HEROES IN THE WORLD OF SCIENCE
The history of the Dodd Walls Centre is an untold story of kiwi pioneering. Perhaps because we talk so much more about sports than science in New Zealand these heroes never became household names like Team New Zealand or the All Blacks yet their achievements are just as extraordinary. DAN WALLS came back to New Zealand in 1971 having completed his PhD and postdoctoral studies at Harvard and Stuttgart Universities. At the time New Zealand was a backwater in physics. Most of the advances were taking place in Europe or America and that was where a brilliant physicist like Dan was expected to set up if he was serious about his career. But Dan, who loved his country, and the lifestyle, chose to return to New Zealand. After a year lecturing at Auckland University he accepted a position at Waikato, a new university with a strong agricultural focus, but an almost invisible physics programme.
In the ten years that followed, Dan together with his close colleague Crispin Gardiner, set up a school of theoretical physics which attracted outstanding students and visitors from around the world, and played a leading international role in developing the field of Quantum Optics. Their pioneering work helped lay the foundation for the field of quantum information and the development of quantum computers, now attracting great attention worldwide.Twenty years earlier another visionary kiwi physicist, JACK DODD carried out pioneering work that helped establish the field of Quantum Optics. In 1952 Jack returned to Otago University from the UK where he had completed his PhD in nuclear physics. There were no resources to continue in nuclear physics so he started afresh in the newly important field of atoms and electromagnetic radiation. The timing of his work was propitious. The invention of the laser in 1960 led to an explosion of interest in the field, and new understanding was required. Jack’s work contributed to the knowledge underpinning this new field.
DISCOVERING THE STRANGE WORLD OF QUANTUM THEORY
The theory behind today’s emerging quantum technologies was first discovered at the beginning of the 20th Century by scientific legends like Einstein, Schrödinger and Heisenberg. It threw everything on its head revealing a vast uncharted realm of physics with completely unfamiliar rules. In this quantum realm a particle could be in two places at once, spin in different directions at the same time and pass through walls. Particles could act like waves and waves like particles. This came as a shock for physicists who thought they had cracked all the important laws of physics. But for theoretical physicists who live for the thrill of exploring and charting new territory, quantum physics became the promised land - a world of great intellectual riches.For decades after the principles of quantum physics were established there was no technology to directly test them and the quantum realm remained largely inaccessible. This changed dramatically when the laser was invented in 1960.
LASERS OPEN QUANTUM WORLD FOR EXPLORATION
A laser is a device which emits a very precise frequency of light in a well directed beam. It provides a way of ‘talking’ to atoms with the greatest delicacy and control that nature allows. A beam of laser light can be used to probe, control and observe the quantum state of atoms, including moving them around one by one. Although the theory behind it was laid down by Einstein in 1917, the first device was only made in 1960. It is an example of pure curiosity driven research, and famously was initially described as a solution looking for a problem. However it did not take long before a multitude of applications became obvious, and it is now a key part of much of 21st century technology.
A GOLDEN ERA OF PHYSICS IN NEW ZEALAND
The Dodd Walls story is inseparable from the story of the laser.Dan Walls was at Harvard when laser technology was beginning to take off. His supervisor Roy Glauber later won the Nobel Prize for developing the theoretical framework for quantum optics, a field made possible by the invention of the laser. After Harvard, Dan worked in Stuttgart with Hermann Haken who pioneered the theory of the laser. He was right at the centre of this emerging field and saw the potential for it. He also realised that it was an ideal fit for New Zealand, requiring much creativity but few expensive resources. It is testimony to his vision that he attracted many top physicists to the rural outskirts of a colonial town at the bottom of the world.
CRISPIN GARDINER was Dan’s closest ally in the early days at Waikato - a brilliant mathematically gifted theoretical physicist. They had been friends at Auckland Grammar School and studied Physics together at Auckland University before going separate ways. Crispin studied nuclear physics at Oxford University, and continued in postdoctoral research abroad until Dan lured him home to New Zealand.HOWARD CARMICHAEL, now a Principal Investigator in the Dodd Walls Centre was also part of the early dream team. He was one of Dan’s first PhD students and followed him from Auckland to Waikato.DWC Principal Investigator, JOHN HARVEY, who now leads the Dodd Walls Development Centre, also joined the team in the early days. Along with Dan, he started work on bio-photonics - the interaction of laser light with biological organisms.One of Dan’s particular forms of genius was his ability to identify the right problems to work on. Throughout his career he travelled the world, keeping in touch with the top labs and staying connected. This was a key to the team’s success. The problems Dan chose to work on often became the basis for theoretical and experimental breakthroughs.The team became world-renowned, especially for their summer schools, which attracted leading physicists from around the world. They developed a capacity to do calculations with the “lofty concepts of quantum theory” that proved relevant and useful to experimentalists around the world. Dan had an irresistible enthusiasm that convinced several experimentalists to change tack and work on the topics he was focussing on.The group’s first major breakthrough was their prediction of “photon anti-bunching”, a phenomenon that, through experiment, could demonstrate the particle-like nature of light. This opened the way to study the quantum properties of light in the lab. This was the subject of Howard’s PhD under Dan’s supervision.Crispin Gardiner developed statistical approaches to modelling laser light and its interactions with atoms that remain the reference point for statistical analysis in many fields today.Howard Carmichael is famous for his “quantum trajectory theory”, which forms the basis for the latest advances in quantum computing and is widely used in simulation software to predict the behaviour of quantum systems.Together the team developed an understanding of light and matter which paved the way for some of the modern developments in photonics and quantum technology.In 1987 Dan took up the Chair of Theoretical Physics at Auckland University while Crispin stayed at Waikato. The move effectively doubled the size of the theoretical quantum optics effort in New Zealand. The two continued to collaborate closely and as their students spread across New Zealand and the world, their legacy travelled with them.
THE OTAGO STORY
For the other half of the Dodd Walls Story we go to Otago University.When Jack Dodd returned to New Zealand in 1952 the laser hadn’t been invented. But new developments in electronic technologies like radar were hinting at the possibility of “communicating” with atoms. Drawn by the promise of this research Jack developed some original ideas to explain the interactions between electromagnetic radiation and atoms which won him a prestigious Nuffield Fellowship to Oxford University in 1959. There, along with his close collaborator and friend George Series, he published his most famous paper on “quantum beats”, which became a landmark for the field. This phenomena predicts a way of observing the quantum nature of atoms. It describes how light shone on an atom can induce two simultaneous quantum states that cause the intensity of the scattered light to surge on and off in beats.
Back in Otago Jack gathered a team of outstanding students and colleagues who tested the ideas further and ran experiments to establish wide acceptance of this theory.Jack Dodd was the father of quantum optics in New Zealand. He was an inspirational leader and a generous supporter of his students and colleagues who went on to have outstanding academic careers in New Zealand and Australia.After those golden years of research, things became somewhat quieter in Otago. Then in 1979 a new recruit arrived. ROB BALLAGH had met Jack Dodd at JILA Colorado, one of the world centres for atomic physics and laser technology. Rob was doing his PhD in theoretical laser physics at the centre of this burgeoning field. At JILA he was surrounded by world leading scientists, some whom went on to win Nobel Prizes for their contribution to laser and atomic physics. It was an incredibly exciting time. But, like Dan Walls and Jack Dodd, Rob loved New Zealand and wanted to return. So he accepted an invitation from Jack, and his colleague Wes Sandle, to join them at Otago University.Rob arrived to find out of date labs and very little funding, but Wes Sandle had a burning ambition and the drive to compete on the world stage. Over the next decade, with Wes’s support, Rob worked hard to maintain his overseas connections and contribute research of international interest. The laser was opening up the possibility of experiments in the quantum realm, but the theory for describing them was challenging. Rob had a particular and early interest in developing computational techniques for solving the complex equations that arose. He used these to both explain experiments, and predict new results. Throughout this time he kept in close contact with Dan Walls and Crispin Gardiner, regularly attending their summer schools.
BOSE EINSTEIN CONDENSATES PUT OTAGO ON THE WORLD STAGE
Just as the invention of the laser did in 1960, the emergence of Bose Einstein Condensates (BECs) in 1995 dramatically changed the field. Where the laser had opened the gates to the quantum realm via the medium of light, BECs gave physicists an unparalleled new system to explore the quantum world of matter.A Bose Einstein Condensate is a new state of matter in which the particle behaviour of atoms is suppressed and it becomes a single wavelike entity. In contrast to normal states of matter, where thermal fluctuations usually mask the underlying quantum properties, a BEC is dominated by its quantum behaviour. Just as Newton and Galileo worked out the laws of motion and gravity by dropping things, bumping them into each other and measuring the outcomes, experimentalists could play with BECs to work out the implications of quantum physics.
The first Bose Einstein Condensate was made in 1995 at JILA in the US. At the time Rob was on leave at Oxford University. He was in the right place at the right time, working with Keith Burnett who was an expert in this new area. At the same time Andrew Wilson, an ex-PhD student from Otago was working in Keith’s lab trying to create a BEC. Together Rob and Andrew hatched a plan to return to Otago and attempt to make a BEC in the lab. Rob came home to raise funding while Andrew finished his postdoctoral fellowship, made important contacts and gathered as much knowledge as he could for the challenge.It is hard to describe how outrageous this ambition was. Making a BEC was a very difficult technological feat. Atoms needed to be suspended in space and cooled to temperatures far below the background temperature of the universe. It was a challenge that many well resourced groups around the world had attempted but not achieved. In contrast to those large teams, Andrew began with one PhD student and a very small budget. Eventually he was able to recruit two key research fellows, and despite all odds they succeeded. In 1998 they were the 11th lab in the world to achieve Bose Einstein Condensation - beating the UK and Australia. The team acknowledged the generous support and guidance of their overseas colleagues.When the BEC was announced a TV crew showed up and a wave of excitement spread across the country. It was a pivotal achievement, rewarding the University for its support of a high risk programme, and also opening the doors to some generous funding from the government supported Marsden fund.This great achievement marked the beginning of a new era at Otago University as one of the world centres for cold atom research. A very notable friend was Bill Phillips who lent his Nobel Prize winning authority to the achievement, singing praises of the group in public lectures and radio interviews. It also enabled Otago to attract top researchers and students who have gone on to achieve world first results. Mikkel Andersen, a current DWC Principal Investigator now holds the world record for controlling individual atoms. Principal Investigator, Jevon Longdell has developed a world-leading quantum memory solution and others are contributing at top level to the development of quantum computing and communication.The transition from pure theoretical to experimental research represents a growth in maturity. The significance of this for New Zealand is that the skills and knowledge-base required for experimental physics transfers to industry. From far flung roots in the obscure realms of quantum theory we have grown a workforce capable of generating new high-tech industries, transforming our economy and contributing to the next wave of quantum technologies.
ACHIEVING CRITICAL MASS THROUGH THE DODD WALLS CENTRE
In 2013-14 the DWC, led by Director David Hutchinson and Deputy Director Neil Broderick, brought together researchers from across New Zealand working in the field of light and won the bid to become a Centre of Research Excellence in 2015. The result has been to supercharge the impact of research and enable more collaborations with industry. One of the aims of the centre is to train a workforce to grow New Zealand’s high tech sector. Now students travel from all around the world to study here. There is a natural synergy between the legacy of Jack Dodd and Dan Walls that has been recognised in the Centre and many exciting collaborations are emerging. By pooling resources and coordinating efforts the Dodd Walls Centre has given quantum optics research in New Zealand critical mass and international recognition.
PROFESSOR JACK NEWTON DODD (1922-2005)
Jack Dodd was a man of great charisma and personal charm, a lively, witty man; one might even say, a professor of the old school. Nevertheless a man who did the first experiments which demonstrated the phenomenon of "quantum beats", and gave the theoretical explanation for them.
Born in Hastings to parents who encouraged a lively intellectual atmosphere in the home, he was deliberately given a middle name to inspire his interest in science. By the time Jack began school, his family had moved to Dunedin, and over his school years he developed a passion in number of areas, becoming an accomplished musician and graceful dancer.
Although his wide ranging interests were sometimes detrimental to his academic studies, he was a student of outstanding ability, and entered the University of Otago to study physics in 1940. Jack threw himself fully into University life, and served as President of the Otago University Student association, before completing his BSc in 1942. He then went into war service, working on scientific problems, before returning to Otago to complete his Master’s degree in 1945, and a year of Honours mathematics in 1946.
In 1947 he was awarded an 1851 Exhibition Scholarship for doctoral study in Birmingham, where he wrote his thesis in nuclear physics. With characteristic energy, he made time for outside activities, including playing in the British open bridge championships in 1948 and representing New Zealand at an International Students Union Congress in Paris in the same year. That year was also a personal landmark when Jack met his future wife Jean, and they married in Coventry in 1950. He completed his doctorate in 1952, and although it was normal at that time for outstanding young New Zealand physicists to remain abroad permanently to further their careers, Jack chose to return to the University of Otago to take up a lecturing position.
He was a visionary, with the ambition to establish physics research of international quality in New Zealand, and since it was not practical to continue in nuclear physics, he started afresh in the field of atoms and electromagnetic radiation. This was an area that was surging ahead with the impetus of recently developed electronic technologies such as radar, and he began working to explain some new and puzzling observations in atomic spectroscopy.
His development of some original ideas in this field led to the award of a Nuffield Fellowship to Oxford in 1959. During that year he developed a close collaboration and lifelong friendship with George Series, as they formalized his ideas to produce a proper theoretical description of the phenomenon which became known as quantum beats. The central idea was that incident radiation could establish a coherent quantum superposition between two atomic levels of different energy, which would subsequently reradiate with a temporal intensity modulation that would characterize the superposition. Jack’s first public presentation of his ideas was given under the stern gaze of Willis Lamb, Professor at Oxford and Nobel laureate for his own work on atomic spectroscopy. Lamb’s initial response was sceptical, but within a few days he reversed his view, and endorsed Jack’s theory.
The elegant paper published to report the findings became widely known as "Dodd and Series" and proved extremely timely, with the field of spectroscopy about to experience explosive growth under the revolutionary impact of the laser. This classic paper was one of a number that helped establish the theoretical foundations of the new field of laser spectroscopy, and later quantum optics, and was widely cited for many years.
When Jack returned to Otago in 1960, he set about creating a research group, and he recruited a team of outstanding students and colleagues. Over the next decade they extended the initial ideas, and carried out a series of experiments which cemented the ideas into wide acceptance. Jack was an inspirational leader, and a generous and loyal supporter of his colleagues and students. Many of the group from those years have gone on to forge outstanding academic careers in New Zealand and Australia, and he took great pleasure in the success of those who succeeded him.
Recognition for his achievements came from a number of sources. In 1967 he was awarded a Visiting Fellowship for a year at JILA, a joint institute between the US National Bureau of Standards and the University of Colorado. Jack became a Fellow of the Royal Society of New Zealand in 1964, and was appointed Beverly Professor of Physics at Otago in 1965, a position he held until his retirement in 1988. He was awarded the Hector medal of the Royal Societyof New Zealand 1976 in recognition of his research achievements. The connections he pioneered with Oxford and JILA have been fruitful and enduring ones for Otago that have benefited many staff and students, and have led to reciprocal visits from colleagues at JILA and Oxford
PROFESSOR DANIEL FRANK WALLS (1942-1999)
Dan Walls, in contrast, impressed immediately by the power of his personality and his personal conviction of the importance of quantum mechanics, of New Zealand and by his absolutely uncompromising view that he would not only do research of international standard in New Zealand, but also of world leading standard, and that the New Zealand science system would have to adapt to this point of view, sooner rather than later. The depth of this conviction became a self-fulfilling prophecy, leading to the current recognition of New Zealand as one of the leading countries in Quantum Optics, Photonics, and Ultra-Cold Atoms.
Dan Walls, like Jack Dodd, was born in Hawkes Bay, but in Napier rather than Hastings. Even though I was born in Hastings only a month later, he and I first met in Auckland, in form 3A at Auckland Grammar School in 1956. For the next five years we were rivals (in the atmosphere of competition still in favour in that institution) for the top places in physics, science and other subjects. We were then both students in the Physics Department of Auckland University from 1961 to 1965, and both of us then left, after completing MSc degrees, for foreign parts, he to Harvard, and myself to Oxford.
In the early seventies, after five years of doctoral and postdoctoral work, we both returned to New Zealand, and by 1972, were both senior lecturers in the University of Waikato. The science departments were established there only in 1970 - hence our job was to set up theoretical physics there. As eager young Turks, we set about doing this with an enthusiasm which did not always meet with approval from the local establishment.
Dan had been a student of Roy Glauber, one of the winners of the 2005 Nobel Prize in physics, who set up the concepts and formalism of Quantum Optics, the study of those aspects of optics in which quantum mechanics played a dominant role. Jack Dodd’s work on quantum beats was a pioneering piece of work in this field, done before the introduction of the laser as a practical experimental tool. Glauber’s work formulated the concepts necessary to describe the physical phenomena now available for study because of the availability of the intense coherent monochromatic light produced by lasers. Dan had also spent a postdoctoral year in Stuttgart with Hermann Haken, one of the pioneers of the quantum theory of the laser, and arrived in New Zealand well equipped to spread the word here. My work overseas had been in particle physics, but like Jack Dodd, I felt something else was appropriate for New Zealand, and I joined Dan in his research.
In the first few years in Waikato we branched out into nonequilibrium thermodynamics of chemical reactions, a field of study that had many formal similarities to the methods of quantum optics, and which led to the formation of significant international connections. However, we soon moved more seriously back into quantum optics, especially after Howard Carmichael arrived from Auckland University to work on a D Phil with Dan and myself as 1st and 2nd supervisor. Dan first became prominent in quantum optics in his prediction, with Howard Carmichael, of the existence of photon antibunching in the spectrum of resonance fluorescence, and thus initiated the study of non-classical light as an experimentally realizable subject.
During this initial period John Harvey, also a graduate of Auckland University who had done doctoral studies overseas took up a postdoctoral fellowship in Auckland University. John had worked on theoretical nuclear physics, but also decided a change was in order. He a Dan decided it might be a good idea to start work on biophotonics. Among other things this led to a joint research effort with the then Ruakura Agricultural research Station on laser measurement of bull sperm motility. Thus John became an experimental laser physicist, and ultimately a photonics researcher.
Dan later became very active in the theory of optical bistability, and in the formulation of proposals for the production of squeezed light. He, Matthew Collett, at that time doing research for his MSc thesis, and myself developed the crucial theoretical foundations required to describe the experiments on squeezed light, predicting correctly the full squeezing spectrum measured by the team of Jeff Kimble (then in Texas, now in Caltech.) After these achievements, the "New Zealand School" of quantum optics was firmly recognized, and we both wrote definitive books on Quantum Optics. Dan’s book was authored with Gerard Milburn, whom he had attracted from Australia to do doctoral work in Waikato, and who is now internationally famous as an expert on quantum information, and is the director of an Australian Centre of Research Excellence in Brisbane based on that subject.
In 1987 Dan took up the Chair of Theoretical Physics at Auckland University, while I stayed at Waikato, and we established a programme of ongoing joint meetings once a month, alternately in Auckland of Hamilton. The effect of Dan’s move was to double the size of the theoretical Quantum Optics effort in New Zealand.
Later Dan moved into theoretical atom optics, and in the last few years he was also active in the field of Bose-Einstein condensation. His ability to identify what the most important problem of the time, and to motivate research students (as well as other researchers from all round the world) to join in research programmes on such problems, was one of his most prominent characteristics. Typically, too, he could see that many problems could be reduced to very simple models, which were amenable to rapid solution.