Lecture 20 Wave-Particle Duality
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Classical and Modern Diffraction Theory
Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3701993/frontmatter.pdf by guest on 29 September 2021 Classical and Modern Diffraction Theory Edited by Kamill Klem-Musatov Henning C. Hoeber Tijmen Jan Moser Michael A. Pelissier SEG Geophysics Reprint Series No. 29 Sergey Fomel, managing editor Evgeny Landa, volume editor Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3701993/frontmatter.pdf by guest on 29 September 2021 Society of Exploration Geophysicists 8801 S. Yale, Ste. 500 Tulsa, OK 74137-3575 U.S.A. # 2016 by Society of Exploration Geophysicists All rights reserved. This book or parts hereof may not be reproduced in any form without permission in writing from the publisher. Published 2016 Printed in the United States of America ISBN 978-1-931830-00-6 (Series) ISBN 978-1-56080-322-5 (Volume) Library of Congress Control Number: 2015951229 Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3701993/frontmatter.pdf by guest on 29 September 2021 Dedication We dedicate this volume to the memory Dr. Kamill Klem-Musatov. In reading this volume, you will find that the history of diffraction We worked with Kamill over a period of several years to compile theory was filled with many controversies and feuds as new theories this volume. This volume was virtually ready for publication when came to displace or revise previous ones. Kamill Klem-Musatov’s Kamill passed away. He is greatly missed. new theory also met opposition; he paid a great personal price in Kamill’s role in Classical and Modern Diffraction Theory goes putting forth his theory for the seismic diffraction forward problem. -
Intensity of Double-Slit Pattern • Three Or More Slits
• Intensity of double-slit pattern • Three or more slits Practice: Chapter 37, problems 13, 14, 17, 19, 21 Screen at ∞ θ d Path difference Δr = d sin θ zero intensity at d sinθ = (m ± ½ ) λ, m = 0, ± 1, ± 2, … max. intensity at d sinθ = m λ, m = 0, ± 1, ± 2, … 1 Questions: -what is the intensity of the double-slit pattern at an arbitrary position? -What about three slits? four? five? Find the intensity of the double-slit interference pattern as a function of position on the screen. Two waves: E1 = E0 sin(ωt) E2 = E0 sin(ωt + φ) where φ =2π (d sin θ )/λ , and θ gives the position. Steps: Find resultant amplitude, ER ; then intensities obey where I0 is the intensity of each individual wave. 2 Trigonometry: sin a + sin b = 2 cos [(a-b)/2] sin [(a+b)/2] E1 + E2 = E0 [sin(ωt) + sin(ωt + φ)] = 2 E0 cos (φ / 2) cos (ωt + φ / 2)] Resultant amplitude ER = 2 E0 cos (φ / 2) Resultant intensity, (a function of position θ on the screen) I position - fringes are wide, with fuzzy edges - equally spaced (in sin θ) - equal brightness (but we have ignored diffraction) 3 With only one slit open, the intensity in the centre of the screen is 100 W/m 2. With both (identical) slits open together, the intensity at locations of constructive interference will be a) zero b) 100 W/m2 c) 200 W/m2 d) 400 W/m2 How does this compare with shining two laser pointers on the same spot? θ θ sin d = d Δr1 d θ sin d = 2d θ Δr2 sin = 3d Δr3 Total, 4 The total field is where φ = 2π (d sinθ )/λ •When d sinθ = 0, λ , 2λ, .. -
Light and Matter Diffraction from the Unified Viewpoint of Feynman's
European J of Physics Education Volume 8 Issue 2 1309-7202 Arlego & Fanaro Light and Matter Diffraction from the Unified Viewpoint of Feynman’s Sum of All Paths Marcelo Arlego* Maria de los Angeles Fanaro** Universidad Nacional del Centro de la Provincia de Buenos Aires CONICET, Argentine *[email protected] **[email protected] (Received: 05.04.2018, Accepted: 22.05.2017) Abstract In this work, we present a pedagogical strategy to describe the diffraction phenomenon based on a didactic adaptation of the Feynman’s path integrals method, which uses only high school mathematics. The advantage of our approach is that it allows to describe the diffraction in a fully quantum context, where superposition and probabilistic aspects emerge naturally. Our method is based on a time-independent formulation, which allows modelling the phenomenon in geometric terms and trajectories in real space, which is an advantage from the didactic point of view. A distinctive aspect of our work is the description of the series of transformations and didactic transpositions of the fundamental equations that give rise to a common quantum framework for light and matter. This is something that is usually masked by the common use, and that to our knowledge has not been emphasized enough in a unified way. Finally, the role of the superposition of non-classical paths and their didactic potential are briefly mentioned. Keywords: quantum mechanics, light and matter diffraction, Feynman’s Sum of all Paths, high education INTRODUCTION This work promotes the teaching of quantum mechanics at the basic level of secondary school, where the students have not the necessary mathematics to deal with canonical models that uses Schrodinger equation. -
Lecture 9, P 1 Lecture 9: Introduction to QM: Review and Examples
Lecture 9, p 1 Lecture 9: Introduction to QM: Review and Examples S1 S2 Lecture 9, p 2 Photoelectric Effect Binding KE=⋅ eV = hf −Φ energy max stop Φ The work function: 3.5 Φ is the minimum energy needed to strip 3 an electron from the metal. 2.5 2 (v) Φ is defined as positive . 1.5 stop 1 Not all electrons will leave with the maximum V f0 kinetic energy (due to losses). 0.5 0 0 5 10 15 Conclusions: f (x10 14 Hz) • Light arrives in “packets” of energy (photons ). • Ephoton = hf • Increasing the intensity increases # photons, not the photon energy. Each photon ejects (at most) one electron from the metal. Recall: For EM waves, frequency and wavelength are related by f = c/ λ. Therefore: Ephoton = hc/ λ = 1240 eV-nm/ λ Lecture 9, p 3 Photoelectric Effect Example 1. When light of wavelength λ = 400 nm shines on lithium, the stopping voltage of the electrons is Vstop = 0.21 V . What is the work function of lithium? Lecture 9, p 4 Photoelectric Effect: Solution 1. When light of wavelength λ = 400 nm shines on lithium, the stopping voltage of the electrons is Vstop = 0.21 V . What is the work function of lithium? Φ = hf - eV stop Instead of hf, use hc/ λ: 1240/400 = 3.1 eV = 3.1eV - 0.21eV For Vstop = 0.21 V, eV stop = 0.21 eV = 2.89 eV Lecture 9, p 5 Act 1 3 1. If the workfunction of the material increased, (v) 2 how would the graph change? stop a. -
Appendix F. Glossary
Appendix F. Glossary 2DEG 2-dimensional electron gas A/D Analog to digital AAAR American Association for Aerosol Research ADC Analog-digital converter AEM Analytical electron microscopy AFM Atomic force microscope/microscopy AFOSR Air Force Office of Scientific Research AIST (Japan) Agency of Industrial Science and Technology AIST (Japan, MITI) Agency of Industrial Science and Technology AMLCD Active matrix liquid crystal display AMM Amorphous microporous mixed (oxides) AMO Atomic, molecular, and optical AMR Anisotropic magnetoresistance ARO (U.S.) Army Research Office ARPES Angle-resolved photoelectron spectroscopy ASET (Japan) Association of Super-Advanced Electronics Technologies ASTC Australia Science and Technology Council ATP (Japan) Angstrom Technology Partnership ATP Adenosine triphosphate B Magnetic flux density B/H loop Closed figure showing B (magnetic flux density) compared to H (magnetic field strength) in a magnetizable material—also called hysteresis loop bcc Body-centered cubic BMBF (Germany) Ministry of Education, Science, Research, and Technology (formerly called BMFT) BOD-FF Bond-order-dependent force field BRITE/EURAM Basic Research of Industrial Technologies for Europe, European Research on Advanced Materials program CAD Computer-assisted design CAIBE Chemically assisted ion beam etching CBE Chemical beam epitaxy 327 328 Appendix F. Glossary CBED Convergent beam electron diffraction cermet Ceramic/metal composite CIP Cold isostatic press CMOS Complementary metal-oxide semiconductor CMP Chemical mechanical polishing -
The Uncertainty Principle (Stanford Encyclopedia of Philosophy) Page 1 of 14
The Uncertainty Principle (Stanford Encyclopedia of Philosophy) Page 1 of 14 Open access to the SEP is made possible by a world-wide funding initiative. Please Read How You Can Help Keep the Encyclopedia Free The Uncertainty Principle First published Mon Oct 8, 2001; substantive revision Mon Jul 3, 2006 Quantum mechanics is generally regarded as the physical theory that is our best candidate for a fundamental and universal description of the physical world. The conceptual framework employed by this theory differs drastically from that of classical physics. Indeed, the transition from classical to quantum physics marks a genuine revolution in our understanding of the physical world. One striking aspect of the difference between classical and quantum physics is that whereas classical mechanics presupposes that exact simultaneous values can be assigned to all physical quantities, quantum mechanics denies this possibility, the prime example being the position and momentum of a particle. According to quantum mechanics, the more precisely the position (momentum) of a particle is given, the less precisely can one say what its momentum (position) is. This is (a simplistic and preliminary formulation of) the quantum mechanical uncertainty principle for position and momentum. The uncertainty principle played an important role in many discussions on the philosophical implications of quantum mechanics, in particular in discussions on the consistency of the so-called Copenhagen interpretation, the interpretation endorsed by the founding fathers Heisenberg and Bohr. This should not suggest that the uncertainty principle is the only aspect of the conceptual difference between classical and quantum physics: the implications of quantum mechanics for notions as (non)-locality, entanglement and identity play no less havoc with classical intuitions. -
Path Integral for the Hydrogen Atom
Path Integral for the Hydrogen Atom Solutions in two and three dimensions Vägintegral för Väteatomen Lösningar i två och tre dimensioner Anders Svensson Faculty of Health, Science and Technology Physics, Bachelor Degree Project 15 ECTS Credits Supervisor: Jürgen Fuchs Examiner: Marcus Berg June 2016 Abstract The path integral formulation of quantum mechanics generalizes the action principle of classical mechanics. The Feynman path integral is, roughly speaking, a sum over all possible paths that a particle can take between fixed endpoints, where each path contributes to the sum by a phase factor involving the action for the path. The resulting sum gives the probability amplitude of propagation between the two endpoints, a quantity called the propagator. Solutions of the Feynman path integral formula exist, however, only for a small number of simple systems, and modifications need to be made when dealing with more complicated systems involving singular potentials, including the Coulomb potential. We derive a generalized path integral formula, that can be used in these cases, for a quantity called the pseudo-propagator from which we obtain the fixed-energy amplitude, related to the propagator by a Fourier transform. The new path integral formula is then successfully solved for the Hydrogen atom in two and three dimensions, and we obtain integral representations for the fixed-energy amplitude. Sammanfattning V¨agintegral-formuleringen av kvantmekanik generaliserar minsta-verkanprincipen fr˚anklassisk meka- nik. Feynmans v¨agintegral kan ses som en summa ¨over alla m¨ojligav¨agaren partikel kan ta mellan tv˚a givna ¨andpunkterA och B, d¨arvarje v¨agbidrar till summan med en fasfaktor inneh˚allandeden klas- siska verkan f¨orv¨agen.Den resulterande summan ger propagatorn, sannolikhetsamplituden att partikeln g˚arfr˚anA till B. -
A Review of Transmission Electron Microscopy of Quasicrystals—How Are Atoms Arranged?
crystals Review A Review of Transmission Electron Microscopy of Quasicrystals—How Are Atoms Arranged? Ruitao Li 1, Zhong Li 1, Zhili Dong 2,* and Khiam Aik Khor 1,* 1 School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore; [email protected] (R.L.); [email protected] (Z.L.) 2 School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore * Correspondence: [email protected] (Z.D.); [email protected] (K.A.K.); Tel.: +65-6790-6727 (Z.D.); +65-6592-1816 (K.A.K.) Academic Editor: Enrique Maciá Barber Received: 30 June 2016; Accepted: 15 August 2016; Published: 26 August 2016 Abstract: Quasicrystals (QCs) possess rotational symmetries forbidden in the conventional crystallography and lack translational symmetries. Their atoms are arranged in an ordered but non-periodic way. Transmission electron microscopy (TEM) was the right tool to discover such exotic materials and has always been a main technique in their studies since then. It provides the morphological and crystallographic information and images of real atomic arrangements of QCs. In this review, we summarized the achievements of the study of QCs using TEM, providing intriguing structural details of QCs unveiled by TEM analyses. The main findings on the symmetry, local atomic arrangement and chemical order of QCs are illustrated. Keywords: quasicrystal; transmission electron microscopy; symmetry; atomic arrangement 1. Introduction The revolutionary discovery of an Al–Mn compound with 5-fold symmetry by Shechtman et al. [1] in 1982 unveiled a new family of materials—quasicrystals (QCs), which exhibit the forbidden rotational symmetries in the conventional crystallography. -
Schrodinger's Uncertainty Principle? Lilies Can Be Painted
Rajaram Nityananda Schrodinger's Uncertainty Principle? lilies can be Painted Rajaram Nityananda The famous equation of quantum theory, ~x~px ~ h/47r = 11,/2 is of course Heisenberg'S uncertainty principlel ! But SchrO dinger's subsequent refinement, described in this article, de serves to be better known in the classroom. Rajaram Nityananda Let us recall the basic algebraic steps in the text book works at the Raman proof. We consider the wave function (which has a free Research Institute,· real parameter a) (x + iap)1jJ == x1jJ(x) + ia( -in81jJ/8x) == mainly on applications of 4>( x), The hat sign over x and p reminds us that they are optical and statistical operators. We have dropped the suffix x on the momentum physics, for eJ:ample in p but from now on, we are only looking at its x-component. astronomy. Conveying 1jJ( x) is physics to students at Even though we know nothing about except that it different levels is an allowed wave function, we can be sure that J 4>* ¢dx ~ O. another activity. He In terms of 1jJ, this reads enjoys second class rail travel, hiking, ! 1jJ*(x - iap)(x + iap)1jJdx ~ O. (1) deciphering signboards in strange scripts and Note the all important minus sign in the first bracket, potatoes in any form. coming from complex conjugation. The product of operators can be expanded and the result reads2 < x2 > + < a2p2 > +ia < (xp - px) > ~ O. (2) I I1x is the uncertainty in the x The three terms are the averages of (i) the square of component of position and I1px the uncertainty in the x the coordinate, (ii) the square of the momentum, (iii) the component of the momentum "commutator" xp - px. -
The Path Integral Approach to Quantum Mechanics Lecture Notes for Quantum Mechanics IV
The Path Integral approach to Quantum Mechanics Lecture Notes for Quantum Mechanics IV Riccardo Rattazzi May 25, 2009 2 Contents 1 The path integral formalism 5 1.1 Introducingthepathintegrals. 5 1.1.1 Thedoubleslitexperiment . 5 1.1.2 An intuitive approach to the path integral formalism . .. 6 1.1.3 Thepathintegralformulation. 8 1.1.4 From the Schr¨oedinger approach to the path integral . .. 12 1.2 Thepropertiesofthepathintegrals . 14 1.2.1 Pathintegralsandstateevolution . 14 1.2.2 The path integral computation for a free particle . 17 1.3 Pathintegralsasdeterminants . 19 1.3.1 Gaussianintegrals . 19 1.3.2 GaussianPathIntegrals . 20 1.3.3 O(ℏ) corrections to Gaussian approximation . 22 1.3.4 Quadratic lagrangians and the harmonic oscillator . .. 23 1.4 Operatormatrixelements . 27 1.4.1 Thetime-orderedproductofoperators . 27 2 Functional and Euclidean methods 31 2.1 Functionalmethod .......................... 31 2.2 EuclideanPathIntegral . 32 2.2.1 Statisticalmechanics. 34 2.3 Perturbationtheory . .. .. .. .. .. .. .. .. .. .. 35 2.3.1 Euclidean n-pointcorrelators . 35 2.3.2 Thermal n-pointcorrelators. 36 2.3.3 Euclidean correlators by functional derivatives . ... 38 0 0 2.3.4 Computing KE[J] and Z [J] ................ 39 2.3.5 Free n-pointcorrelators . 41 2.3.6 The anharmonic oscillator and Feynman diagrams . 43 3 The semiclassical approximation 49 3.1 Thesemiclassicalpropagator . 50 3.1.1 VanVleck-Pauli-Morette formula . 54 3.1.2 MathematicalAppendix1 . 56 3.1.3 MathematicalAppendix2 . 56 3.2 Thefixedenergypropagator. 57 3.2.1 General properties of the fixed energy propagator . 57 3.2.2 Semiclassical computation of K(E)............. 61 3.2.3 Two applications: reflection and tunneling through a barrier 64 3 4 CONTENTS 3.2.4 On the phase of the prefactor of K(xf ,tf ; xi,ti) .... -
Zero-Point Energy and Interstellar Travel by Josh Williams
;;;;;;;;;;;;;;;;;;;;;; itself comes from the conversion of electromagnetic Zero-Point Energy and radiation energy into electrical energy, or more speciÞcally, the conversion of an extremely high Interstellar Travel frequency bandwidth of the electromagnetic spectrum (beyond Gamma rays) now known as the zero-point by Josh Williams spectrum. ÒEre many generations pass, our machinery will be driven by power obtainable at any point in the universeÉ it is a mere question of time when men will succeed in attaching their machinery to the very wheel work of nature.Ó ÐNikola Tesla, 1892 Some call it the ultimate free lunch. Others call it absolutely useless. But as our world civilization is quickly coming upon a terrifying energy crisis with As you can see, the wavelengths from this part of little hope at the moment, radical new ideas of usable the spectrum are incredibly small, literally atomic and energy will be coming to the forefront and zero-point sub-atomic in size. And since the wavelength is so energy is one that is currently on its way. small, it follows that the frequency is quite high. The importance of this is that the intensity of the energy So, what the hell is it? derived for zero-point energy has been reported to be Zero-point energy is a type of energy that equal to the cube (the third power) of the frequency. exists in molecules and atoms even at near absolute So obviously, since weÕre already talking about zero temperatures (-273¡C or 0 K) in a vacuum. some pretty high frequencies with this portion of At even fractions of a Kelvin above absolute zero, the electromagnetic spectrum, weÕre talking about helium still remains a liquid, and this is said to be some really high energy intensities. -
The Paradoxes of the Interaction-Free Measurements
The Paradoxes of the Interaction-free Measurements L. Vaidman Centre for Quantum Computation, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 3PU, England; School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel Reprint requests to Prof. L. V.; E-mail: [email protected] Z. Naturforsch. 56 a, 100-107 (2001); received January 12, 2001 Presented at the 3rd Workshop on Mysteries, Puzzles and Paradoxes in Quantum Mechanics, Gargnano, Italy, September 17-23, 2000. Interaction-free measurements introduced by Elitzur and Vaidman [Found. Phys. 23,987 (1993)] allow finding infinitely fragile objects without destroying them. Paradoxical features of these and related measurements are discussed. The resolution of the paradoxes in the framework of the Many-Worlds Interpretation is proposed. Key words: Interaction-free Measurements; Quantum Paradoxes. I. Introduction experiment” proposed by Wheeler [22] which helps to define the context in which the above claims, that The interaction-free measurements proposed by the measurements are interaction-free, are legitimate. Elitzur and Vaidman [1,2] (EVIFM) led to numerousSection V is devoted to the variation of the EV IFM investigations and several experiments have been per proposed by Penrose [23] which, instead of testing for formed [3- 17]. Interaction-free measurements are the presence of an object in a particular place, tests very paradoxical. Usually it is claimed that quantum a certain property of the object in an interaction-free measurements, in contrast to classical measurements, way. Section VI introduces the EV IFM procedure for invariably cause a disturbance of the system.