I was born on September 11th 1944 in Casablanca, Morocco, in a Jewish family with mixed Sephardic and Ashkenazi origins. My father’s parents were teachers at the Alliance Israëlite universelle (AIU), which operated a network of schools dedicated to the dissemination of French language and culture throughout Jewish communities in North African and Mid-Eastern countries. My paternal grandfather had been one of the first students of the AIU school in the town of Marrakesh, in the last years of the nineteenth century. My paternal grandmother had studied at the same time in Tetouan, in the part of northern Morocco under Spanish influence, in the first AIU school, which had been founded there in 1863. After completing their school years, they both decided to become teachers and, unbeknownst to each other, came to France at the very beginning of the 20th century, to get their degree from the AIU teacher training school in Paris. Although they were both there at the same time, they did not meet then since the boys’ and girls’ schools were separated.
I found a few years ago in one of my grandfather’s notebooks a handwritten recollection of his souvenirs as a young teenager suddenly immersed in 1900 Belle Epoque Paris, seeing for the first time automobiles and trains, enjoying theater shows and silent movies, experiencing with bewilderment a modernity contrasting so much with the medieval atmosphere of Marrakesh at that time. My paternal grandparents met shortly after graduating and returning to Morocco, at the time this country became a French protectorate. They soon married and had seven children, while moving from school to school on successive assignments, ending as headmaster and headmistress of the boys and girl’s AIU schools in the town of Salé, near Rabat. My father, born in 1920, was raised there and studied law in Rabat, becoming a lawyer at the beginning of the Second World War.
My mother’s family emigrated from Russia in the 1920s, in the years following the Bolshevik revolution. Her parents were physicians and chose to settle in Morocco, a country where their Russian medical degrees were recognized. My mother, born in Odessa in 1921, was raised in Casablanca and met my father at the university in Rabat, just before the war, while she was studying to become a teacher in French and German literature. In my early childhood, I was raised in Russian as well as in French, and I remained bilingual until I went to elementary school at the age of six, unfortunately then very quickly losing my fluency in Russian. The community of Russian Jewish immigrants in Casablanca had kept strong links and I remember meeting many of them in my grandparents’ house. Among them was an architect, Casimir Zeligson, who has built several of the Art Nouveau building and villas which still give a special character to the town of Casablanca. The Zeligsons had a daughter, Claudine, with whom my younger brother Joël and I used to play. After a long separation, I met her again in Paris fifteen years later, but here I am anticipating.
I have kept strong memories of this time in Casablanca, of the warm Mediterranean weather, the long rainless summers and mild winters with their flowering bougainvillea and hibiscuses, bathing in the cold Atlantic Ocean whose waves can be so strong and treacherous, especially to a young child. Some remembrances are particularly vivid, like the recurring sirocco storms covering everything with a blanket of sand coming from the Sahara, or the locust invasions, which on several occasions have plagued the fields in the countryside around the city, leaving them barren after they had gone. During the last years of my life there, I witnessed the events leading to the independence of Morocco from the French, understanding that, amid the convulsions and sometime violent events, history was in the making.
When independence finally came in 1956, my parents decided, like many Jews, to leave Morocco and settle in France with their sons Joël, Gilles and me (a fourth son, Michel, was born in Paris in 1959). This was essentially a cultural choice. They had received and given to their children a French education and thought that France was the natural place for the family to go. The first years in Paris were difficult, requiring a painful adjustment, especially during the damp and dark winters, contrasting so much with the vivid colors of the Moroccan weather. Learning at school was a consolation, though. I was a very good student, immediately at the head of my class in the Lycée Carnot where I studied until the “Baccalauréat,” the final degree of the French high school education.
I was indiscriminately interested in literature, history, mathematics and physical sciences. In humanities, I could share my tastes with my parents, who raised my three brothers and me to love reading, going to museums and discussing all kind of issues ranging from ancient history to modern politics. In scientific matters, I was on my own, however, the first in the family to wander in a domain which required a mathematics background. I remember how, early on, I was fascinated by astronomy and by calculus, the notion of derivatives and simple differential equations which describe so directly and so well the laws of dynamics obeyed by moving bodies. This was the time of the first artificial satellites, the sputniks which orbited the earth and launched the American-Soviet race to the moon.
I marveled at the fact that I was able, with the elementary calculus I knew, to compute the escape velocity of rockets, the periods of satellites on their orbits and the gravitational field at the surface of all the planets … I understood then that nature obeys mathematical laws, a fact that did not cease to astonish me. I knew, from that time on, that I wanted to be a scientist. For that, I embarked in the strenuous and demanding “classes préparatoires” of the famed Lycée Louis-Le-Grand, one of the preparatory schools which train the best French students for the contest examinations leading to the “Grandes Ecoles.” They are the engineering and academic schools, which since the French Revolution, have formed the scientific elite of France. These were two years of intensive study where I learned a lot of math and of classical physics. I eventually was admitted in 1963 to the Ecole Polytechnique (ranking first in the national examination, to the great pride of my parents) and at the Ecole Normale Supérieure (ENS). I chose to enter the latter because, at that time, it offered a much better opportunity to embark in a scientist career.
The years as a student at ENS (1963–1967) have left me wonderful memories, contrasting sharply with the strenuous training of the preparatory school. Here, in the middle of the Latin Quarter, I was free to organize my time as I wished, to meet and discuss with students working in all kinds of fields in science or humanities and to enjoy all the distractions and cultural activities Paris has to offer. And I was paid for that, since the “Normaliens” as the ENS students are called, are considered civil servants and receive a generous stipend! These were my formative years as a scientist. Coming so to speak from the physics of the 19th century which was taught in the classes préparatoires, I was immediately thrown into modern physics and the quantum world by the classes of exceptional teachers. Alfred Kastler gave us a lyrical description of the dance of atomic kinetic moments, and gave atoms and photons a near poetic existence. Jean Brossel brought us back to Earth by describing the great experiments thanks to which quantum concepts were established, instilling in us the austere passion for precision. And Claude Cohen-Tannoudji revealed the theory’s formalism to us with extraordinary depth and clarity. I still remember three books I read avidly at the time: Quantum Mechanics by Albert Messiah, where I truly understood the depth and beauty of the quantum theory; Principlesof Nuclear Magnetism by Anatole Abragam, who introduced me to the subtle world of atomic magnetic moments; and Feynman’s Lectureson Physics, which was a revelation.
But physics was only one side of that time’s story. In the spring of 1964, I met Claudine Zeligson again by chance in a Latin Quarter café. She had followed her own path from Casablanca to Paris, where she was studying English, psychology and sociology at La Sorbonne. We resumed a relationship which had been interrupted by a fifteen year latency period and married in 1965, at the age of 21. She later embarked in her own career as a scholar, doing research in sociology and anthropology at the French National Center for Scientific Research (CNRS). We have been together since then, sharing all aspects of life, including a common love for music and painting, movies and travels. Without her love, intellectual stimulation and constant support, nothing would have been possible.
Enthralled by the mysterious beauty of the quantum world, it did not take me long to decide that I wanted to become a quantum physicist. That was the time when various optical methods for the manipulation of atoms were being invented in the Laboratoirede Spectroscopy Hertzienne of ENS, which was to be called later the Kastler Brossel laboratory. I remember the day in the fall of 1966 when, as a young student, I witnessed the joyous turmoil following the announcement of Kastler’s Nobel Prize, attributed to the invention of optical pumping methods. I measured my luck to have just started working in a field which was getting such a worldwide recognition. The Kastler lectures I had attended were immediately illustrated by everyday reality at the ENS laboratory, where in 1967 I started my thesis under the enthusiastic supervision of Claude Cohen-Tannoudji.
I have described in my Nobel Lecture how my interests in physics have naturally evolved from that time on, motivated by the challenge to probe and control the atom-photon interactions processes at the most fundamental level. This adventure started with my PhD work with Claude on the “dressed atom” formalism, analyzing atoms irradiated by radiofrequency fields as being dressed by a cloud of photons surrounding them. We learned how to describe the atoms coupled to photons as a combined entity, whose energy level structure revealed, in a synthetic way, all the properties of the system. At that time, it was unusual to describe the field, especially in the radiofrequency or microwave spectral range, in terms of photons. Some famous physicists even believed that all phenomena in atomic physics, including spontaneous emission, could be explained classically and that the photon was a superfluous concept. They were wrong, as we now know, but it is true that the classical picture viewing the field as a time-varying electromagnetic wave is sufficient to account for all effects involving huge amounts of light quanta.
Claude and I, though, were persuaded that the quantum description of the dressed atom formalism went deeper, giving a more satisfactory interpretation of the phenomena and a better insight into novel effects which were more difficult to predict within the classical approach. Since that time, Claude and I have kept using the dressed atom point of view, along with many other scientists who have adopted it. My main interest has been the interaction of atoms with invisible microwave photons, the kind of photons with which I became familiar during my PhD studies. Claude, with the students he trained after me, extended the formalism to deal with the interaction of atoms with optical fields and used it to explain in a particularly illuminating way the subtle effects involved in the cooling and trapping of atoms with laser light. This eventually led him to the famous studies which were recognized by his 1997 Nobel prize.
The experiments I performed to illustrate the “dressed atom” formalism during my thesis work were done with classical spectral lamps. The laser sources which underwent a spectacular development during the 1960s promised to open new perspectives in atomic physics and I realized that I needed to learn how to use these new tools. After completing my PhD, I chose to become a postdoctoral fellow at Stanford University, in the laboratory of Arthur Schawlow, one of the inventors of the laser. Our son Julien, born in 1970, was a young toddler and our daughter Judith a new born baby when Claudine and I arrived with them in the San Francisco Bay Area in September 1972. The year we spent there has left us wonderful memories. The California weather with its balmy winters reminded us of our childhood in Morocco. We enjoyed a way of life which was very different from the one in Paris, living in a large house on the Stanford campus, close to the natural wilderness of the Pacific coastal mountain range and the ocean beaches, as well as to the sophistication of San Francisco and Los Angeles with their theatres, opera houses and gourmet restaurants. It was an ideal place to raise young children.
In Art Schawlow’s lab, I had a lot of fun with the marvelous toys that were the first tuneable lasers sent as prototypes to California laboratories by the commercial companies of what was to become Silicon Valley. Art’s enthusiasm was contagious. Every day, a new idea would spring up, sometimes wacky, sometimes brilliant. There came the first “edible” laser the day he had the idea of turning those ghastly food jellies of garish colors that he loved to eat into laser amplifying mediums, but also many demonstrations of clever spectroscopic methods, every time pushing the limits of the precision and sensitivity of measurements further. These new spectroscopic methods led to the Nobel Prize awarded to Schawlow in 1981. A young associate professor, Theodor Hänsch, had joined Art’s lab a few months before my arrival there and he was the driving force in the group, always finding new ways to exploit these marvelous laser sources to probe deeper and deeper into atomic spectra.
Art had a great sense of humor, which I believe is essential to maintaining a healthy atmosphere in a laboratory. “To succeed in research,” he often said, “one doesn’t need to know everything about everything, it’s enough to just know a few things that others don’t.” This sentence, pronounced with his contagious kindness and laughter, went a long way in relieving us of the intimidating weight of universal knowledge, which so often inhibits one, whether it is discouraging, or leads to an overly skeptical attitude about the world and the discoveries still to make. The hospitality of Art and Aurelia Schawlow in their campus home was memorable and we have kept strong connections with them long after Claudine and I had left California. It is during one party at the Schawlows that Claudine and I had a chance to meet Felix Bloch, who had been the first to describe the quantum behavior of electrons in solids and had invented magnetic resonance, the phenomenon I had exploited during my PhD work a couple of years earlier. For the young postdoc I was then, it was an awesome experience to interact with a scientist of this stature, a man who had worked with the founding fathers of the quantum theory. This kind of encounter contributed greatly to the excitement of our life in California.
After a few weeks in Stanford, Art gave me a lab room and a pulsed dye laser and told me it was up to me to find something interesting to do with it. With one of his graduate students, Jeffrey Paisner, I decided to try to study atomic quantum beats. They manifest themselves as time modulations in the fluorescence of atoms following a pulsed optical excitation. Such modulations had been observed previously in experiments realized with spectral lamps, but I suspected that with the increased power and sharper pulses produced by lasers, much faster and stronger beat signals should be obtained. When the experiment worked, almost on the first trial, I was exhilarated. For the first time, a project I had conceived and pursued without supervision was working and yielding interesting results. I presented them in the first International Conference on Laser Spectroscopy which took place in Vail, Colorado, in June 1973. The year spent in California was also an opportunity to meet scientists who have left a strong impression on me, and to start a longstanding friendship with some. This has been the case with Ted Hänsch, who has been a friend since then and whom Claudine and I have met on many occasions in the US first, then in Germany when he settled back there in the 1980s. It is also during the Vail meeting that Claudine and I got to know Daniel Kleppner of MIT and his wife Beatrice, who have become lifelong friends.
During my postdoctoral year, I had been thinking about a project to study Rydberg states, very excited atomic levels whose energies are close to the atom’s ionization limit. These states, of gigantic dimensions on the atomic scale, had been already observed in outer space in radio astronomy, but their preparation and study in the laboratory have had to await the development of lasers. My quantum beat experiments in Stanford had persuaded me that these laser sources were indeed very promising for investigating atomic states previously inaccessible to classical spectroscopy. I was fascinated by the prospect of being able to prepare and manipulate atomic matter under such exotic conditions, which should have properties so different from ordinary atoms. I wrote this proposal in an informal letter to Jean Brossel, who was the director of the ENS physics department. By return mail, he immediately offered me a position at ENS and, when I returned to Paris in the fall of 1973, he gave me a laboratory space and the start-up money required to buy the laser equipment for these experiments.
A bright student from ENS, Michel Gross, joined me and, within a few months, we built a new laboratory and started the investigation of these Rydberg atoms, which have been the workhorses of nearly all the experiments I have done since. Brossel had also secured me a research position of “maître de recherche” in the Centre National de la Recherche Scientifique (CNRS), which allowed me to spend all my time doing research, without any mandatory teaching duties. I had always liked the idea of teaching, though, finding it challenging and stimulating to explain scientific ideas and to communicate about science and research. So when in 1975 the opportunity arose, I applied to a position at Paris VI University and was appointed there as a professor. I started teaching basic physics to premedical students and a course about energy to physics undergraduates. At that time, the teaching load of professors was not as heavy as it has since become and I enjoyed splitting my activities between research and teaching.
Brossel had maintained in his laboratory an atmosphere of freedom and trust which seemed to me natural. In retrospect, I now measure how lucky I have been to work in such a favorable environment, without having to write incessant proposals and to submit to constant evaluations. In this context, I have been able to develop my research in the long term, justifying it only by the papers I published and the recognition they received. Time and trust are, I think, worth even more than money. They are two essential ingredients required for good basic science to flourish. I have been lucky to enjoy plenty of them in my early career as an independent scientist. When the conditions changed in the 1980s and research in France became more and more subject to the rules that the global market started to impose, I had to learn how to write proposals and how to answer repeated evaluation requests. My reputation as a scientist was made, though, and I did not have too much trouble adjusting and receiving the grants required for my group to operate in good conditions.
Time, trust and money are certainly necessary, but the most important factor for the success of my research has been the quality of the people I have had the luck to work with. In 1976, Michel Gross was joined by Claude Fabre who started his PhD work with me. Soon thereafter Jean-Michel Raimond completed the group of bright and dedicated “normalien” students working with me, inventing new ways to explore the radiative properties of Rydberg states. For that, we needed good microwave sources, operating at frequencies in the tens of GHz range. In another laboratory of the ENS physics department, a solid state physicist, Philippe Goy, was precisely developing and using such sources for his electron cyclotron resonance experiments. I got him interested in our project and he soon joined us for the exploration of the microwave spectra of alkali atom Rydberg states.
This was a very exciting time in the laboratory, when we started to develop the techniques which have allowed us to control the Rydberg atoms and perform the Cavity Quantum Electrodynamics (Cavity QED) experiments described in my Nobel lecture. Michel Gross and Claude Fabre went on to their own research careers after graduating, while Jean-Michel decided to stay in my group. With Philippe Goy, we supervised several PhD students during the 1980s and received many foreign visitors in our laboratory, including Daniel Kleppner and Luigi Moi, a former student of Adriano Gozzini, a friend and colleague of Kastler, working at the Scuole Normale of Pisa, the Italian sister school of the ENS. Moi became a close friend who pursued later his career as a professor at the University of Siena.
In the mid 1980s we were joined by another exceptionally gifted student, Michel Brune, who also stayed with us after his PhD thesis. At that time, Philippe Goy started a small microwave equipment company, AB Millimetre, which has built custom-made microwave sources spectrum network analyzers for customers all over the world. He has no longer worked directly with us since, although we still consult him when we have to solve an arduous technical problem. Jean-Michel, Michel and I have worked together up to now, training generations of students and postdocs in our lab. All the achievements which have led to the Nobel recognition are theirs as well as mine. Beyond the exhilaration of obtaining interesting results, we have shared the pleasure of exchanging ideas in an atmosphere of trust and friendship. We do take the research seriously, but we like to joke about ourselves. Claudine, who visits us often in the lab, likes to define the spirit in our group as a special mixture of self-confidence and derision. Of course we recognize the value of what we are doing, but at the same time, we try not to take ourselves too seriously.
Teaching was an important part of my activities. Since the early 1980s, Paris VI University and ENS had an agreement under which I could do my teaching at ENS to “normaliens”and to a group of selected students accepted in the ENS curriculum. To graduate students, I taught courses in atomic physics and quantum optics, and to undergraduates, I lectured about electromagnetism and quantum mechanics. At the same time, I had a part-time position as a lecturer at the Ecole Polytechnique, where I had also the opportunity to teach very bright students. I found all this teaching very rewarding, especially since I could always do it on topics which had a more or less direct connection with my own research, finding ways to illustrate the lectures with the description of modern atomic physics or laser experiments.
The 1980s were also years when America called. Harvard had offered me a full time professor position in 1981, but I was not ready to leave Paris and the group I was working so well with. Having loved our year at Stanford, I was however tempted to try another experience as a scientist in America. So when Yale, at the initiative of Vernon Hugues, allowed me to come and do research in New Haven for one term each year, while retaining my Paris position, I accepted the challenge to carry out experiments on both sides of the Atlantic. For a few years, I was able to successfully perform atomic physics experiments at both places. In Paris, it was relatively easy since my group was well organized there and Jean-Michel had the maturity to lead the group activities during the time I was away. In New Haven, I collaborated with Edward Hinds who was a professor at Yale, and with Dieter Meschede, a former student of a Munich colleague, Herbert Walther. Dieter had accepted the postdoc position I had offered him to help me start a research program at Yale.
We did some very good work during that time and we had some bright students who have had very successful careers thereafter. I also loved the opportunity to teach physics in an environment very different from the one I had at ENS or at the Ecole Polytechnique. American undergraduate students are somewhat younger and less mature than the “normaliens” I was used to training in Paris. They know less mathematics. Paradoxically, that makes them less inhibited than the French students and more prone to ask questions, sometimes naïve and sometimes deep. I enjoyed the interaction with them very much. I stayed there during the fall term, with frequent round trips to Paris. Claudine and the children visited often, while staying most of the time in France where they worked and studied. Julien and Judith had turned into teenagers who loved to visit the US for a while, but wanted to attend school in France, where they had their friends and their habits. Working in both places was thus a kind of state superposition that was hard to maintain coherently over a long period of time. In the early 1990s, I decided it was time to stop this experiment and to come back full time to my group in Paris, which had an ambitious research project to carry out. It is indeed at that time that the ideas about manipulating and observing photons non-destructively were developed, as well as those about preparing Schrödinger cat states of light.
These ideas sprang from long-term collaboration we had with Brazilian colleagues. I had had the opportunity to visit Brazil for the first time in 1983 when I participated in one of the first French-Brazilian workshop in quantum optics, held in Rio de Janeiro. Claudine and I were immediately seduced by the beauty of the country, its relaxed atmosphere and the gentleness of the Brazilian people. Since then, we have been to Brazil at least once a year and often more, visiting many parts of this huge country, with such diverse people and natural beauty. The physicists I met there in 1983 were enthusiastic about the possibilities opened for science in a country which was emerging from long years of dictatorship. Most of them had studied and obtained their doctorate in the US, where they had fled during the dark times. Some became good personal friends whom we enjoy to visit in Brazil or to welcome in Paris. Luiz Davidovich and Nicim Zagury, two quantum optics theorists from Rio, became soon familiar with the Paris Cavity QED setup and worked on the theoretical aspects of our experiments. Luiz was with us in Paris in 1987 when we operated our two photon Rydberg atom maser, the topic of Michel Brune’s doctoral thesis.
Jean-Michel Raimond and Michel Brune were naturally involved in this friendly collaboration. It was during a visit that Jean-Michel made to Rio in 1989 that the ideas about the non-destructive counting of photons first emerged. I remember the excitement we shared while communicating by phone calls and mail between Rio, Paris and New Haven, exchanging ideas and discussing the results of the first computer simulations of photon counting that Jean-Michel was doing with Nicim in Rio. A couple of years later, while Luiz was again in Paris for a sabbatical, we realized that the setup we had in mind to count photons non-destructively could be used to generate Schrödinger cat states of light and to study the phenomenon of decoherence. A 1991 paper in PhysicsTodayby Wojciech Zurek, which very clearly described superpositions of harmonic oscillator states and their decoherence, played an important role in this context. When reading this paper, we realized that we were in a position to observe these effects in the laboratory. With our Brazilian colleagues, we wrote a long article in PhysicalReview describing in detail the experiments we were planning. For this, we needed to develop new experimental methods for preparing and manipulating circular Rydberg states and new cavities able to trap photons for a very long time. It took us fifteen years to get a setup allowing us to observe the effects we had predicted in the early 1990s. I have described this adventure in my Nobel Lecture.
The years after my return from Yale were very busy. I resumed my teaching at ENS, under an arrangement which was made possible by the creation of a new structure in the French university system, called the “Institut Universitaire de France” (IUF). Being appointed in the IUF means that, while staying at the University which employs you, for a period of time ranging from 5 to 10 years you get a reduced teaching load and some money to travel or to spend on your research. In 1991 I was lucky to secure one of the first IUF positions and could thus spend more time on research at a time when, in the laboratory, we were struggling to build the setup we were dreaming about in order to manipulate photons “in vivo.” Soon after the appointment to IUF, though, the time I could devote to science was reduced by administrative duties. In 1994 I accepted an appointment as chairman of the ENS physics department. This turned out to be a very demanding task, which I assumed for six years. It is also around that time that I was elected a member of the French Academy of Sciences. With great pride, my parents attended my induction in the Academy, under the famed dome of the Institut de France. My father was already very sick at that time. They lived a few more years and passed away in 1998, a few months apart, after having shared the good and the bad times for more than sixty years.
The 1990s were also the years when ideas about quantum computing and quantum information processing with isolated quantum systems started to become popular and competition with other groups around the world became very strong. With Luiz Davidovich and Nicim Zagury we studied various ways to exploit our Cavity QED setup to perform demonstrations of simple quantum information steps. Some of these ideas have remained theoretical. Others have led to actual experiments. We recognized that our system, in which we were trapping photons was complementary to the one that David Wineland and his Boulder group were working on, in which they were trapping atoms. Some of the experiments we were performing in Paris and in Boulder were very close in spirit. We published back to back two physical Review Letters describing the observation of similar Rabi oscillations in a cavity QED and an ion trap. In 1996 we also prepared “Schrödinger cat states” of harmonic oscillators whose features looked alike and we studied their decoherence in experiments bearing strong similarities. It is at that time that David and I became good friends. Claudine and I convinced David and his wife Sedna to join us on a short vacation trip to Italy in the summer of 1996. Since then we have often met in Boulder or in Paris.
In 1999, Claude Cohen-Tannoudji and Pierre-Gilles de Gennes approached me to find out whether I would be interested in a position at the Collège de France, a very famous institute to which they both belonged. The Collège de France, founded in the sixteenth century, is a unique institution in the French academic system. I had attended many of Claude’s lectures there and I was impressed by the spirit and the values of this institution, in which the professors give public lectures which have to be renewed each year on the topic of their research. No enrollment is required to attend the lectures and there is no final exam. In other words, to prepare a course at the College de France, there is neither a recipe nor a captive audience whose assiduity might be encouraged by the pursuit of a degree. There are only free listeners, who share the same interest and expectation. Each professor tackles this task with their own personality, shaped by their encounters and singular experiences. It makes for a very diverse institution, gathering a broad range of specialists in physical, natural sciences and humanities. The faculty meets three times a year to decide the opening of new positions and to share their views on matters of learning and culture in a unique atmosphere.
The list of former professors at the Collège de France throughout history is impressive. In physics alone, it includes such celebrities as André-Marie Ampère, Leon Brillouin, Paul Langevin, Frederic Joliot, Anatole Abragam, Pierre-Gilles de Gennes and, of course, Claude Cohen-Tannoudji. To be asked to join this club was overwhelming, but I accepted the challenge and paid the traditional pre-election visit to all the professors, fifty in total, to explain them why it was timely to create a chair in the Collège de France on quantum physics. These visits were a unique opportunity to meet colleagues working in fields very far from my own, which turned out to be an enriching experience. I was elected a Professor at the Collège de France in June 2000 and gave the inaugural lecture of my chair in December 2001. I have since given a new course each year, on various topics dealing with quantum information science. Preparing these lectures has been very challenging, and also stimulating for my research. Having to present subtle phenomena as clearly as possible has more than once led me to conceive new experiments to illustrate some physics concepts.
After a few years of teaching, it seemed timely to collect the material from these courses in a book. With Jean-Michel Raimond, who at that time was teaching quantum information at ENS, we embarked in the task of writing a comprehensive volume describing the physics of atoms in cavities, making connections with related problems in quantum optics. This turned out to be a multi-year project, which resulted in the publication of the book “Exploring the quantum: Atoms,cavitiesand photons” in the summer of 2006. It included a detailed theoretical analysis of the coupling of atoms with quantized fields in cavities, along with the experiments we had performed up to then. It also described the related experiments that ion trappers, including David Wineland and his team, had realized and also made comparisons with the physics of cold atoms in optical lattices.
The book appeared exactly at the time when our laboratory got an exceptionally good cavity which finally made possible the experiments we had been dreaming about over the previous fifteen years. In the months and years which followed, with Stefan Kuhr and Igor Dotsenko − two exceptionally gifted postdoctoral fellows both coming from the laboratory of Dieter Meschede, now working in Bonn, Germany − we were able to observe many of the effects we had predicted in theoretical papers and announced in the book. The no-destructive counting of photons trapped in the cavity, the observation of field quantum jumps, the preparation and reconstruction of Schrödinger cat states of the field in the cavity and the direct observation of their decoherence were published in a fast succession of papers. These results were the topics of the PhD work of a succession of very bright and dedicated graduate students, one of whom, Sébastien Gleyzes, joined us a few years later to become a permanent member of our team.
Jean-Michel and I have often reflected upon the fact that our book was completed just before we could include in it the description of the most demonstrative experiments we have performed, which are only analyzed there as proposals. This calls for writing a revised edition incorporating all these results. But the events of the last few years are, for the time being, distracting us from this task. One of these events has been the CNRS Gold Medal, which I received in June 2009. This distinction is accompanied in France by a lot of media attention, which gave me a foretaste of what was going to happen in 2012. During that year I reached my 65th birthday, which was celebrated by a symposium at Collège de France during which I had the pleasure to meet many friends and colleagues coming from all the world for the event. It culminated with a dinner at the Musée Jacquemard André in Paris, before which we could visit a wonderful exhibition of Renaissance European painting. Reaching this symbolic milestone has been preceded by a sad family event. My youngest brother Michel had died in January 2009, before reaching his fiftieth birthday.
During the last three years, I have been busy with the project of starting experimental physics research at the Collège de France. The Collège laboratory buildings dating from the 1930s have been fully remodeled and we intend to move our research labs there from ENS in the coming months, along with those of Jean Dalibard, a colleague, former student of Claude Cohen-Tannoudji who has just been appointed to the Collège de France. Another professor, Antoine Georges, who is a condensed matter theorist, will join us to make up the Physics Institute of the Collège de France. We hope to attract research teams of junior scientists who will be able to start their independent research career in a favorable environment. It will not be an easy task to build, in the prevailing economy, a laboratory nurturing the kind of values that have allowed my research to develop and thrive when I was young. To succeed, the new institute will maintain a strong link with ENS and the Laboratoire Kastler Brossel, which have kept alive the “time and trust” legacy of Jean Brossel. I find the challenge of building a new research unit on these values to be especially stimulating.
In the fall of 2012, two events occurring a month apart have suddenly made my life, and that of Claudine, more hectic. First, I accepted the post of administrator of the Collège de France. Having received so much from this institution, I considered that it was my turn to take charge of its administration and management, at a time when it was expanding into new directions, especially with the opening of its buildings to new labs, in physics, but also in biology and chemistry. And then, a month later, the announcement of the Nobel Prize in Physics has exposed me to a worldwide media attention that the CNRS Gold medal had hardly prepared me for. I have learned during the last few months that it is essential to be able to say “no” to a lot of solicitations in order to keep some coherence in my life as a scientist and as a person.
Reflecting over the events of the last fifty years, I feel very privileged. On the professional side, I have had the luck to embark in a field – atomic physics and quantum optics – which has undergone fantastic developments over this period of time, improving by many orders of magnitudes the sensitivity of experiments and the precision of measurements. Thanks to advances in laser technology, new domains have been explored, in ultra-low temperature physics or in the study of ultrafast phenomena for instance, that we could not even imagine at the time I was working for my PhD. I did not work myself in many of these fields, but I witnessed these developments as a member of a very active and imaginative community of physicists, sharing the excitement and the bewilderment brought about by all these spectacular advances. And in my own research area of Cavity Quantum Electrodynamics, new developments extending the studies to artificial atoms and to a variety of electromagnetic resonators have kept the subject alive and thriving, with many promising developments to expect in the near future.
But above all, I feel privileged in my personal life. Thanks to Claudine and our children, my interests have extended to many areas beyond physics. By pursuing her own intellectual interests and keeping a very active professional career of her own, Claudine has maintained in our lives a balance between science, arts and humanities which has been very enriching to both of us. Since the beginning of my career as a scientist, as often as possible we have traveled together to conferences and meetings, discovering new places and new people and sharing our impressions about them. We have also taken time for vacation away from physics, visiting the natural and man-made wonders of the world, from Egypt to South Africa, from Patagonia to the Gulf of Saint Laurent, from Angkor to the Maya country, from Machu Picchu to the Galapagos islands. Julien and Judith joined us on many of these trips as children or teenagers and we keep wonderful memories of these special times with them. They are now pursuing their own full and interesting lives in Paris, Julien as a medical doctor doing clinical research in internal medicine and Judith as a lawyer. We are enjoying the pleasure and wonderment of witnessing the development and awakening to the world of Judith’s three children, her twin girls Elsa and Rachel (born in 2005) and her boy, Samuel (born in 2009). I know that Claudine, with her love of privacy and her keen judgment, will help keeping our life in the future not so much different from what it has been up to now.
This autobiography/biography was written at the time of the award and later published in the book series Les Prix Nobel/ Nobel Lectures/The Nobel Prizes. The information is sometimes updated with an addendum submitted by the Laureate.
Addendum, January 2018
Serge Haroche was born in 1944 in Casablanca. He graduated from Ecole Normale Supérieure (ENS), receiving his doctorate from Paris VI University in 1971. After a post-doctoral visit to Stanford University, he became full professor at Paris VI University in 1975, a position he held until 2001, when he was appointed Professor at Collège de France (in the chair of quantum physics).
He has been part time professor at Yale University (1984-1993), member of Institut Universitaire de France (1991-2000) and chairman of the ENS Department of Physics (1994-2000). In September 2012, he was appointed “Administrateur du Collège de France” (equivalent to President of this institution), a position he held until September 2015. Since then, he has been Professor Emeritus at Collège de France.
Serge’s research has mostly taken place in the laboratory Kastler Brossel at ENS. His main research activities have been in quantum optics and quantum information science. He has made important contributions to Cavity Quantum Electrodynamics (Cavity QED), the domain of quantum optics which studies the behaviour of atoms interacting strongly with the field confined in a high-Q cavity, a box made of highly reflecting mirrors.
Serge has received many prizes and awards, culminating in the 2012 Nobel Prize in Physics, shared with David Wineland.
Nobel Prizes and laureates
See them all presented here.