DOCSLIB.ORG

Measuring Photon Polarization by Pair Production

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Measuring Photon Polarization by Pair Production MEASURING PHOTON POLARIZATION BY PAIR PRODUCTION Gerardo O. Depaola* and Carlos N. Kozameh* * Facultad de Matemática Astronomía y Física - Univ. Nac. de Córdoba Ciudad Universitaria 5000 Córdoba, Argentina ABSTRACT Recently, a GEANT Monte Carlo code was used to design an outline of the geometry and to simulate the performance of a high energy (10 MeV - 10 GeV) gamma - ray detector (1). It was shown that the incident direction and energy of the incoming photons can be determined from the tracks of the produced electrons - positrons pairs. A natural follow up problem is to study whether this system can be used to detect linearly polarized gamma rays. In principle, this can be done by measuring the azimuthal distribution of the produced pairs since the cross section has a dependence with the vector polarization direction. In this work we first determine the azimuthal angular distribution from the differential cross section for pair production. We then show that the azimuthal distribution of the produced pairs has a very simple angular dependence and can be approximated very accurately by cross section for coplanar events. Finally, we use the simplified cross section to simulate the performance of the detector. I. INTRODUCTION It is worth mentioning that none of these authors computed the azimuthal probability distribution which is The detection of polarized gamma rays is very necessary to perform Monte Carlo simulations. important in astrophysics since it yields a method to In this work we calculate this spatial azimuthal observe accreting matter near a black hole or neutron star. distribution for high energy gamma - rays (10 MeV - 10 Thus, it is worth asking whether the present detectors that GeV) directly from the differential cross section as in have been designed to measure unpolarized gamma rays Bethe - Heitler (7,8) by integrating over the polar angles (1,2,3) could also be used to detect polarized photons. and the positron (electron) energy. The idea to detect polarization of a gamma - ray The integration is made using a Monte Carlo was brought up in the 50’s, by measuring the ratio of the method and the VEGAS routine of Numerical Recipes (9). number of pairs produced in a plane parallel to To check the method, we calculate the total cross section polarization vector, to the number perpendicular to that and show that it yields the tabulated values. direction. The spatial azimuthal distribution so obtained However, since the differential cross section for this shows that the produced pair tends to be coplanar with the process is a very complicated function of the relevant photon incident momentum k. It thus can be replaced by a angles, several authors used approximations with different, simple function that only depends on the angle between the and sometimes opposite, results. As and example, Berlin produced pair and the polarization vector. et. all (4) calculated a higher probability of pair production We then use this anisotropic azimuthal distribution perpendicular to the polarization vector, whereas Wick (5) on the GEANT Monte Carlo code to simulate the obtained the opposite result. Maximon and Olsen (6), performance of a high energy gamma ray detector (1) using quantum mechanic calculations, found that the previously design for unpolarized rays. It should be azimuthal relation asymmetry depended on the angular remarked that we modified the GEANT Monte Carlo code resolution which one measures these probabilities. Thus, for this purpose since the original code only contained depending on this resolution one might have a higher isotropic azimuthal distribution for pair production. probability of pair production in either direction. A major problem in this determination is multiple scatterings which modify the tracks of the particles and a function of the angles Y and f, where Y is the azimuthal tend to nullify azimuthal information. To minimize these angle measured in a plane orthogonal to k between the effects we test different geometry configurations. polarization vector and the projection of the momentum In section II we describe the Monte Carlo parameter p+ on that plane, and f is the difference between the and geometry setup, whereas in section III we discuss the azimuthal angles of the pair (see fig. 1.). spatial azimuthal distribution. Results of simulation are shown in section IV. z II. MONTE CARLO k p+ The simulation is done with GEANT (10) Monte q+ q- p- Carlo code since it offers great geometric programation versatility of experimental equipment. x With this code, the geometric design is Y constructed as follows: we first define a mother volume (called BIGM) who plays the role of the outer space. Inside this volume we define our detection system (called CALO) f who is divided in N identical sub-volumes. Each sub- volume (called SUBC), is itself composed by many layers of material. y All of this volumes have a box form and the coordinate system has its axis Z-axis perpendicular to the material layers and the X - Y axis are parallel to the other sides of the box. The incoming directions q and f are Figure 1. Angles Occurring in the Pair Production. measured with respect to the Z and X axis respectively. The basic geometry of the detector system consists of N=15 SUBC’s and the components of each layer are The calculated spatial azimuthal distribution is showed in table 1. practically zero in all ranges of Y and f except for f = p We do simulations varying the number of layers ( see Fig. 2). This indicates that for high energies the and material thickness for many Gamma - ray energy. particles tend to be coplanar with k. From this figure one can also see that at the maximum probability, i. e. for f = p, the pair has a greater TABLE 1. Thickness and Composition of Each Layer probability to be in a plane perpendicular to the Plane. polarization vector. The ratio of the number of pair produced in the 50 mm Lead plane of polarization vector to the number produced 50 mm Silicon perpendicular to this plane ( the asymmetric ratio) is for 30 mm Copper this figure equal to 0.8 which is in coincidence with 50 mm Carbon Maximon and Olsen (6). 30 mm x 2 Copper Repeating this calculation for different values of 50 mm Carbon energies of the incoming ray yields similar results. 30 mm Copper A fit of this Y distribution at f = p shows that we 50 mm Silicon can approximate the azimuthal distribution by the 3 cm Vacuum following formula : III. SPATIAL AZIMUTHAL DISTRIBUTION ds = A (1 - l cos2 y ) This differential cross section depends on the dy positron energy and the solid angle in the direction of (1) momenta relative to the photon direction k. Thus, to obtain the spatial azimuthal distribution it is necessary to The l parameter represents the degree of integrate in energy and polars angles q+, q- (Fig. 1). asymmetry of the distribution and tends to be constant at In this way we obtain a differential cross section as high energies (Fig. 3) reaching an asymptotic value of 0.2. 16 14 12 10 1 ds 8 2 a(Zr0) dfdy 6 4 3.14 2 2.62 2.09 3.14 2.62 1.57 2.09 y 1.05 1.57 1.05 0.52 f 0.52 0.00 Figure 2. Spatial Azimuthal Distribution of a Pair Created by 100 MeV Photon plus sign) obtained this formula without providing a hint of how the formula was obtained or why the sign in front 0.22 of the parameter was changed. Their value of l obtained for high energies was 0.3 instead of our calculated parameter. 0.20 It is also worth mentioning that formula 1 is only correct for coplanar events, as one can see from figure 2. To do the Monte Carlo simulation one needs the 0.18 spatial azimuthal distribution. However, it follows from Figure 2 that the cross section is significantly different 0.16 from zero for angles corresponding to coplanar events. l Thus, one can reduce the simulation to only coplanar pairs and use formula 1 to sample the angle Y. 0.14 0.12 IV. SIMULATION RESULTS 0.10 101 102 103 Inserting formula (1) into GEANT Monte Carlo code to replace the isotropic distribution usually used in Energy [MeV] this code yields the simulated performance of the detector. The simulated geometry consists on N detection’s planes explained in section II. Each plane is composed Figure 3. The l Parameter in Function of g - Ray principally by a Pb layer (used to produce the pair Energy electron-positron), and two layers of strip Silicon detector of 100 mm wide (one layer is for the X coordinate and the other for Y coordinate) and 50 mm of thickness used to Using phenomenological considerations Kel’ner detect where the particle crosses the plane. Other (11) (with the correct sign ) and Kel’ner et all (12) (with a materials are used as electrical contacts and to give rigidity to the structure. Note that the parameters used in This effect tends to nullify the original angular this simulation are different from the ones used in direction of the pair. reference (1) since the former simulation parameters are To analyze this problem we do simulation with a not sensible enough to measure photon polarization. fictitious azimuthal distribution. We force the pair to be With the X and Y coordinates of each plane we created in coplanar form and only in one plane ( we used construct the track of the pair. It is worth remarking that: Y = 0 ). 1) Gamma - ray incoming direction is determined by In figure 4 we show the angular distribution, in geometrical means through the bisector method as in other level surface, obtained for 100 MeV gamma - ray with detectors (1).
Load more

Recommended publications
  • A Light-Matter Quantum Interface: Ion-Photon Entanglement and State Mapping
    A light-matter quantum interface: ion-photon entanglement and state mapping Dissertation zur Erlangung des Doktorgrades an der Fakult¨atf¨urMathematik, Informatik und Physik der Leopold-Franzens-Universit¨atInnsbruck vorgelegt von Andreas Stute durchgef¨uhrtam Institut f¨urExperimentalphysik unter der Leitung von Univ.-Prof. Dr. Rainer Blatt Innsbruck, Dezember 2012 Abstract Quantum mechanics promises to have a great impact on computation. Motivated by the long-term vision of a universal quantum computer that speeds up certain calcula- tions, the field of quantum information processing has been growing steadily over the last decades. Although a variety of quantum systems consisting of a few qubits have been used to implement initial algorithms successfully, decoherence makes it difficult to scale up these systems. A powerful technique, however, could surpass any size limitation: the connection of individual quantum processors in a network. In a quantum network, “flying” qubits coherently transfer information between the stationary nodes of the network that store and process quantum information. Ideal candidates for the physical implementation of nodes are single atoms that exhibit long storage times; optical photons, which travel at the speed of light, are ideal information carriers. For coherent information transfer between atom and photon, a quantum interface has to couple the atom to a particular optical mode. This thesis reports on the implementation of a quantum interface by coupling a single trapped 40Ca+ ion to the mode of a high-finesse optical resonator. Single intra- cavity photons are generated in a vacuum-stimulated Raman process between two atomic states driven by a laser and the cavity vacuum field.
    [Show full text]
  • GPS and the Search for Axions
    GPS and the Search for Axions A. Nicolaidis1 Theoretical Physics Department Aristotle University of Thessaloniki, Greece Abstract: GPS, an excellent tool for geodesy, may serve also particle physics. In the presence of Earth’s magnetic field, a GPS photon may be transformed into an axion. The proposed experimental setup involves the transmission of a GPS signal from a satellite to another satellite, both in low orbit around the Earth. To increase the accuracy of the experiment, we evaluate the influence of Earth’s gravitational field on the whole quantum phenomenon. There is a significant advantage in our proposal. While the geomagnetic field B is low, the magnetized length L is very large, resulting into a scale (BL)2 orders of magnitude higher than existing or proposed reaches. The transformation of the GPS photons into axion particles will result in a dimming of the photons and even to a “light shining through the Earth” phenomenon. 1 Email: [email protected] 1 Introduction Quantum Chromodynamics (QCD) describes the strong interactions among quarks and gluons and offers definite predictions at the high energy-perturbative domain. At low energies the non-linear nature of the theory introduces a non-trivial vacuum which violates the CP symmetry. The CP violating term is parameterized by θ and experimental bounds indicate that θ ≤ 10–10. The smallness of θ is known as the strong CP problem. An elegant solution has been offered by Peccei – Quinn [1]. A global U(1)PQ symmetry is introduced, the spontaneous breaking of which provides the cancellation of the θ – term. As a byproduct, we obtain the axion field, the Nambu-Goldstone boson of the broken U(1)PQ symmetry.
    [Show full text]
  • Photons and Polarization
    Photons and Polarization Now that we’ve understood the classical picture of polarized light, it will be very enlightening to think about what is going on with the individual photons in some polarization experiments. This simple example will reveal many features common to all quantum mechanical systems. Classical polarizer experiments Let’s imagine that we have a beam of light polarized in the vertical di- rection, which could be produced by passing an unpolarized beam of light through a vertically oriented polarizer. If we now place a second vertically oriented polarizer in the path of the beam, we know that all the light should pass through (assuming reflection is negligible). On the other hand, if the second polarizer is oriented at 90 degrees to the first, none of the light will pass through. Finally, if the second polarizer is oriented at 45 degrees to the first (or some general angle θ) then the intensity of the transmitted beam will be half (or generally cos2(θ) times) the intensity of the original polarized beam. If we insert a third polarizer with the same orientation as the second polarizer, there is no further reduction in intensity, so the reduced intensity beam is completely polarized in the direction of the second polarizer. Photon interpretation of polarization experiments The results we have mentioned do not depend on what the original in- tensity of the light is. In particular, if we turn down the intensity so much that the individual photons are observable (e.g. with a photomultiplier), we get the same results.1 We must then conclude that each photon carries in- formation about the polarization of the light.
    [Show full text]
  • Photon Polarization in Nonlinear Breit-Wheeler Pair Production and $\Gamma$ Polarimetry
    PHYSICAL REVIEW RESEARCH 2, 032049(R) (2020) Rapid Communications High-energy γ-photon polarization in nonlinear Breit-Wheeler pair production and γ polarimetry Feng Wan ,1 Yu Wang,1 Ren-Tong Guo,1 Yue-Yue Chen,2 Rashid Shaisultanov,3 Zhong-Feng Xu,1 Karen Z. Hatsagortsyan ,3,* Christoph H. Keitel,3 and Jian-Xing Li 1,† 1MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi’an Jiaotong University, Xi’an 710049, China 2Department of Physics, Shanghai Normal University, Shanghai 200234, China 3Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany (Received 24 February 2020; accepted 12 August 2020; published 27 August 2020) The interaction of an unpolarized electron beam with a counterpropagating ultraintense linearly polarized laser pulse is investigated in the quantum radiation-dominated regime. We employ a semiclassical Monte Carlo method to describe spin-resolved electron dynamics, photon emissions and polarization, and pair production. Abundant high-energy linearly polarized γ photons are generated intermediately during this interaction via nonlinear Compton scattering, with an average polarization degree of more than 50%, further interacting with the laser fields to produce electron-positron pairs due to the nonlinear Breit-Wheeler process. The photon polarization is shown to significantly affect the pair yield by a factor of more than 10%. The considered signature of the photon polarization in the pair’s yield can be experimentally identified in a prospective two-stage setup. Moreover, with currently achievable laser facilities the signature can serve also for the polarimetry of high-energy high-flux γ photons. DOI: 10.1103/PhysRevResearch.2.032049 Rapid advancement of strong laser techniques [1–4] en- that an electron beam cannot be significantly polarized by a ables experimental investigation of quantum electrodynamics monochromatic laser wave [46–48].
    [Show full text]
  • Arxiv:1907.08877V2 [Physics.Plasm-Ph] 27 Nov 2019 Smaller Than the Laser Wavelength
    Polarized ultrashort brilliant multi-GeV γ-rays via single-shot laser-electron interaction Yan-Fei Li,1, 2 Rashid Shaisultanov,2 Yue-Yue Chen,2 Feng Wan,1, 2 Karen Z. Hatsagortsyan,2, ∗ Christoph H. Keitel,2 and Jian-Xing Li1, 2, y 1MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi’an Jiaotong University, Xi’an 710049, China 2Max-Planck-Institut f¨urKernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany (Dated: November 28, 2019) Generation of circularly-polarized (CP) and linearly-polarized (LP) γ-rays via the single-shot interaction of an ultraintense laser pulse with a spin-polarized counterpropagating ultrarelativistic electron beam has been investigated in nonlinear Compton scattering in the quantum radiation-dominated regime. For the process simulation a Monte Carlo method is developed which employs the electron-spin-resolved probabilities for polarized photon emissions. We show efficient ways for the transfer of the electron polarization to the high- energy photon polarization. In particular, multi-GeV CP (LP) γ-rays with polarization of up to about 95% can be generated by a longitudinally (transversely) spin-polarized electron beam, with a photon flux meeting the requirements of recent proposals for the vacuum birefringence measurement in ultrastrong laser fields. Such high-energy, high-brilliance, high-polarization γ-rays are also beneficial for other applications in high-energy physics, and laboratory astrophysics. Polarization is a crucial intrinsic property of a γ-photon. Nevertheless, the nonlinear regime of Compton scattering is In astrophysics the γ-photon polarization provides detailed beneficial for the generation of polarized γ-photons, because insight into the γ-ray emission mechanism and on properties the polarization is enhanced at high γ-photon energies [12], of dark matter [1, 2].
    [Show full text]
  • Macroscopic Rotation of Photon Polarization Induced by a Single Spin
    ARTICLE Received 17 Nov 2014 | Accepted 7 Jan 2015 | Published 17 Feb 2015 DOI: 10.1038/ncomms7236 OPEN Macroscopic rotation of photon polarization induced by a single spin Christophe Arnold1, Justin Demory1, Vivien Loo1, Aristide Lemaıˆtre1, Isabelle Sagnes1, Mikhaı¨l Glazov2, Olivier Krebs1, Paul Voisin1, Pascale Senellart1,3 &Loı¨c Lanco1,4 Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10 À 3 degrees due to poor spin–photon coupling. Here we report the enhancement by three orders of magnitude of the spin–photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ±6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. 1 Laboratoire de Photonique et de Nanostructures, CNRS UPR 20, Route de Nozay, 91460 Marcoussis, France. 2 Ioffe Physical-Technical Institute of the RAS, 194021 St-Petersburg, Russia. 3 De´partement de Physique, Ecole Polytechnique, F-91128 Palaiseau, France. 4 Universite´ Paris Diderot—Paris 7, 75205 Paris CEDEX 13, France.
    [Show full text]
  • Quantum Physics
    3 Polarization: photons and spin-1/2 particles In this chapter we build up the basic concepts of quantum mechanics using two simple examples, following a heuristic approach which is more inductive than deductive. We start with a familiar phenomenon, that of the polarization of light, which will allow us to introduce the necessary mathematical formalism. We show that the description of polarization leads naturally to the need for a two-dimensional complex vector space, and we establish the correspondence between a polarization state and a vector in this space, referred to as the space of polarization states. We then move on to the quantum description of photon polarization and illustrate the construction of probability amplitudes as scalar products in this space. The second example will be that of spin 1/2, where the space of states is again two-dimensional. We construct the most general states of spin 1/2 using rotational invariance. Finally, we introduce dynamics, which allows us to follow the time evolution of a state vector. The analogy with the polarization of light will serve as a guide to constructing the quantum theory of photon polarization, but no such classical analog is available for constructing the quantum theory for spin 1/2. In this case the quantum theory will be constructed without reference to any classical theory, using an assumption about the dimension of the space of states and symmetry principles. 3.1 The polarization of light and photon polarization 3.1.1 The polarization of an electromagnetic wave The polarization of light or, more generally, of an electromagnetic wave, is a familiar phenomenon related to the vector nature of the electromagnetic field.
    [Show full text]
  • 1. Polarization the Electric and Magnetic Vectors Associated with an Electromagnetic Wave Are Perpendicular to Each Other and to the Direction of Wave Propagation
    Photon polarization Masatsugu Sei Suzuki Department of Physics, SUNY at Binghamton (Date: September 20, 2014) 1. Polarization The electric and magnetic vectors associated with an electromagnetic wave are perpendicular to each other and to the direction of wave propagation. Polarization is a property that specifies the directions of the electric and magnetic fields associated with an EM wave. The direction of polarization is defined to be the direction in which the electric field is vibrating. The plane containing the E-vector is called the plane of oscillation of the wave. Hence the wave is said to be plane polarized in the y direction. We can represent the wave’s polarization by showing the direction of electric field oscillations in a head-on view of the plane of oscillation. 1 2. Unpolarized light All directions of vibration from a wave source are possible. The resultant EM wave is a superposition of waves vibrating in many different directions. This is an unpolarized wave. The arrows show a few possible directions of the waves in the beam. The representing unpolarized light is the superposition of two polarized waves (Ex and Ey) whose planes of oscillation are perpendicular to each other. 2 3 Intensity of transmitted polarized light (1) Malus’ law An electric field component parallel to the polarization direction is passed (transmitted) by a polarizing sheet. A component perpendicular to it is absorbed. The electric field along the direction of the polarizing sheet is given by Ey E cos . Then the intensity I of the polarized light with the polarization vector parallel to the y axis is given by 2 I I0 cos (Malus’ law), where 2 Erms 2 I Savg I0 cos .
    [Show full text]
  • Virtual Photon Polarization and Dilepton Anisotropy in Pion-Nucleon and Heavy-Ion Collisions
    Virtual photon polarization and dilepton anisotropy in pion-nucleon and heavy-ion collisions Polarisation virtueller Photonen und Dileptonanisotropie in Pion-Nukleon- und Schwerionenkollisionen Zur Erlangung des Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigte Dissertation von M. Sc. Enrico Speranza Tag der Einreichung: 16.05.2017, Tag der Prüfung: 26.06.2017 Darmstadt 2018 — D 17 1. Gutachten: Prof. Dr. Bengt Friman 2. Gutachten: Prof. Dr. Tetyana Galatyuk Fachbereich Physik Institut für Kernphysik Virtual photon polarization and dilepton anisotropy in pion-nucleon and heavy-ion collisions Polarisation virtueller Photonen und Dileptonanisotropie in Pion-Nukleon- und Schwerionenkollisionen Genehmigte Dissertation von M. Sc. Enrico Speranza 1. Gutachten: Prof. Dr. Bengt Friman 2. Gutachten: Prof. Dr. Tetyana Galatyuk Tag der Einreichung: 16.05.2017 Tag der Prüfung: 26.06.2017 Darmstadt 2018 — D 17 Bitte zitieren Sie dieses Dokument als: URN: urn:nbn:de:tuda-tuprints-74602 URL: http://tuprints.ulb.tu-darmstadt.de/7460 Dieses Dokument wird bereitgestellt von tuprints, E-Publishing-Service der TU Darmstadt http://tuprints.ulb.tu-darmstadt.de [email protected] Die Veröffentlichung steht unter folgender Creative Commons Lizenz: Namensnennung – Keine kommerzielle Nutzung – Keine Bearbeitung 4.0 Interna- tional https://creativecommons.org/licenses/by-nc-nd/4.0/ Erklärung zur Dissertation Hiermit versichere ich, die vorliegende Dissertation ohne Hilfe Dritter nur mit den angegebenen Quellen und Hilfsmitteln angefertigt zu haben. Alle Stellen, die aus Quellen entnommen wurden, sind als solche kenntlich gemacht. Diese Arbeit hat in gleicher oder ähnlicher Form noch keiner Prüfungsbehörde vorgelegen. Darmstadt, den 16 Mai 2017 (Enrico Speranza) 1 Abstract The goal of this Thesis is to study photon polarization and dilepton anisotropies as a tool to understand hadronic and heavy-ion collisions.
    [Show full text]
  • The Two Golden Rules of Quantum Mechanics with Light Polarization
    Lesson THE TWO GOLDEN RULES OF QUANTUM MECHANICS WITH LIGHT POLARIZATION Created by the IQC Scientific Outreach team Contact: [email protected] Institute for Quantum Computing University of Waterloo 200 University Avenue West Waterloo, Ontario, Canada N2L 3G1 uwaterloo.ca/iqc Copyright © 2021 University of Waterloo Outline THE TWO GOLDEN RULES OF QUANTUM MECHANICS ACTIVITY GOAL: Investigate the superposition and measurement principle using the polarization of light LEARNING OBJECTIVES ACTIVITY OUTLINE The quantum nature of light We start by defining mutually exclusive states of polarization, polarization. and linking the wave and particle pictures through Malus’ law. CONCEPT: Mutually exclusive states and Quantum measurement is a probabilistic process. measurement choice. We then show how any polarization state can be broken down into components and thought of as a superposition of other polarization The superposition and states. measurement principles in quantum mechanics CONCEPT: Superposition is relative to the measurement context. Probabilistic nature of By introducing more polarizers, we observe that measurements can quantum mechanics and change a quantum state, and explain it using the idea of wave probability amplitudes. collapse. CONCEPT: Measuring an unknown quantum state will change it. PREREQUISITE KNOWLEDGE Light is made of particles called photons. Light is an electromagnetic wave with a polarization. Cartesian co-ordinates and trigonometry. SUPPLIES REQUIRED 3 polarizers with labelled orientations Lesson THE TWO GOLDEN RULES OF QUANTUM MECHANICS PHOTONS AND THE WAVE-PARTICLE DEBATE In classical physics, we can neatly separate objects into two categories: particles and waves. In quantum mechanics, that distinction no longer holds. In its simplest form, quantum mechanics is based on the idea that everything is made of particles that have wave-like properties – this is the wave-particle duality.
    [Show full text]
  • Polarization Observables for Millicharged Particles in Photon Collisions
    Polarization observables for millicharged particles in photon collisions Emidio Gabrielli,1, 2, 3 Luca Marzola,3, 4 Edoardo Milotti,5, 2 and Hardi Veerm¨ae3 1Dipartimento di Fisica, Sezione Teorica, Universit`adegli Studi di Trieste Strada Costiera 11, I-34151 Trieste, Italy 2INFN, Sezione di Trieste, Via Valerio 2, I-34127 Trieste, Italy. 3National Institute of Chemical Physics and Biophysics, R¨avala10, 10143 Tallinn, Estonia 4University of Tartu, Institute of Physics, Ravila 14c, 50411 Tartu, Estonia. 5Dipartimento di Fisica, Universit`adegli Studi di Trieste, Via Valerio 2, I-34127 Trieste, Italy. (Dated: November 27, 2018) Particles in a hidden sector can potentially acquire a small electric charge through their interaction with the Standard Model and can consequently be observed as millicharged particles. We systemati- cally compute the production of millicharged scalar, fermion, and vector boson particles in collisions of polarized photons. The presented calculation is model independent and is based purely on the as- sumptions of electromagnetic gauge invariance and unitarity. Polarization observables are evaluated and analyzed for each spin case. We show that the photon polarization asymmetries are a useful tool for discriminating between the spins of the produced millicharged particles. Phenomenological implications for searches of millicharged particles in dedicated photon-photon collision experiments are also discussed. I. INTRODUCTION ance and unitarity, the total cross section of γγ VV tends to a constant in the high energy limit, whereas! −1 Although we observe electric charge quantization in na- the same quantity decreases as s in the cases of spin- ture, this property is not a requirement of the Standard 0 and spin-1/2 MCP.
    [Show full text]
  • Testing Heisenberg's Uncertainty Principle with Polarized Single
    Testing Heisenberg’s Uncertainty Principle with Polarized Single Photons Sofia Svensson [email protected] under the direction of Prof. Mohamed Bourennane Quantum Information & Quantum Optics Department of Physics Stockholm University Research Academy for Young Scientists July 10, 2013 Abstract One of the fundamentals of quantum mechanics is Heisenberg’s uncertainty principle. The principle states that two observables cannot be measured accurately at the same time if their corresponding operators do not commute. The aim of the study was to test the uncertainty principle with the help of polarized single photons dispatched from a helium neon laser at a wavelength of 632.8 nm and an experimental setup similar to the one used in the Stern-Gerlach experiment. The results obtained were within the standard deviation and consistent with the theoretical results derived from the principle, thereby indicating the principle’s validity. Contents 1 Introduction 1 2 Theory 2 2.1 The Stern-Gerlach Experiment . 2 2.2 Polarization of Photons . 5 2.3 Heisenberg’s Uncertainty Principle . 8 2.4 Quantum Cryptography . 8 3 Method 9 3.1 Measurement 1 . 10 3.2 Measurement 2 . 11 3.3 Measurement 3 . 11 3.4 Measurement 4 . 12 4 Results 12 5 Discussion 14 Acknowledgements 15 A Results 17 1 Introduction While more than a century old, quantum mechanics still evokes immerse interest in its promises for future computers, cryptation and materials. An experiment carried out in 1922 by two scientists named Otto Stern and Walther Gerlach, together with a series of other experiments, have given us insight into one of the fundamental concepts of quantum mechanics: superpositions.
    [Show full text]