中科大单分子器件基础研究获新进展

中国科学技术大学合肥微尺度物质科学国家实验室单分子物理化学研究团队,利用低温超高真空扫描隧穿显微镜,巧妙地对三聚氰胺这个比头发丝的六万分之一还细的小分子进行了单分子手术,将其从普通化工原料转变为既有二极管效应又有机械开关效应的双功能单分子器件,为单分子器件的多功能化开辟了新的思路．这一成果发表在近期出版的美国《国家科学院院刊》上．     

Liouville Integrable System and Associated Integrable Coupling

Liouville integrable discrete integrable system is derived based on discrete isospectral problem. It is shown that the hierarchy is completely integrable in the Liouville sense and possesses bi-Hamiltonian structure. Finally, integrable couplings of the obtained system is given by means of semi-direct sums of Lie algebras.     

中子引起的单粒子反转截面的Monte Carlo模拟计算

单粒子效应是蠹民粒子在电子元器件中通过时，靠民电子元器件的电离损伤，导致电子元器件的记录出错。考虑了１０－２０ＭｅＶ中子与硅反应的主要反应道，利用Ｍｏｎｔｅ Ｃｑｒｌｏ方法对中子射入硅器件器中引起的单粒子反转进行模拟，得到质子、α粒子的能量、角度分布。考虑带电粒子在硅片中引起的电离 损伤，对不同临界电荷在１６Ｋ动态ＲＡＭ硅片中有一个灵敏单克发生反转时，中子入射注量及相应在的单粒子反转截面，给出了反     

间隔不变性与相对论拉格朗日力学

文章证明由时空和速度间隔不变性可以导出相对论哈密顿和拉格朗日力学，由此说明哈密顿或拉格朗日为洛仑兹不变量是时空和速度间隔不变性的必然结果。     

单轴晶体包层啁啾光纤光栅中电光效应和弹光效应的理论研究

提出了以单轴晶体材料为包层,光轴平行于光栅主轴(z轴)的新型啁啾光纤光栅模型,应用耦合模理论和传输矩阵方法在理论上分析了该类光纤光栅中的电光效应和弹光效应,理论研究发现在包层施加沿光栅轴向的电场和应变场可以改变布拉格波长和反射谱。得到了3种不同单轴晶体为包层时布拉格波长λB和反射光谱随外加电场和应变场变化的曲线。研究结果表明当轴向外加电场从1×107V/m变化到8×107V/m时λB减小0.12nm,当外加应变场从0变化到0.04时,λB减小0.45nm。     

ICP-AES同时测定高纯碲中钙、铈和钛

ICP-AES法测定高纯碲中的杂质元素Ca、Ce和Ti,进行了碲基体影响、加标回收和精密度实验研究。加标回收率为92%—93%,相对标准偏差小于1%,所得结果令人满意。     

激光干涉法测量弹性模量

从光的干涉原理出发，讨论了金属丝弹性模量的光电测量方法．设计了激光干涉法测量长度微变量的测量装置，并介绍了测量原理，给出了动镜移动方向判别电路．     

N_2(B~3Ⅱ_g)高振动态在Xe原子中的碰撞激发和弛豫

在用双光子激发产生的Xe(5p~56p)原子与N_2分子碰撞过程中,有效地生成了N_2(B~3П_g,v=9～14)振动激发态.观察到相应的Δv=4的N_2(B~3П_g-A~3∑_u~+)辐射跃迁萤光,测量了Xe(6p)原子在N_2中的淬灭速率常数,对碰撞弛豫过程进行了讨论.     

Theoretical study of photon emission from single quantum dot emitter coupled to surface plasmons

Motivated by the recent pioneering advances on nanoscale plasmonics and also nanophotonics technology based on the surface plasmons (SPs), in this work, we give a master equation model in the Lindblad form and investigate the quantum optical properties of single quantum dot (QD) emitter coupled to the SPs of a metallic nanowire. Our main results demonstrate the QD luminescence results of photon emission show three distinctive regimes depending on the distance between QD and metallic nanowire, which elucidates a crossover passing from being metallic dissipative for much smaller emitter-nanowire distances to surface plasmon (SP) emission for larger separations at the vicinity of plasmonic metallic nanowire. Besides, our results also indicate that, for both the resonant case and the detuning case, through measuring QD emitter luminescence spectra and second-order correlation functions, the information about the QD emitter coupling to the SPs of the dissipative metallic nanowire can be extracted. This theoretical study will serve as an introduction to understanding the nanoplasmonic imaging spectroscopy and pave a new way to realize the quantum information devices.     

Transport in graphene nanostructures

Graphene nanostructures are promising candidates for future nanoelectronics and solid-state quantum information technology. In this review we provide an overview of a number of electron transport experiments on etched graphene nanostructures. We briefly revisit the electronic properties and the transport characteristics of bulk, i.e., two-dimensional graphene. The fabrication techniques for making graphene nanostructures such as nanoribbons, single electron transistors and quantum dots, mainly based on a dry etching ??paper-cutting?? technique are discussed in detail. The limitations of the current fabrication technology are discussed when we outline the quantum transport properties of the nanostructured devices. In particular we focus here on transport through graphene nanoribbons and constrictions, single electron transistors as well as on graphene quantum dots including double quantum dots. These quasi-one-dimensional (nanoribbons) and quasi-zero-dimensional (quantum dots) graphene nanostructures show a clear route of how to overcome the gapless nature of graphene allowing the confinement of individual carriers and their control by lateral graphene gates and charge detectors. In particular, we emphasize that graphene quantum dots and double quantum dots are very promising systems for spin-based solid state quantum computation, since they are believed to have exceptionally long spin coherence times due to weak spin-orbit coupling and weak hyperfine interaction in graphene.