Can a quantum measurement be cancelled in a very short period of time
用初中英语简要介绍双缝实验
用初中英语简要介绍双缝实验The Double-Slit ExperimentThe double-slit experiment is a fundamental experiment in quantum mechanics that demonstrates the wave-particle duality of light and other quantum particles. It was first performed by the English physicist Thomas Young in 1801, and it has since become one of the most famous experiments in the history of science.The basic setup of the double-slit experiment is as follows. A source of light, such as a laser or a monochromatic light source, is directed towards a barrier that has two narrow slits cut in it. The light passing through the slits is then projected onto a screen or a detector. When the light passes through the two slits, it creates an interference pattern on the screen, with alternating bright and dark regions.This interference pattern is a clear demonstration of the wave-like nature of light. If light were simply a stream of particles, one would expect to see two separate bright spots on the screen, corresponding to the two slits. However, the interference pattern shows that the light is behaving like a wave, with the waves from the two slits interfering with each other.The double-slit experiment can also be performed with other quantum particles, such as electrons or atoms. When these particles are directed towards the double slit, they also exhibit an interference pattern, indicating that they too have a wave-like nature.The wave-particle duality of quantum particles is a fundamental concept in quantum mechanics. It means that particles can exhibit both wave-like and particle-like properties, depending on the experiment being performed. This is a departure from the classical view of the world, where objects were either waves or particles, but not both.The double-slit experiment has been used to demonstrate the wave-particle duality of various quantum particles, including electrons, neutrons, atoms, and even large molecules. In each case, the interference pattern observed on the screen is a clear indication of the wave-like nature of the particles.One of the most interesting aspects of the double-slit experiment is the role of the observer. When the experiment is set up to detect which slit the particle goes through, the interference pattern disappears, and the particles behave like classical particles. This suggests that the act of measurement or observation can affect the behavior of quantum particles.This is a concept known as the "observer effect" in quantum mechanics, and it has profound implications for our understanding of the nature of reality. It suggests that the very act of observing or measuring a quantum system can alter its behavior, and that the observer is not a passive participant in the experiment.The double-slit experiment has also been used to explore the concept of quantum entanglement, which is another fundamental concept in quantum mechanics. Quantum entanglement occurs when two or more quantum particles become "entangled" with each other, such that the state of one particle is dependent on the state of the other.In the double-slit experiment, the interference pattern can be used to demonstrate the phenomenon of quantum entanglement. For example, if two particles are entangled and then directed towards the double slit, the interference pattern observed on the screen will depend on the state of the entangled particles.Overall, the double-slit experiment is a powerful and versatile tool for exploring the fundamental nature of reality at the quantum level. It has been used to demonstrate the wave-particle duality of light and other quantum particles, the observer effect, and the phenomenon of quantum entanglement. As such, it remains one ofthe most important and influential experiments in the history of science.。
外国教材量子力学概论2ndedition课后练习题含答案
Introduction to Quantum MechanicsOverviewQuantum Mechanics is a branch of Physics that describes the behavior of matter and energy at a microscopic level. This discipline has had a significant impact on modern science and technology, and its principles have been applied to the development of various fields, such as computing, cryptography and medicine. The study of Quantum Mechanics requires a basic understanding of the principles of Mathematics and Physics. The m of this document is to provide an introduction to Quantum Mechanics and to provide a set of practice exercises with answers that will allow students to test their knowledge and understanding of the subject.Fundamental PrinciplesThe fundamental principles of Quantum Mechanics are based on the concept of a wave-particle duality, which means that particles can behave as both waves and particles simultaneously. The behavior of particles at the microscopic level is probabilistic, and it is described by a wave function. A wave function is a complex function that describes the probability of finding a particle at a givenlocation. The square of the amplitude of the wave function gives the probability density of finding the particle at that point in space. The wave function can be used to calculate various physical quantities, such as the position, momentum and energy of a particle.Operators and ObservablesIn Quantum Mechanics, physical quantities are represented by operators. An operator is a mathematical function that acts on a wave function and generates a new wave function as a result. Operators are used to represent physical observables, such as the position, momentum and energy of a particle. The eigenvalues of an operator correspond to the possible results of a measurement of the corresponding observable. The eigenvectors of an operator correspond to the possible states of a particle. The state of a particle is described by a linear combination of its eigenvectors, which is called a superposition.Schrödinger EquationThe Schrödinger Equation is a mathematical equation that describes the time evolution of a wave function. It is based on the principle of conservation of energy, and it representsthe motion of a quantum system in terms of its wave function. The equation is given by:$$\\hat{H}\\Psi=E\\Psi$$where $\\hat{H}$ is the Hamiltonian operator, $\\Psi$ is the wave function, and E is the energy of the system. The Schrödinger Equation is the foundation of Quantum Mechanics, and it is used to calculate various physical properties of a particle, such as its energy and momentum.Practice Exercises1.Calculate the wave function for a particle that isin a 1D box of length L.–Answer: The wave function for a particle in a 1D box is given by:$$\\Psi(x)=\\sqrt{\\frac{2}{L}}\\sin{\\frac{n\\pi x}{L}}$$where n is a positive integer.2.Derive the time-dependent Schrödinger Equation.–Answer: The time-dependent SchrödingerEquation is given by:$$i\\hbar\\frac{\\partial\\Psi}{\\partialt}=\\hat{H}\\Psi$$3.Calculate the momentum operator for a particle in1D.–Answer: The momentum operator for a particle in 1D is given by:$$\\hat{p_x}=-i\\hbar\\frac{\\partial}{\\partial x}$$4.What is the uncertnty principle?–Answer: The uncertnty principle is afundamental principle of Quantum Mechanics thatstates that the position and momentum of a particlecannot be measured simultaneously with arbitraryprecision. Mathematically, it is given by: $$\\Delta x\\Delta p_x\\geq\\frac{\\hbar}{2}$$5.Calculate the energy of a particle in a 1D box oflength L with quantum number n.–Answer: The energy of a particle in a 1D box is given by:$$E_n=\\frac{n^2\\pi^2\\hbar^2}{2mL^2}$$ConclusionQuantum Mechanics is a fascinating and challenging fieldof study that has provided a deeper understanding of the behavior of matter and energy at the microscopic level. Theprinciples of Quantum Mechanics have been applied to various fields of study, including computing, cryptography and medicine, and they have contributed to significant advances in these fields. The practice exercises provided in this document are intended as a tool for students to test their knowledge and understanding of Quantum Mechanics. By solving these exercises, students will gn a deeper understanding of the fundamental principles of Quantum Mechanics and strengthen their problem-solving skills in this exciting field of study.。
汉译英_高级职称
The mistake escaped my notice.
9.只有在显微镜下才能看见红血球。
A microscope is needed (for us) to see red cells.
10.2000年奥运会将在悉尼举行。
Sydneywill host (be the host city for) the 2000 Olympic Games.
After a careful check of the blueprint, they made comments on his design.
6.据说在质量方面这种仪器是优越的。
It is said that this instrument is high in quality.
2.不同国家的社会习俗往往大相径庭。
Social customs are usually different from country to country.
3.我们应该尽我们最大的努力防止这类事故再次发生。
We should do our best to prevent this kind of accident from happening again.
At the end of this century, the world population will be over six billion.
2.去年，这个国家的工农业总产值为两千亿美元。
Last year, the general output value of industry and agriculture of this country was two hundred billion dollars.
measurement science and technology写作要求
Measurement Science and TechnologyIntroductionMeasurement science and technology play a crucial role in various fields, ranging from industry to healthcare. Accurate and reliable measurements are essential for ensuring quality, improving efficiency, and advancing scientific knowledge. In this article, we will explore the importance of measurement science and technology, discuss its applications, and highlight the advancements in this field.The Importance of Measurement Science and TechnologyEnsuring Accuracy and ReliabilityAccurate measurements are fundamental for obtaining reliable data. Measurement science and technology provide the tools and techniques necessary to ensure the accuracy of measurements. Calibration, for instance, is a process used to establish the accuracy of measurement instruments. By calibrating instruments regularly, errors can be minimized, and measurement results can be trusted.Quality Control and AssuranceMany industries rely on measurement science and technology to maintain quality standards. For example, in manufacturing processes, precise measurements are essential to ensure that products meet specifications. By implementing robust measurement techniques and technologies, companies can identify and correct any variations in their production processes, leading to improved quality control and assurance.Advancing Scientific KnowledgeMeasurement science and technology contribute to the advancement of scientific knowledge. Researchers use precise and accurate measurements to gather data and validate hypotheses. By leveraging advancedmeasurement techniques, scientists can investigate phenomena, develop theories, and contribute to the understanding of various scientific disciplines.Applications of Measurement Science and TechnologyHealthcareIn the field of healthcare, measurement science and technology arecrucial for accurate diagnosis, monitoring patient conditions, and developing new treatments. From blood pressure monitors to MRI machines, precise measurements enable physicians to make informed decisions,detect diseases, and track the effectiveness of treatments. Additionally, medical researchers rely on measurement science to conduct clinicaltrials and gather essential data for the development of new drugs and therapies.Environmental MonitoringMeasurement science and technology play a vital role in environmental monitoring and conservation efforts. Monitoring instruments, such as air quality sensors and water quality analyzers, provide valuable data for assessing the impact of human activities on the environment. Accurate measurements help identify pollution sources, track changes over time, and guide policies aimed at reducing environmental degradation.Energy SectorIn the energy sector, measurement science and technology are crucial for optimizing energy production, improving efficiency, and ensuring safety. Precise measurements help operators monitor power generation, detect equipment failures, and identify potential risks. Moreover, advanced measurement techniques enable the development and implementation of renewable energy sources, such as solar and wind power, by accurately measuring their performance and efficiency.NanotechnologyNanotechnology, which deals with materials and structures at the nanoscale, heavily relies on precise measurements. Scientists and engineers use advanced measurement techniques to characterize nanomaterials, analyze their properties, and design innovative nanodevices. Measurements at the nanoscale are essential for understanding quantum phenomena, developing nanomedicine, and creating new materials with improved properties.Advancements in Measurement Science and TechnologyBig Data AnalyticsThe rapid advancements in computing power and data storage have revolutionized measurement science and technology. Big data analytics allows for the processing and analysis of large datasets, enabling researchers to extract valuable insights and patterns that were previously unattainable. By merging data from various sources,scientists can gain a comprehensive understanding of complex systems and improve measurement accuracy.Internet of Things (IoT) and Sensor TechnologyThe proliferation of IoT devices and sensor technology has significantly impacted measurement science and technology. These devices, equippedwith sensors, enable the collection of real-time data, remote monitoring, and automation. In various domains, such as healthcare, environmental monitoring, and industrial processes, IoT and sensor technology have improved measurement accuracy, efficiency, and reliability.Metrology and Standards DevelopmentMetrology, the science of measurement, is continuously evolving to meet the demands of modern technology and industry. Advancements in metrology techniques, such as laser interferometry and atomic force microscopy, have significantly improved measurement accuracy at various scales. Standards development also plays a crucial role in measurement scienceand technology by ensuring interoperability, comparability, and consistency of measurements across different sectors and countries.Quantum MetrologyQuantum metrology, a branch of measurement science, exploits principles from quantum physics to enhance measurement precision. Quantum technologies, such as atomic clocks and quantum sensors, offer significantly higher accuracy compared to traditional measurement methods. Quantum metrology has the potential to revolutionize fields such as navigation, communications, and fundamental physics research.ConclusionMeasurement science and technology are indispensable for accurate, reliable, and meaningful measurements in various fields. From healthcare to environmental monitoring, accurate measurements are essential for quality control, advancing scientific knowledge, and driving innovation. With advancements in big data analytics, IoT, metrology, and quantum technologies, measurement science and technology continue to evolve and shape the world around us.。
怀念鲁润宝同志纪念鲁润宝先生逝世一周年-CiteSeerX
怀念鲁润宝同志在鲁润宝同志辞世2周年之际，鲁润宝先生的夫人（阎永勤）和他的孩子（鲁东宇）编纂出版了“鲁润宝文集”。
陈能宽先生还特地题写了书名。
谨将此书序言以及其中7篇英文文献转载于此，以誌纪念。
（李兴中，2010-10-25）纪念鲁润宝先生逝世一周年（代序言）鲁润宝先生，我的老朋友，你与世长辞已近一年了，你那微胖憨厚的形象一直留在我的脑海之中，你那刻苦钻研的精神永远使我钦佩。
回顾1990年前后，由于“冷聚变”科学问题的研讨，彼此相遇，结交为朋友，随着岁月的增长，我们由相识到相知，建立了深厚的友谊。
你从核物理、理论物理转向“冷聚变”研究，一开始就遇到很多困难，自然科学基金的申请又遭遇挫折，心里着急，也有怨气，但你那执着的劲头却令人感动。
我作为科技管理人员只能在一旁相劝。
因为“冷聚变”项目实属非共识有争议的项目，虽然蕴藏着大的创新，但从非共识到共识需要长期的争论。
而学术问题只能靠学术研究来判断，不能靠行政干预来解决。
因此我建议你最好继续做工作，争取在学术会议和学术刊物上多发表论文，让学术界了解和评议。
你努力工作，陆续发表了一些文章，尤其是1994年，提出了一种新的物理过程“电子——离子束缚态及其引发的核过程”，即“束缚态理论模型”的假说，并概述了这一新物理过程的特点，这是十分值得庆贺的进展。
不管这模型会引来什么样的争议，这种大胆创新的精神值得敬佩。
经过鍥而不舍的努力，查阅了各种文献资料，力图从不同领域中寻找能够支持这个假说的证据。
当你获得某点可能的佐证时，都兴奋地告诉我，我分享着你来之不易的喜悦。
后来，工作局面逐步打开，得到了一定的支持，工作条件获得改善，退休后你继续拼搏，单位也给予少量的但很珍贵的经费，保证了参加学术会议和查阅资料的费用。
你的夫人包揽了一切家务，让你能专心致志，集中精力于工作之中。
更多的刊物接受了你的稿件，在一些学术研讨会中，一些学者对你的新物理过程也甚感兴趣，论文被收入《21世纪100个交叉科学难题》专辑，还参加了2008年中国科协学会组织的新观点、新学说的学术沙龙，并作了三个专题报告。
量子力学英文介绍
量子力学英文介绍Quantum mechanics, also known as quantum physics, is a branch of theoretical physics that describes the behavior of matter and energy at the smallest scales, including subatomic particles like electrons and photons. It is an incredibly complex and counterintuitive theory, but also one of the most successful scientific theories ever developed.Step 1: The Beginnings of Quantum MechanicsQuantum mechanics originated in the early 20th century, primarily through the work of physicists Max Planck, Albert Einstein, Niels Bohr, Werner Heisenberg, and ErwinSchrödinger. Their investigations into the behavior of light and matter led them to develop a new set of mathematical equations that governed the behavior of subatomic particles.Step 2: The Weirdness of Quantum MechanicsQuantum mechanics has a number of strange and seemingly paradoxical features that make it hard to wrap one's head around. For example, particles at the quantum level do not have a definite location until they are measured, and they can exist in multiple states at once. Quantum mechanics also introduced the concept of entanglement, in which particles can become "entangled" so that a measurement of one particle can instantly affect the state of the other, even if they are separated by vast distances.Step 3: Applications of Quantum MechanicsDespite its weirdness, quantum mechanics has a wide range of practical applications. One of the most notable is the development of the transistor, which is a crucialcomponent in modern electronic devices like computers and smartphones. Quantum mechanics also plays a role in materials science, cryptography, and quantum computing, which has the potential to revolutionize computation.Step 4: Current Research in Quantum MechanicsQuantum mechanics continues to be an active area of research and discovery. Areas of current interest include quantum entanglement and teleportation, the development of more efficient quantum algorithms, and exploring the possibilities of quantum computing. Researchers are also investigating the relationship between quantum mechanics and general relativity, the other pillar of modern physics.In conclusion, quantum mechanics is a fascinating and important theory that has revolutionized our understanding of the universe. It has many practical applications and continues to inspire new discoveries and innovations. While its weirdness and complexity can be daunting, it is well worth the effort to understand and appreciate this amazing theory.。
英文版原子物理课件
Bohr Model
Summary: The quantum mechanical model is the most accurate representation of atomic structure and behavior It uses quantum theory to describe the behavior of electrons in atoms
01
Balmer series is a group of spectral lines observed in the spectrum of hydrogen atoms
02
It is named after the Swiss mathematical Jakob Balmer who discovered the series in 1885
03
The Palmer series insists of spectral lines excited by transitions between different energy levels of the hydrogen atom
04
The Balmer series is important in atomic physics as it provides a simple example of quantum mechanical transitions in atoms
03
Atomic Models
The Rutherford model, also known as the planetary model, accounts that the atom constitutions of a positively charged nucleus orbited by negatively charged electrons
第一章 量子力学基础课后习题中英文
第一章量子力学基础第八组：070601337刘婷婷070601339黄丽英070601340李丽芳070601341林丽云070601350陈辉辉070601351唐枋北【1．1】经典物理学在研究黑体辐射、光电效应与氢光谱时遇到了哪些困难？什么叫旧量子论？如何评价旧量子论？【Q1.1】What are the difficulties in the study of blackbody radiation, photoelectric effect and hydrogen spectrum in Classical physics? What is the old quantum theory? How to assess the old quantum theory?解：困难：（1）黑体辐射问题。
黑体就是理论上不反射任何电磁波的物体，黑体辐射是指这类物体的电磁波辐射，由于这类物体不反射,所以由它释放出来的电磁波都来自辐射，实验中在不同的能量区间对黑体辐射规律给出了不同的函数，然而这两个函数无法兼容，是完全不同的，而事实上黑体辐射本该遵循某个唯一的规律。
况且经典理论还无法说明这两个函数中的任意一个.这个问题研究的是辐射与周围物体处于平衡状态时的能量按波长（或频率）的分布。
实验得出的结论是：热平衡时辐射能量密度按波长分布的曲线，其形状和位置只与黑体的绝对温度有关，而与空腔的形状及组成的物质无关。
这一结果用经典理论无法解释。
（2）光电效应。
光照射到金属上时，有电子从金属中逸出。
实验得出的光电效应的有关规律同样用经典理论无法解释。
（3）按照经典电动力学，由于核外电子作加速运动，原子必然坍缩。
经典物理学不能解释原子的稳定性问题。
原子光谱是线状结构的，而按照经典电动力学，作加速运动的电子所辐射的电磁波的频率是连续分布的，这与原子光谱的线状分布不符。
Solution：Difficulties: (1) the problem of blackbody radiation. Blackbody is the objects that can’t reflect electromagnetic waves in theory . And the blackbody radiation is the electromagnetic radiation of such objects. Since these objects can notreflect , the ele- ctromagnetic waves they give off are all from radiation. There aretwo functions in different energy ranges about the blackbody radiation law in experiments .But they can not be compatible. They are completely different. But in fact, blackbody radiation would have followed an unique law. Moreover, the classical theory also can not account for any of these two functions. This issue studies that radiation’s and the surrounding objects’ energy according to wavelength (or frequency) distribution in equilibrium state. The experiments concluded that: the curve’s shape and position that radiation energy densities are distributed according to the wavelength when the system is in thermal equilibrium only apply to the absolute temperature of blackbody, however have nothing to do with the cavity shape and composition of the material. This result can not be explained with classical theory.(2) Photoelectric effect. When light shines on metal, there is electrons escaping from the metal. The laws on the photoelectric effect according to the experiments can not be explained with classical theory too. (3) According to classical electrodynamics, the atoms are bound to collapse because of accelerated motion of extra nuclear electrons. Classical physics can not explain the stability of the atom. The structure of atomic spectrum is linear.However,according to classical electrodynamics, the frequencies of electromagnetic waves which are distributed by the accelerating atoms are continuous, which is inconsistent with the linear spectrum.定义：从1900年普朗克提出振子能量量子化开始，人们力图以某些物理量必须量子化的假定来修正经典力学，用于解释某些宏观现象，并且给出其微观机制。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
(1)
and we can deduce, in the usual way, that measurement of even one of these observables projects both particles into two definite unentangled states, and measurements can be made which will confirm, for instance, the correlations between them. Suppose instead that we measured σA θ ⊗ σB
with respect to z-direction eigenstates, and that, first, both are measured in the zdirection, and then, second, a measurement is made of the observables in (1) using the x-direction. If the first measurement is of the observables (1), the system is projected into one of the states |i, j with probabilities |αij |2 , and if both particles are then measured in the x-direction, each x-eigenstate is obtained with equal probability, and so in an ensemble of the two successive measurements there will be equal probability for each of the four outcomes at the end of the second measurement. But if the first measurement (in the z-direction) is of the observable in (2), then the system is projected into one of the states 1 1 {α1−1 |1, −1 + α−11 |−1, 1 } √ {α11 |1, 1 + α−1−1 |−1, −1 } , √ p1 p− 1 where p1 , p2 are the respective probabilities, given by p1 = | α11 | 2 + | α−1−1 | 2 , p−1 = | α1−1 | 2 + | α−11 |
φ
(2)
This observable represents (as it indicates) the product of the individual particles’ outcomes, and, if the outcomes are treated as ±1, can be regarded as measuring whether their results are the same (eigenvalue +1) or opposite (eigenvalue −1). If a measurement is made, choosing either the observables (1) or the observable (2), the results are compatible, in that the probabilities of getting the results “same” or “opposite” are the same. But if two successive such measurements are made at different angles, incompatible results can be obtained1 . For example, suppose the two particles are initially in the (normalized) sij |i, j
(3)
e-mail: roger.schafir@ This was brought to my attention by G. Adenier [1], though Adenier argued for a viewpoint which is not adopted here.
Can a quantum measurement be cancelled in a very short period of time?
arXiv:quant-ph/0201080v2 21 Aug 2002
R. L. Schafir∗ CISM, London Metropolitan University, London EC3N 1JY, U.K.
2
(4)
(5)
x
and then the probability of, for instance, obtaining the x-eigenstate |1, 1 of the second measurement is 1 | α11 + α−1−1 | 2 + | α1−1 + α−11 | 4
2
at the end
(6)
1 (except for special values of the αij . It is also generally different which is clearly = 4 to the probability of |1, 1 x if the first measurement is omitted, which is
1 | α11 + α−1−1 + α1−1 + α−11 | 4
2
(7)
If we consider how this could be verified by experiment, the obvious question is how to measure whether the observers’ results are the same or opposite while leaving the individual results themselves unknown, and indeed unknowable.2 But this question can be turned into a test of quantum measurement. Suppose the particles are brought together (rather then being measured while spacelike-separated), and the measurement is made by an apparatus which is considered macroscopic, and which measures the two outcomes, multiplies them and retains that result, then irretrievably deletes the original individual results. If more than a very short time elapses between making the individual measurements and deleting them, the results must be appropriate to a measurement of (1), since the individual results could have been noted and recorded (whether they actually were or not). But if deletion takes place in a time so short that it was impossible to record the original results, then we are in the area of ignorance about what exactly constitutes a quantum measurement, and it is conjectural whether the results would be appropriate to (1) or to (2). The situation can obviously be generalised, and does not necessarily need entangled states. Suppose A and B are a complete set of commuting observables on a system, i.e. A and B are degenerate but the degeneracy is lifted when both are measured. Suppose the joint measurement is made, and then, very quickly, a function f (A, B ) is evaluated from the outcomes, and recorded by methods which would usually be regarded as classical, while the values of A and B themselves are discarded
Abstract A test is suggested for whether the obtaining of certain information, and then deleting it too quickly to be retained, constitutes a quantum measurement of that information.