A Coherent Two-Level System in a Superconducting Single-Electron Transistor Observed Through Photon-Assisted Cooper-Pair Tunneling

A coherent two-level system can be constructed in an ultrasmall Josephson-junction circuit, where two charge states are coupled by single Cooper-pair tunneling. To investigate coherence and decoherence in the two-level system, we have measured dc current through a voltage-biased superconducting single-electron transistor. Under microwave irradiation, a current due to photon-assisted Cooper-pair tunneling is induced, which serves as a useful experimental tool for spectroscopic study of the energy levels in the two-level system. We observed energy-level splitting, which is evidence of the coherent superposition of the two charge states.     

High-Precision Displacement Sensing of Monolithic Piezoelectric Disk Resonators Using a Single-Electron Transistor

A single-electron transistor (SET) can be used as an extremely sensitive charge detector. Mechanical displacements can be converted into charge, and hence, SETs can become sensitive detectors of mechanical oscillations. For studying small-energy oscillations, an important approach to realize the mechanical resonators is to use piezoelectric materials. Besides coupling to traditional electric circuitry, the strain-generated piezoelectric charge allows for measuring ultrasmall oscillations via SET detection. Here, we explore the usage of SETs to detect the shear-mode oscillations of a 6-mm-diameter quartz disk resonator with a resonance frequency around 9 MHz. We measure the mechanical oscillations using either a conventional DC SET, or use the SET as a homodyne or heterodyne mixer, or finally, as a radio-frequency single-electron transistor (RF-SET). The RF-SET readout is shown to be the most sensitive method, allowing us to measure mechanical displacement amplitudes below \(10^{-13}\) m. We conclude that a detection based on a SET offers a potential to reach the sensitivity at the quantum limit of the mechanical vibrations.     

Carbon Nanotube Radio-Frequency Single-Electron Transistor

We discuss the theory of the radio-frequency single-electron transistor and the measurements that use multiwalled carbon nanotubes as active elements. Our devices made of plasma-enhanced chemical-vapor-deposition nanotubes yield charge sensitivities of 10-20 μe/ $\sqrt {Hz}$ . PACS numbers: 73.23.Hk, 73.63.Fg, 85.35.Gv, 85.35.Kt.     

Using Membrane Computing for Effective Homology

Effective Homology is an algebraic-topological method based on the computational concept of chain homotopy equivalence on a cell complex. Using this algebraic data structure, Effective Homology gives answers to some important computability problems in Algebraic Topology. In a discrete context, Effective Homology can be seen as a combinatorial layer given by a forest graph structure spanning every cell of the complex. In this paper, by taking as input a pixel-based 2D binary object, we present a logarithmic-time uniform solution for describing a chain homotopy operator $\phi $ for its adjacency graph. This solution is based on Membrane Computing techniques applied to the spanning forest problem and it can be easily extended to higher dimensions.     

Stream Processing of Multichannel EEG Data Using Parallel Computing Technology with NVIDIA CUDA Graphics Processors

Technical Physics Letters - Prospects of using parallel computing technology (PaCT) methods for the stream processing and online analysis of multichannel EEG data are considered. It is shown that...     

下山掘进爆破技术探讨

针对我国部分煤矿下山爆破掘进存在的问题,分析了造成现状的原因,从掏槽位置、掏槽方式、合理布置辅助眼及起爆顺序等方面出发,提出“裂槽、抛渣”新思路,探讨炮眼深度的选择、炮眼数目及装药量的确定,给出了下山掘进爆破的几个建议.     

基于Google的云计算技术

介绍了云计算技术.云计算技术可实现并行计算、分布式计算和网格计算等.以Google云计算平台为例,阐述了云计算三大关键技术:GFS分布式文件、BigTable分布式数据库以及Map-Reduce编程模型.基于Apache的Hadoop-0.20.2平台,通过WordCount实例,分析了云计算的实现机制与工作过程,并讨论了云计算技术的发展问题.     

Single Nucleobase Identification Using Biophysical Signatures from Nanoelectronic Quantum Tunneling

Nanoelectronic DNA sequencing can provide an important alternative to sequencing‐by‐synthesis by reducing sample preparation time, cost, and complexity as a high‐throughput next‐generation technique with accurate single‐molecule identification. However, sample noise and signature overlap continue to prevent high‐resolution and accurate sequencing results. Probing the molecular orbitals of chemically distinct DNA nucleobases offers a path for facile sequence identification, but molecular entropy (from nucleotide conformations) makes such identification difficult when relying only on the energies of lowest‐unoccupied and highest‐occupied molecular orbitals (LUMO and HOMO). Here, nine biophysical parameters are developed to better characterize molecular orbitals of individual nucleobases, intended for single‐molecule DNA sequencing using quantum tunneling of charges. For this analysis, theoretical models for quantum tunneling are combined with transition voltage spectroscopy to obtain measurable parameters unique to the molecule within an electronic junction. Scanning tunneling spectroscopy is then used to measure these nine biophysical parameters for DNA nucleotides, and a modified machine learning algorithm identified nucleobases. The new parameters significantly improve base calling over merely using LUMO and HOMO frontier orbital energies. Furthermore, high accuracies for identifying DNA nucleobases were observed at different pH conditions. These results have significant implications for developing a robust and accurate high‐throughput nanoelectronic DNA sequencing technique.     

Fabrication and Characteristics of Self-Aligned Dual-Gate Single-Electron Transistors

Single-electron transistors that have electrical tunneling barriers are fabricated, and Coulomb oscillation peaks and negative differential transconductance are observed at room temperature (300 K). Operation characteristics and multioscillation peaks are further investigated at low temperature (80 K). The period of Coulomb oscillation is 2.3 V due to an ultrasmall control gate capacitance, and oscillation peaks are shifted through the side gate bias, which is explained by the derived stability plot for dual-gate structures. Even with the side gates electrically floating, the device still operates as a single-electron transistor since the p-n junction barrier plays a role of tunneling barrier. In addition, by changing the bias condition, double dots are formed along the channel and peak splitting is observed.     

分块技术实现图像快速-高精度旋转

本文提出了一种分块技术,在保障图像旋转精度的前提下,实现图像的快速旋转.该算法只需对图像的一小块区域进行旋转,然后通过简单的坐标变换即可获得整幅旋转后的图像.同时为了便于硬件实现,提出了一种用于事先存储仿射变换信息的Dart模型,将该模型与图像分块技术相结合可以消除图像旋转算法中的浮点运算,使得算法适用于一些无法处理浮...     

乙酸乙烯酯的单电子转移活性自由基聚合

采用SET-LRP方法进行了乙酸乙烯酯(VAc)的活性聚合。通过聚合转化率、聚合物相对平均分子量及分子量分布、聚合物核磁共振氢谱分析,研究了额外失活剂(CuCl2)、温度、溶剂等因素对聚合反应的影响。研究结果表明,失活剂CuII在使反应可控性得到增加的同时却降低了反应的转化率;反应速率不会随反应温度的升高持续增加,超过某一临界温度后反应速率反而随温度的升高而降低;与二甲基亚砜(DMSO)为溶剂相比,甲醇(CH3OH)为溶剂时,得到的聚合物的相对平均分子量较高,但分子量分布较宽。     

应用Excel进行统计运算流量的标准差

对测井仪器流量刻度数据进行处理,能够检测仪器的性能,减少计算结果的误差,应用Excel对所测得的数据进行线性回归,在此基础上进行统计运算流量的标准差.结果表明,这种方法能够适用于目前仪器刻度工作的需要.     

新大成二线隧道爆破掘进施工技术

新大成二线隧道紧临既有线隧道,为确保既有线隧道和行车安全,采取了导坑超前三步开挖,中空大直径直眼掏槽,炮眼水压爆破和实时爆破振动监测等技术措施,安全完成了工程,全段施工进度达每月59m。     

Using Electrons on Liquid Helium for Quantum Computing

We describe a quantum computer based on electrons supported by a helium film and localized laterally by small electrodes just under the helium surface. Each qubit is made of combinations of the ground and first excited state of an electron trapped in the image potential well at the surface. Mechanisms for preparing the initial state of the qubit, operations with the qubits, and a proposed readout are described. This system is, in principle, capable of 10 ⁵ operations in a decoherence time.     

A Nanodamascene Process for Advanced Single-Electron Transistor Fabrication

A process design based on a nanowire structure is demonstrated with the fabrication of metallic single-electron transistors. The method is capable of subattofarad resolution resulting in transistors that exhibited Coulomb blockade up to approximately 430 K. An analysis showed that these devices have sufficient operational margin to sustain process fluctuations and still operate within the temperature limits of conventional silicon field effect transistors.     

SEMSIM: Adaptive Multiscale Simulation For Single-Electron Devices

Single-electron devices have drawn much attention in the last two decades. They have been widely used for device research and also show promise as a potential alternative to CMOS circuits due to their ultralow power dissipation. Three techniques have been used for single-electron device modeling in the past, including Monte Carlo (MC), master equation, and SPICE modeling. Among these, MC method provides accuracy, but lacks the time efficiency required for large-scale simulation. In this paper, we introduce an adaptive multiscale approach to single-electron device simulation using MC method as basis, which significantly improves time efficiency while maintaining accuracy. We have shown that it is possible to reduce simulation time up to nearly 40 times and maintain an average error of 3.3%. Going beyond simplistic approximations, we have modeled important secondary effects including cotunneling and Cooper pair tunneling, which are critical for device research.     

Electron Transport Through Thiolized Gold Nanoparticles in Single-Electron Transistor

We propose an analytical parametric model for defining energy spectra of nanoparticles with a number of atoms of up to 3,300. This allows us to perform Monte-Carlo simulations for single-electron transistor (SET) based on gold nanoparticles with a size of up to 5.2 nm at temperatures from 0.1 to 300 K. At the first step, energy spectra were calculated for isomers of gold nanoparticles, consisting of up to 33 gold atoms using methods of quantum mechanics: density functional theory (DFT) with LANL2DZ basis set for “geometry” optimization; unrestricted Hartree–Fock method (UHF)x with SBKJC basis set to evaluate energy parameters of nanoobjects, which include gold atoms with many electrons. It was found that the general structure of the energy spectra changes unsignificantly if the number of atoms is greater than 27. Moreover, the size of the energy gap and the position of energy levels in it are linear functions of one parameter—the total electric charge of the nanoparticle. These features of energy spectra allowed us to perform calculations of the transport characteristics for a real SET using gold nanoparticle as a central conducting island.     

高应力岩巷的控制爆破机理与技术

通过分析研究矿井深部岩巷的高应力分布特征,采用动光弹模型试验对不同应力条件下的爆破作用机理进行了探讨;通过现场试验,提出了适用于高应力岩巷掘进的控制爆破设计与施工技术。     

Efficient Resource Allocation in Fog Computing Using QTCS Model

Infrastructure of fog is a complex system due to the large number of heterogeneous resources that need to be shared. The embedded devices deployed with the Internet of Things (IoT) technology have increased since the past few years, and these devices generate huge amount of data. The devices in IoT can be remotely connected and might be placed in different locations which add to the network delay. Real time applications require high bandwidth with reduced latency to ensure Quality of Service (QoS). To achieve this, fog computing plays a vital role in processing the request locally with the nearest available resources by reduced latency. One of the major issues to focus on in a fog service is managing and allocating resources. Queuing theory is one of the most popular mechanisms for task allocation. In this work, an efficient model is designed to improve QoS with the efficacy of resource allocation based on a Queuing Theory based Cuckoo Search (QTCS) model which will optimize the overall resource management process.     

Frequency Dependence of a Cryogenic Capacitor Measured Using Single Electron Tunneling Devices

A new type of capacitance standard based on counting electronshas been built. The operation of the standard has alreadygiven very promising results for the determination of thevalue of a cryogenic vacuum-gap capacitor. The new capacitancestandard operates at an effective frequency close to dc,whereas capacitance metrology usually implies the use ofbridges operating at a fixed frequency around 1 kHz.Therefore, the frequency dependence of the cryogenic capacitoris critical to the practical application of this standard. Wepresent measurements of this frequency dependence using atechnique that involves the same single electron tunnelingdevices used in the capacitance standard.