有源RLC介观电路的量子涨落

使用正则交换和幺正变换的方法，研究了有源RLC介观电路的量子涨落。结果表明电源电动势ε(t)的有无对电荷和电流的量子涨落没有影响。     

介观二阶并联电路的量子涨落

从有源RLC并联电路的经典运动方程出发,通过引入复正则变量,提出了RLC并联电路的量子化方案.作为应用,研究了压缩真空态下介观并联RLC电路中电压,电流的量子涨落,并对结果进行了讨论.     

介观互感耦合阻尼并联双谐振电路的量子涨落

对介观互感耦合阻尼并联电路作双模耦合阻尼谐振子处理,将其量子化.通过三次幺正变换,将体系的哈密顿量对角化.在此基础上给出了体系的本征能谱,研究了Fock态、真空态下各回路电流和电压的量子涨落.     

介观RLC电路在热真空态下的量子涨落

利用热场动力学的方法研究了介观RLC电路在具有热噪声的真空态下电荷和磁通(电流)的量子涨落.从而得到了有限温度下这一电路在热真空态下的量子涨落与温度的关系.结果表明,介观RLC电路的量子涨落不仅与电路中的元件参量和电路的共振频率ω有关,而且与温度T有关.温度越高,介观RLC电路的量子噪声越大 关键词： 介观RLC电路 热真空态 量子涨落     

介观二阶电路量子涨落的对偶性

讨论了阻尼对介观耗散电路中电荷和电流量子涨落的影响，在能量本征态下比较了介观RLC串、并联电路中电荷和电流的量子涨落，发现它们之间具有对偶性。     

有源轻阻尼RLC介观电路中的波函数及电荷、电流的量子涨落

从有源RLC电路运动方程出发,通过量子化有源RLC电路,计算了低温下电流、电荷的量子涨落以及电源对量子涨落的影响.     

介观电容耦合LC电路在有限温度下的能量及热效应

由正则量子化方法导出了介观电容耦合LC电路体系的哈密顿算符, 利用幺正变换使哈密顿算符对角化. 用系综理论给出了体系的平均能量及其涨落, 在此基础上, 借助于广义Hellmann-Feynman定理, 讨论了有限温度下电路体系中电荷与自感磁通的量子涨落. 结果表明, 体系中电荷与自感磁通的量子涨落不仅与电路元件参数有关, 而且还与温度有关. 关键词： 介观电路 量子涨落 广义Hellmann-Feynman定理 有限温度     

有互感和电源的介观耦合电路的量子涨落

通过正则变换和幺正变换的方法研究了有互感和电源存在的情况下的介观电容耦合电路的量子涨落.结果表明电荷和电流的量子涨落与电源无关;互感的有无对涨落的影响很大;适当选取回路中电器件的参数,可以控制耦合系数K对涨落的影响.并且,每个回路中电荷和电流的量子涨落是相互制约的.     

介观电容耦合LC电路在有限温度下的能量及热效应

由正则量子化方法导出了介观电容耦合LC电路体系的哈密顿算符, 利用幺正变换使哈密顿算符对角化. 用系综理论给出了体系的平均能量及其涨落, 在此基础上, 借助于广义Hellmann-Feynman定理, 讨论了有限温度下电路体系中电荷与自感磁通的量子涨落. 结果表明, 体系中电荷与自感磁通的量子涨落不仅与电路元件参数有关, 而且还与温度有关.     

介观RLC电路中电荷和电流的量子涨落

发展了一种将有源RLC电路量子化的方法,在此基础上,研究了真空态下介观RLC电路中电荷、电流的量子涨落,特别是研究了电阻对量子涨落的影响.     

一种基于分层的量子分组传输方案及性能分析

大规模量子通信网络中,采用量子分组传输技术能有效提升发送节点的吞吐量,提高网络中链路的利用率,增强通信的抗干扰性能.然而量子分组的快速传输与路由器性能息息相关.路由器性能瓶颈将严重影响网络的可扩展性和链路的传输效率.本文提出一种量子通信网络分层结构,并根据量子密集编码和量子隐形传态理论,给出一种基于分层的量子分组信息传输方案,实现端到端的量子信息传输.该方案先将量子分组按照目的地址进行聚类,再按聚类后的地址进行传输.仿真结果表明,基于分层的量子分组信息传输方案能够有效减少量子分组信息在量子通信网络中的传输时间,并且所减少的时间与量子路由器性能与发送的量子分组数量有关.因此,本文提出的量子分组信息传输方案适用于大规模量子通信网络的构建.     

Three-Party Quantum Network Communication Protocols Based on Quantum Teleportation

By utilizing the delocalized correlation of entangled states in quantum information theory, a novel method on acknowledgments of quantum information among three-party is presented, and then two three-party quantum network communication protocols based on quantum teleportation are presented, namely, three-party stop-wait quantum communication protocol and three-party selective automatic repeat quantum communication protocol. In the two proposed protocols, the data frames composed of qubits are teleported via three-party quantum teleportation, the two receivers simultaneously receive quantum frames from the sender, and then return quantum acknowledgment frames or quantum negative acknowledgment frames via quantum entanglement channels. The sender simultaneously receives and deals with quantum acknowledgment frames and quantum negative acknowledgment frames from the two receivers, thus the processing delay on returning quantum frames is reduced. And due to the transience of transferring quantum information, the returning of quantum acknowledgment frames and quantum negative acknowledgment frames are completed instantaneously, the proposed protocols reduce the transmission delay and improve the communication efficiency. During the whole course of communications, the classical channels are only used to transmit the measurement message, so the burdens of classical channels are reduced.     

Novel quantum secret image-sharing scheme

In this paper, we propose a novel quantum secret image-sharing scheme which constructs m quantum secret images into m+1 quantum share images. A chaotic image generated by the logistic map is utilized to assist in the construction of quantum share images first. The chaotic image and secret images are expressed as quantum image representation by using the novel enhanced quantum representation. To enhance the confidentiality, quantum secret images are scrambled into disordered images through the Arnold transform. Then the quantum share images are constructed by performing a series of quantum swap operations and quantum controlled-NOT operations. Because all quantum operations are invertible, the original quantum secret images can be reconstructed by performing a series of inverse operations. Theoretical analysis and numerical simulation proved both the security and low computational complexity of the scheme, which has outperformed its classical counterparts. It also provides quantum circuits for sharing and recovery processes.     

量子算法与量子计算实验

从量子体系的基本特性出发 ,介绍了量子计算的基本概念和物理背景 ,系统阐述了几种主要的量子算法以及量子计算在实验方面的发展现状。对比经典计算机 ,讨论了量子计算机的优越性、实现量子计算的困难和以期克服的途径。     

Quantum Permanents and Hafnians via Pfaffians

Quantum determinants and Pfaffians or permanents and Hafnians are introduced on the two-parameter quantum general linear group. Fundamental identities among quantum Pf, Hf, and det are proved in the general setting. We show that there are two special quantum algebras among the quantum groups, where the quantum Pfaffians have integral Laurent polynomials as coefficients. As a consequence, the quantum Hafnian is computed by a closely related quantum permanent and identical to the quantum Pfaffian on this special quantum algebra.     

两二能级原子在共同环境下的量子关联动力学

通过精确求解带有偶极-偶极相互作用的两个二能级原子与一个共同热库相互作用模型, 得到了两原子间量子纠缠和量子失谐(quantum discord)的解析表达式. 综合考虑了环境的非马尔可夫效应、原子间的偶极-偶极相互作用以及原子的本征频率同腔模中心频率之间的失谐量对两原子间量子纠缠和quantum discord的影响. 研究显示: 在非马尔可夫机制下, 且原子的本征频率与腔模中心频率是共振时, 当两原子初态处于纠缠态时, 原子间偶极-偶极相互作用可以显著抑制包括量子纠缠和quantum discord等量子关联的衰减, 更特别的是, 如果原子的本征频率同腔模中心频率有一定的失谐时, 利用原子间偶极-偶极相互作用可大大地延长两原子退纠缠的时间; 当两原子初态处于可分离态时, 从短时间来看, 原子间偶极-偶极相互作用可以提高量子纠缠和quantum discord振荡的振幅,而在长时间极限下, 原子间偶极-偶极相互作用不会改变量子纠缠和quantum discord达到的稳定值. 最后, 讨论了原子间偶极-偶极相互作用对量子纠缠和quantum discord动力学不同的影响. 关键词： 量子纠缠 量子失谐 共同环境 偶极-偶极相互作用     

量子算法与量子计算实验

从量子体系的基本特性出发,介绍了量子计算的基本概念和物理背景,系统阐述了几种主要的最子算法以及量子计算在实验方面的发展现状。 对比经典计算机,讨论了量子计算机的优越性、实现量子计算的困难和以期克服的途径。     

Quantum metrology

The statistical error is ineluctable in any measurement. Quantum techniques, especially with the development of quantum information, can help us squeeze the statistical error and enhance the precision of measurement. In a quantum system, there are some quantum parameters, such as the quantum state, quantum operator, and quantum dimension, which have no classical counterparts. So quantum metrology deals with not only the traditional parameters, but also the quantum parameters. Quantum metrology includes two important parts： measuring the physical parameters with a precision beating the classical physics limit and measuring the quantum parameters precisely. In this review, we will introduce how quantum characters （e.g., squeezed state and quantum entanglement） yield a higher precision, what the research areas are scientists most interesting in, and what the development status of quantum metrology and its perspectives are.     

Quantum Discord in Two-Qubit System Constructed from the Yang–Baxter Equation

Quantum correlations among parts of a composite quantum system are a fundamental resource for several applications in quantum information. In general, quantum discord can measure quantum correlations. In that way, we investigate the quantum discord of the two-qubit system constructed from the Yang-Baxter Equation. The density matrix of this system is generated through the unitary Yang-Baxter matrix R. The analytical expression and numerical result of quantum discord and geometric measure of quantum discord are obtained for the Yang-Baxter system. These results show that quantum discord and geometric measure of quantum discord are only connect with the parameter θ, which is the important spectral parameter in Yang Baxter equation.     

Parametric instabilities in quantum plasmas with electron exchange-correlation effects

Parametric instabilities induced by the nonlinear interaction between high frequency quantum Langmuir waves and low frequency quantum ion-acoustic waves in quantum plasmas with the electron exchange-correlation effects are presented.By using the quantum hydrodynamic equations with the electron exchange-correlation correction,we obtain an effective quantum Zaharov model,which is then used to derive the modified dispersion relations and the growth rates of the decay and four-wave instabilities.The influences of the electron exchange-correlation effects and the quantum effects on the existence of quantum Langmuir waves and the parametric instabilities are discussed in detail.It is shown that the electron exchange-correlation effects and quantum effects are strongly coupled.The quantum Langmuir wave can propagate in quantum plasmas only when the electron exchange-correlation effects and the quantum effects satisfy a certain condition.The electron exchange-correlation effects tend to enhance the parametric instabilities,while quantum effects suppress the instabilities.