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Physics Today
Michael Stephen Feld Ramachandra Rao Dasari, Daniel Kleppner, Charles H. Holbrow
Published Nov 1, 2010 • 0 citations
Abstract Michael Stephen Feld died in Boston on 10 April 2010, at age 69, after an eight-year struggle with multiple myeloma. He was widely known for his contributions to fundamental laser physics and for pioneering lasers and spectroscopy to biomedical problems.Feld was born 11 November 1940 in Brooklyn, New York. He graduated from Lynbrook High School on Long Island in 1958 and from MIT in 1963 with an SB degree in humanities and sciences and an SM degree in physics. He stayed on at MIT to earn a PhD in physics in 1967 for research on laser spectroscopy under Ali Javan. In 1968 Feld joined the MIT physics department as an assistant professor and went on to a varied and productive career as a member of the physics faculty. Feld’s graduate research laid the foundation for a lifelong interest in quantum optics. He established his presence in that field by demonstrating superradiance—the enhancement by coherence effects of the emission of light from a collection of radiators—in a molecular gas. By pursuing that problem in the face of skeptics who thought that Doppler broadening would make the effect impossible to observe, he demonstrated an independence of thought and scientific determination that would mark his career. His research in quantum optics led Feld into the field of cavity quantum electrodynamics. In 1987 he began a series of experiments on radiative shifts and enhanced and suppressed spontaneous emission of single atoms in an optical resonator. Those culminated in his development of the single-atom laser in 1994.From 1976 until his death, Feld was director of MIT’s Harrison Spectros-copy Laboratory. In that role he fostered collaborations among physicists, chemists, biologists, materials scientists, and physicians by welcoming them to participate in the laboratory. To support cooperative research, he established the MIT Regional Laser Facility, funded by NSF, and the MIT Laser Biomedical Research Center, funded by the National Institutes of Health. One of the research center’s many achievements was the development of the diffraction phase microscope (shown in the photo), which yields nanoscale quantitative measurements of the structure and dynamics of live red blood cells.Feld was notably direct. He questioned with equal intensity, acuteness, and persistence academic administrators, janitors, colleagues, waiters, students, and deliverymen. That quality helped him develop fruitful collaborations with scientists from a wide range of fields. Starting in the 1980s, those collaborations helped him turn his attention increasingly to applying lasers and laser-based techniques to biomedicine and biomedical engineering. Feld was an early leader in the use of light scattering, fluorescence spectroscopy, and Raman spectroscopy to investigate arterial plaque in vivo and to provide early cancer detection in some organs. In recent years his research shifted; rather than use those intensity-based modalities, he used field-based light scattering to develop low-coherence interferometry and to explore how to suppress turbidity and obtain images from inside apparently opaque tissue. Near-IR Raman spectroscopy has made it possible to measure levels of blood glucose through the skin without the prick of a needle. Quantitative phase microscopy has produced three-dimensional maps of the refractive index of live cells free of labels or dyes. It also permits early diagnosis of breast cancer and assessment of whether cells at the margins of a cancerous lesion are themselves cancerous. For his foundational contributions to laser spectroscopy and the biomedical use of spectroscopy, Feld received the 2008 William F. Meggers Award from the Optical Society of America.Throughout his career Feld enthusiastically engaged in undergraduate and graduate teaching at MIT. He supervised more than 50 PhD theses. Reflecting his breadth of interest, they were in chemistry, mechanical engineering, bioengineering, and materials research, as well as in physics, and several were part of the MIT-Harvard Health Sciences and Technology program.The 1963 March on Washington marked the beginning of Feld’s lifelong concern about minority graduate education in physics at MIT. He cochaired the committee that initiated establishment of MIT’s Dr Martin Luther King Jr Visiting Professors Program, and, with characteristic direct action, he personally guided five minority graduate students to their PhD degrees.One of those students was Ronald McNair, who went on to a career as an astronaut. Feld and McNair became close friends, and their teaching was reciprocal: Feld mentored McNair in physics; McNair taught Feld karate. Feld obtained a brown belt and was proud to be outdone by his twin sons, Jonathan and David, who became black belts. As was typical, once Feld became interested in karate, he made a serious study of its physics. He presented widely appreciated talks on the physics of karate with demonstrations that sometimes included his sons; he and McNair coauthored articles on karate. McNair’s death in the space shuttle Challenger accident in 1986 was a deep personal loss for Feld.Michael Feld was a creative, innovative physicist and a man of great charm, always asking for more effort, more time, and more insight from his collaborators and students. Many of them are today advancing laser physics, quantum optics, biomedicine, and biomedical engineering along paths that he opened. Through their work Feld’s already large impact on the scientific community continues to grow.Michael Stephen FeldDONNA COVENEY, MIT MEWS SERVICEPPT|High resolution© 2010 American Institute of Physics.
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Michael Stephen Feld died in Boston on 10 April 2010, at age 69, after an eight-year struggle with multiple myeloma. He was widely known for his contributions to fundamental laser physics and for pioneering lasers and spectroscopy to biomedical problems.Feld was born 11 November 1940 in Brooklyn, New York. He graduated from Lynbrook High School on Long Island in 1958 and from MIT in 1963 with an SB degree in humanities and sciences and an SM degree in physics. He stayed on at MIT to earn a PhD in physics in 1967 for research on laser spectroscopy under Ali Javan. In 1968 Feld joined the MIT physics department as an assistant professor and went on to a varied and productive career as a member of the physics faculty. Feld’s graduate research laid the foundation for a lifelong interest in quantum optics. He established his presence in that field by demonstrating superradiance—the enhancement by coherence effects of the emission of light from a collection of radiators—in a molecular gas. By pursuing that problem in the face of skeptics who thought that Doppler broadening would make the effect impossible to observe, he demonstrated an independence of thought and scientific determination that would mark his career. His research in quantum optics led Feld into the field of cavity quantum electrodynamics. In 1987 he began a series of experiments on radiative shifts and enhanced and suppressed spontaneous emission of single atoms in an optical resonator. Those culminated in his development of the single-atom laser in 1994.From 1976 until his death, Feld was director of MIT’s Harrison Spectros-copy Laboratory. In that role he fostered collaborations among physicists, chemists, biologists, materials scientists, and physicians by welcoming them to participate in the laboratory. To support cooperative research, he established the MIT Regional Laser Facility, funded by NSF, and the MIT Laser Biomedical Research Center, funded by the National Institutes of Health. One of the research center’s many achievements was the development of the diffraction phase microscope (shown in the photo), which yields nanoscale quantitative measurements of the structure and dynamics of live red blood cells.Feld was notably direct. He questioned with equal intensity, acuteness, and persistence academic administrators, janitors, colleagues, waiters, students, and deliverymen. That quality helped him develop fruitful collaborations with scientists from a wide range of fields. Starting in the 1980s, those collaborations helped him turn his attention increasingly to applying lasers and laser-based techniques to biomedicine and biomedical engineering. Feld was an early leader in the use of light scattering, fluorescence spectroscopy, and Raman spectroscopy to investigate arterial plaque in vivo and to provide early cancer detection in some organs. In recent years his research shifted; rather than use those intensity-based modalities, he used field-based light scattering to develop low-coherence interferometry and to explore how to suppress turbidity and obtain images from inside apparently opaque tissue. Near-IR Raman spectroscopy has made it possible to measure levels of blood glucose through the skin without the prick of a needle. Quantitative phase microscopy has produced three-dimensional maps of the refractive index of live cells free of labels or dyes. It also permits early diagnosis of breast cancer and assessment of whether cells at the margins of a cancerous lesion are themselves cancerous. For his foundational contributions to laser spectroscopy and the biomedical use of spectroscopy, Feld received the 2008 William F. Meggers Award from the Optical Society of America.Throughout his career Feld enthusiastically engaged in undergraduate and graduate teaching at MIT. He supervised more than 50 PhD theses. Reflecting his breadth of interest, they were in chemistry, mechanical engineering, bioengineering, and materials research, as well as in physics, and several were part of the MIT-Harvard Health Sciences and Technology program.The 1963 March on Washington marked the beginning of Feld’s lifelong concern about minority graduate education in physics at MIT. He cochaired the committee that initiated establishment of MIT’s Dr Martin Luther King Jr Visiting Professors Program, and, with characteristic direct action, he personally guided five minority graduate students to their PhD degrees.One of those students was Ronald McNair, who went on to a career as an astronaut. Feld and McNair became close friends, and their teaching was reciprocal: Feld mentored McNair in physics; McNair taught Feld karate. Feld obtained a brown belt and was proud to be outdone by his twin sons, Jonathan and David, who became black belts. As was typical, once Feld became interested in karate, he made a serious study of its physics. He presented widely appreciated talks on the physics of karate with demonstrations that sometimes included his sons; he and McNair coauthored articles on karate. McNair’s death in the space shuttle Challenger accident in 1986 was a deep personal loss for Feld.Michael Feld was a creative, innovative physicist and a man of great charm, always asking for more effort, more time, and more insight from his collaborators and students. Many of them are today advancing laser physics, quantum optics, biomedicine, and biomedical engineering along paths that he opened. Through their work Feld’s already large impact on the scientific community continues to grow.Michael Stephen FeldDONNA COVENEY, MIT MEWS SERVICEPPT|High resolution© 2010 American Institute of Physics.
In the early hours of 9 February 2001, the physics community lost one of its most distinguished members, Leonard Mandel, after a long illness. Mandel was the Lee DuBridge Professor Emeritus of Physics and Optics at the University of Rochester, having become emeritus only a few months before he died, at the age of 73, at his home in Pittsford, New York.Born on 9 May 1927 in Berlin, Germany, where his father had emigrated from Eastern Europe, Mandel received a BSc in mathematics and physics in 1947 and a PhD in nuclear physics in 1951 from Birkbeck College, University of London, in the UK. He became a technical officer at Imperial Chemical Industries Ltd in Welwyn, UK, in 1951. In 1955, he became a lecturer and, later, senior lecturer at Imperial College, University of London. He remained at Imperial College until 1964, when he joined the University of Rochester as a professor of physics. Mandel is widely credited as being one of the founding fathers of the field of quantum optics. Although he made seminal contributions across most of quantum optics, the central theme of his research was the exploration of the nature of light through insightful theoretical analyses and a set of pioneering experiments that have become landmarks in the field. Not since the beginning of quantum mechanics has an individual so intimately investigated and so dramatically advanced our understanding of the quantum aspects of light.Mandel’s early interest in quantum optics was stimulated by the Hanbury Brown–Twiss experiments, in which correlations in the fluctuations of photocurrents from two photodetectors illuminated by light from a distant source reveal information about the spatial coherence properties of the light. Mandel’s entrance into the debate about the appropriate theoretical description of this experiment was a basic paper published in 1958 in the Proceedings of the Physical Society (London) in which the so-called Mandel formula for photoelectric counting made its first appearance.In 1968, Mandel’s research group performed the now famous experiment involving interference at the single photon level: Two beams derived from independent lasers were attenuated to a level such that the average interval between photon emissions was very long compared to the transit time through the apparatus. Interference fringes were nonetheless recorded. As in the Hanbury Brown–Twiss experiment, the detection scheme explored interference of the fourth order in the amplitudes of the fields, as opposed to the more familiar second-order interference (as in a Michelson interferometer, for example), but now with an ingenious extension. Over the next three decades, Mandel continued to refine fourth-order interferometry into a powerful tool for investigating the quantum nature of light. It is now a standard technique used worldwide.Perhaps spurred by the debate about the quantum statistical properties of lasers and other light sources, Mandel and his students were among the first to carry out basic experiments from 1967 to 1968 to elucidate the coherence properties of the laser in the transition from incoherent to coherent emission around threshold. In the ensuing decades, those early studies grew into diverse investigations of more complex laser behavior, including mode correlation and competition in ring lasers, and optical bistability and first-order phase transitions in dye lasers. Mandel played a leading role in the quest to investigate states of the electromagnetic field with manifestly quantum or nonclassical characteristics. In 1977, his group made a historic advance in this endeavor with the first observation of photon anti-bunching in the case of the fluorescent light from a single atom. Subsequently, Mandel and one of his students made the first measurements of another nonclassical effect, namely, sub-Poissonian photon statistics. In the early 1980s, Mandel initiated what would become a landmark set of experiments involving pairs of photons produced by the fission of a pump photon in the process of parametric down conversion. Following earlier work by others on the correlation between photon pairs in atomic cascades, Mandel and his students first demonstrated a key nonclassical aspect of the down conversion process and were able to achieve a localized one-photon state.Pursuing the theme of fourth-order interference with pairs of photons in the late 1980s, Mandel and his students demonstrated quantum spatial beating, violations of local realism, and phase memory due to quantum entanglement with the vacuum. His group showed that P. A. M. Dirac’s well-known statement about single-photon interference must be modified to assert that, in fourth-order interference, a pair of photons interferes only with the pair itself. He and his students also introduced what became known as the Hong-Ou-Mandel interferometer. Beyond what had by then become “the standard model” of manifestly quantum effects, Mandel’s genius for probing the quantum realm led to advances throughout the 1990s that challenged and ultimately redefined our understanding of the quantum character of light and, more generally, of quantum measurement. For example, in 1991, Mandel and his students reported a remarkable experiment involving interference from the superposition of fields from two different but coherent parametric processes. They showed that the mere possibility of making a measurement destroyed an interference pattern, even if this possibility went unrealized. In 1995, Mandel’s group, in an experiment with photon pairs, demonstrated a central tenet of quantum mechanics: that there is no physical reality for elemental quantum processes in the absence of a measurement. Mandel supervised the thesis research of 39 students, many of whom have subsequently become leading figures in science and technology. He earned the lifelong respect of his students for his detailed and conscientious stewardship of their scientific development. He made frequent rounds of his laboratories to interact with each of his students and to provide help ranging from optical alignment and electronic design to theoretical calculations. Not wanting to interrupt a student at work, he would sometimes quietly approach in his soft-soled shoes to view the activity at hand, leading to more than a few startled heart skips. In response to a student’s query, “Can you see a signal yet?” as some component of an apparatus was being aligned, would come his distinctively British reply, “Not a sausage!” Once, when the need arose to regulate the water cooling for an oil diffusion pump, he solved the problem the next morning with a flow switch commandeered from a washing machine at home.In addition to his work at the frontiers of physics, Mandel was an excellent teacher. He had a special interest in neophyte science students and developed the first course at the University of Rochester for non-science majors, which he taught regularly for 20 years. From 1966 to 1995, he was one of the main organizers of a well-known series of international conferences called the Rochester Conferences on Coherence and Quantum Optics. Mandel was the coauthor of Optical Coherence and Quantum Optics (Cambridge U. Press, 1995) and the coeditor of several conference proceedings. In 1980, a paper on coherence properties of optical fields, which he coauthored in 1965, was designated a Citation Classic by the Institute of Scientific Publications. In 1988, that paper was listed as one of the 100 most-cited articles published in the Review of Modern Physics since 1955. Mandel received many top awards, including the Frederic Ives Medal (1993) and the Max Born Medal (1982) from the Optical Society of America. He received the Marconi Medal (1987) from the Italian Research Council and the Thomas Young Award (1989) from the British Institute of Physics. In May 2001, Mandel was elected posthumously to membership in the National Academy of Sciences.Mandel was a scientist with a warm personality, humility, compassion, and a delightful sense of humor. He enjoyed a happy family life with his wife Jeanne, a ballet teacher with whom he shared the love for ballet, and with their two children. He adored his four grandchildren and took lively interest in all their activities. Those of us who were fortunate to have been associated with Mandel as students, colleagues, or friends will remember him with deep affection and utmost respect. He will be greatly missed. Leonard Mandel PPT|High resolution© 2001 American Institute of Physics.
Peter Franken was a remarkable man. Immediately after the invention of the laser in 1960, he realized its potentialities for nonlinear effects. His revolutionary paper on second harmonic generation appeared in 1961. It started a revolution in optics, in spite of the fact that some picture editor had removed the spectral spot that was the proof of the effect. Within a few years the experimental field exploded and Bloembergen and collaborators had developed the theory of the new effects to a point that merited his textbook of 1965. Peter Franken turned 70 in 1998 and the traditional Festschrift was prepared. Unfortunately he passed away in 1999, and the book appeared as a dedication to his memory. And a very suitable one it is, because it covers many of the topics he initiated and much of the recent developments following from them. As a long-time friend and colleague, Professor Prokhorov writes the introduction. The book has reviews of topics in nonlinear optics, following their developments up to the late 1990s: Atomic time standards (Ramsay), Femtosecond phenomena at nonlinear optical boundaries (Bloembergen et al ), Nuclear excitation in plasmas (Sobelman) and Raman scattering (Powell and Basiev). Novel fields with strong connections to optics are presented: Quantum interference effects on optical dispersion (Scully et al ), Excitonic features in semiconductor cavities (Gibbs et al ), Nonlinear atom optics (Meystre et al ) and Laser-induced particle emission spectroscopy with atomic resolution (Letokhov). The field mentioned last has been developed by Professor Letokhov in recent years, and I do not know any other place where its methods and potentialities are presented in this detail. The book is a valuable source of information on recent progress in the topics included. It summarizes many important developments of contemporary laser physics. If one wants to get an overview of this research, the book is very valuable. The level of treatment varies a little, from purely descriptive to highly detailed; that is inevitable when many authors are involved. Reading the text requires a certain ability to discern and choose; hence it is no textbook for students. A mature and interested reader, however, can learn much from the book. The most recent developments will, no doubt, become dated, but so much material is central to the field of research that the main part of the text is of lasting value. Groups and individuals working in the area of laser physics will find the volume challenging and useful as a general reference. Here one can look up earlier material and find out its relevance to the most recent progress. Stig Stenholm
Among all the inventions that quantum physics has produced, the laser holds a particularly important place, both for the rich story of successive discoveries that led to its birth, and for the role it has played in fundamental and applied research. I recall here the lineage of theoretical discoveries and experiments that have marked this history, restricting myself to the contribution of lasers to blue sky science and leaving apart its well-known role in various domains of technology. This story started from advances in the old quantum theory, from Einstein’s theoretical description of stimulated emission to O. Stern’s experimental discovery of the spatial quantization of the electron spin. Nuclear magnetic resonance, atomic clocks, optical pumping, and masers followed and the pace of discoveries accelerated with the appearance of the laser in 1960. This extraordinary light source has since enabled breakthroughs in fundamental physics and opened up fields of research that could not even have been imagined at the time of its birth. I was fortunate to begin my career in physics at this crossroad of atomic physics and optics. I give in this article my personal view of the great adventures in fundamental research in which I participated as an actor or spectator, from the cooling and trapping of atoms by light, to the physics of quantum gases of bosons and fermions, the manipulation of individual quantum particles and quantum simulations. Many other areas of fundamental physics, which I will only mention briefly, owe their development to lasers and further advances are still to be expected in the years to come.
This book attempts to bridge the enormous gap between introductory quantum mechanics and the research front of modern optics and scientific fields that make use of light in one step. Hence, while it is suitable as a reference for the specialist in quantum optics, it also targets the nonspecialists from other disciplines who need to understand light and its uses in research. With a unique approach it introduces a single analytic tool, namely the density matrix, to analyze complex optical phenomena encountered in traditional as well as cross‐disciplinary research. It moves swiftly in a tight sequence from elementary to sophisticated topics in quantum optics, including laser tweezers, laser cooling, coherent population transfer, optical magnetism, electromagnetically induced transparency (EIT), squeezed light, and cavity quantum electrodynamics (QED). A systematic approach is used that starts with the simplest systems – stationary two‐level atoms – then introduces atomic motion, adds more energy levels, and moves on to discuss first‐, second‐, and third‐order coherence effects that are the basis for analyzing new optical phenomena in incompletely characterized systems. Unconventional examples and original problems are used to engage even seasoned researchers in exploring a mathematical methodology with which they can tackle virtually any new problem involving light. An extensive bibliography makes connections with mathematical techniques and subject areas which can extend the benefit of each section to guide readers further. The steady progression from “simple” to “elaborate” makes the book accessible not only to students from traditional subject areas that make use of light (physics, chemistry, electrical engineering, and materials science), but also to researchers from the “hyphenated” subjects of modern science and engineering: the biophysicists using mechanical effects of light, photochemists developing coherent control for rare species detection, biomedical engineers imaging through scattering media, electromechanical engineers working on molecular design of materials for electronics and space, electrical and computer engineers developing schemes for quantum computation, cryptography, frequency references, and so on. To try to identify techniques and ideas that are universal enough to be applied across the bewildering landscape of research on intersecting boundaries of emerging modern disciplines is a great challenge of out time. “Lectures on Light” offers selected insights on quantum dynamics and quantum theory of light for exactly this purpose.
The field of quantum optics rests on the work of Roy Glauber, who helped elucidate the nature of light as both particles and waves. According to Glauber, quantum optics allowed "all sorts of experiments...that never could have been done before." He suggests that it was not his "small revelation" that the Nobel Committee awarded, but rather the decades of research that followed his own. Nonetheless, Glauber received one-half of the 2005 Nobel Prize in Physics "for his contribution to the quantum theory of optical coherence" while the other half was shared by John Hall and Theodor Hänsch for their work on laser-based precision spectroscopy. Glauber admits that the behavior of light seems strange and unintuitive--yet the phenomena that Einstein called "spooky action at a distance" may have many practical applications. In this candid interview, Glauber shares his thoughts about working at Los Alamos National Laboratory--his shock to learn that he was helping to build The Bomb, and his dismay about how it was used. At Los Alamos, Glauber met two of his major influences: Julian Schwinger, who was Glauber's thesis advisor at Harvard, and Los Alamos scientific director Robert Oppenheimer, who facilitated his early post-doctoral research. Glauber also tells a poignant account of how his marriage fell victim to the social upheaval of the 1960's, and how he was left to raise two children alone. Despite the difficulties of reconciling academia with family, Glauber is amused to find himself revered by women as "someone who has raised children and nonetheless had a successful academic career."
I thank Rodger Walser and his colleagues for organizing this conference to celebrate George \nSudarshan’s birthday and landmark achievements in science. It is an honor for me to be here and \nalso a great pleasure to be back in Austin to join the chorus of the FOGS. \nI would like begin with a brief historical introduction and then turn to topics that we \nhaven’t heard so much about thus far in the symposium, namely experiments in Quantum Optics. \nLet me remind you that blackbody radiation has had a profound impact on physics since the time \nof Planck. However, even in more modern times after the development of quantum mechanics \nand quantum electrodynamics, one really did not know how to describe the underlying field \nfluctuations as required for diverse interference phenomena. Emil Wolf laid critical foundations \nfor this enterprise with his theory of classical coherence developed in collaboration with Max \nBorn in their classic book Principles of Optics. \nA great challenge to the physics community was the experiment by R. H. Brown and R. \nQ. Twiss in 1956 [1], which led to a confusing and controversial time for photons and fields. In \n1958 Leonard Mandel helped to resolve the controversy by explaining how light fluctuations are \nconverted to photocurrents in the detection process, albeit in with a classical description of the \nfield [2]. The confusion arose from the effort to understand, on the one hand, interference \nphenomena that are expressed in terms of the complex amplitude of the electromagnetic field, for \nwhich only a classical description was available. On the other hand, quantum electrodynamics \nhad been developed based upon energy eigenstates (i.e., Fock states) with photons as quanta. It \nwas really difficult to understand how the electric and magnetic fields behave in terms of these \nquantum states. For example, the expectation value of any electromagnetic field is zero in a Fock \nstate. The confusion was compounded by the historic invention of the maser and laser and by the \npressing need for quantum theories of the dynamical processes of these and other laboratory \nadvances.