双量子点电荷比特的散粒噪声谱

考虑基底声子热库的耗散效应,推导了双量子点电荷比特的主方程,并利用全计数统计方法计算了双量子点电荷比特的平均电流和Fano因子.结果表明:声子热库的耗散引起平均电流关于其峰值的非对称分布和Fano因子双峰的非对称分布,并且随着声子热库温度T的升高,平均电流的非对称分布越强,Fano因子的峰值逐渐降低,直至超泊松分布行为消失.     

嵌入T型耦合双量子点介观A-B环系统的显著Fano 效应

利用平均场近似理论,研究了一个嵌入T型弱耦合双量子点的介观环系统的基态性质. 结果表明,体系中复杂的基态性质源于Kondo效应与Fano效应相互竞争. 当介观环的尺寸达到足以产生完全Kondo共振时,随双量子点间耦合强度的增强,尖锐的持续电流峰出现了,且越发显著,这说明体系中存在着显著的Fano 效应. 但介观环的Kondo共振持续电流峰值却几乎不发生变化,这为测定Kondo 屏蔽云提供了一个新的可能模型. 关键词： 耦合量子点 持续电流 Kondo效应 Fano 效应     

对一类超混沌图像加密算法的密码分析与改进

对一种超混沌图像加密算法及其改进版进行了安全性分析, 结果表明该类算法的置乱过程都是与混淆过程相脱离的, 且混淆过程的加密公式简单; 因此都不能抵抗选择明文和选择密文攻击. 进而提出了一种改进的加强型超混沌图像加密算法; 改进算法包含两轮像素值替代加密操作, 并使得密文与明文、密钥之间的关系更复杂. 安全性分析和实验测试表明, 改进算法不仅克服了原算法不能抵御选择明文和选择密文攻击的缺陷; 而且具有时间开销更小和抗差分攻击性能更好的优势.     

硅烯:一种新型的二维狄拉克电子材料

要硅烯是单原子层的硅薄膜,其结构与石墨烯类似,由于其奇特的物理性质特别是狄拉克—费米特性,在近年来引起了人们的关注。文章简要介绍了硅烯这一全新的二维体系在实验上的一些进展,包括实现硅烯在表面上的外延生长,重构的结构表征和相变,狄拉克电子特性的证实,以及可能具有的超导转变等。     

推广的Jaynes-Cummings模型中原子纠缠的时间演化和热纠缠态

利用共生纠缠度研究了一个推广Jaynes Cummings模型中两原子纠缠的时间演化和有限温度下系统热纠缠态. 结果表明，腔场中两原子展现出周期性的纠缠演化过程，演化周期随原子偶极 偶极相互作用强度的增大而减小；在有限温度下，系统的共生纠缠度随温度的升高而降低，当趋近临界温度时，系统纠缠现象消失，这一临界温度值与原子偶极-偶极相互作用强度成正比. 对于典型的实验数据，临界温度约在10-5K数量级. 此外，在这种Jaynes Cummings模型中存在量子相位转变. 关键词： Jaynes Cummings模型 原子纠缠态 热纠缠态 共生纠缠度 偶极 偶极相互作用     

Synthesis,characterization and theoretical study of 2-azido-4- nitroimidazole-based energetic salts

The 2-azido-4-nitroimidazole-based energetic salts were synthesized in a simple and straightforward manner. The structures of these new salts were determined by IR, 1H NMR and 13C NMR spectroscopy and elemental analysis. These salts also exhibited high positive enthalpies of formation, high nitrogen content, and moderate detonation properties.     

Proposal for teleporting an entangled coherent state via the dispersive atom–cavity-field interaction

A proposal is presented for teleporting an entangled coherent state. The process of the teleportation is achieved through the dispersive atom–cavity-field interaction. In our proposal, only measurement on the cavity field and on the singlet atomic state are used.     

Entanglement dephasing of spatially separated multiparticle GHZ states coupled to a squeezed environment

In tokamak plasmas, it is recognized that ITG (ion temperature gradient instability) and trapped electron modes (TEM) are held responsible for turbulence giving rise to anomalous transport. The present work focuses on the building of a model including trapped kinetic ions and trapped kinetic electrons. For this purpose, the dimensionality is reduced by averaging the motion over the cyclotron motion and the “banana” orbits, according to the fact that the instabilities are characterized by frequencies of the order of the low trapped particle precession frequency. Moreover, a set of action-angle variables is used. The final model is 4D (two-dimensional phase space parametrized by the two first adiabatic invariants namely the particle energy and the trapping parameter). In this paper, the trapped ion and electron modes (TIM and TEM) are studied by using a linear analysis of the model. This work is currently performed in order to include trapped electrons in an existing semi lagrangian code for which TIM modes are already taken into account. This study can be considered as a first step in order to include kinetic trapped electrons in the 5D gyrokinetic code GYSELA [J. Abiteboul et al., ESAIM Proc. 32, 103 (2011)].