My father, Georg, had studied law at the Universitat Berlin for some years, and in the first World War had been an artillery officer. He was of a philosophical bend of mind and a man of independent opinions.

In the depth of the depression he just managed to make a living in real estate. When the family fortunes had shrunk to ownership of a heavily mortgaged apartment building located in an overwhelmingly Communist part of Berlin, it seemed reasonable to move into one of the apartments ourselves as nobody paid any rent.

Cannons were deployed on the streets on occasion and the class war had entered the class rooms. After a few bloody noses administered by a burly repeater, I shifted my interests from roaming the streets more towards playing with rudimentary radio receivers and noisy and smelly experiments in my mother's kitchen. In the spring of 1933 my mother, a very energetic lady, saw to it that, at the age of ten, I entered the Gymnasium zum Grauen Kloster, the oldest Latin school in Berlin, which counted Bismarck amongst its Alumni. This involved a stiff entrance examination and I was admitted on a scholarship. My father at that time expressed the opinion that I probably would be happier as a plumber. However, he apparently didn't quite believe this himself.

Thus, in years before, he had bought me an erector set and books on the lives of famous inventors and Greek mythology, and when I was ill he had given me the encyclopedia to read. I supplemented the school curriculum with do-it-yourself radio projects until I had hardly any time left for my class work. Only tutoring from my father rescued me from disaster. Reading popular radio books deepened my interest in physics. While physics was taught at the Kloster only in the later grades, in the public library I read books with titles such as "Umsturz im Weltbild der Physik" and learned about the Balmer series and Bohr's energy levels of the hydrogen atom. My teachers at the Kloster were excellent, I remember in particular Dr. Richter, who taught Latin and Greek, and Dr. Splettstoesser, who taught biology and physics. Richter liked to expand on the classical works, which we were reading in class. I spent most of the ample breaks in related intense discussions with a group of classmates, Heppke, Hubner, Landau and Leiser while others engaged in boxing matches. Splettstoesser was a working scientist who spent Summers as a visitor with a marine biology institute on the Adriatic. I jumped a term and graduated in the spring of 1940.

Having received a notice from the draft board, I found it wise to volunteer for the anti-aircraft artillery and a motorized unit. I was not able to serve as a radio man but was assigned to a gun crew and never rose above the rank of senior private. Sent to relieve the German armies at Stalingrad, my battery was extremely lucky to escape the encirclement. A few months later I was even more lucky to be ordered back to Germany to study physics under an army program at the Universit?t Breslau in 1943. After one year of study, I was sent to the Western Front and captured in the Battle of the Bulge. I spent a year in an American prisoner of war camp in France and was released early in 1946. Supporting myself with the repair and barter of prewar radios, I took up my study of physics again at the Universit?t G?ttingen. Here I attended lectures by Pohl, Richard Becker, Hans Kopfermann and Werner Heisenberg; Max v. Laue and Max Planck attended the physics colloquia. At the funeral of Planck I was chosen to be one of the pall bearers. At the university, I greatly enjoyed repeating the Frank-Hertz experiment, the Millikan oil drop, Zeemann effect, Hull's magnetron, Langmuir's plasma tube and other classic modern physics experiments in an excellent laboratory class run by Wolfgang Paul. In one of his Electricity & Magnetism classes Becker drew a dot on the blackboard and declared "Here is an electron..." Having heard in another class that the wave function of an electron at rest spreads out over all of space, and having read about ion trapping in radio tubes in my teens set me to wonder how one might realize Becker's localization feat in the laboratory. However, that had to wait a while. In 1948, in Kopfermann's Institute, which was heavily oriented towards hyperfine structure studies, I completed an experimental Diplom-Arbeit (master's thesis) on a Thomson mass spectrograph under Peter Brix. The results were published in "Die photographischen Wirkungen mittelschneller Protonen II," the first paper of which I was a (co)author. Soon thereafter, I began work on my doctoral thesis under Hubert Kruger in the same Institute. Well prepared by a series of excellent Institute seminars on the NMR work of Bloch and of Purcell, we were able to successfully compete with workers at Harvard University. In 1949 we discovered Nuclear Quadrupole Resonance and reported it in our paper "Kernquadrupolfrequenzen in festem Dichloraethylen." My doctoral thesis had the title "Kernquadrupolfrequenzen in kristallinen Jodverbindungen." This work led to an invitation to join Walter Gordy's well known microwave laboratory at Duke University as postdoctoral associate.

At Duke I had the pleasure of making the acquaintance of James Frank, Fritz London, Lothar Nordheim and Hertha Sponer. I advised Hugh Robinson, a graduate student of Gordy's in an NQR experiment, did my own research and also contributed some NMR expertise to an experiment by Bill Fairbank and Gordy on spin statistics in 3He/4He mixtures, gaining some very useful low temperature experience in this brief collaboration. Through Gordy's and Nordheim's good offices I was able to receive a visiting assistant professor appointment at the University of Washington with a charge to advise Edwin Uehling's students during his sabbatical and to do independent research. I had built my first electron impact tube during a brief interlude in 1955 in George Volkoffs laboratory at the University of British Columbia. Prior to that I had attempted a paramagnetic resonance experiment on free atoms in Gottingen and succeeded in doing so at Duke. During seminars at Gattingen on the magnetic resonance techniques of Rabi and of Kastler, it had occurred to me that because of the analogy between an atom and a radio dipole antenna, (a), alignment of the atom should show up in its optical absorption cross section, and (b), electron impact should produce aligned excited atoms. I put these two ideas to good use in 1956 in Seattle in an experiment entitled "Paramagnetic Resonance Reorientation of Atoms and Ions Aligned by Electron Impact." In this paper I first pointed out the usefulness of ion trapping for high resolution spectroscopy and mentioned the 1923 Kingdon trap as a suitable device. This work also brought me into close contact with spin exchange between electron and target atom, which gave me the idea for my 1958 experiment "Spin Resonance of Free Electrons Polarized by Exchange Collisions." However, first I had to learn how to produce polarized atoms, which could then transfer their orientation to trapped electrons. Falling back on buffer gas techniques developed in my 1955 Duke paper "Atomic Phosphorus Paramagnetic Resonance Experiment," I quickly demonstrated in my 1956 Seattle paper "Slow Spin Relaxation of Optically Polarized Sodium Atoms" how to efficiently produce and monitor a polarized atom cloud. Trapping the electrons in a neutralizing ion cloud slowly diffusing in the buffer gas, I was able to carry out the spin resonance experiment. My optical transmission monitoring scheme proved also very useful in the development of rubidium vapor magnetometers and frequency standards by Earl Bell and Arnold Bloom at Varian Associates, in which I acted as a consultant. The rubidium frequency standard is still the least expensive, smallest and most widely used commercial atomic frequency standard. The thesis "Experimental Upper Limit for the Permanent Electric Dipole Moment of Rb85 by Optical Pumping Techniques" of my first graduate student, Earl Ensberg, also made use of these novel optical pumping schemes and was finished in 1962. These early results were improved orders of magnitude by my doctoral student Philip Ekstrom in his 1971 thesis "Search for Differential Linear Stark Shift in Cs133 and Rb85 Using Atomic Light Modulation Oscillators." I was not satisfied with the plasma trapping scheme used for the electrons and asked my student, Keith Jefferts, to study ion trapping in an electron beam traversing a field free vacuum space between two grids. Also, I began to focus on the magnetron/Penning discharge geometry, which, in the Penning ion gauge, had caught my interest already at G?ttingen and at Duke. In their 1955 cyclotron resonance work on photoelectrons in vacuum Franken and Liebes had reported undesirable frequency shifts caused by accidental electron trapping. Their analysis made me realize that in a pure electric quadrupole field the shift would not depend on the location of the electron in the trap. This is an important advantage over many other traps that I decided to exploit. A magnetron trap of this type had been briefly discussed in J.R. Pierce's 1949 book, and I developed a simple description of the axial, magnetron, and cyclotron motions of an electron in it. With the help of the expert glassblower of the Department, Jake Jonson, I built my first high vacuum magnetron trap in 1959 and was soon able to trap electrons for about 10 sec and to detect axial, magnetron and cyclotron resonances. About the same time, my G?ttinger colleague, Otto Osberghaus, sent me a research report on the Paul rf ion cage. This trap had very desirable properties for atomic ions and it did not require a magnetic field. Therefore, I asked my student, Fouad Major, to experiment with a simplified cylindrical version of such a trap in the hope that it might be useful in hfs resonance experiments on hydrogenic helium ions. The early results were very encouraging and Jefferts also switched to the Paul trap. In 1962, Jefferts and Major both finished their Doctoral Theses entitled respectively "Alignment of Trapped H2+ Molecular Ions by Selective Photodissociation" and "The Orientation of Electrodynamically Contained He4 Ions." As a continuation of the latter, a new postdoc, Norval Fortson, Major and I published the 1966 paper "Ultrahigh Resolution DF=0 ± 13He+ HFS Spectra by an Ion Storage-Exchange Collision Technique." My own attempts to detect the polarization of the electrons acquired from a polarized beam of alkali atoms in my Penning (magnetron) trap, described in a 1961 research report to the NSF "Spin Resonance of Free Electrons," were not so quickly successful. However in this work I was much impressed by seeing the beam of sodium atoms traversing my glass apparatus in the reflected light from a sodium vapor street lamp adapted as illuminating light source. Only a later concerted effort by Gr?ff and Werth at Bonn, reinforced by Major and Fortson, as visitors, made a similar spin resonance experiment work in 1968. In the 1966 paper with Fortson and Major, I also proposed to develop an infrared laser based on ions in an rf trap. To this end my student, David Church, completed a thesis in 1969 entitled "Storage and Radiative Cooling of Light Ion Gases in RF Quadrupole Traps." In this work we demonstrated a race-track-shaped trap and cooled the ions by coupling to a resonant LC circuit. In parallel work my student, Stephan Menasian, in 1968, with some help from G.R. Huggett, succeded in cooling Hg+ ions in a race-track-trap with a helium buffer gas and in detecting them by optical absorption. Jefferts' research on hfs spectra of H2+ was continued in Seattle by my postdoc Charles Richardson and later by Menasian in his 1973 doctoral thesis "High Resolution Study of the (1, 1/2, 1/2) - (1, 1/2,3/2) HFS Transition in H2+." The resolution in the 3He+ hfs work was greatly enhanced in work with my colleague Fortson and my postdoc Hans Schuessler. Realizing in 1961 that precision measurements of the electron magnetic moment would require a large magnetic field and that Becker's electron localization feat might be approximated in a Penning trap, I began to consider other avenues for magnetic resonance experiments. Some success in the electron work, achieved with the help of my new student, Fred Walls, was described in our 1968 paper "'Bolometric' Technique for the RF Spectroscopy of Stored Ions." I reviewed the work on ions and electrons up to 1968 in two articles "Radiofrequency Spectroscopy of Stored Ions."

The able assistance of two postdocs, David Wineland and my former student Phil Ekstrom, made the isolation of a single electron become a reality in 1973 with our paper "Monoelectron Oscillator." Measuring its magnetic moment was another story. At G?ttingen in the late forties I had attended a seminar given by Helmut Friedburg, a doctoral Student of Wolfgang Paul, on focussing spins with a magnetic hexapole. This may be viewed as a refinement of the Stern-Gerlach effect. In subsequent discussions with fellow students a rumor of a Stern-Gerlach experiment for electrons was brought up, and also Bohr's and Pauli's thesis that such experiments were impossible in principle. Though it greatly piqued my interest, I could not understand this thesis. Stimulated by a 1927 paper of Brillouin on the subject, I followed another of the guiding principles formulated by Bohr: "In my Institute we take nothing absolutely serious, including this statement." In 1973 I proposed, together with Ekstrom, to monitor spin and cyclotron quantum numbers of the lone electron by means of the "continuous Stern-Gerlach effect" in an abstract "Proposed g-2/dvz Experiment on Stored Single Electron or Positron." My new postdoc Robert Van Dyck, Philip Ekstrom and myself reported the first such experiment in our 1976 paper "Axial, Magnetron, and Spin-Cyclotron Beat Frequencies Measured on Single Electron Almost at Rest in Free Space (Geonium)." This work also already made use of the important technique of side band cooling of the electron. The demonstration of sideband cooling had eluded us in earlier attempts undertaken together with Walls and later with Wineland. Encouraged by the success of the monoelectron oscillator I had also published in 1973 an abstract "Proposed 1014 Dv < v Laser Fluorescence Spectroscopy on Tl+ Mono-Ion Oscillator." Unfortunately, this proposal infuriated one of the agencies funding our research to the degree that they terminated their support almost immediately. I was rescued by a prize from the Humboldt Foundation and an invitation by Gisbert zu Putlitz to initiate the proposed laser spectroscopy project in his Institute at the Universit?t Heidelberg. As the fruit of these efforts a paper "Localized visible Ba+ mono-ion oscillator" by Neuhauser, Hohenstatt, Toschek and myself appeared in 1980.

In 1981 Van Dyck, my doctoral student Paul Schwinberg and myself extended the electron work to its antiparticle in our paper "Preliminary Comparison of the Positron and Electron Spin Anomalies" and I reviewed it in an article "Invariant Frequency Ratios in Electron and Positron Geonium Spectra Yield Refined Data on Electron Structure." In 1986 we published a detailed paper "Electron Magnetic Moment from Geonium Spectra: Early Experiments and Background Concepts" and in 1987 our collaboration reported a 4 parts in 1012 resolution in the g factor for electron and positron in "New High-Precision Comparison of Electron and Positron g Factors." A very promising scheme to detect cyclotron excitation through the small relativistic mass increase accompanying it was published in a 1985 paper "Observation of Relativistic Bistable Hysteresis in the Cyclotron Motion of a Single Electron" together with my postdoc, Gerald Gabrielse, and William Kells, a visitor from Fermi Lab.

Two years after the Heidelberg pioneering work an individual magnesium ion was isolated in Seattle with my postdoc Warren Nagourney and my student Gary Janik. The latter's thesis bore the title "Laser Cooled Single Ion Spectroscopy of Magnesium and Barium." "Shelved optical electron amplifier: Observation of quantum jumps," was published in 1986 with my colleague Nagourney, and Jon Sandberg, an exceptional undergraduate assistant. The paper introduced a new technique which has made optical spectroscopy on an individual ion possible with record resolution and reproducibility. To date the best resolution has been realized at NIST by a group headed by my former collaborator Wineland. Peter Toschek who had made important contributions to the visible ion work in Heidelberg has built up a thriving laboratory for monoion-spectroscopy at the Universit?t Hamburg. With Herbert Walther a collaboration almost came off in 1974. Walther, with his large staff and excellent facilities in Munich, has since developed his own expertise in the field and made outstanding contributions to it. Gabrielse, now a full professor at Harvard, has assembled a large group and is trapping and cooling antiprotons at CERN.

In the 1988 paper "A Single Atomic Particle Forever Floating at Rest in Free Space: New Value for Electron Radius" I have surveyed the field and suggested new avenues for its extension. More precise measurements of the g factor of the electron may well be the most promising approach to study its structure. No less important, a trapped individual atomic ion may reveal itself as a timekeeping element of unsurpassed reproducibility. The research effort in Seattle continues on troth projects. The National Science Foundation has supported my research since 1958 without interruption. Initially the Army Office of Ordnance Research and the Office of Naval Research did also provide support for many years.

I am married to Diana Dundore, a practising physician. I have a grown son, Gerd, from an earlier marriage to Irmgard Lassow who is deceased.

I do regular hatha yoga exercises, enjoy waltzing, hiking in the foothills, reading, listening to classical music, and watching ballet performances.