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Cambridge University Press eBooks

Introduction to the Cambridge University Press Edition

Christopher A. Fuchs

Published Jan 6, 2011• 0 citations
Publisher

Abstract

I imagine it is hard to write a book; I am not sure I could ever do that. But since I discovered the medium of email in 1990, I have never stopped writing. I write, rewrite, and hone my ideas almost exclusively with the aid and clarifying influence of that wonderful tool. The influence may be subliminal, but it is there overpoweringly: if you really want to get an idea worked out for yourself, make it understandable to another mind through correspondence, where your face cannot be seen, but your voice must be heard – do it over and over again, gearing each presentation to each individual mind. Connect the idea to every aspect of life you can. If you stand the test, you are making progress, and often unbeknownst to yourself, transforming the initial seed of an idea into a more resilient and compelling structure. This collection of emails, graciously reprinted by Cambridge University Press with the encouragement of Simon Capelin, is predominantly a record of my honing one such idea – The Paulian Idea – as I came of age with the field of quantum information. If I can entertain the reader along the way, that is just as well too.

DOI
10.1017/cbo9780511762789.002

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reprinted in the British trade journal Physics World in 1990, three separate and 5 lengthy replies from establishment physicists were printed in subsequent issues. For outsiders, especially scientists who rely on physicist's theories in their own fields, this situation is disquieting. Moreover, many recall their introduction to quantum mechanics as a startling, if not shocking, experience. A molecular biologist related how he had started in theoretical physics but, after hearing the ideology of quantum mechanics, marched straight to the Reg­ istrar's office and switched fields. A colleague recalled how her undergraduate chemistry professor religiously entertained queries from the class - until one day he began with the words: "No questions will be permitted on today's lecture." The topic, of course, was quantum mechanics. My father, an organic chemist at a Midwestern university, also had to give that dreaded annual lecture. Around age 16, I picked up a little book he used to prepare and was perplexed by the author's tone, which seemed apologetic to the point of pleading. It was my first brush with the quantum theory. 6 Eventually, I went to graduate school in physics. By then I had acquired an historical bent, which developed out of an episode in my freshman year in college. To relieve the tedium of the introductory physics course, I set out to understand Einstein's theory of relativity (the so-called Special Theory of 1905, not the later and more difficult General Theory of 1915). This went badly at first.

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The review by Daniel M. Greenberger of Russell Stannard’s The New World of Mr. Tompkins (Physics Today, June 2000, page 57) intrigued me sufficiently that I obtained a copy of this revised and extended version of George Gamow’s (now dated) three classic works for the general reader. I agree with much of what Greenberger writes. Stannard has “done a remarkable job of preserving the mood and feeling of the original,” and I hope that at least some of the few small slips will be edited out before this commendable book is reprinted.One error, however, struck me rather forcibly. In the diagram on page 159, the professor is lecturing to his evening audience, which contains the (as usual) dozing Mr. Tompkins. A slide of the Bohr-Sommerfeld orbits for principal quantum numbers n = 2,3 has been projected onto the screen. Unfortunately, the orbits with highest azimuthal quantum number (orbital angular momentum quantum number l) are shown as ellipses with the highest eccentricity, while the s-orbits (l = 0) are shown as circles. This confusion of “penetrating” with “nonpenetrating” orbits is common, occasioned perhaps by the recollection that in the wave-mechanical picture, the s-orbitals are spherically symmetrical, albeit with the important property that their probability densities peak at the origin. This property is of vital importance, for example, for the Lamb shift and the Fermi contact interaction in hyperfine structure, quite apart from the fact that the quantum defects are therefore largest for the s-orbitals in many-electron atoms. For comparison purposes, excellent diagrams of these two distinctly different forms of representation may be found in reference 11. H. E. White, Introduction to Atomic Spectra, McGraw-Hill, New York, (1934), pp. 47–71..How did this unfortunate mistake occur in the new work? On turning to its predecessor, 2 2. G. Gamow, Mr. Tompkins in Paperback, Cambridge U. Press, (1965) pp. 132–133. one finds on page 132 a picture containing the same Bohr–Sommerfeld orbits and, in addition, the quantization rules in the “old quantum theory” and formulas for the energies. (A keen-eyed reader will spot that the electronic charge e is raised to the wrong power in two places.) Moreover, in this diagram by Gamow himself, the orbitals are labeled in exactly the same incorrect fashion: The s- and d-labels should be interchanged.This brought to mind the amusing account in Gamow’s delightful “informal autobiography” My World Line (I write from memory of a book read well over two decades ago), in which he describes his initial difficulties on arrival from Russia at the University in Göttingen, home of the “new quantum theory,” around 1928. The easier problems having already been solved, his contemporaries were then working on aspects of atomic theory requiring considerable dexterity in advanced special function theory, and the sort of heavy algebraic manipulation (“exerei”) that Gamow disliked, topology and group theory being more appealing to him. On a certain day, the frustrated young Gamow was sitting on a park bench, wondering what to do. His eye fell on the description by Ernest Rutherford, in the Philosophical Magazine that he happened to be carrying, of a now rather implausible idea invoked to explain the escape of alpha particles from the atomic nucleus. In a flash of inspiration, Gamow sketched out in his mind the correct explanation, involving “quantum tunneling” and the now famous “Gamow factor.” When one considers the author’s age of barely 24 years, the ensuing paper 3 3. G. Gamow, Z. Phys. 51, 204 (1928) https://doi.org/10.1007/BF01343196. makes an astonishing impression of both maturity and unusual clarity, attributes that of course lent themselves admirably in due course to writing the “Tompkins” books.Making a hypothesis of my own, I surmised that his inattention to detail regarding the electron orbitals was perhaps a consequence of this early predilection for nuclear, rather than atomic, physics. But no—on turning to my last source, 4 4. G. Gamow, Mr. Tompkins Explores the Atom, Cambridge U. Press, (1946), pp. 72–74. I found not only the best drawing of all three (again by Gamow), but the orbits correctly labeled! No doubt the professor himself could comment most aptly on this mutilation of his original over time.REFERENCESSection:ChooseTop of pageREFERENCES <<1. H. E. White, Introduction to Atomic Spectra, McGraw-Hill, New York, (1934), pp. 47–71. Google Scholar2. G. Gamow, Mr. Tompkins in Paperback, Cambridge U. Press, (1965) pp. 132–133. Google Scholar3. G. Gamow, Z. Phys. 51, 204 (1928) https://doi.org/10.1007/BF01343196. Google ScholarCrossref, CAS4. G. Gamow, Mr. Tompkins Explores the Atom, Cambridge U. Press, (1946), pp. 72–74. Google Scholar© 2001 American Institute of Physics.

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12 June 1999, “Interest in Pauli” I have come across a reference to a paper of yours that I have not been able to obtain. May I ask of you to send me a reprint of it? The paper is: C. P. Enz, “Wolfgang Pauli and the Role of the Observer in Modern Physics,” in Philosophy of the Natural Sciences: Proceedings of the 13th International Wittgenstein Symposium , edited by P. Weingartner and G. Schurz (Verlag Holder–Pichler–Temsky, Vienna, 1989), pp. 110–119. I have read several of your other papers on Pauli's thought and have been uniformly pleased with each. I am especially interested in his ideas concerning the demise of the “detached-observer” notion within quantum theory. (I would also be interested in any of your other works on the subject that may have been written since your 1992 article, “Wolfgang Pauli between Quantum Reality and the Royal Path of Dreams.” This is the latest one that I am aware of.) About myself, I am a theoretical physicist at Caltech who specializes in quantum information theory and quantum computing. I am well acquainted with your colleague Nicolas Gisin at the University of Geneva. 21 August 1999, “One More Article?” Upon my return from Cambridge a couple of weeks ago, I found in my mailbox your package full of wonderful papers! Thank you so much.

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I imagine it is hard to write a book; I am not sure I could ever do that. But since I discovered the medium of email in 1990, I have never stopped writing. I write, rewrite, and hone my ideas almost exclusively with the aid and clarifying influence of that wonderful tool. The influence may be subliminal, but it is there overpoweringly: if you really want to get an idea worked out for yourself, make it understandable to another mind through correspondence, where your face cannot be seen, but your voice must be heard – do it over and over again, gearing each presentation to each individual mind. Connect the idea to every aspect of life you can. If you stand the test, you are making progress, and often unbeknownst to yourself, transforming the initial seed of an idea into a more resilient and compelling structure. This collection of emails, graciously reprinted by Cambridge University Press with the encouragement of Simon Capelin, is predominantly a record of my honing one such idea – The Paulian Idea – as I came of age with the field of quantum information. If I can entertain the reader along the way, that is just as well too.
reprinted in the British trade journal Physics World in 1990, three separate and 5 lengthy replies from establishment physicists were printed in subsequent issues. For outsiders, especially scientists who rely on physicist's theories in their own fields, this situation is disquieting. Moreover, many recall their introduction to quantum mechanics as a startling, if not shocking, experience. A molecular biologist related how he had started in theoretical physics but, after hearing the ideology of quantum mechanics, marched straight to the Reg­ istrar's office and switched fields. A colleague recalled how her undergraduate chemistry professor religiously entertained queries from the class - until one day he began with the words: "No questions will be permitted on today's lecture." The topic, of course, was quantum mechanics. My father, an organic chemist at a Midwestern university, also had to give that dreaded annual lecture. Around age 16, I picked up a little book he used to prepare and was perplexed by the author's tone, which seemed apologetic to the point of pleading. It was my first brush with the quantum theory. 6 Eventually, I went to graduate school in physics. By then I had acquired an historical bent, which developed out of an episode in my freshman year in college. To relieve the tedium of the introductory physics course, I set out to understand Einstein's theory of relativity (the so-called Special Theory of 1905, not the later and more difficult General Theory of 1915). This went badly at first.
The review by Daniel M. Greenberger of Russell Stannard’s The New World of Mr. Tompkins (Physics Today, June 2000, page 57) intrigued me sufficiently that I obtained a copy of this revised and extended version of George Gamow’s (now dated) three classic works for the general reader. I agree with much of what Greenberger writes. Stannard has “done a remarkable job of preserving the mood and feeling of the original,” and I hope that at least some of the few small slips will be edited out before this commendable book is reprinted.One error, however, struck me rather forcibly. In the diagram on page 159, the professor is lecturing to his evening audience, which contains the (as usual) dozing Mr. Tompkins. A slide of the Bohr-Sommerfeld orbits for principal quantum numbers n = 2,3 has been projected onto the screen. Unfortunately, the orbits with highest azimuthal quantum number (orbital angular momentum quantum number l) are shown as ellipses with the highest eccentricity, while the s-orbits (l = 0) are shown as circles. This confusion of “penetrating” with “nonpenetrating” orbits is common, occasioned perhaps by the recollection that in the wave-mechanical picture, the s-orbitals are spherically symmetrical, albeit with the important property that their probability densities peak at the origin. This property is of vital importance, for example, for the Lamb shift and the Fermi contact interaction in hyperfine structure, quite apart from the fact that the quantum defects are therefore largest for the s-orbitals in many-electron atoms. For comparison purposes, excellent diagrams of these two distinctly different forms of representation may be found in reference 11. H. E. White, Introduction to Atomic Spectra, McGraw-Hill, New York, (1934), pp. 47–71..How did this unfortunate mistake occur in the new work? On turning to its predecessor, 2 2. G. Gamow, Mr. Tompkins in Paperback, Cambridge U. Press, (1965) pp. 132–133. one finds on page 132 a picture containing the same Bohr–Sommerfeld orbits and, in addition, the quantization rules in the “old quantum theory” and formulas for the energies. (A keen-eyed reader will spot that the electronic charge e is raised to the wrong power in two places.) Moreover, in this diagram by Gamow himself, the orbitals are labeled in exactly the same incorrect fashion: The s- and d-labels should be interchanged.This brought to mind the amusing account in Gamow’s delightful “informal autobiography” My World Line (I write from memory of a book read well over two decades ago), in which he describes his initial difficulties on arrival from Russia at the University in Göttingen, home of the “new quantum theory,” around 1928. The easier problems having already been solved, his contemporaries were then working on aspects of atomic theory requiring considerable dexterity in advanced special function theory, and the sort of heavy algebraic manipulation (“exerei”) that Gamow disliked, topology and group theory being more appealing to him. On a certain day, the frustrated young Gamow was sitting on a park bench, wondering what to do. His eye fell on the description by Ernest Rutherford, in the Philosophical Magazine that he happened to be carrying, of a now rather implausible idea invoked to explain the escape of alpha particles from the atomic nucleus. In a flash of inspiration, Gamow sketched out in his mind the correct explanation, involving “quantum tunneling” and the now famous “Gamow factor.” When one considers the author’s age of barely 24 years, the ensuing paper 3 3. G. Gamow, Z. Phys. 51, 204 (1928) https://doi.org/10.1007/BF01343196. makes an astonishing impression of both maturity and unusual clarity, attributes that of course lent themselves admirably in due course to writing the “Tompkins” books.Making a hypothesis of my own, I surmised that his inattention to detail regarding the electron orbitals was perhaps a consequence of this early predilection for nuclear, rather than atomic, physics. But no—on turning to my last source, 4 4. G. Gamow, Mr. Tompkins Explores the Atom, Cambridge U. Press, (1946), pp. 72–74. I found not only the best drawing of all three (again by Gamow), but the orbits correctly labeled! No doubt the professor himself could comment most aptly on this mutilation of his original over time.REFERENCESSection:ChooseTop of pageREFERENCES <<1. H. E. White, Introduction to Atomic Spectra, McGraw-Hill, New York, (1934), pp. 47–71. Google Scholar2. G. Gamow, Mr. Tompkins in Paperback, Cambridge U. Press, (1965) pp. 132–133. Google Scholar3. G. Gamow, Z. Phys. 51, 204 (1928) https://doi.org/10.1007/BF01343196. Google ScholarCrossref, CAS4. G. Gamow, Mr. Tompkins Explores the Atom, Cambridge U. Press, (1946), pp. 72–74. Google Scholar© 2001 American Institute of Physics.
I was honored to see my book Quantum Information: An Overview (Springer, 2007) reviewed alongside David Mermin’s masterful new textbook ( Quantum Computer Science: An Introduction, Cambridge University Press, 2007). However, I was disappointed by reviewer Barbara Terhal’s facile and inappropriate approach (Physics Today, Physics Today 0031-9228 61 3 2008 54 https://doi.org/10.1063/1.2897953. March 2008, page 54 ).Terhal states, “The preface of the book speaks of his intentions: to write a text that provides an overview of the fundamentals of the field.” However, my intent, which was thoroughly laid out in the preface, goes far beyond that characterization. As a result, my necessary constraints on the book are misrepresented and underappreciated. In particular, I made it clear that the book was intended as “a handy reference … that also treats foundational aspects of quantum mechanics connected with quantum information science.” Unlike Mermin’s excellent monograph, mine was never intended to serve as an easily read introduction to the field or to provide unique insight. An overview such as mine cannot be the same thing as a textbook and should not be evaluated as one.Terhal further complains that the monograph contains little by way of personal insight, but that point was made clear both in the foreword by Tommaso Toffoli and in the preface. When presenting a subject as nascent and controversial as quantum information science, it is a good idea, particularly in the case of an overview, not to inject too much of oneself.More surprisingly, after recognizing that my book does provide a comprehensive overview of this rapidly expanding area, the reviewer questions “whether there is an audience for such encyclopedic texts, especially given the easy access to online sources of information such as the arXiv e-print server and Wikipedia.” That question is relatively easily answered: Yes, there is periodically a need for a concise and comprehensive monograph that is above the anarchy and distortions on Wikipedia and to a lesser extent the e-print servers and that can serve those with mathematical training and limited free time to cull accurate treatments from the Web.Moreover, because quantum information science is an area that transcends physics itself, the physics itself can sometimes be distorted, a situation more prevalent in online offerings such as Wikipedia and e-prints. Can one seriously rely on Wikipedia and e-print servers as clear and valid guides to the foundation and breadth of quantum information science? Are those the sources where researchers outside the area can obtain an organized overview of the subject? The unevenness and unreliable nature of the perspectives offered on free portions of the Web are reasons why I chose to write Quantum Information in the first place.Another aspect of my monograph, also clearly noted in its preface, is that the book discusses “a number of pertinent … results from earlier decades of the twentieth century … because they will likely prove important to future progress in both quantum mechanics and information theory.” Terhal’s only mention of that aspect was apparently her reference to the unspecified portion of the text she considered “mathematical and superfluous detail.” My reason for including that extra material is to show the extent to which quantum information science is grounded in fundamental physics and is capable of making great contributions to quantum foundations, provided the physics remains squarely in view.Like a standard quantum measurement, the effect of this lukewarm book review is, in all likelihood, irreversible. Fortunately, though, many who have carefully read the book’s preface and who, therefore, have understood the entirety of its purpose and constraints have expressed their satisfaction with the book over the 16 months since its publication. Those readers have been glad to have a reliable source to guide them into this exploding body of literature.© 2008 American Institute of Physics.
12 June 1999, “Interest in Pauli” I have come across a reference to a paper of yours that I have not been able to obtain. May I ask of you to send me a reprint of it? The paper is: C. P. Enz, “Wolfgang Pauli and the Role of the Observer in Modern Physics,” in Philosophy of the Natural Sciences: Proceedings of the 13th International Wittgenstein Symposium , edited by P. Weingartner and G. Schurz (Verlag Holder–Pichler–Temsky, Vienna, 1989), pp. 110–119. I have read several of your other papers on Pauli's thought and have been uniformly pleased with each. I am especially interested in his ideas concerning the demise of the “detached-observer” notion within quantum theory. (I would also be interested in any of your other works on the subject that may have been written since your 1992 article, “Wolfgang Pauli between Quantum Reality and the Royal Path of Dreams.” This is the latest one that I am aware of.) About myself, I am a theoretical physicist at Caltech who specializes in quantum information theory and quantum computing. I am well acquainted with your colleague Nicolas Gisin at the University of Geneva. 21 August 1999, “One More Article?” Upon my return from Cambridge a couple of weeks ago, I found in my mailbox your package full of wonderful papers! Thank you so much.