Recent developments of quantum dot based micro-LED based on non-radiative energy transfer mechanism

With regard to micro-light-emitting diodes(micro-LEDs),their excellent brightness,low energy consumption,and ultrahigh resolution are significant advantages.However,the large size of traditional inorganic phosphors and the number of side defects have restricted the practical applications of small sized micro-LEDs.Recently,quantum dot(QD)and nonradiative energy transfer(NRET)have been proposed to solve existing problems.QDs possess nanoscale dimensions and high luminous efficiency,and they are suitable for NRET because they are able to nearly contact the micro-LED chip.The NRET between QDs and micro-LED chip further improves the color conversion efficiency(CCE)and effective quantum yield(EQY)of full-color micro-LED devices.In this review,we discuss the NRET mechanism for QD micro-LED devices,and then nano-pillar LED,nano-hole LED,and nano-ring LED are introduced in detail.These structures are beneficial to the NRET between QD and micro-LED,especially nano-ring LED.Finally,the challenges and future envisions have also been described.

Post-processing Free Quantum Random Number Generator Based on Avalanche Photodiode Array

Quantum random number generators adopting single negligible dead time of avalanche photodiodes （APDs） photon detection have been restricted due to the non- We propose a new approach based on an APD array to improve the generation rate of random numbers significantly. This method compares the detectors＇ responses to consecutive optical pulses and generates the random sequence. We implement a demonstration experiment to show its simplicity, compactness and scalability. The generated numbers are proved to be unbiased, post-processing free, ready to use, and their randomness is verified by using the national institute of standard technology statistical test suite. The random bit generation efficiency is as high as 32.8% and the potential generation rate adopting the 32× 32 APD array is up to tens of Gbits/s.

Synthesis,Crystal Structure and Quantum Chemical Investigation of Bis-Schiff Base Compounds Derived from2-phenyl-1,2,3-triazole-4-carboxaldehyde with Diamine

Two new schiff base N,N＇-bis（（2-phenyl-2H-1,2,3-triazol-4-yl）methylene）-1,3-propanediamine （1） and N,N＇-bis（（2-phenyl-2H-1,2,3-triazol-4-yl）methylene） -1,4-butanediamine （2） were synthesized by condensation of 2-phenyl-1,2,3-triazole-4-carboxaldehyde with diamine, and characterized by elemental analysis, IR, IH NMR and MS spectra. Their crystal structures were determined by X-ray single crystal diffraction. Both crystals belong to the monoclinic system, space group P21/c. For compound 1（C21H20N8, Mr=384.45）： a = 16.314（3）, b =5.7168（11）, c = 21.316（4） A, β = 105.3（2）°, Z = 4, V = 1917.6（7） A^3, De =1.332 g/cm^3, F（000） = 808,μ = 0.086 mm 1, R = 0.0533 and wR = 0.1460; for compound 2 （C22H22N8, Mr=398.48）： a = 8.6156（17）, b = 5.2964（11）, c = 22.665（5）A, β = 100.54（3）°, Z = 2, V = 1016.8（4） A^3, De= 1.302 g/cm^3, F （000） = 420, μ = 0.083 mm^-1, R = 0.0373 and wR = 0.1155. Based on the crystal data, quantum chemistry calculation was performed on the two title compounds by means of Gaussian 98 program. The molecular orbital energies and atomic net charges population were obtained. Furthermore, we antilyzed their active atoms. The investigation can serve as a theoretical guide to study the synthesis and activity of the title compounds.

III-Nitride-Based Quantum Dots and Their Optoelectronic Applications

During the last two decades, III-nitride-based quantum dots(QDs) have attracted great attentions for optoelectronic applications due to their unique electronic properties. In this paper, we first present an overview on the techniques of fabrication for III-nitride-based QDs. Then various optoelectronic devices such as QD lasers, QD light-emitting diodes(LEDs), QD infrared photodetectors(QDIPs) and QD intermediate band(QDIB) solar cells(SCs) are discussed. Finally, we focus on the future research directions and how the challenges can be overcome.

Quantum discord of two-qutrit system under quantum-jump-based feedback control

This paper studies quantum discord of two qutrits coupled to their own environments independently and coupled to the same environment simultaneously under quantum-jump-based feedback control. Our results show that spontaneous emission, quantum feedback parameters, classical driving, initial state, and detection efficiency all affect the evolution of quantum discord in a two-qutrit system. We find that under the condition of designing proper quantum-jump-based feedback parameters, quantum discord can be protected and prepared. In the case where two qutrits are independently coupled to their own environments, classical driving, spontaneous emission, and low detection efficiency have negative effect on the protection of quantum discord. For different initial states, it is found that the evolution of quantum discord under the control of appropriate parameters is similar. In the case where two qutrits are simultaneously coupled to the same environment,the classical driving plays a positive role in the generation of quantum discord, but spontaneous emission and low detection efficiency have negative impact on the generation of quantum discord. Most importantly, we find that the steady discord depends on feedback parameters, classical driving, and detection efficiency, but not on the initial state.

A Novel Basis Splitting Eavesdropping Scheme in Quantum Cryptography Based on the BB84 Protocol

We propose a novel strategy numed basis-splitting scheme to split the intercepted quanta into several portions based on different bases, for eavesdropping in the process of quantum cryptography. Compared with intercept- resend strategy, our simulation results of the basis-splitting scheme under the non-ideal condition show a greater performance, especially with the increase of the length of shifted bits. Consequently our scheme can aid eaves- dropper to gather much more useful information.

Twin-Field Quantum Key Distribution Protocol Based on Wavelength-Division-Multiplexing Technology

Quantum key distribution(QKD) generates information-theoretical secret keys between two parties based on the physical laws of quantum mechanics. Following the advancement in quantum communication networks, it becomes feasible and economical to combine QKD with classical optical communication through the same fiber using dense wavelength division multiplexing(DWDM) technology. This study proposes a detailed scheme of TF-QKD protocol with DWDM technology and analyzes its performance, considering the influence of quantum channel number and adjacent quantum crosstalk on the secret key rates. The simulation results show that the scheme further increases the secret key rate of TF-QKD and its variants. Therefore, this scheme provides a method for improving the secret key rate for practical quantum networks.

Cryptanalysis and improvement of a quantum secret sharing scheme based on χ-type entangled states

In the paper [2010 Chin. Phys. B 19 050306], Yang et al. put forward a novel three-party quantum secret sharing protocol of secure direct communication based on x-type entangled states, they claimed that the scheme is secure. However, in this paper, we study the security of the protocol and find that it is insecure. Applying intercept and resend attack, the agent Bob can obtain Alice＇s secret without the help from the other agent Charlie. In the end, we give our effective modification for its improvement.

Novel Adder Circuits Based On Quantum-Dot Cellular Automata (QCA)

Quantum-dot cellular automaton (QCA) is a novel nanotechnology that provides a very different computation platform than traditional CMOS, in which polarization of electrons indicates the digital information. This paper demonstrates designing combinational circuits based on quantum-dot cellular automata (QCA) nanotechnology, which offers a way to implement logic and all interconnections with only one homogeneous layer of cells. In this paper, the authors have proposed a novel design of XOR gate. This model proves designing capabilities of combinational circuits that are compatible with QCA gates within nano-scale. Novel adder circuits such as half adders, full adders, which avoid the fore, mentioned noise paths, crossovers by careful clocking organization, have been proposed. Experiment results show that the performance of proposed designs is more efficient than conventional designs. The modular layouts are verified with the freely available QCA Designer tool.

Influence of homodyne-based feedback control on the entropic uncertainty in open quantum system

For an open quantum system containing two qubits under homodyne-based feedback control, we investigate the dynamical behaviors of quantum-memory-assisted entropic uncertainty.Moreover, we analyze the influence of feedback modes and coefficients on the entropic uncertainty.Numerical investigations show that the memory qubit should be placed in a non-dissipative channel if the single dissipative channel condition can be chosen, which helps reduce the entropic uncertainty of the system.For the homodyne feedback control F =λσx(or F =λσy), due to different roles of the entangled qubits A and B, when they are subject to feedback control with different feedback coefficients λ, the exchange of feedback coefficients will cause variations of the entropic uncertainty.When the feedback coefficient corresponding to the memory qubit B is larger(λB >λA), the steady value of the entropic uncertainty will be small, which is conducive to enhancing the robustness of the system.However, for the feedback control F =λσz, the difference between the feedback coefficients has no effect on the steady values of the entropic uncertainty.

Quantum secure direct communication protocol with blind polarization bases and particles＇ transmitting order

This paper presents a modified secure direct communication protocol by using the blind polarization bases and particles＇ random transmitting order. In our protocol, a sender （Alice） encodes secret messages by rotating a random polarization angle of particle and then the receiver （Bob） sends back these particles as a random sequence. This ensures the security of communication.

A Simple Security Proof for Entanglement-Based Quantum Key Distribution

Quantum cryptography exploits the quantum mechanical properties of communication lines to enhance the security of the so-called key distribution. In this work, we explain the role played by quantum mechanics in cryptographic tasks and also investigate how secure is quantum cryptography. More importantly, we show by a simple security proof that for any state sent by the sender, the eavesdropper can only guess the output state with a probability that will allow her not to learn more than half of the classical Shannon information shared between the legitimate parties. This implies that with high probability, the shared key is secure.

Optimization of a GaN-based irregular multiple quantum well structure for a dichromatic white LED

GaN-based irregular multiple quantum well （IMQW） structures assembled two different types of QWs emitting complementary wavelengths for dichromatic white light-emitting diodes （LEDs） are optimized in order to obtain near white light emissions. The hole distributions and spontaneous emission spectra of the IMQW structures are analysed in detail by fully considering the effects of strain, well-coupling, valence band-mixing and polarization effect through employing a newly developed theoretical model from the k. p theory. Several structure parameters such as well material component, well width, layout of the wells and the thickness of harrier between different types of QWs are employed to analyse how these parameters together with the polarization effect influence the electronic and the optical properties of IMQW structure. Numerical results show that uniform hole distributions in different types of QWs are obtained when the number of the QWs emitting blue light is two, the number of the QWs emitting yellow light is one and the barrier between different types of QWs is 8nm in thickness. The near white light emission is realized using GaN-based IMQW structure with appropriate design parameters and injection level.

Formation and dissociation of protonated cytosine–cytosine base pairs in i-motifs by ab initio quantum chemical calculations

Formation and dissociation mechanisms of C-C＋ base pairs in acidic and alkaline environments are investigated, employing ab initio quantum chemical calculations. Our calculations suggest that, in an acidic environment, a cytosine monomer is first protonated and then dimerized with an unprotonated cytosine monomer to form a C-C＋ base pair; in an alkaline environment, a protonated cytosine dimer is first unprotonated and then dissociated into two cytosine monomers. In addition, the force for detaching a C-C＋ base pair was found to be inversely proportional to the distance between the two cytosine monomers. These results provide a microscopic mechanism to qualitatively explain the experimentally observed reversible formation and dissociation of i-motifs.

G-CPT Symmetry of Quantum Emergence and Submergence—An Information Conservational Multiagent Cellular Automata Unification of CPT Symmetry and CP Violation for Equilibrium-Based Many-World Causal Analysis of Quantum Coherence and Decoherence

An equilibrium-based YinYang bipolar dynamic Generalization of CPT (G-CPT) symmetry is introduced based on energy/information conservational quantum emergence-submergence. As a bottleneck of quantum computing, quantum decoherence or collapse has been plaguing quantum mechanics for decades. It is suggested that the crux of the problem can trace its origin back to the incompleteness of CPT symmetry due to the lack of holistic representation for equilibrium-based bipolar coexistence. In this work, the notion of quantum emergence-submergence is coined as two opposite processes with bipolar energy/information conservation. The new notion leads to G-CPT symmetry supported by a Bipolar Quantum Cellular Automata (BQCA) interpretation of quantum mechanics. It is shown that the new interpretation further leads to the unification of electromagnetic particle-antiparticle bipolarity and gravitational action-reaction bipolarity as well as CPT symmetry and CP violation into a philosophically, geometrically and logically different quantum gravity theory. On one hand, G-CPT symmetry enables a Bipolar Quantum Agent (BQA) to emerge as a bipolar quantum superposition or entanglement coupled to a globally coherent BQCA;on the other hand, G-CP violation supports a causal theory of BQA submergence or decoupling from the global coherence. In turn, BQAs can submerge from one world but emerge in another within YinYang bipolar quantum geometry. It is suggested that all logical, physical, social, biological and mental worlds are bipolar quantum entangled under G-CPT symmetry. It is contended that G-CPT symmetry constitutes an analytical paradigm of quantum mechanics and quantum gravity—a fundamental departure from “what goes around comes around”. The new paradigm leads to a number of predictions and challenges.

非掺杂型Si/SiGe异质结外延与表征

以自旋为编码单元的硅基半导体量子计算与传统微电子工艺兼容,易拓展且可以同位素纯化提高退相干时间,因而备受关注.本研究工作通过分子束外延生长了高质量非掺杂型Si/SiGe异质结并测试了二维电子气迁移率.球差电镜观察到原子级尖锐界面,原子力显微镜表征显示其表面均方根粗糙度仅为0.44 nm,低温下迁移率达到20.21×10^(4)cm^(2)·V^(–1)·s^(–1).不同栅压下载流子浓度和迁移率的幂指数为1.026,材料丁格比值在7—12之间,表明载流子主要受到背景杂质散射和半导体/氧化物的界面散射.

计及不确定性的随机暂态稳定约束最优潮流

为应对电力系统中不确定性对系统安全稳定造成的显著影响,提出一种计及不确定性的随机暂态稳定约束最优潮流方法。首先,采用威布尔和正态分布分别描述风电和负荷两种不确定性变量。其次,设置相应的置信水平,基于机会约束理论建立相应的概率约束,以期望值形式表达目标函数,从而建立计及不确定性的随机暂态稳定约束最优潮流模型。然后,通过半不变量法和Gram-Charlier级数求取电力系统输出变量的累积分布函数,并利用改进量子粒子群算法进行求解。最后,算例分析验证了所提方法的优越性和有效性。

基于格的伪随机函数研究综述

伪随机函数是密码学领域最基本的原语之一,其自提出以来便备受关注.近几十年间发展起来的格理论在密码领域取得了很多重要的应用成果,特别是格上很多困难问题被普遍认为具备抵抗量子攻击的特性,在后量子密码方案设计中处于核心地位.对于格上伪随机函数的研究正式起始于Banerjee、Peikert和Rosen在2012年欧密会上发表的工作.此后,密码学家们围绕如何基于格困难问题设计伪随机函数方案开展了大量研究,特别是在提升伪随机函数方案的安全性、效率和并行性,以及扩展伪随机函数的功能方面取得了诸多成果.本文对格上伪随机函数的研究现状进行综述:总结了伪随机函数的通用构造方法以及格上伪随机函数依赖的底层困难问题;整理了现有基于格困难问题设计的伪随机函数方案,重点关注这些方案在提升安全性、效率或并行性方面采用的技术以及取得的成果;整理了格上具备扩展功能的伪随机函数的研究进展,包括具有密钥同态性质的伪随机函数、约束伪随机函数、水印伪随机函数以及可验证伪随机函数.

硅基InGaN/GaN多量子阱微盘器件的发光、探测和数据传输

光源和探测器的集成可有效促进轻量化和小型化光电系统的发展,InGaN/GaN多量子阱器件中发光与探测共存现象为收发一体芯片的设计提供了可能。本文采用标准半导体工艺制备了硅片上集成的圆盘形InGaN/GaN多量子阱阵列器件,并对其发光、探测以及基本通信特性进行了研究。微盘型器件中的共振模式有助于提升其探测特性,同时各向同性的辐射特性有助于器件作为光源时与探测器在空间上的耦合。作为光源,该器件的开启电压为2.5 V,中心波长455 nm,-3 dB带宽为5.4 MHz。作为探测器,该器件对紫外到蓝光波段的光有响应,探测性能随波长增加而减弱,截止波长450 nm。在365 nm光源激发下,该器件具有最高开关比7.2×10^(4),下降沿时间为0.41 ms。同时,基于单个微盘器件,本文构建并演示了半双工通信系统,在不同频段实现数据传输。这项研究对于电驱动光源制备以及收发一体的光通信具有重要意义。

生物质碳点用于细菌成像和检测研究进展

随着细菌感染和抗生素耐药性形势越来越严峻,对开发快速、简单、灵敏的细菌检测和成像技术的需求越来越迫切。使用天然原料或者将低价值废弃物为原料得到的生物质碳点,不仅保留了传统半导体量子点优异的光电特性,还具有更好的生物相容性、更低的制备成本以及绿色环保的合成方法,符合未来能源可持续发展的趋势。生物质碳点已在细菌成像和检测上表现出极大的潜力,但面对如此丰富的生物质来源,如何选择合适的碳源并结合生物质碳点的优点构建效果更好的细菌成像和检测方法仍存在问题。本篇综述梳理了生物质碳点的种类,概述了生物质碳点在细菌成像和检测中的应用,对生物质碳点作为成像和检测传感器的不足进行了分析,希望为开发出更符合需求的成像探针和更有效的检测方法提供参考。