Distillability sudden death and sudden birth in a two-qutrit system under decoherence at finite temperature

Distillability sudden death and sudden birth in a two-qutrit system locally subject to amplitude damping channel at a finite temperature have been studied in detail. By using the negativity and the realignment criterion, the results show that certain initially prepared free entangled states under amplitude damping channel at a finite temperature may become bound entangled or separable states in a finite time. Moreover, we have also demonstrated initially prepared bound entangled or separable states may also become distillable entangled states in a finite time.     

Enhancing quantum coherence and quantum Fisher information by quantum partially collapsing measurements

We consider the enhancement effect of quantum partially collapsing measurements, i.e., weak measurement and quantum measurement reversal, on quantum coherence and quantum Fisher information, both of which are transmitted through a spin-chain channel. For the state parameter lying in the region \((\pi /2,\ \pi )\), weak measurement can enhance quantum coherence and quantum Fisher information. For the state parameter lying in the region \((0,\ \pi /2)\), quantum coherence and quantum Fisher information can be enhanced by quantum measurement reversal combined with weak measurement. We assume the probabilistic nature of the method should be responsible for the enhancement.     

Thermal entanglement and lower bound of the geometric discord for a two-qutrit system with linear coupling and nonuniform external magnetic field

The effects of temperature and linear coupling constant on the lower bound of the geometric discord and negativity of a qutrit–qutrit system in Heisenberg model with (and without) parallel and antiparallel external magnetic fields have been investigated. We show that the lower bound of the geometric discord and negativity are about zero for negative linear coupling constant in parallel magnetic fields, while they are nonzero in the finite antiparallel magnetic fields. For negative linear coupling constant, as temperature increases, both measures become zero faster than in the case of positive linear coupling constant in antiparallel magnetic fields.     

Entanglement dynamics of a two-qutrit system under DM interaction and the relevance of the initial state

Using concurrence as a measure of entanglement, we present analytical and numerical study of entanglement dynamics in a two-qutrit system in the presence of the Dzyaloshinskii–Moriya interaction, as a function of the parameters involved. Three distinct initial states: a superposition of the ground and the first excited state, the Bell-type state and a superposition of qutrit coherent states will be considered in this investigation.     

Unitary invariant discord as a measures of bipartite quantum correlations in an N-qubit quantum system

We introduce a measure of quantum correlations in the N-qubit quantum system which is invariant with respect to the SU(2 ^N ) group of transformations of this system. This measure is a modification of the quantum discord introduced earlier and is referred to as the unitary or SU(2 ^N )-invariant discord. Since the evolution of a quantum system is equivalent to the proper unitary transformation, the introduced measure is an integral of motion and is completely defined by eigenvalues of the density matrix. As far as the calculation of the unitary invariant discord is rather complicated computational problem, we propose its modification which may be found in a simpler way. The case N?=?2 is considered in details. In particular, it is shown that the modified SU(4)-invariant discord reaches the maximum value for a pure state. A geometric measure of the unitary invariant discord of an N-qubit state is introduced and a simple formula for this measure is derived, which allows one to consider this measure as a witness of quantum correlations. The relation of the unitary invariant discord with the quantum state transfer along the spin chain is considered. We also compare the modified SU(4)-invariant discord with the geometric measure of SU(4)-invariant discord of the two-qubit systems in the thermal equilibrium states governed by the different Hamiltonians.     

A system for extracting three-dimensional measurements from a stereo pair of TV cameras

Obtaining accurate three-dimensional (3-D) measurement from a stereo pair of TV cameras is a task requiring camera modeling, calibration, and the matching of the two images of a real 3-D point on the two TV pictures. A system that models and calibrates the cameras and pairs the two images of a real-world point in two pictures, either manually or automatically, was implemented at JPL. This system is operating and provides three-dimensional measurement resolution of ± 5 mm at distances of about 2 m.     

Quantum simulation of structure switching in a molecular system

This article presents the results of ab initio quantum simulation of graphite-like structure formation from amorphous carbon. It is devoted to explaining a resistivity switching mechanism in experiments on phase-change memory. In this work, a two-scale molecular dynamics model is used, which consists of Car-Parrinello quantum molecular dynamics (CPMD) and modified Ehrenfest molecular dynamics. The results of simulation point out to the appearance of a layered graphite-like molecular structure at an increase in temperature. These changes in the atomic configuration can be considered as a second-order phase transition in nanostructured material, which leads to threshold resistivity switching. For calculations, the IBM BlueGene/P supercomputer installed at the Faculty of Computational Mathematics and Cybernetics of Moscow State University was used.     

The dynamics of local quantum uncertainty and trace distance discord for two-qubit <Emphasis Type="Italic">X</Emphasis> states under decoherence: a comparative study

We employ the concepts of local quantum uncertainty and geometric quantum discord based on the trace norm to investigate the environmental effects on quantum correlations of two bipartite quantum systems. The first one concerns a two-qubit system coupled with two independent bosonic reservoirs. We show that the trace discord exhibits frozen phenomenon contrarily to local quantum uncertainty. The second scenario deals with a two-level system, initially prepared in a separable state, interacting with a quantized electromagnetic radiation. Our results show that there exists an exchange of quantum correlations between the two-level system and its surrounding which is responsible for the revival phenomenon of non-classical correlations.     

Peculiarities of null string motion in the gravitational field of a radially expanding or radially collapsing multistring system

We have found a solution to the Einstein equations for the case of radial expansion or radial collapse of a multistring system having a layered structure. It has been shown that the influence of the gravitational field of such multistring system can lead to stable oscillations of a test null string in the vicinity of a fixed (stationary) point in space, which can be regarded as a spatially localized particle with a nonzero effective rest mass. In this case, the ability of multistring systems to create such particles can be considered as a possible alternative to the Higgs mechanism. It has also been noted that for a gas of null strings, creation of particles with nonzero effective rest mass is possible at early stages of the Universe evolution, where due to high pressures and a domain structure of such a gas, mutual penetration of null strings belonging to neighboring domains was unavoidable and could emerge in mass. At later stages, due to expansion of the Universe, such an opportunity could be lost.     

An explicit form for the closed-loop system matrix of a partially uncontrollable linear system†

An explicit expression for the closed-loop system matrix of a partially uncontrollable linear system is presented. This matrix shows very clearly the eigenproperties of the closed-loop system and, in particular, the relationship between controllability and eigenvalue assignment.     

Optimal control of a linear system subject to partially specified input noise

One of the most basic problems in control theory is that of controlling a discrete‐time linear system subject to uncertain noise with the objective of minimizing the expectation of a quadratic cost. If one assumes the noise to be white, then solving this problem is relatively straightforward. However, white noise is arguably unrealistic: noise is not necessarily independent, and one does not always precisely know its expectation. We first recall the optimal control policy without assuming independence and show that, in this case, computing the optimal control inputs becomes infeasible. In the next step, we assume only the knowledge of lower and upper bounds on the conditional expectation of the noise and prove that this approach leads to tight lower and upper bounds on the optimal control inputs. The analytical expressions that determine these bounds are strikingly similar to the usual expressions for the case of white noise.     

Learning multi-organ and tumor segmentation from partially labeled datasets by a conditional dynamic attention network

Multi-organ segmentation is a critical prerequisite for many clinical applications. Deep learning-based approaches have recently achieved promising results on this task. However, they heavily rely on massive data with multi-organ annotated, which is labor- and expert-intensive and thus difficult to obtain. In contrast, single-organ datasets are easier to acquire, and many well-annotated ones are publicly available. It leads to the partially labeled issue: How to learn a unified multi-organ segmentation model from several single-organ datasets? Pseudo-label-based methods and conditional information-based methods make up the majority of existing solutions, where the former largely depends on the accuracy of pseudo-labels, and the latter has a limited capacity for task-related features. In this paper, we propose the Conditional Dynamic Attention Network (CDANet). Our approach is designed with two key components: (1) multisource parameter generator, fusing the conditional and multiscale information to better distinguish among different tasks, and (2) dynamic attention module, promoting more attention to task-related features. We have conducted extensive experiments on seven partially labeled challenging datasets. The results show that our method achieved competitive results compared with the advanced approaches, with an average Dice score of 75.08%. Additionally, the Hausdorff Distance is 26.31, which is a competitive result.     

Multi-target localisation and circumnavigation by a multi-agent system with bearing measurements in 2D space

This paper investigates the problem of multi-target localisation and circumnavigation by a multi-agent system in two-dimensional space, where each target's bearing measurement can be obtained by at least one agent. Both stationary and slowly-moving targets are considered. An estimator is designed to estimate the target position; then a distributed estimation algorithm is designed for each agent to cooperatively estimate the centroid of multi-target; and finally, based on the first two steps, a circumnavigation controller is devised to guarantee that each agent circumnavigates all targets around the multi-target centroid with a desired radius. The convergence of the estimation algorithm and the stability of the circumnavigation controller are proved. A numerical simulation is provided to verify the correctness of the conclusion and the effectiveness of the proposed algorithm.     

Dephasing of Quantum Bits by a Quasi-Static Mesoscopic Environment

We examine coherent processes in a two-state quantum system that is strongly coupled to a mesoscopic spin bath and weakly coupled to other environmental degrees of freedom. Our analysis is specifically aimed at understanding the quantum dynamics of solid-state quantum bits such as electron spins in semiconductor structures and superconducting islands. The role of mesoscopic degrees of freedom with long correlation times (local degrees of freedom such as nuclear spins and charge traps) in qubit-related dephasing is discussed in terms of a quasi-static bath. A mathematical framework simultaneously describing coupling to the slow mesoscopic bath and a Markovian environment is developed and the dephasing and decoherence properties of the total system are investigated. The model is applied to several specific examples with direct relevance to current experiments. Comparisons to experiments suggests that such quasi-static degrees of freedom play an important role in current qubit implementations. Several methods of mitigating the bath-induced error are considered.Dedicated to Anton Zeilinger, whose work has inspired exploration of quantum phenomenon in many avenues of physics and beyond.     

防腐工程中阴极保护电流检测系统的设计

介绍了一种水下钢桩防腐阴极保护电流检测系统及相关的硬件电路的设计,用以实现远距离无人化检测与监控。介绍了系统硬件结构、通信网络配置以及有关的芯片与微处理器,阐述了软件的设计思路。试验表明,该系统结构简单、成本低廉、性能可靠,能满足工业现场的需要。     

一种面向软件生命周期的授权保护系统设计与实现

当今软件行业开发模式由独立开发转向协同开发,销售形式由软件整体销售转向权限控制销售,原有的加密狗、注册码等单项软件保护技术已很难适应当前软件在开发、销售及使用等过程中各环节对产权保护所提出的新需求,软件侵权问题日益严重。针对以上情况,设计了一种面向软件生命周期的新型软件授权保护系统,该系统综合使用U-Key技术、身份认证及数字签名技术、证书链和硬件加密技术,并采用了可由开发商自填写的组件功能模板和以组件为基本授权实体的许可证文件技术加以实现。实现表明,系统结构合理,各项功能正确,可以满足软件在开发、销售和使用环节上对安全性的需求。     

On primary output estimation by use of secondary measurements asinput signals in system identification

In many cases, vital output variables in, e.g., industrial processes cannot be measured online. It is then of interest to estimate these primary variables from manipulated and measured inputs and the secondary output measurements that are available. In order to identify an optimal estimator from input-output data, a suitable model structure must be chosen. The paper compares use of ARMAX and output error (OE) structures in prediction error identification methods, theoretically and through simulations     

Solving conflicts in information merging by a flexible interpretation of atomic propositions

Although many techniques for merging conflicting propositional knowledge bases have already been proposed, most existing work is based on the idea that inconsistency results from the presence of incorrect pieces of information, which should be identified and removed. In contrast, we take the view in this paper that conflicts are often caused by statements that are inaccurate rather than completely false, suggesting to restore consistency by interpreting certain statements in a flexible way, rather than ignoring them completely. In accordance with this view, we propose a novel approach to merging which exploits extra-logical background information about the semantic relatedness of atomic propositions. Several merging operators are presented, which are based on different formalizations of this background knowledge, ranging from purely qualitative approaches, related to possibilistic logic, to quantitative approaches with a probabilistic flavor. Both syntactic and semantic characterizations are provided for each merging operator, and the computational complexity is analyzed.     

Determination of a time-dependent heat transfer coefficient from non-standard boundary measurements

In this paper the determination of the time-dependent heat transfer coefficient in one-dimensional transient heat conduction from a non-standard boundary measurement is investigated. For this inverse nonlinear ill-posed problem the uniqueness of the solution holds. Numerical results obtained using the boundary element method are presented and discussed.