Computational procedure to determine quantum state evolution in Fock space

A new algorithm to solve the quantum state evolution of a system described by a general quadratic Hamiltonian form in creation and the annihilation operators of Fock space is presented. The nonlinear equation for the dynamic operators are obtained in the matrix representation, and by a recursive relation the time evolution operator in the Fock basis is constructed. The method permits to obtain the evolution of entangled quantum states of interacting subsystems when the Hamiltonian of the whole system is in the above mentioned form. Numerical solution with the method is sufficiently accurate to safely analyze the important question of quantum state transfer between the interacting subsystems. A qubits transfer is discussed as an illustrative example when the method is applied to a system described by a particular quadratic Hamiltonian form.     

A strong direct product theorem for quantum query complexity

We show that quantum query complexity satisfies a strong direct product theorem. This means that computing k copies of a function with fewer than k times the quantum queries needed to compute one copy of the function implies that the overall success probability will be exponentially small in k. For a boolean function f, we also show an XOR lemma—computing the parity of k copies of f with fewer than k times the queries needed for one copy implies that the advantage over random guessing will be exponentially small. We do this by showing that the multiplicative adversary method, which inherently satisfies a strong direct product theorem, characterizes bounded-error quantum query complexity. In particular, we show that the multiplicative adversary bound is always at least as large as the additive adversary bound, which is known to characterize bounded-error quantum query complexity.     

Linear and integrable nonlinear evolution of the qutrit

Quantum Information Processing - In quantum circuit design, the question arises how to distribute qubits, used in algorithms, over the various quantum computers, and how to order them within a...     

云存储加密数据去重删除所有权证明方法

随着云计算服务的广泛应用,为了节省磁盘空间和带宽,出现了一种新技术：客户端去重复化.但近期发现了一种针对该技术的新型攻击：攻击者只需获得原始文件的一个摘要信息,即文件的散列值,即可从服务器端获得全部原始文件.为了解决上述安全问题,提出了一个密码学安全的、高效的证明方案来支持多客户端加密文件的去重复删除场景.通过抽样检测、动态系数和随机选择的原始文件检索值使方案达到安全与高效的目标;同时,还提出了一种巧妙的分布式捎带技术,将文件加密密钥的分发过程与所有权证明过程同步实施.最后,对所提方案进行了严格的安全性证明和深入的性能分析与仿真,结果表明,所提的方案不仅能达到可证明的安全级别,而且执行效率较高,尤其在减少客户端计算负载方面.     

The Correlation Conversion property of quantum channels

Transmission of quantum entanglement will play a crucial role in future networks and long-distance quantum communications. Quantum key distribution, the working mechanism of quantum repeaters and the various quantum communication protocols are all based on quantum entanglement. On the other hand, quantum entanglement is extremely fragile and sensitive to the noise of the communication channel over which it has been transmitted. To share entanglement between distant points, high fidelity quantum channels are needed. In practice, these communication links are noisy, which makes it impossible or extremely difficult and expensive to distribute entanglement. In this work, we first show that quantum entanglement can be generated by a new idea, exploiting the most natural effect of the communication channels: the noise itself of the link. We prove that the noise transformation of quantum channels that are not able to transmit quantum entanglement can be used to generate distillable (useable) entanglement from classically correlated input. We call this new phenomenon the Correlation Conversion property of quantum channels. The proposed solution does not require any non-local operation or local measurement by the parties, only the use of standard quantum channels. Our results have implications and consequences for the future quantum communications and for global-scale quantum communication networks. The discovery also revealed that entanglement generation by local operations is possible.     

基于CORBA的智能建筑管理系统IBMS的设计与实现

信息共享在智能建筑管理系统中起着十分重要的作用。由于传统的智能建筑中各个控制子系统和管理系统相互独立,又没有一个统一的管理系统来集中管理,所以信息共享的程度很低。本文描述的基于COBA技术设计的智能建筑管理系统（IBMS）,是针对建筑物内所有子系统为典型的分布式系统和特征来设计和开发的一个集成的管理系统。该系统采用ORB作为软件总线,通过统一的接口将分布于楼宇内的各个控制子系统集成起来,为各个子系统提供一个统一的操作管理平台,实现了智能建筑内各个子系统之间的互操作,以达到信息交换和信息共享的目的。     

Decentralized stabilization for expanding construction oflarge-scale systems

A decentralized stabilization problem compatible with expanding the construction of large-scale systems is considered. It is assumed that a large-scale system is obtained by adding new subsystems one after another. When a new subsystem is connected to an already interconnected portion, a local controller is designed for the new subsystem so that both the subsystem and the resultant expanded system are stable. The proper-stable-factorization approach is used for calculating the local controllers. Sufficient conditions on subsystems for such stabilization are presented. They are expressed in terms of the solvability of linear matrix equations over the ring of stable rational matrices     

Quantum probabilistically cloning and computation

In this article we make a review on the usefulness of probabilistically cloning and present examples of quantum computation tasks for which quantum cloning offers an advantage which cannot be matched by any approach that does not resort to it. In these quantum computations, one needs to distribute quantum information contained in states about which we have some partial information. To perform quantum computations, one uses state-dependent probabilistic quantum cloning procedure to distribute quantum information in the middle of a quantum computation. And we discuss the achievable efficiencies and the efficient quantum logic network for probabilistic cloning the quantum states used in implementing quantum computation tasks for which cloning provides enhancement in performance.     

Input/output-to-state stability of switched nonlinear systems with an improved average dwell time approach

This paper investigates the input/output-to-state stable (IOSS) property of the switched systems under average dwell time (ADT) switching signals in two cases: 1) all of the subsystems are IOSS, 2) parts of the subsystems are IOSS, and proposes a number of new results on stability analysis. First, we present a new IOSS result for the switched nonlinear systems whose subsystems are IOSS with an improved ADT method. Second, extending the improved ADT method to unforced nominal switched nonlinear systems in which parts of subsystems are stable, we establish a new stability analysis result. IOSS property of switched nonlinear systems in which parts of subsystems are IOSS, we show that if the average dwell time is large enough and if the fraction of time where one of the non-IOSS system is active is not too big, then IOSS property of the switched system can be established. It should be pointed that the main results obtained in this paper have some advantages over the exiting ones. Finally, two illustrative examples with simulation verify the correctness and validity of our results.     

批量代理量子盲签名方案

在经典密码学中的代理签名和盲签名基础之上,提出了批量代理量子盲签名方案.利用三进制两粒子量子纠缠系统的方法来进行密钥分配和文件量子态序列的编码.所有待签名的文件在通信过程中都被文件所有者的私钥加密.与经典盲签名方案不同之处在于,引入了试签名及对试签名的认证,以及双重身份(仲裁和代理)者的高效批量代理盲签名.安全性分析和效率讨论表明,通过仲裁者提供安全的批量代理盲签名的方法来完成对大量文件的高效盲签名是可行的.     

Pole placement approach to coherent passive reservoir engineering for storing quantum information

Reservoir engineering is the term used in quantum control and information technologies to describe manipulating the environment within which an open quantum system operates. Reservoir engineering is essential in applications where storing quantum information is required. From the control theory perspective, a quantum system is capable of storing quantum information if it possesses a so-called decoherence free subsystem (DFS). This paper explores pole placement techniques to facilitate synthesis of decoherence free subsystems via coherent quantum feedback control. We discuss limitations of the conventional `open loop'' approach and propose a constructive feedback design methodology for decoherence free subsystem engineering. It captures a quite general dynamic coherent feedback structure which allows systems with decoherence free modes to be synthesized from components which do not have such modes.     

VRML技术在面向CSCW的母线槽布线专家系统中的应用

VRML技术是一种集成了多媒体技术和虚拟现实技术的网络3D技术,利用它可以很方便地在Web上建立一个3D虚拟协同空间,文中将这项技术应用到电气设计领域,建立了一个松散耦合的、基于Internet/Intranet的三维异地同步CSCW系统,解决了配电系统中母线槽系统设计这个三维,异地、多人的协同设计问题。     

Unified quantum no-go theorems and transforming of quantum pure states in a restricted set

The linear superposition principle in quantum mechanics is essential for several no-go theorems such as the no-cloning theorem, the no-deleting theorem and the no-superposing theorem. In this paper, we investigate general quantum transformations forbidden or permitted by the superposition principle for various goals. First, we prove a no-encoding theorem that forbids linearly superposing of an unknown pure state and a fixed pure state in Hilbert space of a finite dimension. The new theorem is further extended for multiple copies of an unknown state as input states. These generalized results of the no-encoding theorem include the no-cloning theorem, the no-deleting theorem and the no-superposing theorem as special cases. Second, we provide a unified scheme for presenting perfect and imperfect quantum tasks (cloning and deleting) in a one-shot manner. This scheme may lead to fruitful results that are completely characterized with the linear independence of the representative vectors of input pure states. The upper bounds of the efficiency are also proved. Third, we generalize a recent superposing scheme of unknown states with a fixed overlap into new schemes when multiple copies of an unknown state are as input states.     

Evaluation of two traffic distribution strategies for adual-network multiprocessor system

The effect of nonuniform traffic patterns is studied based on simulation and analysis when two multistage networks are used in parallel to interconnect processors and memory modules in a shared-memory system. The networks considered are identical copies of buffered multi stage networks. The authors consider the following two strategies to distribute the total traffic between the two networks: distribute the traffic randomly among the networks, and route the nonuniform component of the traffic to one network and the uniform component to the other. To facilitate the implementation of these strategies in a system, a technique to detect nonuniformities in the network traffic at run-time and change the routing strategy dynamically is discussed. The authors compare this technique to an ideal scheme by means of analysis and simulation. The results show that the run-time detection scheme performs very close to the ideal case. The effectiveness of dual networks in tolerating short bursts of nonuniform traffic is also demonstrated     

一个基于集中管理的协作式Web缓存系统

共享不同代理的缓存Web文档是减少通信量和减轻网络瓶颈的重要方法。在分析原有Web缓存通信协议（ICP）的基础上,提出了一种新的协作Web缓存系统（CMCS）并作了分析比较。通过将HTTP请求均匀分散到系统各个代理,消除了代理之间庞大的通信开销以及由此带来的处理负担。在动态变化的网络环境下,有效地将各个代理组织起来,处理来自服务器的文档。另外也克服了以往每个代理里有大量冗余内容,造成各个代理内容趋向的情形。     

A new decentralised controller design method for a class of strongly interconnected systems

In this paper, two interconnected structures are first discussed, under which some closed-loop subsystems must be unstable to make the whole interconnected system stable, which can be viewed as a kind of strongly interconnected systems. Then, comparisons with small gain theorem are discussed and large gain interconnected characteristics are shown. A new approach for the design of decentralised controllers is presented by determining the Lyapunov function structure previously, which allows the existence of unstable subsystems. By fully utilising the orthogonal space information of input matrix, some new understandings are presented for the construction of Lyapunov matrix. This new method can deal with decentralised state feedback, static output feedback and dynamic output feedback controllers in a unified framework. Furthermore, in order to reduce the design conservativeness and deal with robustness, a new robust decentralised controller design method is given by combining with the parameter-dependent Lyapunov function method. Some basic rules are provided for the choice of initial variables in Lyapunov matrix or new introduced slack matrices. As byproducts, some linear matrix inequality based sufficient conditions are established for centralised static output feedback stabilisation. Effects of unstable subsystems in nonlinear Lur'e systems are further discussed. The corresponding decentralised controller design method is presented for absolute stability. The examples illustrate that the new method is significantly effective.     

A new approach to the study of parameter insensitivity

In this paper a new approach to the study of parameter insensitivity of a linear, time-varying, continuous and finite-dimensional system is introduced. Following this approach, a unique theory is developed for the analysis of insensitivity to both ‘large’ and ‘small’ parameter variations; moreover, a decomposition of the system into four subsystems is obtained which is based on the dependence upon parameters of both the input-state and state-output relationships.     

滞后离散广义不确定系统的变结构控制

首先引入一种新的受限系统等价分解形式．将所给的系统分解成两个低维的子系统．其次设计了带有差分补偿器的切换函数，使得系统在准切换流形上的运动渐近稳定．然后在不确定项有界的条件下设计了离散变结构控制律，使得在控制的作用下，系统的解的轨迹于有限步内进入准切换流形的一个邻域内，并最终收敛干原点邻域内的一个小的抖振．最后给出了数值仿真曲线，以说明该综合设计方法的可行性和有效性．