DOCSLIB.ORG

Entangled Histories

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

MIT-CTP-4642 Entangled Histories Jordan Cotler1 and Frank Wilczek1;2 1. Center for Theoretical Physics, MIT, Cambridge MA 02139 USA 2. Origins Project, Arizona State University, Tempe AZ 25287 USA February 8, 2015 Abstract We introduce quantum history states and their mathematical framework, thereby reinterpreting and extending the consistent histories approach to quantum theory. Through thought experiments, we demonstrate that our formalism allows us to an- alyze a quantum version of history in which we reconstruct the past by observations. In particular, we can pass from measurements to inferences about \what happened" in a way that is sensible and free of paradox. Our framework allows for a richer under- standing of the temporal structure of quantum theory, and we construct history states that embody peculiar, non-classical correlations in time. Many quantities of physical interest are more naturally expressed in terms of histories than in terms of \observables" in the traditional sense, i.e. operators in Hilbert space that 2 act at a particular time. The accumulated phase exp i dt~v · A~ of a particle moving in ´1 an electromagnetic potential, or its accumulated proper time, are simple examples. We may ask: Having performed a measurement of this more general, history-dependent sort of observable, what have we learned? For conventional observables, the answer is that we learn our system is in a particular subspace of Hilbert space, that is the eigenspace corresponding to the observable's measured value. Here we propose a general framework for formulating and interpreting history-dependent observables. Over the last thirty years, the quantum theory of histories has been approached from several directions. In the 1980's, Griffiths developed a mathematically precise formulation of the Copenhagen interpretation [1]. Griffiths was able to elucidate seemingly paradoxical experiments by enforcing a consistent interpretation of quantum evolution. Omn`es,Gell- Mann, Hartle, Isham, and Linden, among others, enriched the mathematics and physics of Griffith’s theory of \consistent histories" [2]-[11]. In particular, Gell-Mann and Hartle focused on applying consistent histories to decoherence and quantum cosmology, while Isham and Linden's work has uncovered deep mathematical structure at foundations of quantum mechanics [12]. 1 Histories are of course an explicit element of Feynman's path integral. In the early 1990's, Farhi and Gutmann developed a generalized theory of the path integral, which clarifies what is meant by the path integral \trajectories" of a spin system, or any other system with non-classical features [13]. Here we will construct a formal structure that builds on these two lines of work, and il- luminates the question posed in our first paragraph. We will also analyze several instructive examples, where we apply the formalism to analyze quasi-realistic thought experiments. 1 Mathematics of History States 1.1 History Space We will work with a vector space that allows for access to the evolution of a system at multiple times. This vector space is called the history Hilbert space H, and is defined by the tensor product from right to left of the admissible Hilbert spaces of our system at sequential times. Explicitly, for n times t1 < ··· < tn, we have H := Htn · · · Ht1 (1) where Hti is the admissible Hilbert space at time ti. Restricting the admissible Hilbert spaces Ht1 and Htn corresponds to pre- and post-selection respectively. In this paper, we will be primarily concerned with history Hilbert spaces defined over a discrete set of times. It is possible to work with history Hilbert spaces over a continuum of times, but doing so requires the full apparatus of the Farhi-Gutmann path integral [13]. The history Hilbert space H is also equipped with bridging operators T (tj; ti), where T (tj; ti): Hti !Htj . These bridging operators encode unitary time evolution. 1.2 History States We would like to define a mathematical object that encodes the evolution of our system through time { a notion of \quantum state" for history space { that supports an inner product and probability interpretation. One might at first think that an element of H such as j (tn)i · · · j (t1)i would be the desired mathematical object, but a different concept appears more fruitful. For us, \history states" are elements of the linear space Proj(H) spanned by projectors from H!H. Henceforth, we will call Proj(H) the \history state space." For example, if H is the history space of a spin-1/2 particle at three times t1 < t2 < t3, then an example history state is [z−] [x+] [z+] (2) where we use the notation [z+] := jz+ihz+j. The history state in Eqn. (2) can be considered as a quantum trajectory: the particle is spin up in the z-direction at time t1, spin-up in 2 the x-direction at time t2, and spin-down in the z-direction at time t3. Since Proj(H) is a complex vector space, another example of a history state is α [z−] [x+] [z+] + β [z+] [x−] [z+] (3) for complex coefficients α and β. The history state in Eqn. (3) is a superposition of the history states [z−] [x+] [z+] and [z+] [x−] [z+]. It can be interpreted, roughly, as meaning that the particle takes both quantum trajectories, but with different amplitudes. Precise physical interpretation of history states like the one in Eqn. (3) requires more structure. For example, it is not obviously true (and usually is false) that one can measure the particle to take the trajectory [z−] [x+] [z+] with probability proportional to jαj2, or the other trajectory with probability proportional to jβj2. To discuss probabilities, generalizing the Born rule, we need an inner product. Furthermore, we have not yet defined which mathematical objects correspond to measurable quantities. For a history space H with n times t1 < ··· < tn, a general history state takes the form X jΨ) = αi[ai(tn)] · · · [ai(t1)] (4) i where each [ai(tj)] is a one-dimensional projector [ai(tj)] : Htj !Htj , and αi 2 C. We have decorated the history state with a soft ket j · ) which is suggestive of a wave function. In our theory, a history state is the natural generalization of a wave function, and has similar algebraic properties. Note that such sums of products of projectors will also accommodate products of hermitean operators more generally. 1.3 Inner Product In defining a physically appropriate inner product between history states the K operator, defined by X KjΨ) = αiK([ai(tn)] · · · [ai(t1)]) (5) i X = αi[ai(tn)]T (tn; tn−1)[ai(tn−1)] · · · [ai(t2)]T (t2; t1)[ai(t1)] (6) i where T (tj; ti) is the bridging operator associated with the history space, plays a central role. Note that K maps a history state in Proj(H) to an operator which takes Ht1 !Htn . Using the K operator, we equip history states with the positive semi-definite inner product [1] h i (ΦjΨ) := Tr (KjΦ))yKjΨ) (7) This inner product induces a semi-norm on history states, and we call (ΨjΨ) the \weight" of jΨ). It reflects the probability of jΨ) occurring. Note that the inner product is degenerate, in the sense that (ΨjΨ) = 0 does not imply that jΨ) = 0. 3 We say that a history state jΨ) is normalized if (ΨjΨ) = 1. If jΨ) has non-zero weight, then jΨ) jΨ) = (8) p(ΨjΨ) is normalized. We will use this \bar" notation throughout the rest of the paper. At this point, an example may be welcome. If H is the history space of a spin-1/2 particle at three times t1 < t2 < t3 equipped with a trivial bridging operator T = 1, then 1 K [z−] [x+] [z+] = jz−ihz+j (9) 2 Let us interpret the factor of 1=2 on the right-hand side of the above equation. Since the bridging operator for the history space is the identity, any particle which is spin-up in the z-direction at time t1 will continue to be in that state at times t2 and t3. However, the history state in Equation (9) is [z−] [x+] [z+] which appears to subvert the unitary evolution imposed by the bridging operator. This subversion comes at a cost, which is the amplitude 1=2. We will later see that histories which do not follow unitary evolution have a suppressed probability of being measured, with the suppression factor proportional to the absolute square of the coefficient generated by the K operator. In the case of Equation (9), the \suppression" is a factor of j1=2j2 = 1=4. 1.4 Families We will be interested in subspaces that both admit an orthogonal basis (possibly including history states of zero norm), and contain the history state 1tn · · · 1t1 , which corresponds to a system being in a superposition of all possible states at each time. The orthogonal set of history states which spans such a subspace will be called a \family" of history states. More formally: i Definition We say fjY )g is a family of history states if i j i i (1) (Y jY ) = 0 for i 6= j and (Y jY ) = 0 or 1, and P i (2) i ci jY ) = 1tn · · · 1t1 for some complex ci. Requirement (1) is Griffiths’ \strong consistent histories condition" [1]-[3]. Contrary to earlier work, we see no reason to impose the requirement that history states, regarded as operators, commute. It is not essential that history states commute i i since they are not themselves observables. However, projectors of the form jY )(Y j are i i j j observables. By orthogonality, [jY )(Y j; jY )(Y j] = 0 for all i; j, so commutativity of the corresponding observables is automatic.
Recommended publications
  • Unrestricted Immigration and the Foreign Dominance Of

    Unrestricted Immigration and the Foreign Dominance Of

    Unrestricted Immigration and the Foreign Dominance of United States Nobel Prize Winners in Science: Irrefutable Data and Exemplary Family Narratives—Backup Data and Information Andrew A. Beveridge, Queens and Graduate Center CUNY and Social Explorer, Inc. Lynn Caporale, Strategic Scientific Advisor and Author The following slides were presented at the recent meeting of the American Association for the Advancement of Science. This project and paper is an outgrowth of that session, and will combine qualitative data on Nobel Prize Winners family histories along with analyses of the pattern of Nobel Winners. The first set of slides show some of the patterns so far found, and will be augmented for the formal paper. The second set of slides shows some examples of the Nobel families. The authors a developing a systematic data base of Nobel Winners (mainly US), their careers and their family histories. This turned out to be much more challenging than expected, since many winners do not emphasize their family origins in their own biographies or autobiographies or other commentary. Dr. Caporale has reached out to some laureates or their families to elicit that information. We plan to systematically compare the laureates to the population in the US at large, including immigrants and non‐immigrants at various periods. Outline of Presentation • A preliminary examination of the 609 Nobel Prize Winners, 291 of whom were at an American Institution when they received the Nobel in physics, chemistry or physiology and medicine • Will look at patterns of
  • Frank Wilczek on the World's Numerical Recipe

    Frank Wilczek on the World's Numerical Recipe

    Note by All too often, we ignore goals, genres, or Frank Wilczek values, or we assume that they are so apparent that we do not bother to high- light them. Yet judgments about whether an exercise–a paper, a project, an essay Frank Wilczek response on an examination–has been done intelligently or stupidly are often on the dif½cult for students to fathom. And since these evaluations are not well world’s understood, few if any lessons can be numerical drawn from them. Laying out the criteria recipe by which judgments of quality are made may not suf½ce in itself to improve qual- ity, but in the absence of such clari½- cation, we have little reason to expect our students to go about their work intelligently. Twentieth-century physics began around 600 b.c. when Pythagoras of Samos pro- claimed an awesome vision. By studying the notes sounded by plucked strings, Pythagoras discovered that the human perception of harmony is connected to numerical ratios. He examined strings made of the same material, having the same thickness, and under the same tension, but of different lengths. Under these conditions, he found that the notes sound harmonious precisely when the ratio of the lengths of string can be expressed in small whole numbers. For example, the length ratio Frank Wilczek, Herman Feshbach Professor of Physics at MIT, is known, among other things, for the discovery of asymptotic freedom, the develop- ment of quantum chromodynamics, the invention of axions, and the discovery and exploitation of new forms of quantum statistics (anyons).
  • The Future of the Quantum T by JAMES BJORKEN

    The Future of the Quantum T by JAMES BJORKEN

    FOREWORD The Future of the Quantum T by JAMES BJORKEN N THIS ISSUE of the Beam Line, we cele- brate the one hundredth anniversary of the birth of the quantum theory. The story of Ihow Max Planck started it all is one of the most marvelous in all of science. It is a favorite of mine, so much so that I have already written about it (see “Particle Physics—Where Do We Go From Here?” in the Winter 1992 Beam Line, Vol. 22, No. 4). Here I will only quote again what the late Abraham Pais said about Planck: “His reasoning was mad, but his madness had that divine quality that only the greatest transitional figures can bring to science.”* A century later, the madness has not yet com- pletely disappeared. Science in general has a way of producing results which defy human intuition. But it is fair to say that the winner in this category is the quantum theory. In my mind Max Planck, circa 1910 quantum paradoxes such as the Heisenberg (Courtesy AIP Emilio Segrè Visual Archives) uncertainty principle, Schrödinger’s cat, “collapse of the wave packet,” and so forth are far more perplexing and challenging than those of relativity, whether they be the twin paradoxes of special relativity or the black hole physics of classical general relativity. It is often said that no one really understands quantum theory, and I would be the last to disagree. In the contributions to this issue, the knotty questions of the interpreta- tion of quantum theory are, mercifully, not addressed. There will be no mention of the debates between Einstein and Bohr, nor the later attempts by *Abraham Pais, Subtle is the Lord: Science and the Life of Albert Einstein, Oxford U.
  • Quantum Theory Cannot Consistently Describe the Use of Itself

    Quantum Theory Cannot Consistently Describe the Use of Itself

    ARTICLE DOI: 10.1038/s41467-018-05739-8 OPEN Quantum theory cannot consistently describe the use of itself Daniela Frauchiger1 & Renato Renner1 Quantum theory provides an extremely accurate description of fundamental processes in physics. It thus seems likely that the theory is applicable beyond the, mostly microscopic, domain in which it has been tested experimentally. Here, we propose a Gedankenexperiment 1234567890():,; to investigate the question whether quantum theory can, in principle, have universal validity. The idea is that, if the answer was yes, it must be possible to employ quantum theory to model complex systems that include agents who are themselves using quantum theory. Analysing the experiment under this presumption, we find that one agent, upon observing a particular measurement outcome, must conclude that another agent has predicted the opposite outcome with certainty. The agents’ conclusions, although all derived within quantum theory, are thus inconsistent. This indicates that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner. 1 Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland. Correspondence and requests for materials should be addressed to R.R. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:3711 | DOI: 10.1038/s41467-018-05739-8 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-05739-8 “ 1”〉 “ 1”〉 irect experimental tests of quantum theory are mostly Here, | z ¼À2 D and | z ¼þ2 D denote states of D depending restricted to microscopic domains. Nevertheless, quantum on the measurement outcome z shown by the devices within the D “ψ ”〉 “ψ ”〉 theory is commonly regarded as being (almost) uni- lab.
  • Ettore Majorana: Genius and Mystery

    Ettore Majorana: Genius and Mystery

    «ETTORE MAJORANA» FOUNDATION AND CENTRE FOR SCIENTIFIC CULTURE TO PAY A PERMANENT TRIBUTE TO GALILEO GALILEI, FOUNDER OF MODERN SCIENCE AND TO ENRICO FERMI, THE "ITALIAN NAVIGATOR", FATHER OF THE WEAK FORCES ETTORE MAJORANA CENTENARY ETTORE MAJORANA: GENIUS AND MYSTERY Antonino Zichichi ETTORE MAJORANA: GENIUS AND MYSTERY Antonino Zichichi ABSTRACT The geniality of Ettore Majorana is discussed in the framework of the crucial problems being investigated at the time of his activity. These problems are projected to our present days, where the number of space-time dimensions is no longer four and where the unification of the fundamental forces needs the Majorana particle: neutral, with spin ½ and identical to its antiparticle. The mystery of the way Majorana disappeared is restricted to few testimonies, while his geniality is open to all eminent physicists of the XXth century, who had the privilege of knowing him, directly or indirectly. 3 44444444444444444444444444444444444 ETTORE MAJORANA: GENIUS AND MYSTERY Antonino Zichichi CONTENTS 1 LEONARDO SCIASCIA’S IDEA 5 2 ENRICO FERMI: FEW OTHERS IN THE WORLD COULD MATCH MAJORANA’S DEEP UNDERSTANDING OF THE PHYSICS OF THE TIME 7 3 RECOLLECTIONS BY ROBERT OPPENHEIMER 19 4 THE DISCOVERY OF THE NEUTRON – RECOLLECTIONS BY EMILIO SEGRÉ AND GIANCARLO WICK 21 5 THE MAJORANA ‘NEUTRINOS’ – RECOLLECTIONS BY BRUNO PONTECORVO – THE MAJORANA DISCOVERY ON THE DIRAC γ- MATRICES 23 6 THE FIRST COURSE OF THE SUBNUCLEAR PHYSICS SCHOOL (1963): JOHN BELL ON THE DIRAC AND MAJORANA NEUTRINOS 45 7 THE FIRST STEP TO RELATIVISTICALLY DESCRIBE PARTICLES WITH ARBITRARY SPIN 47 8 THE CENTENNIAL OF THE BIRTH OF A GENIUS – A HOMAGE BY THE INTERNATIONAL SCIENTIFIC COMMUNITY 53 REFERENCES 61 4 44444444444444444444444444444444444 Ettore Majorana’s photograph taken from his university card dated 3rd November 1923.
  • Nobel Laureates Endorse Joe Biden

    Nobel Laureates Endorse Joe Biden

    Nobel Laureates endorse Joe Biden 81 American Nobel Laureates in Physics, Chemistry, and Medicine have signed this letter to express their support for former Vice President Joe Biden in the 2020 election for President of the United States. At no time in our nation’s history has there been a greater need for our leaders to appreciate the value of science in formulating public policy. During his long record of public service, Joe Biden has consistently demonstrated his willingness to listen to experts, his understanding of the value of international collaboration in research, and his respect for the contribution that immigrants make to the intellectual life of our country. As American citizens and as scientists, we wholeheartedly endorse Joe Biden for President. Name Category Prize Year Peter Agre Chemistry 2003 Sidney Altman Chemistry 1989 Frances H. Arnold Chemistry 2018 Paul Berg Chemistry 1980 Thomas R. Cech Chemistry 1989 Martin Chalfie Chemistry 2008 Elias James Corey Chemistry 1990 Joachim Frank Chemistry 2017 Walter Gilbert Chemistry 1980 John B. Goodenough Chemistry 2019 Alan Heeger Chemistry 2000 Dudley R. Herschbach Chemistry 1986 Roald Hoffmann Chemistry 1981 Brian K. Kobilka Chemistry 2012 Roger D. Kornberg Chemistry 2006 Robert J. Lefkowitz Chemistry 2012 Roderick MacKinnon Chemistry 2003 Paul L. Modrich Chemistry 2015 William E. Moerner Chemistry 2014 Mario J. Molina Chemistry 1995 Richard R. Schrock Chemistry 2005 K. Barry Sharpless Chemistry 2001 Sir James Fraser Stoddart Chemistry 2016 M. Stanley Whittingham Chemistry 2019 James P. Allison Medicine 2018 Richard Axel Medicine 2004 David Baltimore Medicine 1975 J. Michael Bishop Medicine 1989 Elizabeth H. Blackburn Medicine 2009 Michael S.
  • The Consistent Histories Approach to the Stern-Gerlach Experiment

    The Consistent Histories Approach to the Stern-Gerlach Experiment

    The Consistent Histories Approach to the Stern-Gerlach Experiment Ian Wilson An undergraduate thesis advised by Dr. David Craig submitted to the Department of Physics, Oregon State University in partial fulfillment of the requirements for the degree BSc in Physics Submitted on May 8, 2020 Acknowledgments I would like to thank Dr. David Craig, for guiding me through an engaging line of research, as well as Dr. David McIntyre, Dr. Elizabeth Gire, Dr. Corinne Manogue and Dr. Janet Tate for developing the quantum curriculum from which this thesis is rooted. I would also like to thank all of those who gave me the time, space, and support I needed while writing this. This includes (but is certainly not limited to) my partner Brooke, my parents Joy and Kevin, my housemate Cheyanne, the staff of Interzone, and my friends Saskia, Rachel and Justin. Abstract Standard quantum mechanics makes foundational assumptions to describe the measurement process. Upon interaction with a “classical measurement apparatus”, a quantum system is subjected to postulated “state collapse” dynamics. We show that framing measurement around state collapse and ill-defined classical observers leads to interpretational issues, and artificially limits the scope of quantum theory. This motivates describing measurement as a unitary process instead. In the context of the Stern-Gerlach experiment, the measurement of an electron’s spin angular momentum is explained as the entanglement of its spin and position degrees of freedom. Furthermore, the electron-environment interaction is also detailed as part of the measurement process. The environment plays the role of a record keeper, establishing the “facts of the universe” to make the measurement’s occurrence objective.
  • Theoretical Physics Group Decoherent Histories Approach: a Quantum Description of Closed Systems

    Theoretical Physics Group Decoherent Histories Approach: a Quantum Description of Closed Systems

    Theoretical Physics Group Department of Physics Decoherent Histories Approach: A Quantum Description of Closed Systems Author: Supervisor: Pak To Cheung Prof. Jonathan J. Halliwell CID: 01830314 A thesis submitted for the degree of MSc Quantum Fields and Fundamental Forces Contents 1 Introduction2 2 Mathematical Formalism9 2.1 General Idea...................................9 2.2 Operator Formulation............................. 10 2.3 Path Integral Formulation........................... 18 3 Interpretation 20 3.1 Decoherent Family............................... 20 3.1a. Logical Conclusions........................... 20 3.1b. Probabilities of Histories........................ 21 3.1c. Causality Paradox........................... 22 3.1d. Approximate Decoherence....................... 24 3.2 Incompatible Sets................................ 25 3.2a. Contradictory Conclusions....................... 25 3.2b. Logic................................... 28 3.2c. Single-Family Rule........................... 30 3.3 Quasiclassical Domains............................. 32 3.4 Many History Interpretation.......................... 34 3.5 Unknown Set Interpretation.......................... 36 4 Applications 36 4.1 EPR Paradox.................................. 36 4.2 Hydrodynamic Variables............................ 41 4.3 Arrival Time Problem............................. 43 4.4 Quantum Fields and Quantum Cosmology.................. 45 5 Summary 48 6 References 51 Appendices 56 A Boolean Algebra 56 B Derivation of Path Integral Method From Operator
  • Consistent Histories

    Consistent Histories

    Chapter 12 Local Weak Property Realism: Consistent Histories Earlier, we surmised that weak property realism can escape the strictures of Bell’s theorem and KS. In this chapter, we look at an interpretation of quantum mechanics that does just that, namely, the Consistent Histories Interpretation (CH). 12.1 Consistent Histories The basic idea behind CH is that quantum mechanics is a stochastic theory operating on quantum histories. A history a is a temporal sequence of properties held by a system. For example, if we just consider spin, for an electron a history could be as follows: at t0, Sz =1; at t1, Sx =1; at t2, Sy = -1, where spin components are measured in units of h /2. The crucial point is that in this interpretation the electron is taken to exist independently of us and to have such spin components at such times, while in the standard view 1, 1, and -1 are just experimental return values. In other words, while the standard interpretation tries to provide the probability that such returns would be obtained upon measurement, CH provides the probability Pr(a) that the system will have history a, that is, such and such properties at different times. Hence, CH adopts non-contextual property realism (albeit of the weak sort) and dethrones measurement from the pivotal position it occupies in the orthodox interpretation. To see how CH works, we need first to look at some of the formal features of probability. 12.2 Probability Probability is defined on a sample space S, the set of all the mutually exclusive outcomes of a state of affairs; each element e of S is a sample point to which one assigns a number Pr(e) satisfying the axioms of probability (of which more later).
  • Works of Love

    Works of Love

    reader.ad section 9/21/05 12:38 PM Page 2 AMAZING LIGHT: Visions for Discovery AN INTERNATIONAL SYMPOSIUM IN HONOR OF THE 90TH BIRTHDAY YEAR OF CHARLES TOWNES October 6-8, 2005 — University of California, Berkeley Amazing Light Symposium and Gala Celebration c/o Metanexus Institute 3624 Market Street, Suite 301, Philadelphia, PA 19104 215.789.2200, [email protected] www.foundationalquestions.net/townes Saturday, October 8, 2005 We explore. What path to explore is important, as well as what we notice along the path. And there are always unturned stones along even well-trod paths. Discovery awaits those who spot and take the trouble to turn the stones. -- Charles H. Townes Table of Contents Table of Contents.............................................................................................................. 3 Welcome Letter................................................................................................................. 5 Conference Supporters and Organizers ............................................................................ 7 Sponsors.......................................................................................................................... 13 Program Agenda ............................................................................................................. 29 Amazing Light Young Scholars Competition................................................................. 37 Amazing Light Laser Challenge Website Competition.................................................. 41 Foundational
  • The Discovery of Asymptotic Freedom

    The Discovery of Asymptotic Freedom

    The Discovery of Asymptotic Freedom The 2004 Nobel Prize in Physics, awarded to David Gross, Frank Wilczek, and David Politzer, recognizes the key discovery that explained how quarks, the elementary constituents of the atomic nucleus, are bound together to form protons and neutrons. In 1973, Gross and Wilczek, working at Princeton, and Politzer, working independently at Harvard, showed that the attraction between quarks grows weaker as the quarks approach one another more closely, and correspondingly that the attraction grows stronger as the quarks are separated. This discovery, known as “asymptotic freedom,” established quantum chromodynamics (QCD) as the correct theory of the strong nuclear force, one of the four fundamental forces in Nature. At the time of the discovery, Wilczek was a 21-year-old graduate student working under Gross’s supervision at Princeton, while Politzer was a 23-year-old graduate student at Harvard. Currently Gross is the Director of the Kavli Institute for Theoretical Physics at the University of California at Santa Barbara, and Wilczek is the Herman Feshbach Professor of Physics at MIT. Politzer is Professor of Theoretical Physics at Caltech; he joined the Caltech faculty in 1976. Of the four fundamental forces --- the others besides the strong nuclear force are electromagnetism, the weak nuclear force (responsible for the decay of radioactive nuclei), and gravitation --- the strong force was by far the most poorly understood in the early 1970s. It had been suggested in 1964 by Caltech physicist Murray Gell-Mann that protons and neutrons contain more elementary objects, which he called quarks. Yet isolated quarks are never seen, indicating that the quarks are permanently bound together by powerful nuclear forces.
  • High Energy Physics Quantum Information Science Awards Abstracts

    High Energy Physics Quantum Information Science Awards Abstracts

    High Energy Physics Quantum Information Science Awards Abstracts Towards Directional Detection of WIMP Dark Matter using Spectroscopy of Quantum Defects in Diamond Ronald Walsworth, David Phillips, and Alexander Sushkov Challenges and Opportunities in Noise‐Aware Implementations of Quantum Field Theories on Near‐Term Quantum Computing Hardware Raphael Pooser, Patrick Dreher, and Lex Kemper Quantum Sensors for Wide Band Axion Dark Matter Detection Peter S Barry, Andrew Sonnenschein, Clarence Chang, Jiansong Gao, Steve Kuhlmann, Noah Kurinsky, and Joel Ullom The Dark Matter Radio‐: A Quantum‐Enhanced Dark Matter Search Kent Irwin and Peter Graham Quantum Sensors for Light-field Dark Matter Searches Kent Irwin, Peter Graham, Alexander Sushkov, Dmitry Budke, and Derek Kimball The Geometry and Flow of Quantum Information: From Quantum Gravity to Quantum Technology Raphael Bousso1, Ehud Altman1, Ning Bao1, Patrick Hayden, Christopher Monroe, Yasunori Nomura1, Xiao‐Liang Qi, Monika Schleier‐Smith, Brian Swingle3, Norman Yao1, and Michael Zaletel Algebraic Approach Towards Quantum Information in Quantum Field Theory and Holography Daniel Harlow, Aram Harrow and Hong Liu Interplay of Quantum Information, Thermodynamics, and Gravity in the Early Universe Nishant Agarwal, Adolfo del Campo, Archana Kamal, and Sarah Shandera Quantum Computing for Neutrino‐nucleus Dynamics Joseph Carlson, Rajan Gupta, Andy C.N. Li, Gabriel Perdue, and Alessandro Roggero Quantum‐Enhanced Metrology with Trapped Ions for Fundamental Physics Salman Habib, Kaifeng Cui1,