GaAs/AlGaAs多量子阱材料差分反射光谱

介绍了一种新型的空间调制光谱技术—差分反射 ( DR)光谱技术 .利用振动光束差分反射测试系统 ,获得了 Ga As/Al Ga As多量子阱材料的 DR谱 ,初步分析了 DR信号的产生机制 .通过与材料的 PR谱及反射光谱的一阶微商谱比较分析 ,论证了 DR光谱技术用于多量子阱量子化跃迁观测的理论可行性 ,并从实验角度证明了 Ga As/Al Ga As多量子阱材料的 DR谱具有反射率谱对能量的一阶微商线型特征     

三种卟啉类光敏剂的荧光量子产率

实验研究了喜泊分(Hiporfin),血啉甲醚(HMME)和癌光啉(PsD-007)等3种国产卟啉类光敏剂在水溶液中的吸收和荧光光谱特性,并利用对照法首次测定了它们在水溶液中的荧光量子产率.Hiporfin,HMME和PsD-007具有相似的吸收光谱和荧光发射特性,它们的荧光量子产率分别为0.013,0.026和0.020.实验表明光敏剂的荧光量子产率还与溶液中的氧含量有关.实验结果为光动力学诊断中光敏剂的选择,以及相应最佳荧光激发和检测波长的选取提供了理论依据.     

基于嵌入式通信网络的数据协调

根据量子密码通信的实际需要,构建了一套嵌入式通信网络,实现动态数据传输。选用Spartan3s 1500MB开发板,采用软硬件协同设计方法,用EDK构建了一个基于Xilinx SOPC的网络通信系统,并设计了高斯随机数IP核来生成随机数,利用该系统可以在两台PC机和FPGA板上进行高速远距离的数据传输,实现量子密码通信中的数据协调。     

超导电路与体声波谐振器组成的量子iSWAP门方案

高保真度量子门的物理实现是量子计算和量子通信的关键技术之一。根据电路量子声动力学和量子电动力学,提出了由两个具有较长相干时间的超导transmon qubit和一个具有高机械品质因数的薄膜体声波谐振器组成的量子门方案,体声波谐振器起到类似微波光子通道的作用,使两个transmon qubit之间实现量子态交互。该文先用Butterworth van Dyke模型分析体声波谐振器在方案中的等效电路,构建系统的量子化哈密顿量,再用二能级原子 声子混合量子态形式编码系统的量子态,通过调节外磁场来调控系统的输入态,系统的输出态可通过测量模块得到。在Jaynes Cummings模型下,该系统能完成具有高保真度的量子相位交换（iSWAP）门操作。     

面向长距离量子通信的双光子关联成像技术

量子时域鬼成像利用光子对的时间-频率关联性实现了50km光纤链路上的图像传送,有望应用于量子通信的协议中。然而,现有方案的成像质量较差,成像速度较慢,因此其应用性在一定程度上受到了限制。文章对已有成像方案进行了较大的改进,利用可编程滤波器数字设定待成像信息,进而实现了二维图像信息的自动化实时传送。实验结果证明,改进方案的成像质量和速度均有显著改善,有利于推动量子关联成像在量子通信领域的应用。     

Exploiting WiMAX for covert transmission of secret data over fading channel

Worldwide Interoperability for Microwave Access (WiMAX) is the broadband wireless access technique that provides rapid broadband services to domestic and enterprise users. Owing to the broadcast characteristic of the WiMAX system, transmitted data security is crucial, particularly when the messages are confidential. In this work, exploiting of WiMAX to convey sensitive secret information is presented. In the first phase, we exploited conventional WiMAX (fast Fourier transform [FFT]‐WiMAX), and in the second phase, we propose a wavelet packet transform (WPT)–based WiMAX for covert communication. The quality evaluation of both covert transmission models (FFT‐WiMAX and WPT‐WiMAX) over the fading channel is done in this work. The experimental outcomes of the proposed WPT‐WiMAX covert transmission system reveal a significant enhancement in error rate (bit error rate) and peak signal‐to‐noise ratio for a given signal‐to‐noise ratio.     

Enhancing quality of experience using peer‐to‐peer overlay on device‐to‐device communications

With the recent development of LTE‐A/5G technologies, data sharing among mobile devices offer an attractive opportunity to reduce Internet access. However, it requires smart strategies to share the data with low trade‐offs in time, cost, and energy. Several existing schemes offer a super‐peer‐based two‐tier model using a distributed hash table (DHT) organization for smart devices having device‐to‐device (D2D)/Bluetooth/WiFi capabilities. The primary focus of these schemes has been to reduce Internet usage by increased D2D content sharing. However, the real challenge is not in creating a two‐tier model, but evolving an efficient overlay that offers enhanced opportunities for D2D content sharing over the existing model. In this paper, we formulated a P‐median‐based selection of tier‐1 devices in a distribution network and solved it using the Lagrangian relaxation method. The tier‐2 devices become clients seeking content sharing services from tier‐1 devices. A strong motivation in this work is to raise a user's perception of the grade of service known as quality of experience (QoE). We analyzed the challenge for QoE assessment in resource‐constrained smartphones under the proposed model of enhanced D2D communication. Our focus is to establish a framework to evaluate QoE for applications and services over LTE‐A/5G networks with an improved D2D communication level. The simulation and the experimental results validate the claim that substantial improvements in QoE are possible with the proposed mathematical model for selecting and placing tier‐1 mobile devices and maintaining a DHT for D2D communication.     

双光子B-J模型中类克尔介质对量子态保真度的影响

研究了充满类克尔介质的高 Q腔中二能级原子与单模相干光场发生双光子相互作用 (双光子 B- J模型 )时 ,类克尔介质对该体系量子态保真度的影响。结果表明 :当类克尔介质与光场耦合较强时 ,原子的量子态保真度为 1,即原子处于退纠缠状态 ,此时光场对原子的作用被类克尔介质所屏蔽。     

赝形δ掺杂AIGaAs／InGaAds／GaAs量子阱的光致发光性质研究

测量了一系列不同隔离层（ｓｐａｃｅｒ）厚度、阱宽和硅δ掺杂浓度的单边掺杂的赝形高电子迁移率晶体管（ｐＨＥＭＴｓ）量子阱的变温和变激发功率光致发光谱,详细研究了（ｅｌ－ｈｈ１）和（ｅ２－ｈｈ１）两人发光峰之间的动态竞争发光机制,并运用有限差分法自治求解薛定谔方程和泊松方程以得出电子限制势、子带能极以及相应的电子包络波函数、子带占据几率和δ掺杂电子转移效率,研究了两个峰的相对积分发光强度随隔离层厚度、阱宽和δ掺杂浓度的变化。     

Correlated electron-hole transitions in wurtzite GaN quantum dots:the effects of strain and hydrostatic pressure

Within the effective-mass and finite-height potential barrier approximation,a theoretical study of the effects of strain and hydrostatic pressure on the exciton emission wavelength and electron-hole recombination rate in wurtzite cylindrical GaN/Al_xGa_1-xN quantum dots（QDs） is performed using a variational approach.Numerical results show that the emission wavelength with strain effect is higher than that without strain effect when the QD height is large（> 3.8 nm）,but the status is opposite when the QD height is small（< 3.8 nm）.The height of GaN QDs must be less than 5.5 nm for an efficient electron-hole recombination process due to the strain effect.The emission wavelength decreases linearly and the electron-hole recombination rate increases almost linearly with applied hydrostatic pressure.The hydrostatic pressure has a remarkable influence on the emission wavelength for large QDs,and has a significant influence on the electron-hole recombination rate for small QDs.Furthermore,the present numerical outcomes are in qualitative agreement with previous experimental findings under zero pressure.