Theoretical potential function represented by networks

The model of theoretical potential function represented by networks has been proposed. Quantum chemicalab initio method is used to ralculnte the interionic potential of molten salt systems. The physical contents of network potential are indicated with Born-Mayer-Huggins empirical potential functions, whose deviation from the theoretical potential owing to its approximation is corrected using back propagation artificial neural networks (BP-ANN). Preliminary results have shown that the theoretical potential function networks are useful for the computer simulations of molten salt systems     

Monte Carlo calculation method on low energy electron scattering in polybasic medium

A novel Monte Carlo method of simulating low energy electron (LEE) scattering in polybasic medium is presented. The Mott cross section is adopted to describe the elastic scattering of LEE, and a mean cross section idea is proposed instead of usual determination of the scattering center. The Joy’s modified Bethe equation is used to calculate energy loss of LEE. The scattering processes of LEE in bulk PMMA have been simulated. And the electron backscattering coefficients, the electron interaction range and energy dissipation distribution of LEE in bulk PMMA have been calculated and compared with those calculated by the method of determining scattering center.     

Superconducting nanowire single-photon detection system and demonstration in quantum key distribution

We developed a superconducting nanowire single-photon detection(SNSPD) system based on Gifford-McMahon cryocooler for quantum communication applications.Environmental factors which may influence the system performance are intensively studied.Those factors include temperature fluctuations,the ambient magnetic field and the background radiation.By optimizing the bias circuit,the stability of SNSPD system to electrical noise and disturbance was effectively enhanced,thus making it more suitable for field application.A 4-channel SNSPD system with quantum efficiency higher than 4% at the dark count rate of 10 Hz for λ=1550 nm is integrated and applied into a quantum key distribution(QKD) experiment.QKD was successfully carried out over 100 km optical fiber with the final secure key rate of 1.6 kbps and the quantum bit error rate of less than 2%.     

B3G宽带移动MIMO无线信道

从考察信道产生机理出发,得到信道系数的离散时间表达式,分析了统计分布和时间、空间的相关性.仿真结果显示,此时的信道系数幅度不能简单地用瑞利分布来描述,其时间相关性显示出一定的随机性,空间相关性与角度扩展有关并在收发端产生不同影响.     

一种新的Zero-Forcing BLAST 联合检测算法

在有效利用双向迫零(BID-ZF)检测算法和并行干扰消除(PIC)检测算法的基础上,提出了一种ZF-BLAST的联合检测算法:BID-PIC.仿真结果表明,这种新的算法在低复杂度的情况下可以获得比单纯使用BID-ZF或者ZF-PIC的性能好.