约里奥·居里夫妇获诺贝尔奖道路的启示

约里奥.居里夫妇因发现人工放射性物质而获1935年诺贝尔化学奖,但他们也一度错失了发现中子和正电子的良机.从约里奥.居里夫妇获诺贝尔奖的道路中,可以获得很多方法论意义上的启示:注重理论思维,重视学术交流的作用,对传统观念要有敢于质疑的精神,正确处理理论与实验的关系,重视实验手段的作用和有准备捕捉机遇的头脑.     

2014年诺贝尔物理学奖给我们的启示

2014年诺贝尔物理学奖授予高效蓝色发光二极管,这是一项具有重大经济和社会效益的技术发明。文章讨论该届诺贝尔物理学奖及获奖人的经历给我们的启示,包括三位诺贝尔奖获得者的洞察力以及持续多年围绕一个重大问题攻关的精神;结合中国科技界现状,本文将着重探讨评价重大科研成果的标准,以及日本科研模式和企业文化中可供国内科技工作者借鉴的积极因素。     

现代物理在中国

1998年 ,美籍华裔物理学家崔琦因其在八十年代初关于电流在强磁场中的量子效应的重大发现 ,获得了当年的诺贝尔物理学奖。这已是自 1 95 7年华人科学家杨振宁、李政道由于发现弱相互作用中宇称不守恒获得诺贝尔奖以来 ,第六位华人科学家获此殊荣了。其中 ,杨振宁、李振道在获诺贝尔奖时 ,尚未加入美国籍 ,所以至今诺贝尔基金会的记录仍然表明 ,有两位中国物理学家获得了诺贝尔奖。本世纪五十年代以来共有六位华人获诺贝尔奖这一事实不能不说是全体中国人 ,包括海外华人的极大骄傲 ,并引为自豪。因为他们的成功 ,终归与中华民族的文化教育传…     

近红外Ⅱ区荧光Ag2S量子点及其在活体影像中的应用

正当今生物医学的发展已由传统基于症状的治疗模式向以信息为依据的精准诊疗模式转变,医学影像技术是精准诊疗的重要工具,它的发展反映和引领着临床医学的进步。X射线的发现和计算机X射线断层技术(Computed Tomography, CT)的发明,分别获得1901年和1979年诺贝尔奖;1983年,核磁共振技术(MR)的发明也获得了诺贝尔奖。上述等影像技术可无创地实现体内病变组织的观察,为生物医学的研究及临床实践带来了全新性变革。尽管如此,目前的医学影像技术看到的大多是病变的     

物理学知识与诺贝尔生理学及医学奖

 世界医学界的最高奖项是诺贝尔生理学及医学奖．从１９０１年开始颁发诺贝尔奖以来,应用物理学知识（包括物理学的理论、技术和方法）于生理学及医学研究取得重要成果,从而荣获诺贝尔生理学及医学奖的,大约占该奖项总获奖数的１／５左右．而这其中有许多是物理学家获得的．下面是几个典型获奖事例．最早将物理学应用于医学而获诺贝尔奖的是丹麦医学家尼·吕·芬森．他利用光学原理研制出分光滤光聚光器,用以治疗皮肤结核等皮肤病,取得显著疗效,从而荣获１９０３年的诺贝尔生理学及医学奖,成为获得诺贝尔奖的第一位临床医生,并成为现代光线疗法的创始人．     

基于压电探测判定激光支持燃烧波和爆轰波的点燃阈值

为了获得激光支持燃烧波和爆轰波的点燃阈值,采用压电探测器检测波长为1 064 nm的Nd:YAG激光作用在铝靶表面所产生的应变和冲压。从实验结果观察到压电信号的变化分为3个阶段,分别为光热弹性应变阶段、等离子体增强耦合阶段和激光支持爆轰波对靶表面的压力阶段,并从理论上研究了这3个阶段的激光与靶材料相互作用的机理,从而可以从压电信号是否发生跃变判断出激光支持燃烧波和激光支持爆轰波的点燃阈值,与其它方法所得到结果基本吻合。     

基于压电探测判定激光支持燃烧波和爆轰波的点燃阈值

为了获得激光支持燃烧波和爆轰波的点燃阈值,采用压电探测器检测波长为1 064nm的Nd:YAG激光作用在铝靶表面所产生的应变和冲压。从实验结果观察到压电信号的变化分为3个阶段,分别为光热弹性应变阶段、等离子体增强耦合阶段和激光支持爆轰波对靶表面的压力阶段,并从理论上研究了这3个阶段的激光与靶材料相互作用的机理,从而可以从压电信号是否发生跃变判断出激光支持燃烧波和激光支持爆轰波的点燃阈值,与其它方法所得到结果基本吻合。     

Bi_2Sr_2Ca(Cu_(1-x)Zn_x)_2O_(8 δ)单晶体的扫描隧道显微谱

198 6年 ,ＩＢＭ苏黎世实验室的两位科学家因研制成功扫描隧道显微镜 (ＳＴＭ )而被授予诺贝尔奖 ;同年 ,同是这个实验室的Ｂｅｄｎｏｒｚ和Ｍ櫣ｌｌｅｒ发现了铜氧化物高温超导体 ,为此 ,他俩于次年也获得了诺贝尔奖 .最近 ,来自美国加州大学的Ｐａｎ等利用ＳＴＭ完成了一项有关高温超导机理的重要研究 .他们的研究对象是Ｚｎ掺杂Ｂｉ - 2 2 12单晶体 .通过拓扑成像和隧穿谱的测量 ,研究者们发现 :在杂质原子Ｚｎ格点的周围存在“十字样”的局域杂质态———这是该效应被预言以来首次获得的实验观察 .尽管高温超导体的组分、结构复杂多样 ,…     

物理学知识与诺贝尔生理学及医学奖

世界医学界的最高奖项是诺贝尔生理学及医学奖．从１９０１年开始颁发诺贝尔奖以来，应用物理学知识（包括物理学的理论、技术和方法）于生理学及医学研究取得重要成果，从而荣获诺贝尔生理学及医学奖的，大约占该奖项总获奖数的１／５左右．而这其中有许多是物理学家获得的．下面是几个典型获奖事例． 最早将物理学应用于医学而获诺贝尔奖的是丹麦医学家尼·吕·芬森．他利用光学原理研制出分光滤光聚光器，用以治疗皮肤结核等皮肤病，取得显著疗效，从而荣获１９０３年的诺贝尔生理学及医学奖，成为获得诺贝尔奖的第一位临床医生，并成为…     

巴黎高等物理化学学院的精英人才培养模式与物理类课程设计

巴黎高等物理化学学院是法国培养物理、化学和生物学专业研究型精英人才的高等学府,并因居里夫妇等多位获得诺贝尔奖的著名科学家曾工作于此而闻名于世。本文介绍了巴黎高等物理化学学院的发展历程与科学文化的传承,理工结合的课程设计与精英人才培养模式,及其理论与实验并重、跨学科、小规模和高质量的办学特色。在新工科建设人才培养模式的探索与改革中,高校要突破原来的学科界限与产业划分,培养跨学科的创新型人才。巴黎高等物理化学学院的优质教育资源、先进的工程教育理念、特色的课程体系和教学方法,对培养创新工程人才具有启示意义。     

A new layered space--time detection algorithm for frequency selective fading multiple-input multiple-output channels based on particle filter

In this paper, a new observation equation of non-Gaussian frequency selective fading Bell Labs layered space time (BLAST) architecture system is proposed, which is used for frequency selective fading channels and non-Gaussian noise in an application environment of BLAST system. With othogonal matrix triangularization (QR decomposition) of the channel matrix, the static observation equation of frequency selective fading BLAST system is transformed into a dynamic state space model, and then the particle filter is used for space--time layered detection. Making the full use of the finite alphabet of the digital modulation communication signal, the optimal proposal distribution can be chosen to produce particle and update the weight. Incorporated with current method of reducing error propagation, a new space--time layered detection algorithm is proposed. Simulation result shows the validity of the proposed algorithm.     

Photoelectron diffraction: from phenomenological demonstration to practical tool

The potential of photoelectron diffraction—exploiting the coherent interference of directly-emitted and elastically scattered components of the photoelectron wavefield emitted from a core level of a surface atom to obtain structural information—was first appreciated in the 1970s. The first demonstrations of the effect were published towards the end of that decade, but the method has now entered the mainstream armoury of surface structure determination. This short review has two objectives: First, to outline the way that the idea emerged and the way this evolved in my own collaboration with Neville Smith and his colleagues at Bell Labs in the early years: Second, to provide some insight into the current state-of-the art in application of (scanned-energy mode) photoelectron diffraction to address two key issue in quantitative surface structure determination, namely, complexity and precision. In this regard a particularly powerful aspect of photoelectron diffraction is its elemental and chemical-state specificity.     

Excitons in GaAs quantum wells

This paper attempts to summarize some of the salient properties of excitons in GaAs quantum wells and in doing so it will emphasize work at AT&T Bell Labs with which the authors have been associated. Although the text relies heavily on published material, an effort has been made to stress new material, and where feasible, unpublished aspects, e.g., figures, related to earlier work. Topics discussed on the quasi-2D excitons in GaAs quantum well include: their inherent tendency for intrinsic free-exciton emission, exciton binding energies, bound and localized excitons including biexcitons and excitons bound to neutral impurities, effects of n- and p-type modulation and antimodulation doping, and the developments leading to a proposed set of quantum well parameters that results in acceptable fits to the observed exciton transitions for GaAs quantum wells with both square and parabolic potential profiles.     

Quantum teleportation of a polarization state with a complete bell state measurement

We report a quantum teleportation experiment in which nonlinear interactions are used for the Bell state measurements. The experimental results demonstrate the working principle of irreversibly teleporting an unknown arbitrary polarization state from one system to another distant system by disassembling into and then later reconstructing from purely classical information and nonclassical EPR correlations. The distinct feature of this experiment is that all four Bell states can be distinguished in the Bell state measurement. Teleportation of a polarization state can thus occur with certainty in principle.     

Static and tunable dispersion management with higher order mode fibers

Few mode fibers have recently attracted a lot of attention, because of the prospect of enhanced design flexibility, unique modal properties, and the existence of several simultaneous light-paths in them. After the pioneering experiments by Craig Poole from Bell Labs in 1993, an application that faded away but saw a re-emergence in 2000-2003 was higher order mode dispersion compensation. In this scheme, mode converters are used to selectively propagate the signal in a higher order mode of a few-mode fiber. Demonstrations over the last few years have shown that this novel technology can provide several benefits over the conventional dispersion compensating fiber, such as lower nonlinearity, higher dispersions, potentially lower loss, and most interestingly, a format to realize tunable dispersion compensation devices. It also has attendant trade-offs arising from the need to manage modal interference, and a complex architecture that may make it more costly. This talk will review the physics and technology of the higher order mode dispersion compensator and discuss its future directions.     

Reliable teleportation in trapped ions

We study a method for the implementation of a reliable teleportation protocol (theoretically, 100% of success) of internal states in trapped ions. The generation of the quantum channel (any of four Bell states) may be done respecting technical limitations on individual addressing and without claiming the Lamb-Dicke regime. An adequate Bell analyzer, that transforms unitarily the Bell basis into a completely disentangled one, is considered. Probable sources of error and fidelity estimations of the teleportation process are studied. Finally, we discuss experimental issues, proposing a scenario in which the present scheme could be implemented. Received 1st June 2000 and Received in final form 17 August 2000     

Testing the structure of multipartite entanglement with Bell inequalities

We show that the rich structure of multipartite entanglement can be tested following a device-independent approach. Specifically we present Bell inequalities for distinguishing between different types of multipartite entanglement, without placing any assumptions on the measurement devices used in the protocol, in contrast with usual entanglement witnesses. We first address the case of three qubits and present Bell inequalities that can be violated by W states but not by Greenberger-Horne-Zeilinger states, and vice versa. Next, we devise 'subcorrelation Bell inequalities' for any number of parties, which can provably not be violated by a broad class of multipartite entangled states (generalizations of Greenberger-Horne-Zeilinger states), but for which violations can be obtained for W states. Our results give insight into the nonlocality of W states. The simplicity and robustness of our tests make them appealing for experiments.     

Orbital entanglement and violation of Bell inequalities in mesoscopic conductors

We propose a spin-independent scheme to generate and detect two-particle entanglement in a mesoscopic normal-superconductor system. A superconductor, weakly coupled to the normal conductor, generates an orbitally entangled state by injecting pairs of electrons into different leads of the normal conductor. The entanglement is detected via violation of a Bell inequality, formulated in terms of zero-frequency current cross correlators. It is shown that the Bell inequality can be violated for arbitrary strong dephasing in the normal conductor.     

Preparation of bell states with controlled white noise

We report two methods for producing Bell States with an arbitrary amount of white noise. White noise in this context refers to controlled admixtures of unpolarized light. Our methods differ from previous experiments in that we use the minimum necessary elements for generating a Bell state by c-w spontaneous parametric down conversion. We also investigated the spectral properties of a mixed state and show that one of our methods introduces irreversible noise into the Bell state, making a permanent mixed state.     

Deterministic nondestructive state analysis for polarization-spatial-time-bin hyperentanglement with cross-Kerr nonlinearity

We present a deterministic nondestructive hyperentangled Bell state analysis protocol for photons entangled in three degrees of freedom(DOFs),including polarization,spatial-mode,and time-bin DOFs.The polarization Bell state analyzer and spatial-mode Bell state analyzer are constructed by polarization parity-check quantum nondemolition detector(P-QND)and spatial-mode parity-check quantum nondemolition detector(S-QND)using cross-Kerr nonlinearity,respectively.The time-bin Bell state analyzer is constructed by the swap gate for polarization state and time-bin state of a photon(P-T swap gate)and P-QND.The Bell states analyzer for one DOF will not destruct the Bell states of other two DOFs,so the polarization-spatial-time-bin hyperentangled Bell states can be determinately distinguished without destruction.This deterministic nondestructive state analysis method has useful applications in quantum information protocols.