《对玻恩及其学派的系列研究》连载(14)——哪位物理学家首先提出了可观察性原则?

物理学家和科学史家都认为,可观察性原则对于量子力学的建立非常重要.1925年海森伯的"一人文章"发表后,很多与量子力学史相关的著述都认为,可观察性原则由海森伯提出.事实上他不是第一个提出可观察性原则的物理学家.马克斯·玻恩在1920年出版的著作中对这一思想即有描述,1919至1920年间在法兰克福大学任教授时,他还曾多次向朗德表述这一思想.很多文献证据表明,海森伯是在哥廷根,直接从玻恩这里了解到可观察性原则的.     

走向统一的自然力 强力、弱力和电磁力的大统一(Ⅱ)

<正>(2)量子力学1923年,德布罗意提出物质波假说,随后,人们通过实验发现:一束粒子流穿过晶体后能像光一样产生干涉和衍射现象,从而认识到一切微观客体(包括光子在内)都同时具有粒子性和波动性,即所谓"波粒二象性",在此基础上,薛定谔于1926年建立了波动力学;稍前,海森伯从玻尔的对应原理出发提出了矩阵力学的概念,之后,薛定谔证明波动力学和矩阵力学在数学上是等价的;1926年,玻恩对德布罗意物质波提出了统计解释,这样,描述微观客体运动规律的量子力学便在量子论的基础上完善地建立起来了。     

可观察性原则起源考

量子力学是20世纪最伟大的科学贡献;量子力学也是20世纪对人类文明影响最大的科学理论.但是对于有的量子力学重要思想的起源还存在混乱的认识.可观察性原则是建立量子力学时的一个重要的思想方法.对于其起源有多种说法.通过分析充分可靠的文献资料,得出的结论是:所谓海森伯的可观察性原则,直接来自于玻恩及其哥廷根物理学派的影响,玻恩是早于海森伯明确表述这一思想原则的人.     

海森伯矩阵力学

重述了矩阵力学的理论框架,包括位置动量不对易关系,算符的海森伯运动方程,非简并微扰论,给出了一维谐振子的矩阵力学求解过程.     

邮票上的物理学史“非汉字符号”——量子力学的建立(续)

矩阵力学和波动力学都是关于微观运动的理论 ,概括的是相同的经验领域 ,但是在外观上却显得如此不同 .波动力学使用的微分方程这一数学工具更为物理学家所熟悉 ,并且易于用来解决各种问题 ,这就使它更广泛地被接受 ,也成为讲授量子力学的主要形式 .它具有一种“连续的、经典的”外貌 ,以波为基本概念 .矩阵力学则相反 ,它的数学工具是代数 ,强调的是不连续性 ,尽管它否认轨道 ,它的基本概念是粒子 .讲量子力学创立史不能忘记泡利的贡献 (图 6 ,奥地利 1 983年 ,逝世 2 5年 ;图 7,圣文森及格林纳丁斯1 995年 ) .海森伯 1 92 5年摸索着建立量…     

《对玻恩及其学派的系列研究》连载⑧——玻恩对弟子杨立铭研究工作的高度评价

杨立铭是玻恩培养的第三个中国物理博士,也是他培养的最后一位中国学生.1950年至1951年,玻恩在写给一些重要物理学家(如玻尔、海森伯、费米、魏格纳、约当等人)以及写给一些重要期刊的信函中,高度评价杨立铭当时的研究成果.阅读这些信函,可以感觉到玻恩培养学生的强烈责任心以及那份对中国弟子的欣赏与喜爱.这些以前不为世人所知晓的信函,是中国物理学与世界接轨的宝贵、动人的文献,需要中国物理学史研究者进一步深入研究,需要更多中国物理界人士了解并关注.     

狄拉克获诺贝尔奖的经过

 20世纪物理学的第一位巨人当然是爱因斯坦。但谁是第二位,谁又是第三位呢?这个问题的答案就因人而异。扬振宁先生在一次演讲中曾经说过,他最佩服的3位当代物理学家,是爱因斯坦,费米和狄拉克。杨先生说,狄拉克解决问题的方法像是神来之笔,读狄拉克的论述有秋水文章不染尘的感觉。我们想在这里来说说狄拉克获诺贝尔物理奖的事.20世纪20年代中期参与量子力学建立的,主要是格丁根学派的玻恩、海森伯和约尔丹,剑桥的狄拉克,法国的德布罗意和奥地利的薛定谔。1924年玻恩意识到需要有一种新的数学规则来从经典力学过渡到量子力学。     

封面说明

量子力学是微观世界的基本物理规律.同爱因斯坦独力创立相对论不同,量子力学是由许多物理学家在不同的地方、从不同的角度、按不同的思路建立起来的,整个建立过程延续了好几年时间.其中最重大的两步是海森伯于1925年建立矩阵力学和薛定谔于1926年建立波动力学.鉴于波动力学是量     

《对玻恩及其学派的系列研究》连载②——玻恩如何培育物理英才?(下)

<正>3作为伯乐的玻恩除了正常的教学与学术研讨外,玻恩还是一位出色的善于识别千里马的伯乐,他能够发现年轻人的长处并因材施教,对不同的年轻人给出有价值的不同忠告.朗德、伦敦、迈耶夫人、奥本海默、德尔布吕克、海森伯等等都得到过玻恩的特殊帮助.我们仅举几例说明玻恩如何栽培、提携和指点年轻的物理学子.3.1朗德(Alfred Landé)1962年3月朗德对库恩等人说,他参加了玻恩教师生涯的第一门课,他回忆说:"很显然他对     

《对玻恩及其学派的系列研究》连载⑥——玻恩与爱因斯坦之间的深厚友谊

相对论和量子力学是20世纪物理学的核心贡献.相对论几乎由爱因斯坦一个人缔造,而量子力学的最早形式——矩阵力学则是玻恩率领众弟子共同创造.玻恩与爱因斯坦是终生好友,深入了解他们之间的交往、他们之间的友谊、他们之间的学术争论,今天的人们从中仍然能受到很好的教育.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.