Material science for quantum computing with atom chips

In its most general form, the atom chip is a device in which neutral or charged particles are positioned in an isolating environment such as vacuum (or even a carbon solid state lattice) near the chip surface. The chip may then be used to interact in a highly controlled manner with the quantum state. I outline the importance of material science to quantum computing (QC) with atom chips, where the latter may be utilized for many, if not all, suggested implementations of QC. Material science is important both for enhancing the control coupling to the quantum system for preparation and manipulation as well as measurement, and for suppressing the uncontrolled coupling giving rise to low fidelity through static and dynamic effects such as potential corrugations and noise. As a case study, atom chips for neutral ground state atoms are analyzed and it is shown that nanofabricated wires will allow for more than 10⁴ gate operations when considering spin-flips and decoherence. The effects of fabrication imperfections and the Casimir–Polder force are also analyzed. In addition, alternative approaches to current-carrying wires are briefly described. Finally, an outlook of what materials and geometries may be required is presented, as well as an outline of directions for further study.     

Prospects for fast Rydberg gates on an atom chip

Atom chips are a promising candidate for a scalable architecture for quantum information processing provided a universal set of gates can be implemented with high fidelity. The difficult part in achieving universality is the entangling two-qubit gate. We consider a Rydberg phase gate for two atoms trapped on a chip and employ optimal control theory to find the shortest gate that still yields a reasonable gate error. Our parameters correspond to a situation where the Rydberg blockade regime is not yet reached. We discuss the role of spontaneous emission and the effect of noise from the chip surface on the atoms in the Rydberg state.     

Microtrap arrays on magnetic film atom chips for quantum information science

We present two different strategies for developing a quantum information science platform, based on our experimental results with magnetic microtrap arrays on a magnetic-film atom chip. The first strategy aims for mesoscopic ensemble qubits in a lattice of ~5 μm period, so that qubits can be individually addressed and interactions can be mediated by Rydberg excitations. The second strategy aims for direct quantum simulators using sub-optical lattices of ~100 nm period. These would allow the realization of condensed matter inspired quantum many-body systems, such as Hubbard models in new parameter regimes. The two approaches raise quite different issues, some of which are identified and discussed.     

芯片表面气泡瑕疵检测方法

为解决芯片工业生产过程的瑕疵检测问题,提出了一种快速准确的瑕疵检测方法.针对图像采集过程中光照不均匀问题,给出了一种基于均值切块的快速光照补偿方法;另外,为了进行气泡瑕疵的特征提取,给出了一种简单的线性图像融合方法;最后,利用最大熵分割方法分割融合图像,并对瑕疵点进行分割和标记.实验结果表明,在小幅度改变原图像的基础上...     

A new classification approach for neural networks hardware: from standards chips to embedded systems on chip

The aim of this paper is to propose a new classification approach of artificial neural networks hardware. Our motivation behind this work is justified by the following two arguments: first, during the last two decades a lot of approaches have been proposed for classification of neural networks hardware. However, at present there is not a clear consensus on classification criteria and performances. Second, with the evolution of the microelectronic technology and the design tools and techniques, new artificial neural networks (ANNs) implementations have been proposed, but they are not taken into consideration in the existing classification approaches of ANN hardware. In this paper, we propose a new approach for classification of neural networks hardware. The paper is organized in three parts: in the first part we review most of existing approaches proposed in the literature during the period 1990–2010 and show the advantages and disadvantages of each one. In the second part, we propose a new classification approach that takes into account most of consensual elements in one hand and in the other hand it takes into consideration the evolution of the design technology of integrated circuits and the design techniques. In the third part, we review examples of neural hardware achievements from industrial, academic and research institutions. According to our classification approach, these achievements range from standard chips to VLSI ASICs, FPGA and embedded systems on chip. Finally, we enumerate design issues that are still posed. This could help to give new directions for future research work.     

Feasibility of PSO-ANN model for predicting surface settlement caused by tunneling

The potential surface settlement, especially in urban areas, is one of the most hazardous factors in subway and other infrastructure tunnel excavations. Therefore, accurate prediction of maximum surface settlement (MSS) is essential to minimize the possible risk of damage. This paper presents a new hybrid model of artificial neural network (ANN) optimized by particle swarm optimization (PSO) for prediction of MSS. Here, this combination is abbreviated using PSO-ANN. To indicate the performance capacity of the PSO-ANN model in predicting MSS, a pre-developed ANN model was also developed. To construct the mentioned models, horizontal to vertical stress ratio, cohesion and Young’s modulus were set as input parameters, whereas MSS was considered as system output. A database consisting of 143 data sets, obtained from the line No. 2 of Karaj subway, in Iran, was used to develop the predictive models. The performance of the predictive models was evaluated by comparing performance prediction parameters, including root mean square error (RMSE), variance account for (VAF) and coefficient correlation (R ²). The results indicate that the proposed PSO-ANN model is able to predict MSS with a higher degree of accuracy in comparison with the ANN results. In addition, the results of sensitivity analysis show that the horizontal to vertical stress ratio has slightly higher effect of MSS compared to other model inputs.     

Feasibility of imperialist competitive algorithm to predict the surface settlement induced by tunneling

Surface settlement is considered as an adverse effect induced by tunneling in the civil projects. This paper proposes the use of the imperialist competitive algorithm (ICA) for predicting the maximum surface settlement (MMS) resulting from the tunneling. For this work, three forms of equations, i.e., linear, quadratic and power are developed and their weights are then optimized/updated with the ICA. The requirement datasets were collected from the line No. 2 of Karaj urban railway, in Iran. In the ICA models, vertical to horizontal stress ratio, cohesion and Young’s modulus, as the effective parameters on the MSS, are adopted as the inputs. The statistical performance parameters such as root mean square error (RMSE), mean bias error (MBE), and square correlation coefficient (R²) are presented and compared to validate the performance. The findings indicate that the developed ICA-based models with the R² of 0.979, 0.948 and 0.941, obtained from ICA power, ICA quadratic and ICA linear models, respectively, are the acceptable and accurate tools to estimate MSS, and furthermore prove their prediction capability for future research works in this field.

     

A surface mesh deformation method near component intersections for high-fidelity design optimization

Aerodynamic shape optimization based on computational fluid dynamics (CFD) requires three steps: updating the geometry based on the design variables, updating the CFD surface mesh for the new geometry, and updating the CFD volume mesh based on the new surface mesh. While there are many tools available for the first and third steps, the methods available for the second step are insufficient for geometries that have intersecting components. For these geometries, the CFD surface mesh needs to be updated near component intersections to conform to the component geometries and the updated intersection curves. To address this need, we introduce a method that can deform the CFD surface mesh nodes near component intersections. The method can handle arbitrary design changes for each intersecting component as long as the geometric topology is unchanged. Furthermore, the method is suitable for gradient-based optimization because it smoothly deforms every CFD surface node without introducing topological changes in the CFD surface mesh. In this paper, we detail each step of the proposed method and visualize the range of design changes that can be achieved with this approach. Finally, we use the proposed method in an aerodynamic shape optimization problem to optimize the wing-body intersection of the DLR-F6 configuration. These results demonstrate the effectiveness of the proposed method in a high-fidelity design optimization framework. The method applies to both structured and unstructured CFD meshes and makes it possible to use computer-aided design and conceptual design geometry tools within high-fidelity design optimization.

     

Path‐following algorithms and experiments for an unmanned surface vehicle

This paper addresses the problem of path following in two‐dimensional space for underactuated unmanned surface vehicles (USVs), defining a set of guidance laws at the kinematic level. The proposed nonlinear Lyapunov‐based control law yields convergence of the path‐following error coordinates to zero. Furthermore, the introduction of a virtual controlled degree of freedom for the target to be followed on the path removes singularity behaviors present in other guidance algorithms proposed in the literature. Some heuristic approaches are then proposed to face the problem of speed of advance adaptation based on path curvature measurement and steering action prediction. Finally a set of experimental results of all the proposed guidance laws, carried out with the Charlie USV, demonstrates the feasibility of the proposed approach and the performance improvements, in terms of precision in following the reference path and transient reduction, obtained by introducing speed adaptation heuristics. © 2009 Wiley Periodicals, Inc.     

Matrix method for simulating the tunneling transfer

We develop an efficient approach for computer simulation of stationary scattering and tunneling transfer across an arbitrary one-dimensional potential barrier. New algorithms and programs were worked out and tested and the convergence of the method in question was examined.     

Investigations of the capillary effect for gripping silicon chips

Capillary forces in microsystems are very powerful. During wet etching they can cause sticking or even destruction of moving or underetched parts of the microstructure. But capillary forces can also be used in a controlled way for gripping and handling of micro objects. This paper shows that forces exerted on a silicon chip with dimensions of 4 × 4 mm² and a thickness of 600 m are approximately 200-times higher than the inertial force of the chip. The force exerted is dependent on the gap height and can be estimated for different drop sizes with simple estimation formulas or with solutions from differential equations. A numerical solution gives a better understanding of the non-linear behavior of a capillary liquid in a gap. The result of the investigation shows the behavior of the capillary effect in small gaps. For small gap widths and liquid volumes the force developed is overestimated by conventional formulas and calculations. Additionally the general behavior of liquids in microgaps are shown, which also can help to design other liquid based microsystems e.g. micro biological sensor systems.The author is thankful for the support given for this work by Prof. Dr.-Ing. L. Kiesewetter from the Technical University of Brandenburg/Germany.     

一种基于多层感知器的机器人快速推理学习方法

从多层感知器原理分析出发,该文提出一种适变学习因子法用于对学习算法的改进,并将改进的算法用于“逃避”机器人推理网络的实例样本的学习。仿真结果表明,改进后BP的算法可显著加速网络训练速度,并且学习过程具有较好的收敛性及较强的鲁棒性.     

用于微流控制备的3D打印机设计

针对微流控芯片传统加工工艺成本较高,工时较长等问题提出了一种低成本、适用于微流控芯片制备的3D打印机设计方案,该设计方案由3D打印机本体和上位机控制软件组成,其中上位机控制软件负责将事先建好的三维模型进行分析、切片,并生成G-code格式文件;3D打印控制系统负责接收、解析G-code文件及转化为打印机可识别的控制指令以完成物体的快速成型。详细阐述了3D打印机各功能模块的具体实现,给出了测试打印结果,证明该打印机具有成本低、精度高的优点。     

Monitoring the tool wear,surface roughness and chip formation occurrences using multiple sensors in turning

Tool wear, chip formation and surface roughness of workpiece under different cutting conditions have been investigated in machining using acoustic emission (AE) and vibration signature in turning. The investigation has shown that the AE and vibration components can effectively respond to the different occurrences in turning including tool wear and surface roughness. The AE has shown a very significant response to the tool wear progression whereas the resultant vibration (V) represented the surface roughness in turning. The vibration components V_x, V_y and V_z described the chip formation type and are found to have the most significant response to the change of feed, depth of cut and cutting speed respectively. The amplitude of vibration components, V_x, V_y and V_z increased with the increase of feed rate, depth of cut and cutting speed respectively. Even though the frequency of different signal components fluctuated at the different stages of tool wear and at different cutting conditions, the frequency of vibration components was always within a band of 98–40 kHz, and the AE has varied between 51 kHz and 620 kHz.     

Utilization of albumin-based sensor chips for the detection of metal content and characterization of metal–protein interaction by surface plasmon resonance

We report here the use of albumin-based biosensor chips for the determination of metal content and characterization of metal–protein interaction by surface plasmon resonance. Bovine serum albumin was immobilized onto a carboxymethylated dextran matrix and used for metal detection. The temperature for the analysis was defined and the highest interaction was observed at 25 °C. The albumin sensor chip binds cadmium, zinc or nickel in a concentration-dependent manner, but not magnesium, manganese and calcium. The optimal buffer condition used for the analysis contains 0.01 M HEPES, pH 7.4, 1 mM NaCl and 0.005% Tween-20. Using this condition, a linear calibration curve within the range of 10⁻⁸ to 10⁻⁴ M can be established for the metals. However, a dramatic increase in binding capacity was observed when metal concentration was higher than 10⁻⁴ M and reached a plateau at 10⁻² M. The detection limit for Cd can reach as low as 1 ppb. When measuring a solution containing two species of metal ions with the albumin chip, an additive effect was observed for Ni and Zn. However, 20–30% reduction in resonance response was found upon mixing Cd with Zn or Ni. These observations are consistent with the binding characteristics of albumin. The feasibility of measuring serum metal content by the albumin chip was examined. A linear calibration curve can be established if the samples are boiled and passed through a gel filtration column. The binding affinity of metal with albumin can also be achieved by using the sensor chip. The binding affinity follows the order of Ni > Zn > Cd. These results indicate that the albumin-based sensor chip is useful not only in the quantification of metal content, but also in the characterization of the biochemical properties of albumin.     

A method to integrate an atom in a molecule without explicit representation of the interatomic surface

A method to obtain accurate integrated properties according to the theory of “Atoms in Molecules” for any atom is proposed. Classical integration algorithms using explicit representations of the interatomic surfaces (IAS) bounding the integrated atom suffer from the presence of regions where the charge density is extremely flat. This phenomenon is typically caused by ring critical points and leads to unacceptable integration errors. The present paper extends a previously published integration algorithm (Mol. Phys. 87 (1996) 1169) by introducing a procedure that can find an atomic boundary if the interatomic surface is not explicitly known. This hybrid algorithm — which uses analytical interatomic surfaces whenever they are available and adequate but does not necessarily require them — enables the accurate and efficient integration of any atom. A robust and effective code is implemented in MORPHY97 and applied to two representative examples.     

On the integration of design and test for chips embedding MEMS

This article illustrates how fault-based, defect-oriented test approaches can be applied to the problem of testing the next generation of chips embedding MEMS