23 page