On Markovian Limit in Quantum Open Systems

The dynamics of spherical harmonic oscillator interacting with radiation field is investigated. It is shown that the irreversibility of time evolution is due to the appearance of resonances. Reduced dynamics is given in terms of multi-time correlation functions in the Markovian limit, which includes higher order corrections in the coupling constant.     

On non-Markovian Time Evolution in Open Quantum Systems

Non-Markovian reduced dynamics of an open system is investigated. In the case when the initial state of the reservoir is the vacuum state, an approximation is introduced which makes it possible to construct a reduced dynamics which is completely positive.     

Perfect Manipulation of Open Stochastic Quantum Systems with Imperfect Detection

International Journal of Control, Automation and Systems - Utilizing the homodyne-based feedback control, this paper studies the influence of quantum detection efficiency on the state transfer...     

Description of Quantum Dynamics of Open Systems Based on Collision-Like Models

Master equations in the Lindblad form describe evolution of open quantum systems that are completely positive and simultaneously have a semigroup property. We analyze the possibility to derive this type of master equations from an intrinsically discrete dynamics that is modelled as a sequence of collisions between a given quantum system (a qubit) with particles that form the environment. In order to illustrate our approach we analyze in detail how the process of an exponential decay and the process of decoherence can be derived from a collision-like model in which particular collisions are described by SWAP and controlled-NOT interactions, respectively.Presented at the 36th Symposium on Mathematical Physics, “Open Systems & Quantum Information”, Toruń, Poland, June 9-12, 2004.     

Coherence, Teleportation, and Open Systems. Comments on Interpretation of Quantum Mechanics

A physical and philosophical discussion of quantum phenomena of coherence, teleportation and open systems is given. We attempt to show that modern physics can give some impulses for new solutions or new tendencies in philosophy. One of the questions is the problem of what is basic in quantum physics: "substances" or "situations", the problem of an observer or two observers at least, of a whole and a part, or distributive or collective sets, of particle-wave complementarity, and of modalities such as possibility, necessity, probability, potentiality, etc.     

An Open Secure Mobile Agent Framework for Systems Management

The Mobile Agent (MA) technology is gainingimportance in the distributed management of networks andservices for heterogeneous environments. MA-basedmanagement systems could represent an interestingalternative to traditional tools built upon theclient/server model, either SNMP- or CMIP-based. Twomain requirements currently limit the acceptance of MAsolutions for management: the need of interoperabilityand the request for security. Without security,management systems cannot suit global untrustedenvironments, such as the Internet; withoutinteroperability, they cannot interact with existingtools and legacy systems. The paper describes an MA-basedmanagement system with security and interoperability asthe two main design objectives. It is an open managementframework that grants interoperability by providing compliance with CORBA, the most diffusedstandard in the area of object-oriented components. Inaddition, it is based on a thorough security model andprovides a wide range of tools and mechanisms to build and enforce flexible securitypolicies.     

Quantum Physical Symbol Systems

Because intelligent agents employ physically embodied cognitive systems to reason about the world, their cognitive abilities are constrained by the laws of physics. Scientists have used digital computers to develop and validate theories of physically embodied cognition. Computational theories of intelligence have advanced our understanding of the nature of intelligence and have yielded practically useful systems exhibiting some degree of intelligence. However, the view of cognition as algorithms running on digital computers rests on implicit assumptions about the physical world that are incorrect. Recently, the view is emerging of computing systems as goal-directed agents, evolving during problem solving toward improved world models and better task performance. A full realization of this vision requires a new logic for computing that incorporates learning from experience as an intrinsic part of the logic, and that permits full exploitation of the quantum nature of the physical world. This paper proposes a theory of physically embodied cognitive agents founded upon first-order logic, Bayesian decision theory, and quantum physics. An abstract architecture for a physically embodied cognitive agent is presented. The cognitive aspect is represented as a Bayesian decision theoretic agent; the physical aspect is represented as a quantum process; and these aspects are related through von Neumann’s principle of psycho-physical parallelism. Alternative metaphysical positions regarding the meaning of quantum probabilities and the role of efficacious choices by agents are discussed in relation to the abstract agent architecture. The concepts are illustrated with an extended example from the domain of science fiction.     

Collapse of the Hierarchy of Constant-Depth Exact Quantum Circuits

We study the quantum complexity class \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}}\) of quantum operations implementable exactly by constant-depth polynomial-size quantum circuits with unbounded fan-out gates. Our main result is that the quantum OR operation is in \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}}\), which is an affirmative answer to the question posed by Høyer and ?palek. In sharp contrast to the strict hierarchy of the classical complexity classes: \({\mathsf{NC}^{0} \subsetneq \mathsf{AC}^{0} \subsetneq \mathsf{TC}^{0}}\), our result with Høyer and ?palek’s one implies the collapse of the hierarchy of the corresponding quantum ones: \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}=\mathsf{QAC}^\mathsf{0}_\mathsf{f}=\mathsf{QTC}^\mathsf{0}_\mathsf{f}}\). Then, we show that there exists a constant-depth subquadratic-size quantum circuit for the quantum threshold operation. This allows us to obtain a better bound on the size difference between the \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}}\) and \({\mathsf{QTC}^\mathsf{0}_\mathsf{f}}\) circuits for implementing the same operation. Lastly, we show that, if the quantum Fourier transform modulo a prime is in \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}}\), there exists a polynomial-time exact classical algorithm for a discrete logarithm problem using a \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}}\) oracle. This implies that, under a plausible assumption, there exists a classically hard problem that is solvable exactly by a \({\mathsf{QNC}^\mathsf{0}_\mathsf{f}}\) circuit with gates for the quantum Fourier transform.     

面向大数据的开源推荐系统分析

处在大数据时代,人们面临的重要问题是如何处理庞大的过量信息,并且如何应对数据惊人的增长趋势。论文重点讨论了面向大数据的推荐系统（RS）,分析现有的开源推荐系统,然后通过评价指标（以及大数据的4V定义）阐述开源推荐系统如何应对大数据时代不断变换的挑战。     

实例讲解七层协议参考模型

对OSI七层协议参考模型的概念,通过用寄信收信的过程,形象的说明了每一层的功能,以QQ信息的发送过程为例,深入探讨了通过七层进行网络互联.     

Pure Decoherence in Quantum Systems

A popular model of decoherence based on the linear coupling to harmonic oscillator heat baths is analysed and shown to be inappropriate in the regime where decoherence dominates over energy dissipation, called pure decoherence regime. The similar mechanism essentially related to the energy conservation implies that, on the contrary to some recent conjectures [21], chaotic environments can be less efficient decoherers than regular ones. Finally, the elastic scattering mechanism is advocated as the simplest source of pure decoherence.     

Quantum Computing and Information Extraction for Dynamical Quantum Systems

We discuss the simulation of complex dynamical systems on a quantum computer. We show that a quantum computer can be used to efficiently extract relevant physical information. It is possible to simulate the dynamical localization of classical chaos and extract the localization length with quadratic speed up with respect to any known classical computation. We can also compute with algebraic speed up the diffusion coefficient and the diffusion exponent, both in the regimes of Brownian and anomalous diffusion. Finally, we show that it is possible to extract the fidelity of the quantum motion, which measures the stability of the system under perturbations, with exponential speed up. The so-called quantum sawtooth map model is used as a test bench to illustrate these results. PACS: 03.67.Lx, 05.45.Mt     

磁悬浮系统的精确积分流形控制设计

基于非性磁悬浮系统的奇异摄动特点,研究了一种精确几何积分流形控制方法,使磁悬浮系统的稳态流形能够无误差地跟踪给定设计流形。将复杂奇异摄动磁悬浮系统按照不同时间尺度分解为降阶系统和边界层,以线性降阶系统设计流形为例,推算出稳定慢控制的具体形式并说明参数稳定范围,结合稳定边界层的快控制,最终推算出磁悬浮系统的复合控制规律。仿真和实验均证明该控制算法能够保证降价系统的流形无误差地跟踪给定的设计流形。利用该算法能够使磁悬浮系统无误差地跟踪任意给定的设计流形,从而提高磁悬浮系统的动态特性。输出流形与设计流形的一致性还可以用来简化系统模型,降低磁悬浮车辆系统动力学分析的复杂程度。     

An Open Model for Hypermedia and Its Application to Geographical Information Systems

This paper describes the design and implementation of a multimedia information management environment that is based on an open model for hypermedia. The model, known as Microcosm, is currently implemented in Microsoft Windows and supports many different media types. The open nature of the model and the separation of the links from the data, allows links to be applied across any application running under Windows or the OS/2 version 2 desktop, thus creating a truly integrated environment. One example, which is, discussed in the paper, is the integration of a hypermedia database with a geographical information system. The paper also discusses the application of novel interfaces to dynamic media within a hypermedia system, including the use of moving icons (micons).     

Aspects of Quantum Chaos in Generic Systems

Hamiltonian dynamical systems with a small number of degrees of freedom, and having ergodic classical dynamics, exhibit universal statistical laws as for their spectral fluctuations of quantal energy levels around the (non-universal) smooth average of the spectral staircase. This finding is one of the cornerstones of the stationary problems in quantum chaos: The so-called Bohigas-Giannoni-Schmit conjecture [16] states that in such cases the level statistics of the random matrix theories (of GOE if there is an antiunitary symmetry in the system, or of GUE otherwise) apply. This conjecture has been supported by many numerical experiments, but also by the semiclassical results of Berry [7], and it has recently been announced to be proven by Andreev et al [1], but under stronger conditions than ergodicity (exponential decay of classical correlations). In cases of classical integrability we also find universality, namely the statistics is typically Poissonian, although there are exceptions, whose measure somehow is expected to be zero or, at least, very small. Finally, there is the class of systems with mixed classical dynamics (regular motions coexisting in the classical phase space with chaotic regions), which are dynamically generic systems, in which case a semiclassical theory can be set up [10, 67, 53, 54]. We present recent results on this class of Hamiltonian systems.     

Computation in Sofic Quantum Dynamical Systems

We analyze how measured quantum dynamical systems store and process information, introducing sofic quantum dynamical systems. Using recently introduced information-theoretic measures for quantum processes, we quantify their information storage and processing in terms of entropy rate and excess entropy, giving closed-form expressions where possible. To illustrate the impact of measurement on information storage in quantum processes, we analyze two spin-1 sofic quantum systems that differ only in how they are measured.     

Exact Stability Analysis of 2-D Systems Using LMIs

In this note, we propose necessary and sufficient conditions for the asymptotic stability analysis of two-dimensional (2-D) systems in terms linear matrix inequalities (LMIs). By introducing a guardian map for the set of Schur stable complex matrices, we first reduce the stability analysis problems into nonsingularity analysis problems of parameter-dependent complex matrices. Then, by means of the discrete-time positive real lemma and the generalized$cal S$-procedure, we derive LMI-based conditions that enable us to analyze the asymptotic stability in an exact (i.e., nonconservative) fashion. It turns out that, by employing the generalized$cal S$-procedure, we can derive smaller size of LMIs so that the computational burden can be reduced.     

一种改进的量子旋转门量子遗传算法

量子遗传算法易陷入局部极值.为此,提出一种改进量子旋转门的量子遗传算法.将量子比特的概率幅值应用于染色体编码,使用量子旋转门实现染色体的更新操作,从而实现目标的优化求解.理论分析及实验结果表明,该算法以概率1收敛,强收敛于1-ε,与双链遗传算法相比,能增加算法复杂度,延长平均时间,对验证函数1收敛次数由3次增加到7次,对验证函数2收敛次数由8次增加到9次.