Quantum Correlations in a Generalized Spin Star System

The problem of detecting quantum signatures in the correlations formed in dynamical evolution of quantum bipartite systems receives a lot of attention in current literature. Generally speaking, the occurrence of correlations between two observables of a system does not necessarily reflect nonclassical behaviour. In this paper, the exact dynamics of a pair of uncoupled spins 1/2 interacting with a common spin 1/2 bath is investigated. Starting from a separable initial condition, the ability of the system to develop purely quantum correlations is brought to light. Physical interpretation of the concurrence function as well as a suggestion on how to measure it are given.     

Further Results on the Observability of Quantum Systems Under General Measurement

In this paper, we present a collection of results on the observability of quantum mechanical systems, in the case the output is the result of a discrete nonselective measurement. By defining an effective observable, we extend previous results, on the Lie algebraic characterization of observable systems, to general measurements. Further results include the characterization of a ‘best probe’ (i.e. a minimally disturbing probe) in indirect measurement and a study of the relation between disturbance and observability in this case. We also discuss how the observability properties of a quantum system relate to the problem of state reconstruction. Extensions of the formalism to the case of selective measurements are also given.     

Quantum Logic and Quantum Theory in a Game-Theoretic Perspective

Extensive games of imperfect information, together with the associated semantic machinery, can be brought to bear on logical aspects of quantum-theoretic phenomena. Among other things, this kinship implies that propositional logic of informational independence is useful in understanding such quantum theoretic issues as non-locality and EPR-type paradoxes, and that quantum logic exhibits the overall game-theoretical notion of uncertainty.     

Quantum and Classical Correlations of Spatial and Spin Degrees of Freedom in Quantum Rings

A one-dimensional mesoscopic ring with one input and two output leads acts as a spintronic beam splitter. The spatial degree of freedom, i.e., the presence of two different possible output channels, gets intertwined with the spin direction as a consequence of quantum interference and spin-orbit interaction. We investigate this kind of spatial-spin correlation, and show that the output density operator contains no quantum entanglement in the important special case when the device polarizes a perfectly random input spin state. However, the correlations are in general not purely classical, we also present specific input states with maximal spatial-spin entanglement after the ring.     

Quantum Set Theory Extending the Standard Probabilistic Interpretation of Quantum Theory

The notion of equality between two observables will play many important roles in foundations of quantum theory. However, the standard probabilistic interpretation based on the conventional Born formula does not give the probability of equality between two arbitrary observables, since the Born formula gives the probability distribution only for a commuting family of observables. In this paper, quantum set theory developed by Takeuti and the present author is used to systematically extend the standard probabilistic interpretation of quantum theory to define the probability of equality between two arbitrary observables in an arbitrary state. We apply this new interpretation to quantum measurement theory, and establish a logical basis for the difference between simultaneous measurability and simultaneous determinateness.     

Kolmogorov Probability Spaces Describing Accardi Models of Quantum Correlations

In this paper we consider several Kolmogorov type models describing some quantum correlations. The main ideas beyond most of these models comes back to pioneering works of Accardi (see [1, 10, 15] and references therein); because of that we call some of them the Accardi models. Namely we discuss, in our frame, the Kolmogorov type Accardi model of the Aspect version [2] of the Einstein-Podolsky-Rosen (EPR) experiment [3].     

Non-Markovian Quantum Error Deterrence by Dynamical Decoupling in a General Environment

A dynamical decoupling(DD) scheme for the prevention of errors in the non-Markovian (usually corresponding to low temperature, short time, and strong coupling) regimes suitable for qubits constructed out of a multilevel structure is studied. We use the effective spin-boson model (ESBM) introduced recently [K. Shiokawa and B. L. Hu, Phys. Rev. A70, 062106 (2004)] as a low temperature limit of the quantum Brownian oscillator model, where one can obtain exact solutions for a general environment with colored noises. In our decoupling scheme, a train of pairs of strong pulses are used to evolve the interaction Hamiltonian instantaneously. Using this scheme we show that the dynamical decoupling method can suppress 1/f noise with slower and hence more accessible pulses than previously studied, but it still fails to decouple super-Ohmic types of environments.      

General Point Sampling with Adaptive Density and Correlations

Analyzing and generating sampling patterns are fundamental problems for many applications in computer graphics. Ideally, point patterns should conform to the problem at hand with spatially adaptive density and correlations. Although there exist excellent algorithms that can generate point distributions with spatially adaptive density or anisotropy, the pair‐wise correlation model, blue noise being the most common, is assumed to be constant throughout the space. Analogously, by relying on possibly modulated pair‐wise difference vectors, the analysis methods are designed to study only such spatially constant correlations. In this paper, we present the first techniques to analyze and synthesize point patterns with adaptive density and correlations. This provides a comprehensive framework for understanding and utilizing general point sampling. Starting from fundamental measures from stochastic point processes, we propose an analysis framework for general distributions, and a novel synthesis algorithm that can generate point distributions with spatio‐temporally adaptive density and correlations based on a locally stationary point process model. Our techniques also extend to general metric spaces. We illustrate the utility of the new techniques on the analysis and synthesis of real‐world distributions, image reconstruction, spatio‐temporal stippling, and geometry sampling.     

On a Sufficient Condition for Additivity in Quantum Information Theory

In this paper we give a sufficient condition for additivity of the minimum output entropy for a pair of given channels and an analytic verification of this condition for specific quantum channels breaking a closely related multiplicativity property [1, 2]. This yields validity of the additivity conjecture for these channels, a result obtained by a different method in [3]. Our proof relies heavily upon certain concavity properties of the output entropy, which are of independent interest.__________Translated from Problemy Peredachi Informatsii, No. 2, 2005, pp. 9–25.Original Russian Text Copyright © 2005 by Datta, Holevo, Suhov.This work was initiated when the second author was an overseas visiting scholar at St John’s College, Cambridge. Afterwards he was supported by the Russian Scientific School Program, project no. 1758.2003.1. The first and third authors worked in association with the CMI, University of Cambridge - MIT.     

A Quantum Theory of Consciousness

The relationship between quantum collapse and consciousness is reconsidered under the assumption that quantum collapse is an objective dynamical process. We argue that the conscious observer can have a distinct role from the physical measuring device during the process of quantum collapse owing to the intrinsic nature of consciousness; the conscious observer can know whether he is in a definite state or a quantum superposition of definite states, while the physical measuring device cannot “know”. As a result, the consciousness observer can distinguish the definite states and their quantum superposition, while the physical measuring device without consciousness cannot do. This provides a possible quantum physical method to distinguish man and machine. The new result also implies that consciousness has causal efficacies in the physical world when considering the existence of quantum collapse. Accordingly consciousness is not reducible or emergent, but a new fundamental property of matter. This may establish a quantum basis for panpsychism, and make it be a promising solution to the hard problem of consciousness. Furthermore, it is suggested that a unified theory of matter and consciousness includes two parts: one is the psychophysical principle or corresponding principle between conscious content and matter state, and the other is the complete quantum evolution of matter state, which includes the definite nonlinear evolution element introduced by consciousness and relating to conscious content. Lastly, some experimental schemes are presented to test the proposed quantum theory of consciousness.

Large Deviations in Quantum Information Theory

We obtain asymptotic estimates for the probabilities of events of special types, which are useful in quantum information theory, especially for identification in noisy channels.     

Mathematical Theory of Duality Quantum Computers

We present a mathematical theory for a new type of quantum computer called a duality quantum computer that has recently been proposed. We discuss the nonunitarity of certain circuits of a duality quantum computer and point out a paradoxical situation that occurs when mixed states are considered. It is shown that a duality quantum computer can measure itself without needing a separate measurement apparatus to determine its final state.      

A Computational Model for Quantum Measurement

Quantum Information Processing - Is the dynamical evolution of physical systems objectively a manifestation of information processing by the universe? We find that an affirmative answer has...     

Simplification of Additivity Conjecture in Quantum Information Theory

We simplify some conjectures in quantum information theory; the additivity of minimal output entropy, the multiplicativity of maximal output p-norm and the superadditivity of convex closure of output entropy. In this paper, by using some unital extension of quantum channels, we show that proving one of these conjectures for all unital quantum channels would imply that it is also true for all quantum channels.      

智能设备的通用测试

根据计算机监控系统的特点，用VB6.0开发通用的计算机监控系统测试软件。该软件既能充当主控机，又能充当受控机，还可用来破译通讯协议，可靠性高，实用性强，可广泛应用于智能设备的测试及计算机监控系统。同时，对Microsoft的MSComm通讯控件中的bug作了修正。     

量子衍生自适应中值滤波

受量子信息处理理论的启发,提出了一种基于量子测量和量子态坍缩的自适应中值滤波原理。在提出的中值滤波中,移动窗内的图像像素采用量子叠加态表示,通过由窗内像素特征生成的测量算子对窗口图像的作用调整中值运算窗口的大小和形状。一种测量算子的生成方法被提出。计算机仿真表明,所提出的中值滤波器与传统的中值滤波器相比,具有更好的滤波效果。