气候系统和全球变暖——解读2021年诺贝尔物理奖

2021年诺贝尔物理学奖授予了两位气候学家和一位理论物理学家,以表彰他们在“理解复杂物理系统领域所做出的开创性贡献”.相信很多人会感到惊讶,为什么诺贝尔物理学奖授予了两位气候学家.本文将从以下几方面给予解读:为什么气候系统被称为复杂的物理系统,全球变暖的现状和未来,全球变暖的物理基础和科学简史,两位气候学家是如何基于基础物理理论建立了预测全球变暖的模型,以及检测和归因人类活动导致全球变暖的方法.     

从辐射对流平衡到全球气候模式——诺奖得主真锅淑郎工作解读

2021年诺贝尔物理学奖授予了两位气候学家和一位理论物理学家,以表彰他们在"理解复杂物理系统领域所做出的开创性贡献".文章主要介绍其中一位气候学家真锅淑郎(Syukuro Manabe)的工作.作为一个复杂物理系统,全球气候系统具有高度的复杂性,作为对这个复杂系统的高度近似,真锅淑郎的辐射对流平衡模型计算首次明确无误地...     

德默尔特和他的离子陷阱

 汉斯·德默尔特是美国西雅图市华盛顿大学物理系教授.由于他发明了用电磁陷阱捕捉质子、电子和离子的技术,并将这种技术应用于原子基本常数和光谱学的测量,瑞典皇家科学院授于他1989年诺贝尔物理学奖.同他一起获得1989年诺贝尔物理学奖的还有西德波恩大学教授沃尔夫冈·保罗,他主要的成就在于五十年代发明了使用六极磁场将原子束聚于一束射线的方法.另一位获奖的物理学家是美国哈佛大学的诺曼·拉姆齐教授,他的功绩在于发明了一种精确观察原子辐射和测量原子辐射的方法,这种方法构成了目前世界上使用的时间标准的基础.授奖委员会主席英瓦尔·林格伦说:“他们三人创造了准确的测量方注,由于有了这些方法才有可能进行某些实验,从而迫使人们考虑一些基本的物理定律,特别是关于时间和空间的定律”。他们的获奖充分证明了实验物理技术在科学研究中的重要地位。     

诺贝尔物理学奖110年知识竞答（Ⅳ）

在诺贝尔物理学奖颁发110年之际,《现代物理知识》编辑部举办＂诺贝尔物理学奖110年知识竞答＂活动,从2011年第3期起,杂志连续刊登竞答题目。本期为填字题,表格中每一行均对应一位1901年至2000年诺贝尔物理学奖得主的姓名。希望本刊的新老读者积极参与,请将问题答案寄到：北京918信箱《现代物理知识》编辑部（邮编：100049）,或发送电子邮件到mp@mail.ihep.ac.cn。答题同时,欢迎大家将自己在阅读诺贝尔物理学奖相关资料时的体会（如诺贝尔物理学奖获得者事迹对个人工作、学习上的激励,个人对某个获奖学科领域的了解、认识等）一并发来,本刊将择优刊登。     

诺贝尔物理学奖110 年知识竞答(Ⅲ)

 编者按：在诺贝尔物理学奖颁发110 年之际,《现代物理知识》编辑部举办“诺贝尔物理学奖110 年知识竞答”活动,从2011 年第3 期起,杂志连续刊登竞答题目。本期为是非题,要求在判断对错的同时,能指出错误并改正。希望本刊的新老读者积极参与,请将问题答案寄到：北京918 信箱《现代物理知识》编辑部(邮编：100049),或发送电子邮件到mp@mail.ihep.ac.cn。答题同时,欢迎大家将自己在阅读诺贝尔物理学奖相关资料时的体会(如诺贝尔物理学奖获得者事迹对个人工作、学习上的激励,个人对某个获奖学科领域的了解、认识等)一并发来,本刊将择优刊登。     

气候变化归因：应对气候变化的科学基础——从诺奖得主克劳斯·哈塞尔曼谈起

2021年诺贝尔物理学奖颁发给德国学者克劳斯·哈塞尔曼(Klaus Hasselmann)与另外两位科学家。克劳斯·哈塞尔曼是著名的海洋学家、气象和气候学家、物理学家。文章将简述哈塞尔曼的研究经历,介绍他在大气响应中的信噪比和气候变化归因的多模态指纹方法等方面的重要学术成就。还将结合最新的政府间气候变化专门委员会第六次评估报告中有关气候变化归因的主要结论,阐述在哈塞尔曼的开创性工作基础上建立起来的气候变化归因理论与方法,构成了人类合作应对气候变化的重要科学基础之一。     

百年诺贝尔物理学奖探析

分析了100年诺贝尔物理学奖的获奖项目和记录,由此阐述了物理学思想的内涵和可借鉴的研究方法,同时指出了评审诺贝尔物理学奖获奖项目的失误以及由此带来的遗憾.     

2014年度诺贝尔物理学奖获得者

<正>2014年诺贝尔物理学奖被授予日本科学家赤崎勇、天野浩和日裔美籍科学家中村修二,用以表彰这三位科学家在20世纪90年代分别独立在开发蓝光LED技术上的卓越贡献。诺贝尔奖委员会高度称赞了这三位科学家的研究成果,指出他们的发明具有巨大的意义,并强调诺贝尔奖的建立就是要奖励那些旨在造福人类福祉的科学家们。     

2018年度诺贝尔物理学奖揭晓

北京时间10月2日下午5点50分,2018年诺贝尔物理学奖揭晓。荣获此次殊荣的是:美国科学家亚瑟·阿什金(Arthur Ashkin)、法国科学家杰拉德·莫罗(Gerard Mourou),加拿大科学家唐娜·斯特里克兰(Donna Strickland)。三位物理学家因在激光物理研究领域的工作突出而获奖。     

诺贝尔物理学奖获得者中的父子

 诺贝尔物理学奖是诺贝尔奖最初设立的五大奖项之一。自1901年12月10日颁发第一届诺贝尔物理学奖以来,100多年中已有160多位物理学家获此殊荣。有趣的是,获奖者中竟有好几对父子。共享一届诺贝尔物理学奖的父子在这些获奖父子中,有一对是因为同一课题而共享殊荣的。他们就是英国的亨利·布拉格（SirWilliamHenryBragg,1862～1942）和他的儿子劳伦斯·布拉格（SirWilliamLawrenceBragg,1890～1971）,因创立极其重要的科学分支--X射线晶体结构分析,而分享1915年的诺贝尔物理学奖。亨利·布拉格,1862年7月3日出生在坎伯兰的威斯特瓦。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.