Geometric phase,quantum Fisher information,geometric quantum correlation and quantum phase transition in the cavity-Bose–Einstein-condensate system

We investigate the quantum phase transition of an atomic ensemble trapped in a single-mode optical cavity via the geometric phase and quantum Fisher information of an extra probe atom which is injected into the optical cavity and interacts with the cavity field. We also find that the geometric quantum correlation between two probe atoms exhibits a double sudden transition phenomenon and show this double sudden transition phenomenon is closely associated with the quantum phase transition of the atomic ensemble. Furthermore, we propose a theoretical scheme to prolong the frozen time during which the geometric quantum correlation remains constant by applying time-dependent electromagnetic field.     

Scalable architecture for quantum information processing with atoms in optical micro-structures

We review recent experimental progress towards quantum information processing and quantum simulation using neutral atoms in two-dimensional (2D) arrays of optical microtraps as 2D registers of qubits. We describe a scalable quantum information architecture based on micro-fabricated optical elements, simultaneously targeting the important issues of single-site addressability and scalability. This approach provides flexible and integrable configurations for quantum state storage, manipulation, and retrieval. We present recent experimental results on the initialization and coherent one-qubit rotation of up to 100 individually addressable qubits, the coherent transport of atomic quantum states in a scalable quantum shift register, and discuss the feasibility of two-qubit gates in 2D microtrap arrays.     

Optimal control of active transport across a biological membrane

We propose an optimal control principle for active transport across a biological membrane. The modeling of the membrane is based on Hill and Kedem's thermodynamic model. The performance function used to evaluate the optimality of the transport involved the rate of time-dependent changes in the concentration of particles in all the membrane layers as the state variables, and the number of receptor sites on the membrane as the control input. We decided that the optimal transport state is achieved when this cost function has been minimized under the constraints of the system equations characterizing the membrane modeling. The changes in the number of particles in the membrane layer evoked by changes in the kinetic parameters can be explained by the compensatory action of the optimal control strategy in order to prevent excessive decrease or increase of the molecular particles in all the membrane layers. The changes in the number of receptors in the paths of some physiological states can be explained by the optimal control modeling of the membrane transport. This model will be made available to create and evaluate an artificial membrane. This work was presented, in part, at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1996     

Scheduling bulk file transfers with start and end times

The advancement of optical networking technologies has enabled e-science applications that often require transport of large volumes of scientific data. In support of such data-intensive applications, we develop and evaluate control plane algorithms for scheduling bulk file transfers, where each transfer has a start time and an end time. We formulate the scheduling problem as a special type of the multi-commodity flow problem. To cope with the start and end time constraints of the file-transfer jobs, we divide time into uniform time slices. Bandwidth is allocated to each job on every time slice and is allowed to vary from slice to slice. This enables periodical adjustment of the bandwidth assignment to the jobs so as to improve a chosen performance objective: throughput of the concurrent transfers. In this paper, we study the effectiveness of using multiple time slices, the performance criterion being the tradeoff between achievable throughput and the required computation time. Furthermore, we investigate using multiple paths for each file transfer to improve the throughput. We show that using a small number of paths per job is generally sufficient to achieve near optimal throughput with a practical execution time, and this is significantly higher than the throughput of a simple scheme that uses single shortest path for each job.     

Image Sequence Interpolation Using Optimal Control

The problem of finding an interpolating image between two given images in an image sequence is considered. The problem is formulated as an optimal control problem governed by a transport equation, i.e. we aim at finding a flow field which transports the first image as close as possible to the second image. This approach bears similarities with the Horn and Schunck method for optical flow calculation but in fact the model is quite different. The images are modeled in the space of functions of bounded variation and an analysis of solutions of transport equations in this space is included. Moreover, the existence of optimal controls is proven and necessary conditions are derived. Finally, two algorithms are given and numerical results are compared with existing methods. The new method is competitive with state-of-the-art methods and even outperforms several existing methods.     

广域光传送网逻辑拓扑的优化设计

基于波分复用的光组网技术是下一代传送网的最佳解决方案，分组业务光传送网结构设计的核心是虚拓扑的最优化问题．描述了最优虚拓扑问题的主要特点，提出了一种广域光传送网优化虚拓扑的设计原则，优化的目标是使吞吐量最大并且使延迟最小,并采用Prufer数的方法来随机产生一组可行的虚拓扑算法，给出了将虚拓扑嵌入到给定的物理网络的一种启发式算法，并使用遗传算法(GA)来优化虚拓扑，从而得到最优解．光传送网虚拓扑的设计问题在实践上非常重要，提出的方法对于实践者具有重要的指导作用．     

Simulating Weyl points and nodal loops in an optical superlattice

We propose a scheme to simulate Weyl points and nodal loops with ultracold atoms in an optical lattice that is subjected to realizable synthetic magnetic field and synthetic dimension. We show that a Hofstadter-like Hamiltonian with a cyclically parameterized on-site energy term can be realized in a tunable two-dimensional optical superlattice, based on the laser-assisted atomic tunneling method. This model effectively describes a three-dimensional periodic lattice system under magnetic fluxes, where a synthetic dimension is encoded by a cyclical phase of the optical lattice potential. For different atomic hopping configurations, the single-particle bands are demonstrated to, respectively, exhibit Weyl points and nodal loops in the extended three-dimensional Brillouin zone. Furthermore, we illustrate that the mimicked Weyl points and nodal loops can be experimentally detected by measuring the atomic transfer fraction in Bloch–Zener oscillations.     

Numerical and experimental characterization of 3-phase rectification of nanobead dielectrophoretic transport exploiting Brownian motion

We report on a transport system for nanobeads that exploits Brownian motion as the main actuation source, saving energy compared to a purely electrostatic transport system of the same geometry. The transport system employs a microfluidic channel to restrict Brownian motion of the nanobeads to only one dimension and a 3-phase dielectrophoretic flashing ratchet to bias the spatial probability distribution into the rectification direction for one-dimensional transport. A numerical model of the system is developed and applied to investigate its performance. A micromachined transport system is fabricated and employed to experimentally validate the model with the confirmation of the optimal operation point. Numerical model and experiments have shown good agreement.     

Characterization of micro‐cell discharge in AC‐PDPs by spatio‐temporal optical emission spectroscopy

Abstract— We have developed highly resolved spatio‐temporal optical emission spectroscopy to investigate the discharge characteristics of coplanar type ac plasma‐display panels (AC‐PDPs). Spatio‐temporal emission profiles were measured for relevant lines of atomic He, Ne, Xe, and ionic Xe in He‐Xe and Ne‐Xe systems with various Xe concentrations and total gas pressures. The surface‐discharge behavior in coplanar PDPs has been clarified.     

Time optimal control of second-order systems with transport lag†

The time optimal control of particular second–order systems with constant transport lags is determined by application of Pontryagin's Maximum Principle. A system with a delayed control and a system with a delayed state are considered. The optimal control for these systems is compared with the optimal control of a similar system which does not contain transport lag. It is found that the optimal control is essentially bang–bang but that it is non–unique under certain conditions.     

Entanglement of two hybrid optomechanical cavities composed of BEC atoms under Bell detection

In this paper, firstly, we consider bipartite entanglement between each part of an optomechanical cavity composed of one-dimensional Bose–Einstein condensate (BEC). We investigate atomic collision on the behaviour of the BEC in the week photon–atom coupling constant and use Bogoliubov approximation for the BEC. Secondly under above condition, we propose a scheme for entanglement swapping protocol which involves tripartite systems. In our investigation, we consider a scenario where BECs, moving mirrors, and optical cavity modes are given in a Gaussian state with a covariance matrix. By applying the Bell measurement to the output optical field modes, we show how the remote entanglement between two BECs, two moving mirrors, and BEC-mirror modes in different optomechanical cavity can be generated.     

A performance model for an asynchronous optical buffer

We investigate the behaviour of an asynchronous optical buffer by means of a continuous-time queuing model. Through a limit procedure, previously obtained results for a discrete-time queuing model are translated to a continuous-time setting. We also show that the same results can be obtained by a direct analysis using Laplace transforms. Closed-form expressions are obtained for the cases of exponentially distributed burst sizes, deterministic burst sizes and mixtures of deterministic burst sizes.

The performance of asynchronous optical buffers shows the same characteristics as that of synchronous optical buffers: a reduction in throughput due to the creation of voids on the outgoing channel and a burst loss probability that is strongly influenced by the choice of fiber delay line granularity. The optimal value of the latter depends on the burst size distribution and the offered load.     

GMPLS-based OBS光传输网络体系结构

提出一种采用GMPLS协议作为控制面的光突发交换（OBS）网络体系结构,给出了网络结构、节点功能模型、控制包格式和新增控制信令交换接口的建议。提出的网络结构是在OBS的突发控制包用通用标签代替地址,并使用GMPLS协议栈完成路由和信令功能,实现流量工程和生存性研究。     

A robustness result for stochastic control

The solution of a stochastic control problem depends on the underlying model. The actual real world model may not be known precisely and so one solves the problem for a hypothetical model, that is in general different but close to the real one; the optimal (or nearly optimal) control of the hypothetical model is then used as solution for the real problem.In this paper, we assume that, what is not precisely known, is the underlying probability measure that determines the distribution of the random quantities driving the model. We investigate two ways to derive a bound on the suboptimality of the optimal control of the hypothetical problem when this control is used in the real problem. Both bounds are in terms of the Radon–Nikodym derivative of the underlying real world measure with respect to the hypothetical one. We finally investigate how the bounds compare to each other.     

Numerical solution of a conspicuous consumption model with constant control delay

We derive optimal pricing strategies for conspicuous consumption products in periods of recession. To that end, we formulate and investigate a two-stage economic optimal control problem that takes uncertainty of the recession period length and delay effects of the pricing strategy into account.This non-standard optimal control problem is difficult to solve analytically, and solutions depend on the variable model parameters. Therefore, we use a numerical result-driven approach. We propose a structure-exploiting direct method for optimal control to solve this challenging optimization problem. In particular, we discretize the uncertainties in the model formulation by using scenario trees and target the control delays by introduction of slack control functions.Numerical results illustrate the validity of our approach and show the impact of uncertainties and delay effects on optimal economic strategies. During the recession, delayed optimal prices are higher than the non-delayed ones. In the normal economic period, however, this effect is reversed and optimal prices with a delayed impact are smaller compared to the non-delayed case.     

Adjoint-based derivative computations for the optimal control of discontinuous solutions of hyperbolic conservation laws

We propose a rigorous procedure to obtain the adjoint-based gradient representation of cost functionals for the optimal control of discontinuous solutions of conservation laws. Hereby, it is not necessary to introduce adjoint variables for the shock positions. Our approach is based on stability properties of the adjoint equation. We give a complete analysis for the case of convex scalar conservation laws. The adjoint equation is a transport equation with discontinuous coefficients and special reversible solutions must be considered to obtain the correct adjoint-based gradient formula. Reversible solutions of the adjoint transport equation and the required stability properties are analyzed in detail.     

Numerical Solution of Optimal Control Problems with Constant Control Delays

We investigate a class of optimal control problems that exhibit constant exogenously given delays in the control in the equation of motion of the differential states. Therefore, we formulate an exemplary optimal control problem with one stock and one control variable and review some analytic properties of an optimal solution. However, analytical considerations are quite limited in case of delayed optimal control problems. In order to overcome these limits, we reformulate the problem and apply direct numerical methods to calculate approximate solutions that give a better understanding of this class of optimization problems. In particular, we present two possibilities to reformulate the delayed optimal control problem into an instantaneous optimal control problem and show how these can be solved numerically with a state-of-the-art direct method by applying Bock’s direct multiple shooting algorithm. We further demonstrate the strength of our approach by two economic examples.      

A heuristic for placement of limited range wavelength converters in all-optical networks

Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the optical fiber. Wavelength converters play an important role in enhancing the fiber utilization and reducing the overall call blocking probability of the network. As the distortion of the optical signal increases with the increase in the range of wavelength conversion in optical wavelength converters, limited range wavelength conversion assumes importance. Placement of wavelength converters is a NP complete problem [K.C. Lee, V.O.K. Li, IEEE J. Lightwave Technol. 11 (1993) 962–970] in an arbitrary mesh network. In this paper, we investigate heuristics for placing limited range wavelength converters in arbitrary mesh wavelength routed optical networks. The objective is to achieve near optimal placement of limited range wavelength converters resulting in reduced blocking probabilities and low distortion of the optical signal. The proposed heuristic is to place limited range wavelength converters at the most congested nodes, nodes which lie on the long lightpaths and nodes where conversion of optical signals is significantly high. We observe that limited range converters at few nodes can provide almost the entire improvement in the blocking probability as the full range wavelength converters placed at all the nodes. Congestion control in the network is brought about by dynamically adjusting the weights of the channels in the link thereby balancing the load and reducing the average delay of the traffic in the entire network. Simulations have been carried out on a 12-node ring network, 14-node NSFNET, 19-node European Optical Network (EON), 28-node US long haul network, hypothetical 30-node INET network and the results agree with the analysis.     

基于卡尔曼滤波的自主式水下航行器大尺度编队控制

针对网络环境下环境噪声对自主式水下航行器编队控制的影响,提出一种利用卡尔曼滤波实时估计AUV最优运动状态的编队控制方法.将空间间隔较远的多AUV系统建模为多智能体系统,从大尺度上研究其编队控制问题.为了得到每个AUV速度状态的最优估计值,每个AUV都嵌入一个全局卡尔曼滤波器,利用该全局滤波器进行最优估计从而计算出噪声环境下其自身的最优位置.仿真结果验证了所给出的控制策略的有效性.     

Hyperbolic optimal control and fuzzy control

In this paper, we consider a new approach to fuzzy control which entails the formulation of a novel state-space representation and a new form of optimal control problem. Basically, in this new formulation, linear functions in the conventional state-space representation and cost functional are replaced by hyperbolic functions. We give a solution for this new, infinite-time, optimal control problem, which we call hyperbolic optimal control. Furthermore, we show that the resulting optimal controller is in fact a Mamdani-type fuzzy controller with Gaussian membership functions and center of gravity defuzzification. These results enable us to investigate analytically important issues, such as stability and robustness, pertaining to fuzzy controllers as well as add a powerful theoretical framework to the field of fuzzy control