ModernQuantum MechanicsJ. J. SakuraiRevised Edition
Modern Quantum Mechanics Revised Edition J. J. Sakurai Late, University of California, Los Angeles San Fu Tuan, Editor University of Hawaii, Manoa Addison-Wesley Publishing Company Reading, Massachusetts. Menlo Park, Califomia. New York Don Mills, Ontario. Wokingham, England. Amsterdam. Bonn Sydney. Singapore. Tokyo. Madrid. San Juan. Milan. Paris
Sponsoring Editor: Stuart W. JohnsonAssistant Editor: Jennifer DugganSenior Production Coordinator: Amy WillcuttManufacturing Manager:Roy LoganLibrary of Congress Cataloging-in-Publication DataSakurai, J.J.(Jun John),1933-1982Modern quantum mechanics / J. J. Sakurai ; San Fu Tuan, editor.Rev. ed.p.cm.Includes bibliographical references and index.ISBN 0-201-53929-21.Quantum theory.I.Tuan, San Fu,1932-.II.Title.QC174.12.S251994530.1'2—dc2093-17803CIPCopyright 1994 by Addison-Wesley Publishing Company, Inc.All rights reserved. No part of this publication may be rcproduced, stored ina retrieval system, or transmitted, in any form or by any means, electronic,mcchanical, photocopying, recording, or otherwise, without the prior writtenpermission of the pubisher. Printed in the United States of America.56783910-MA-9695
ForewordJ. J. Sakurai was always a very welcome guest here at CERN, for he was oneof those rare theorists to whom the experimental facts are even moreinteresting than the theoretical game itself. Nevertheless, he delighted intheoretical physics and in its teaching. a subject on which he held strongopinions. He thought that much theoretical physics teaching was both toonarrow and too remote from application: "...we see a number of sophisti-cated, yet uneducated, theoreticians who are conversant in the Lsz for-malism of the Heisenberg field operators, but do not know why an excitedatom radiates, or are ignorant of the quantum theoretic derivation ofRayleigh's law that accounts for the blueness of the sky.' And he insistedthat the student must be able to use what has been taught: "The reader whohas read the book but cannot do the exercises has learned nothing."He put these principles to work in his fine book Advanced QuantumMechanics (1967) and in Invariance Principles and Elementary Particles(1964), both of which have been very much used in the CERN library. Thisnew book, Modern Quantum Mechanics, should be used even more, by alarger and less specialized group. The book combines breadth of interestwith a thorough practicality. Its readers will find here what they need toknow, with a sustained and successful effort to make it intelligible.J. J. Sakurai's sudden death on November 1, 1982 left this bookunfinished. Reinhold Bertlmann and I helped Mrs. Sakurai sort out herhusband's papers at CERN. Among them we found a rough, handwrittenversion of most of the book and a large collection of exercises. Though onlythree chapters had been completely finished,it was clear that the bulk of thecreative work had been done. It was also clear that much work remained tofill in gaps, polish the writing, and put the manuscript in order.That the book is now finished is due to the determination of NorikoSakurai and the dedication of San Fu Tuan. Upon her husband's death,Mrs. Sakurai resolved immediately that his last effort should not go towaste. With great courage and dignity she became the driving force behindthe project, overcoming all obstacles and setting the high standards to bemaintained. San Fu Tuan willingly gave his time and energy to the editingand completion of Sakurai's work. Perhaps only others close to the hecticfield of high-energy theoretical physics can fully appreciate the sacrificeinvolved.For me personally, J. J. had long been far more than just a particu-larly distinguished colleague. It saddens me that we will never again laughtogether at physics and physicists and life in general, and that he will notsee the success of his last work. But I am happy that it has been brought tofruition.John S. BellCERN, Genevaili
Preface to the Revised EditionSince 1989 the Editor has enthusiastically pursued a revised edition ofModern Quantum Mechanics by his late great friend J. J. Sakurai, in orderto extend this text's usefulness into the twenty-first century. Much con-sultation took place with the panel of Sakurai friends who helped with theoriginal edition, but in particular with Professor Yasuo Hara of TsukubaUniversity and Professor Akio Sakurai of Kyoto Sangyo University inJapan.The major motivation for this project is to revise the main text.There are three important additions and/or changes to the revised edition,which otherwise preserves the original version unchanged. These includea reworking of certain portions of Section 5.2 on time-independent per-turbation theory for the degenerate case by Professor Kenneth Johnson ofM.I.T., taking into account a subtle point that has not been properly treatedby a number of texts on quantum mechanics in this country. ProfessorRoger Newton of Indiana University contributed refinements on lifetimebroadening in Stark effect, additional explanations of phase shifts at res-onances, the optical theorem, and on non-normalizable state. These appearas "remarks by the editor" or editor's note"in the revised edition. Pro-fessor Thomas Fulton of the Johns Hopkins University reworked his Cou-lomb Scattering contribution (Section 7.13) so that it now appears as ashorter text portion emphasizing the physics, with the mathematical detailsrelegated to Appendix CThough not a major part of the text, some additions were deemednecessary to take into account developments in quantum mechanics thathave become prominent since November 1, 1982. To this end, two sup-plements are included at the end of the text. Supplement I is on adiabaticchange and geometrical phase (popularized by M. V. Berry since 1983)and is actually an English translation of the supplement on this subjectAkio Sakurai for the Japanese version of ModernwrittenbyProfessorQuantum Mechanics (copyright Yoshioka-Shoten Publishing of Kyoto).Supplement II is on non-exponential decays written by my colleague here,Professor Xerxes Tata, and read over by Professor E. C. G. Sudarshan ofthe University of Texas at Austin. Though non-exponential decays have along history theoretically, experimental work on transition rates that testsindirectly such decays was done only in 1990. Introduction of additionalmaterial is of course a subjective matter on the part of the Editor; thereaders will evaluate for themselves its appropriateness. Thanks to Pro-fessor Akio Sakurai, the revised edition has been “finely toothcombed"for misprint errors of the first ten printings of the original edition. Mycolleague, Professor Sandip Pakvasa, provided overall guidance and en-couragement to me throughout this process of revision.iv