Table Of ContentCoherence
in Spectroscopy
and Modern Physics
NATO ADVANCED STUDY INSTITUTES SERIES
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Volume 35 - Correlation Functions and Quasiparticle Interactions
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Volume 37 - Coherence in Spectroscopy and Modern Physics
edited by F. T. Arecchi, R. Bonifacio, and M. O. Scully
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Coherence
in Spectroscopy
and Modern Physics
Edited by
F. T. Arecchi
University of Florence
and National Institute of Optics
Florence, Italy
R. Bonifacio
University ofM ilan
Milan, Italy
and
M.O. Scully
University of Arizona
Tucson, Arizona
PLENUM PRESS. NEW YORK AND LONDON
Published in cooperation with NATO Scientific Affairs Division
Library of Congress Cataloging in Publication Data
Nato Advanced Study Institute on Coherence in Spectroscopy and Modern Physics,
Versilia, Italy, 1977.
Coherence in spectroscopy and modern physics.
(NATO advanced study institutes series: Series B, Physics; v. 37)
"Proceedings of the NATO Advanced Study Institute on Coherence in Spectroscopy
and Modern Physics held at Villa LePianore, Versilia, Italy, July 17-30, 1977."
Includes index.
1. Coherence (Optics) - Congresses. 2. Spectrum analysis - Congresses. 3. Phys
ics - Congresses. I. Arecchi, F. T. II. Bonifacio, R. III. Scully, MarIan Orvil, 1939-
IV. Title. V. Series.
QC476.C6N37 1977 536 78-14474
ISBN-13: 978-1-4613-2873-5 e-ISBN-13: 978-1-4613-2871-1
001: 10.1007/978-1-4613-2871-1
Proceedings of the NATO Advanced Study Institute on Coherence in
Spectroscopy and Modern Physics held at Villa LePianore, Versilia,
Italy, July 17-30, 1977
© 1978 Plenum Press, New York
Softcover reprint of the hardcover 1s t edition 1978
A Division of Plenum Publishing Corporation
227 West 17th Street, New York, N.Y. 10011
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted,
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without permission from the Publisher
PREFACE
This volume contains the lectures and seminars presented at
the NATO Advanced Study Institute on "Coherence in Spectroscopy
and Modern Physics," the seventh course of the International School
of Quantum Electronics, affiliated with the "Ettore Majorana"
Centre for Scientific Culture, Erice, Sicily. The Institute was
held at Villa LePianore (Lucca), Versilia, Italy, July 17-30, 1977.
The International School of Quantum Electronics was started in
1970 with the aim of providing instruction for young researchers
and advanced students already engaged in the area of quantum
electronics or wishing to switch to this area from a different
background. From the outset the School has been under the
direction of Prof. F. T. Arecchi, then at the University of Pavia,
now at the University of Florence, and Dr. D. Roess of Siemens,
Munich. Each year the Directors choose a subject of particular
interest, alternating fundamental topics with technological ones,
and ask colleagues specifically competent in a given area to take
the scientific responsibility for that course.
The past courses were devoted to the following themes:
1971: "Physical and Technical Measurements with Lasers"
1972: "Nonlinear Optics and Short Pulses"
1973: "Laser Frontiers: Short Wavelength and High Powers"
1974: "Cooperative phenomena in Multicomponent Systems"
1975: "Molecular Spectroscopy and Photochemistry with Lasers"
1976: "Coherent Optical Engineering"
The purpose of the present course was to provide instruction
in the field of modern physics and spectroscopy as it is influenced
by coherent quantum-mechanical phenomena. It is generally acknow
ledged that this rapidly developing field of research, besides
offering an intellectual challenge, has had a significant impact
on modern technology.
Prof. R. Bonifacio, University of Milan, and Prof. M. o. Scully,
University of Arizona, undertook the scientific direction of the
v
PREFACE
present course, selecting the specific topics and lectures.
The lectures collected in this volume cover the basic concepts
and principles of coherence in quantum optics as well as in other
areas of physics together with the most promising applications.
We wish to express our appreciation to the NATO Scientific
Affairs Division, whose financial support made this Institute
possible. We also acknowledge the contribution of the following:
CISE
IBM Italia
Philips, Eindhoven
Siemens, Munich
We finally thank the secretaries of Divisione Elettronica
Quantistica, CISE, Mrs. G. Ravini and Miss M. Oriani, for their
valuable assistance in the organization of the Institute and in
the preparation of these proceedings, and Miss A. Camnasio of
Servizio Documentazione, CISE, and again Mrs. G. Ravini for their
assistance during the course itself.
F. T. Arecchi
R. Bonifacio
M. o. Scully
CONTENTS
A - Basic Tools
Coherence in Spectroscopy 1
A. Kastler
Coherence in Synergetics 21
H. Haken
B - Coherence in Spin-like Systems
Coherent Optical Transients . . • • . . . . • . . . 41
R. G. Brewer
Mean Field Theory of Optical Bistability and Resonance
Fluorescence . . . . . • • • • . 85
L. A. Lugiato and R. Bonifacio
Optical Bistability and Differential Gain 111
H. M. Gibbs, S. L. McCall, and T. N. C. Venkatesan
Super fluorescence Experiments • 121
H. M. Gibbs
Coherent Two-Photon Amplication in an Inverted Medium 131
L. M. Narducci, L. G. Johnson, E. J. Seibert, and
W. W. Eidson
C - Coherence in Atomic Spectroscopy
High Resolution Spectroscopy in Atomic Rydberg States 151
S. Haroche
The Method of Separated Fields in Optics 173
V. P. Chebotayev
Coherence in Beam-Foil Spectroscopy . 195
H. J. Andra
Magnetic Resonances in Sodium Vapours Oriented by a C. W. Dye
Laser • ..• • . . • . . • • . • . . 219
G. Alzetta
vii
viii CONTENTS
D - Applications of Coherence to Physical Systems
Superconductivity and Quantum Optics •••••• 231
A. Di Rienzo, D. Rogovin, M. Scully, R. Bonifacio,
L. Lugiato, and M. Milani
Surface Plasmon Effects on Molecular Decay Processes near
Metallic Interfaces • • • • 261
H. Morawitz
Introduction to Picosecond Spectroscopy 301
B. Bosacchi
Picosecond Spectroscopy and Solid State Physics 305
B. Bosacchi
Coherent Effects in Picosecond Spectroscopy 329
A. Laubereau and W. Kaiser
Nonthermal Microwave Resonances in Living Cells 347
F. Keilmann
E - New Laser Sources
The Free Electron Laser: A Single Particle Classical Model • • 361
A. Bambini and A. Renieri
Frequency Tunability and High Speed Modulation of Far Infrared
Optically Pumped Lasers by Stark Effect • • • • • •• 381
F. Strumia
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index
397
COHERENCE IN SPE CTROSCOPY
A Ifred Kastler
Laboratoire de Spectroscopie Hertzienne de "Ecole
Normale S uperieure - Universite Paris VI
75231 PARIS Cedex 05, France
INTRODUCTION
The general subject of this conference is "coherence". The
first object of our investigation must be the answer to the question:
what is the meaning of the word "coherence". What is its defini
tion? It may be used in every day language and in the language of
science. Its opposite is "incoherence". I believe the word "cohe
rence" means in general some correlation between things or events,
some state of "order",while "incoherence" means "no relation"
or "disorder".
By scientists the word "coherence" has been first used in the
field of physical optics. We say that two light-beams, able to pro
duce interference fringes by their superposition, must be coherent.
In the wave-theory of light this means that their must be a defini
te relation, invariant in time, between the phases of their vibra
tions. If we note these vibrations by the expressions:
::::
where W is their com mun circular frequency and where Cf. and CPa.
are their phases, we say that these vibrations are coherent if their
phase difference
A¥,= 'f. - 'f
&.
remains constant in time during a time interval which is large com
pared to period T = ,:tr/1Al of the vibrations.
The vibrations are incoherent if ~'f changes rapidly in a random
2 A. KASTLER
manner during tim e and takes all values between 0 and 2 Tl'.
Such a definite relation between phases of vibrations is an ele
ment of "order" and can be expressed by a definite value of "ne
guentropy" w hi Ie incoherence is an element of "disorder" and cor
responds to a high entropy.
When, during the two last decades of the 19th century Ludwig
Boltzmann1, studying the behaviour of an ideal gas of molecules,
established his famous H-theorem and established the relation bet
ween the thermodynamic concept of entropy S and the statistic con
cept of probabi lity W, he had to make the hypothesis of "molekula
re Unordnung", that is to say :he had to admit that in the initial
state already there was same "disorder" among the molecules of
the gas. This was necessary to guarantee the evolution of the gas
to a higher state of disorder, to maximum entropy. When in
1900 Max Planck established his famous formula for black-body
radiation, he had to make an analogous hypothesis which he cal
led "Hypothesis der natUrlichen Strahlung". In his mind the word
"naturlich" was synonimous with "incoherent". He had to postula
te the absence of any definite phase-relation between the vibra
tion of the monochromatic "resonators" in equilibrium with cavity
radiation. We know that instead of considering with Planck such
material reson~ors, we can consider - as ~as been shown by
Lord Rayleigh in 1900 and used by Debye in 1910 - the radia-
tion itself in a cavity as composed of quantised "steady waves",
sti" called "Eigenschwingungen" or" cavity-modes ". Their num
ber per unit volume and unit-frequency range is independant of the
shape of the cavity and of the nature of its walls. The vibrations
of these cavity modes must be "incoherent". Only in this case the
addition-theorem of their entropy is valid and can be applied. This
incoherence is a necessary postulate for obtaining Planck's formu
la.
COHERENCE IN ATOMIC SPECTROSCOPY
We may now consider same special, but interesting Cases of
coherence in spectroscopy, limiting us to atom ic spectroscopy.
MAGNETIC RESONANCE
As a first example we consider the simple case of paramagne
tic atoms or nuclei in a steady magnetic field B. Each particle pos
jl etA.
sesses a small magnetic moment along an axis To this
magnetic moment is associated a mechanical angular momentum ~
