量子纠缠和经典热光的关联成像

关联成像理论和实验证明了光可以用特殊的方式传递经典信息文章中将介绍纠缠光和热光的关联成像实验．并从理论上分析经典热光源和双光子纠缠源在关联性质上的差异。     

Narratives of quantum theory in the age of quantum technologies

Quantum technologies can be presented to the public with or without introducing a strange trait of quantum theory responsible for their non-classical efficiency. Traditionally the message was centered on the superposition principle, while entanglement and properties such as contextuality have been gaining ground recently. A less theoretical approach is focused on simple protocols that enable technological applications. It results in a pragmatic narrative built with the help of the resource paradigm and principle-based reconstructions. I discuss the advantages and weaknesses of these methods. To illustrate the importance of new metaphors beyond the Schrödinger cat, I briefly describe a non-mathematical narrative about entanglement that conveys an idea of some of its unusual properties. If quantum technologists are to succeed in building trust in their work, they ought to provoke an aesthetic perception in the public commensurable with the mathematical beauty of quantum theory experienced by the physicist. The power of the narrative method lies in its capacity to do so.     

量子计算机的发展现状与趋势

量子计算机是一种新型的运算工具,它具有强大的并行处理数据的能力,可解决现有计算机难以运算的数学问题,因此,它成为世界各国战略竞争的焦点。本文综述了量子计算机目前的发展状况和可扩展、可容错的量子计算机物理体系的实验研究进展,并分析了美国最近启动研制量子芯片的微型曼哈顿计划对我国构成的严峻挑战。     

量子纠缠态制备、操纵的实验研究

量子纠缠是量子信息学中最重要也是最为奇特的一个课题.在量子信息学中,量子信息的处理离不开量子态及其操纵,而量子纠缠态毫无疑问是各种各样的量子态中最重要的一种. 利用光子纠缠态开展了以下实验研究:(1)利用连续波激光束泵浦非线性晶体的自发参量下转换过程,制备出了双光子偏振纠缠态,具有较高亮度和纠缠度,并具有纠缠度可调谐的特点. 利用这种纠缠源,制备了量子信息学中一种重要的混合态——Werner态,采用的方案使得Werner态中纠缠的成分是可控制的.(2)利用线性光学元件以及路径比特概念的引入,在实验上用单光子实现了Buek-Hillery普适克隆机,实验结果表明,对任意的输入纯态,此克隆机输出的2份拷贝与初始态均达到5/6的保真度,与理论计算一致.(3)在实验上利用自发参量下转换系统制备的双光子偏振最大纠缠态及非最大纠缠态进行了CHSH不等式的检验,验证了对于2比特纠缠纯态,"纠缠"等价于"Bell不等式违背"这一结论.(4)除了局域隐变量理论之外,还有一种主要的隐变量理论——环境无关的隐变量理论(NCHV),关于这种隐变量,类似于Bell不等式,有一个Kochen-Specker理论,其主要内容是证明NCHV和量子力学的矛盾. 完成了一个用单光子实现的检验Kochen-Spcker理论的实验,实验结果证明了NCHV是不存在的.     

Drone-based entanglement distribution towards mobile quantum networks

Satellites have shown free-space quantum-communication ability; however, they are orbit-limited from full-time all-location coverage. Meanwhile, practical quantum networks require satellite constellations, which are complicated and expensive, whereas the airborne mobile quantum communication may be a practical alternative to offering full-time all-location multi-weather coverage in a cost-effective way. Here, we demonstrate the first mobile entanglement distribution based on drones, realizing multi-weather operation including daytime and rainy nights, with a Clauser-Horne-Shimony-Holt S-parameter measured to be 2.41 ± 0.14 and 2.49 ± 0.06, respectively. Such a system shows unparalleled mobility, flexibility and reconfigurability compared to the existing satellite and fiber-based quantum communication, and reveals its potential to establish a multinode quantum network, with a scalable design using symmetrical lens diameter and single-mode-fiber coupling. All key technologies have been developed to pack quantum nodes into lightweight mobile platforms for local-area coverage, and arouse further technical improvements to establish wide-area quantum networks with high-altitude mobile communication.     

Micius Witnesses “Spooky Action” over 1200km from Outer Space

"Spooky action" triumphs in outer space: A joint team of CAS scientists reported in a cover article in Science the successful survival of quantum entanglement over a distance of1200+ km, and a violation of Bell Inequality.     

量子科学实验卫星——“墨子号”

北京时间2016年8月16日凌晨1时45分,"墨子号"量子科学实验卫星在酒泉卫星发射中心成功发射。该卫星是世界第一颗从事空间尺度量子科学实验的卫星。升空之后,它将配合多个地面站,在国际上率先实现星地高速量子密钥分发、星地双向量子纠缠分发及空间尺度量子非定域性检验、地星量子隐形传态,以及探索广域量子密钥组网等实验。"墨子号"量子科学实验卫星将扩大我国在量子通信领域的国际领先地位,为未来覆盖全球的天地一体化广域量子通信网络建立基础,并将加深人类对量子力学基本原理的理解。     

Realization of Shor's algorithm on an optical quantum computer

Aresearch team led by Prof.PAN Jianwei with the University of Science and Technology of China(USTC),CAS has been successful in performing Shor's algorithm,a quantum algorithm for factorization,in an optical quantum computer.The feat is also independently made by another team led by Andrew White from the University of Queensland in Brisbane,Australia.Both results were published in the 19 December,2007 issue of Physics Review Newsletters.     

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.     

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.     

The energy glitch: Speculative histories and quantum counterfactuals

Energy (in all its conceptualizations and connotations) is a glitch, a bug, an error. Energy is presented here as a roadblock in efforts to articulate and formulate a coherent physical model of the universe, as well as an impediment to achieving just and equitable social relations. Energy broke physics and broke society. This article traces conundrums and uncertainties that prevail in physics today, from the irreconcilability of quantum dynamics and gravitational spacetime to the unsatisfactory postulation of dark energy, and the profusion of probabilistic reasoning. I offer a brief history of thermodynamics and its entanglement with industrial capitalism via the steam engine. I explore alternate histories of energy (hydrodynamic and metabolic) and speculate on the potential social implications of these counterfactual trajectories. Finally, building on the novel Constructor Theory paradigm, I entertain the possibility of replacing energy with informed noticing as the undergirding architecture of physics, replacing dynamics with discernment as the underbelly of the discipline. The operation within is not to argue that the current course of energy-based physics is “incorrect,” but rather that it is problematic both for reasons of cosmological compatibility and the social disharmony it has wrought.     

Quantum anomalous Hall effect

Hall efect is a well-known electromagnetic phenomenon that has been widely applied in the semiconductor industry.he quantum Hall efect discovered in two-dimensional electronic systems under a strong magnetic ield provided new insights into condensed mater physics,especially the topological aspect of electronic states.he quantum anomalous Hall efect is a special kind of the quantum Hall efect that occurs without a magnetic ield.It has long been sought ater because its realization will signiicantly facilitate the studies and applications of the quantum Hall physics.In this paper,we review how the idea of the quantum anomalous Hall efect was developed and how the efect was inally experimentally realized in thin ilms of a magnetically doped topological insulator.     

试析光机智能的语境瓶颈———基于诺尔蒂的量子光学计算机理论

诺尔蒂在《光速思考——新一代光计算机与人工智能》一书中,以量子计算和光学语言为基础,设想了量子计算机系统原理及新一代光电计算机发展远景,认为光机智能终将超越人类智能。文章从表征和计算的角度对这一系统设想进行了批判。     

Quantum simulation of particle pair creation near the event horizon

Though it is still a big challenge to unify general relativity and quantum mechanics in modern physics, the theory of quantum field related with the gravitational effect has been well developed and some striking phenomena are predicted, such as Hawking radiation. However, the direct measurement of these quantum effects under general relativity is far beyond present experiment techniques. Fortunately, the emulation of general relativity phenomena in the laboratory has become accessible in recent years. However, up to now, these simulations are limited either in classical regime or in flat space whereas quantum simulation related with general relativity is rarely involved. Here we propose and experimentally demonstrate a quantum evolution of fermions in close proximity to an artificial black hole on a photonic chip. We successfully observe the acceleration behavior, quantum creation, and evolution of a fermion pair near the event horizon: a single-photon wave packet with positive energy escapes from the black hole while negative energy is captured. Our extensible platform not only provides a route to access quantum effects related with general relativity, but also has the potentiality to investigate quantum gravity in future.     

计算机病毒及预防

随着计算机在社会生活各个领域的广泛运用,计算机病毒攻击与防范技术也在不断拓展。为了读者对病毒有个清楚的了解,首先介绍了计算机病毒的基本情况,阐述了计算机病毒的机理,并提出了计算机病毒的预防措施和清除办法。     

医学院校计算机应用基础课程教学改革探讨

随着计算机技术的发展,计算机已经普遍应用到社会各个领域,计算机基础课程成为了当今各高等院校必须开设的一门公共课。并且,计算机在医学界的应用也越来越重要,医学院校的学生掌握好最基本的计算机操作是势在必行。     

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.     

A direct measurement method of quantum relaxation time

The quantum relaxation time of electrons in condensed matters is an important physical property, but its direct measurement has been elusive for a century. Here, we report a breakthrough that allows direct determination of quantum relaxation time at zero and non-zero frequencies using optical measurement. Through dielectric loss function, we connect bound electron effects to the physical parameters of plasma resonance and find an extra term of quantum relaxation time from inelastic scattering between bound electrons and conduction electrons at non-zero frequencies. We demonstrate here that the frequency-dependent inelastic polarization effect of bound electrons is the dominant contribution to quantum relaxation time of conduction electrons at optical frequencies, and the elastic polarization effect of bound electrons also dramatically changes the plasma resonance frequency through effective screening to charge carriers.