Electric field manipulation enhanced by strong spin-orbit coupling: promoting rare-earth ions as qubits

Quantum information processing based on magnetic ions has potential for applications as the ions can be modified in their electronic properties and assembled by a variety of chemical methods. For these systems to achieve individual spin addressability and high energy efficiency, we exploited the electric field as a tool to manipulate the quantum behaviours of the rare-earth ion which has strong spin-orbit coupling. A Ce:YAG single crystal was employed with considerations to the dynamics and the symmetry requirements. The Stark effect of the Ce³⁺ ion was observed and measured. When demonstrated as a quantum phase gate, the electric field manipulation exhibited high efficiency which allowed up to 57 π/2 operations before decoherence with optimized field direction. It was also utilized to carry out quantum bang-bang control, as a method of dynamic decoupling, and the refined Deutsch-Jozsa algorithm. Our experiments highlighted rare-earth ions as potentially applicable qubits because they offer enhanced spin-electric coupling which enables high-efficiency quantum manipulation.     

Semiconductor quantum computation

Semiconductors, a significant type of material in the information era, are becoming more and more powerful in the field of quantum information. In recent decades, semiconductor quantum computation was investigated thoroughly across the world and developed with a dramatically fast speed. The research varied from initialization, control and readout of qubits, to the architecture of fault-tolerant quantum computing. Here, we first introduce the basic ideas for quantum computing, and then discuss the developments of single- and two-qubit gate control in semiconductors. Up to now, the qubit initialization, control and readout can be realized with relatively high fidelity and a programmable two-qubit quantum processor has even been demonstrated. However, to further improve the qubit quality and scale it up, there are still some challenges to resolve such as the improvement of the readout method, material development and scalable designs. We discuss these issues and introduce the forefronts of progress. Finally, considering the positive trend of the research on semiconductor quantum devices and recent theoretical work on the applications of quantum computation, we anticipate that semiconductor quantum computation may develop fast and will have a huge impact on our lives in the near future.     

Quantum dynamics of two photons in the coherent feedback system composing of two separated resonators coupling to a waveguide

Quantum coherent feedback based on waveguide quantum electrodynamics plays important roles in quantum devices design and quantum information processing. In this paper, we study the coherent dynamics of the quantum network composed of two separated resonators coupling to a waveguide. Using the dynamical feedback equation in Markovian regime, we obtain the analytical solutions to the output states for the two photons incident from the same or different directions of the waveguide. The two- photon scattering properties are analyzed based on the analytical expressions. It is found that the output states of the two photons can be controlled well by the phase induced by the single photon propagating between the two separated resonators. The results given in this paper are helpful in designing quantum devices at few-photon level.     

New rationale for large metazoan embryo manipulations on chip-based devices

The lack of technologies that combine automated manipulation, sorting, as well as immobilization of single metazoan embryos remains the key obstacle to high-throughput organism-based ecotoxicological analysis and drug screening routines. Noticeably, the major obstacle hampering the automated trapping and arraying of millimetre-sized embryos on chip-based devices is their substantial size and mass, which lead to rapid gravitational-induced sedimentation and strong inertial forces. In this work, we present a comprehensive mechanistic and design rationale for manipulation and passive trapping of individual zebrafish embryos using only hydrodynamic forces. We provide evidence that by employing innovative design features, highly efficient hydrodynamic positioning of large embryos on a chip can be achieved. We also show how computational fluid dynamics-guided design and the Lagrangian particle tracking modeling can be used to optimize the chip performance. Importantly, we show that rapid prototyping and medium scale fabrication of miniaturized devices can be greatly accelerated by combining high-speed laser prototyping with replica moulding in poly(dimethylsiloxane) instead of conventional photolithography techniques. Our work establishes a new paradigm for chip-based manipulation of large multicellular organisms with diameters well above 1 mm and masses often exceeding 1 mg. Passive docking of large embryos is an attractive alternative to provide high level of automation while alleviating potentially deleterious effects associated with the use of active chip actuation. This greatly expands the capabilities of bioanalyses performed on small model organisms and offers numerous and currently inaccessible laboratory automation advantages.     

On the impact of quantum computing technology on future developments in high-performance scientific computing

Quantum computing technologies have become a hot topic in academia and industry receiving much attention and financial support from all sides. Building a quantum computer that can be used practically is in itself an outstanding challenge that has become the ‘new race to the moon’. Next to researchers and vendors of future computing technologies, national authorities are showing strong interest in maturing this technology due to its known potential to break many of today’s encryption techniques, which would have significant and potentially disruptive impact on our society. It is, however, quite likely that quantum computing has beneficial impact on many computational disciplines. In this article we describe our vision of future developments in scientific computing that would be enabled by the advent of software-programmable quantum computers. We thereby assume that quantum computers will form part of a hybrid accelerated computing platform like GPUs and co-processor cards do today. In particular, we address the potential of quantum algorithms to bring major breakthroughs in applied mathematics and its applications. Finally, we give several examples that demonstrate the possible impact of quantum-accelerated scientific computing on society.     

从智慧地球和绿色地球看现代光电技术的发展机遇

光电信息传感和光电能量转换是建设智慧地球和绿色地球的重要关键技术。根据当前光电信息传感器以及光电能量转换器件的发展趋势,应努力发展大规模焦平面列阵;提高红外传感器件工作温度,发展室温工作器件;扩展光电传感器工作波段,发展多波段器件;发展光、热、电、磁、分子、质量、应力以及单光子传感器等多种传感技术。本文还对如何发展太阳能光伏电池提出若干看法。     

A new epoch of quantum manipulation

he behavior of individual microscopic particles,such as an atom(or a photon),predicted using quantum mechanics,is dramatically diferent from the behavior of classical particles,such as a planet,determined using classical mechanics.How can the counter-intuitive behavior of the microscopic particle be veriied and manipulated experimentally?David Wineland and Serge Haroche,who were awarded the Nobel Priz in physics in 2012,developed a set of methods to isolate the ions and photons from their environment to create a genuine quantum system.Furthermore,they also developed methods to measure and manipulate these quantum systems,which open a path not only to explore the fundamental principles of quantum mechanics,but also to develop a much faster computer:a quantum computer.     

单分子操纵与调控

由于具备在空间和能量尺度的高分辨表征能力以及纳米局域探针特点,扫描隧道显微术已经成为近年来对单分子体系进行空间、结构操纵和物理、化学性质调控的重要工具。它可以操纵单分子及其组元在材料表面进行各种运动模式乃至化学反应,并通过电致等外场效应调节单分子体系的量子态,从而在新型材料探索、纳米器件设计、化学反应机理研究与控制等领域具有极大的应用潜力。     

Ultra-sensitive hybrid diamond nanothermometer

Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors because of their long spin coherence time under ambient conditions. However, their spin resonances are relatively insensitive to non-magnetic parameters such as temperature. A magnetic-nanoparticle-nanodiamond hybrid thermometer, where the temperature change is converted to the magnetic field variation near the Curie temperature, were demonstrated to have enhanced temperature sensitivity () (Wang N, Liu G-Q and Leong W-H et al. Phys Rev X 2018; 8: 011042), but the sensitivity was limited by the large spectral broadening of ensemble spins in nanodiamonds. To overcome this limitation, here we show an improved design of a hybrid nanothermometer using a single NV center in a diamond nanopillar coupled with a single magnetic nanoparticle of copper-nickel alloy, and demonstrate a temperature sensitivity of . This hybrid design enables detection of 2 mK temperature changes with temporal resolution of 5 ms. The ultra-sensitive nanothermometer offers a new tool to investigate thermal processes in nanoscale systems.     

Experimental measurement of the quantum geometric tensor using coupled qubits in diamond

Geometry and topology are fundamental concepts, which underlie a wide range of fascinating physical phenomena such as topological states of matter and topological defects. In quantum mechanics, the geometry of quantum states is fully captured by the quantum geometric tensor. Using a qubit formed by an NV center in diamond, we perform the first experimental measurement of the complete quantum geometric tensor. Our approach builds on a strong connection between coherent Rabi oscillations upon parametric modulations and the quantum geometry of the underlying states. We then apply our method to a system of two interacting qubits, by exploiting the coupling between the NV center spin and a neighboring ¹³C nuclear spin. Our results establish coherent dynamical responses as a versatile probe for quantum geometry, and they pave the way for the detection of novel topological phenomena in solid state.     

Optofluidic planar reactors for photocatalytic water treatment using solar energy

Optofluidics may hold the key to greater success of photocatalytic water treatment. This is evidenced by our findings in this paper that the planar microfluidic reactor can overcome the limitations of mass transfer and photon transfer in the previous photocatalytic reactors and improve the photoreaction efficiency by more than 100 times. The microreactor has a planar chamber (5 cm×1.8 cm×100 μm) enclosed by two TiO(2)-coated glass slides as the top cover and bottom substrate and a microstructured UV-cured NOA81 layer as the sealant and flow input∕output. In experiment, the microreactor achieves 30% degradation of 3 ml 3×10(-5)M methylene blue within 5 min and shows a reaction rate constant two orders higher than the bulk reactor. Under optimized conditions, a reaction rate of 8% s(-1) is achieved under solar irradiation. The average apparent quantum efficiency is found to be only 0.25%, but the effective apparent quantum efficiency reaches as high as 25%. Optofluidic reactors inherit the merits of microfluidics, such as large surface∕volume ratio, easy flow control, and rapid fabrication and offer a promising prospect for large-volume photocatalytic water treatment.     

Outlook on moving of computing services towards the data sources

The internet of things (IoT) is potentially interconnecting unprecedented amounts of raw data, opening countless possibilities by two main logical layers: become data into information, then turn information into knowledge. The former is about filtering the significance in the appropriate format, while the latter provides emerging categories of the whole domain. This path of the data is a bottom-up flow. On the other hand, the path of the process is a top-down flow, starting at the strategic level of business and scientific institutions. Today, the path of the process treasures a sizeable amount of well-known methods, architectures and technologies: the so called Big Data. On the top, Big Data analytics aims variable association (e-commerce), data mining (predictive behaviour) or clustering (marketing segmentation). Digging the Big Data architecture there are a myriad of enabling technologies for data taking, storage and management. However the strategic aim is to enhance knowledge with the appropriate information, which does need of data, but not vice versa. In the way, the magnitude of upcoming data from the IoT will disrupt the data centres. To cope with the extreme scale is a matter of moving the computing services towards the data sources. This paper explores the possibilities of providing many of the IoT services which are currently hosted in monolithic cloud centres, moving these computing services into nano data centres (NaDa). Particularly, data-information processes, which usually are performing at sub-problem domains. NaDa distributes computing power over the already present machines of the IP provides, like gateways or wireless routers to overcome latency, storage cost and alleviate transmissions. Large scale questionnaires have been taken for 300 IT professionals to validate the points of view for IoT adoption. Considering IoT is by definition connected to the Internet, NaDa may be used to implement the logical low layer architecture of the services. Obviously, such distributed NaDa send results on a logical high layer in charge of the information-knowledge turn. This layer requires the whole picture of the domain to enable those processes of Big Data analytics on the top.     

Realizing quinary charge states of solitary defects in two-dimensional intermetallic semiconductor

Creating and manipulating multiple charge states of solitary defects in semiconductors is of essential importance for solitary defect electronics, but is fundamentally limited by Coulomb''s law. Achieving this objective is challenging, due to the conflicting requirements of the localization necessary for the sizable band gap and delocalization necessary for a low charging energy. Here, using scanning tunneling microscopy/spectroscopy experiments and first-principles calculations, we realized exotic quinary charge states of solitary defects in two-dimensional intermetallic semiconductor Sn₂Bi. We also observed an ultralow defect charging energy that increases sublinearly with charge number rather than displaying the usual quadratic behavior. Our work suggests a promising route for constructing multiple defect-charge states by designing intermetallic semiconductors, and opens new opportunities for developing quantum devices with charge-based quantum states.     

Quantum mechanics experiment mimicked by stochastic calculations

The paper presents a stochastic calculations algorithm that mimics the photon polarization experiments of quantum mechanics. This experiment is usually used to introduce the quantum computing approach. Stochastic filters that operate on stochastic numbers in a mode similar to that of polarized filter operation on random polarized photons are introduced.     

政策迎合能否兼顾高质量发展? ———制造业企业的研发操纵与生产率

制造业企业通过研发操纵迎合政策门槛值，可以获取税收减免等政策性优惠，但刻意的研发操纵行为却不一定带来企业生产率水平的提高。本文基于2008~2018年ACF法测算的微观企业生产率数据及B-样条基函数展开的非参数分位数模型，更加真实地捕获研发操纵对企业生产率的非线性异质影响，结果发现：（1）研发操纵对企业生产率存在非线性影响，随着研发操纵不断增加，会抑制企业生产率。（2）研发操纵在不同分位点存在显著异质效应，在低分位点处对研发操纵敏感程度更高，即企业生产率水平越低，研发操纵所带来的负面影响越显著。（3）非国有企业更有动机进行研发操纵，且对生产率负面影响更显著。此外，研发操纵对不同地区或技术类型企业生产率影响不同，其中对高技术类型、中西部地区负面影响更显著。（4）研发操纵对企业生产率影响存在显著的滞后效应。中国企业不应盲目研发操纵，应与自身生产率密切结合，为适度研发操纵提升企业生产率目标提供决策依据。     

基于专利的技术融合测度方法及实证研究

随着科学社会的发展,多学科领域间不断发生知识流动,使得不同的技术发生融合。对其进行早期识别和探测,将有利于企业及时发现机会,并调整技术创新战略。现有的基于专利的技术融合测量及预测研究尚未形成一个完整的体系。针对此问题,提出一个测度技术融合的框架,该框架以专利数据为依据,从聚合性、耦合性、均衡性三个角度对其进行分析,全方位的分析了技术融合所形成的整体网络以及构成网络的各技术主体,最后对网络的均衡程度进行了研究。以德温特专利数据库中的纯电动汽车技术和信息技术的融合为实例对模型进行验证。最后根据三个维度可以筛选出在融合水平较高且融合范围较广的技术,以及相对较稳定的技术组合。相关企业和研发结构可以根据筛选出的最优技术或技术组合进行选择性研发,推动相关产业的融合升级。     

基于专利的技术融合测度方法及实证研究

随着科学社会的发展，多学科领域间不断发生知识流动，使得不同的技术发生融合。对其进行早期识别和探测，将有利于企业及时发现机会，并调整技术创新战略。现有的基于专利的技术融合测量及预测研究尚未形成一个完整的体系。针对此问题，提出一个测度技术融合的框架，该框架以专利数据为依据，从聚合性、耦合性、均衡性三个角度对其进行分析，全方位的分析了技术融合所形成的整体网络以及构成网络的各技术主体，最后对网络的均衡程度进行了研究。以德温特专利数据库中的纯电动汽车技术和信息技术的融合为实例对模型进行验证。最后根据三个维度可以筛选出在融合水平较高且融合范围较广的技术，以及相对较稳定的技术组合。相关企业和研发结构可以根据筛选出的最优技术或技术组合进行选择性研发，推动相关产业的融合升级。     

Manipulating single annealed polyelectrolyte under alternating current electric fields: Collapse versus accumulation

Effective manipulation and understanding of the structural and dynamic behaviors of a single polyelectrolyte (PE) under alternating current (AC) electric fields are of great scientific and technological importance because of its intimate relevance to emerging bionanotechnology. In this work, we employ fluorescence correlation spectroscopy (FCS) to study the conformational and AC-electrokinetic behaviors of a model annealed PE, poly(2-vinyl pyridine) (P2VP) under both spatially uniform and non-uniform AC fields at a single molecule level. Under spatially uniform AC-fields, we observe a gradual and continuous coil-to-globule conformational transition (CGT) of single P2VP at varied AC-frequency when a critical AC-field strength is exceeded, in contrast to the pH-induced abrupt CGT in the absence of AC-fields. On the contrary, under spatially non-uniform AC-fields, we observe field-driven net flow and accumulation of P2VP near high AC-field regions due to combined AC electro-osmosis and dielectrophoresis but surprisingly no conformational change. Thus, distinct AC-electric polarization effect on single annealed PE subject to AC-field homogeneity is suggested.     

A droplet acoustofluidic platform for time-controlled microbead-based reactions

Droplet microfluidics is a powerful method used to characterize chemical reactions at high throughput. Often detection is performed via in-line optical readout, which puts high demands on the detection system or makes detection of low concentration substrates challenging. Here, we have developed a droplet acoustofluidic chip for time-controlled reactions that can be combined with off-line optical readout. The principle of the platform is demonstrated by the enzymatic conversion of fluorescein diphosphate to fluorescein by alkaline phosphatase. The novelty of this work is that the time of the enzymatic reaction is controlled by physically removing the enzymes from the droplets instead of using chemical inhibitors. This is advantageous as inhibitors could potentially interact with the readout. Droplets containing substrate were generated on the chip, and enzyme-coupled microbeads were added into the droplets via pico-injection. The reaction starts as soon as the enzyme/bead complexes are added, and the reaction is stopped when the microbeads are removed from the droplets at a channel bifurcation. The encapsulated microbeads were focused in the droplets by acoustophoresis during the split, leaving the product in the side daughter droplet to be collected for the analysis (without beads). The time of the reaction was controlled by using different outlets, positioned at different lengths from the pico-injector. The enzymatic conversion could be measured with fluorescence readout in a separate PDMS based assay chip. We show the ability to perform time-controlled enzymatic assays in droplet microfluidics coupled to an off-line optical readout, without the need of enzyme inhibitors.