Australian physicist Gerard Milburn and I coined the phrase “e Second Quantum Revolution” in an invited paper, entitled “Quantum Technology: e Second Quantum Revolution,” which was published in 2003 in The Philosophical Transactions of the Royal Society of London, a journal founded in 1662 that claims to be “the world’s rst science journal.” (A number of Isaac Newton’s papers appeared in this journal in the 1600s and 1700s, and then came ours in 2003. So much for quality control.) is paper began its life as a National Aeronautics and Space Administration (NASA) Technical Brief that I routed to various NASA program managers in the early 2000s as a tutorial on quantum technologies. I had stolen the term “Quantum Technology” from a book Milburn published in Australia in 1996 by that same name.1 In the fall of 2002, I mentioned to Milburn at a workshop that I was working on this paper and he informed me that he had been asked to write a review article for The Philosophical Transactions of the Royal Society of London, on exactly that topic, and so we joined forces, and this publication was the result. It is likely the rst (and probably the last) time a NASA Technical Brief made it into The Philosophical Transactions of the Royal Society of London. at paper has been cited only a paltry 47 times but I often see it quoted in talks and public lectures, particularly the rst sentence of the abstract: “We are currently in the midst of a second quantum revolution. e rst quantum revolution gave us new rules that govern physical reality. e second quantum revolution will take these rules and use them to develop new technologies.” Without reproducing this entire paper, which is easy enough for you to read yourself, let me blunder on a bit about what ideas we were trying to get across.2
Australian physicist Gerard Milburn and I coined the phrase “e Second Quantum Revolution” in an invited paper, entitled “Quantum Technology: e Second Quantum Revolution,” which was published in 2003 in The Philosophical Transactions of the Royal Society of London, a journal founded in 1662 that claims to be “the world’s rst science journal.” (A number of Isaac Newton’s papers appeared in this journal in the 1600s and 1700s, and then came ours in 2003. So much for quality control.) is paper began its life as a National Aeronautics and Space Administration (NASA) Technical Brief that I routed to various NASA program managers in the early 2000s as a tutorial on quantum technologies. I had stolen the term “Quantum Technology” from a book Milburn published in Australia in 1996 by that same name.1 In the fall of 2002, I mentioned to Milburn at a workshop that I was working on this paper and he informed me that he had been asked to write a review article for The Philosophical Transactions of the Royal Society of London, on exactly that topic, and so we joined forces, and this publication was the result. It is likely the rst (and probably the last) time a NASA Technical Brief made it into The Philosophical Transactions of the Royal Society of London. at paper has been cited only a paltry 47 times but I often see it quoted in talks and public lectures, particularly the rst sentence of the abstract: “We are currently in the midst of a second quantum revolution. e rst quantum revolution gave us new rules that govern physical reality. e second quantum revolution will take these rules and use them to develop new technologies.” Without reproducing this entire paper, which is easy enough for you to read yourself, let me blunder on a bit about what ideas we were trying to get across.2
The turn of the XXth century witnessed a revolution in physics comparable to Isaac Newton’s discovery of the universal laws of mechanics and of gravitation three centuries earlier. The world required to be described in novel terms, as the immutable, deterministic view of our familiar universe had given way to a new world picture, one which featured chance, flux, and an incessant upsurge of waves of matter. Such a worldview was so radically new and counterintuitive that it gave rise to strong debates, to the effect that Albert Einstein himself tried to oppose it on the grounds that “God does not play dice”. In spite of the intense debates that accompanied its emergence, quantum mechanics quickly proved an incredibly efficacious new tool to understand and to predict a wide array of new phenomena. It was so successful that in no time it broke free from the environment of research labs to become part of daily life, making it possible, for example, to understand why some materials were conductors, while others were insulators. Along with it, came, too, the discovery of transistors, on which much of modern electronics rests. It also led to understand how novel materials known as superconductors allow the transport of electricity with no loss, thus paving the way for new developments in the fields of medical imagery or energy distribution. Other aspects of the quantum theory led to the development of atomic clocks of astounding accuracy, which would be wrong by no more than fifteen seconds, had they been set at the beginning of the universe. A hundred years later, at the turn of the XXIst century, Quantum mechanics has lost none of its astounding power. Contemporary research has undertaken the task of exploring its less immediately perceptible aspects. Groundbreaking developments have ensued, such as the teleportation of grains of light or the possibility, once predicted by the great physicist Richard Feynman, to build, one day, novel computers which, unlike the ones we are familiar with today, will be able to process innumerable numbers of operations in parallel. The Wright Colloquium will be for us the occasion to explore, in the company of five internationallyknown specialists in the field, some of the fascinating aspects of quantum mechanics. We will appraise how efficiently quantum physics can describe our world, and confront its limitation when it is faced with the infinitely small (in relation to recent experiments carried out at the CERN) as with the incommensurably large scale of sidereal spaces. We will appreciate the extent to which quantum physics already has impacted our everyday lives, and evoke the way in which novel fields such as quantum computers and quantum information will entail profound changes in the future. The quantum adventure has only just begun! Monday 15 November 2010 - 18h30 Jochen Mannhart Center for Electronic Correlations and Magnetism, University of Augsburg, Germany Quantum Physics on the Scale of Daily Life Tuesday 16 November 2010 - 18h30 Wolfgang Ketterle Nobel Laureate 2001 (Physics), Department of Physics, Massachusetts Institute of Technology, Cambridge, U.S.A. When freezing cold is not cold enough New forms of matter close to absolute zero temperature Wednesday 17 November 2010 - 18h30 David Gross Nobel Laureate 2004 (Physics), Kavli Institute for Theoretical Physics, University of California, Santa-Barbara, U.S.A. Quantum Mechanics of the Very, Very Small and the Very, Very Large Thursday 18 November 2010 - 18h30 Alain Aspect CNRS senior scientist and Professor Institut d'Optique and Ecole Polytechnique Palaiseau, France. From Einstein’s intuition to quantum bits: a new quantum age? Vendredi 19 novembre 2010 - 18h30 Rainer Blatt Institute of Quantum Optics and Quantum Information, Austrian Academy of Sciences and University of Innsbruck, Austria The Quantum Way of Doing Computations
The quantum revolutions: from concepts to technology The development of quantum mechanics in the beginning of the twentieth century was a unique intellectual adventure, which obliged scientists and philosophers to change radically the concepts they used to describe the world. After these heroic efforts, it became possible to understand the stability of matter, the mechanical and thermal properties of materials, the interaction between radiation and matter, and many other properties of the microscopic world that had been impossible to understand with classical physics. A few decades later, that conceptual revolution enabled a technological revolution , at the root of our information-based society. It is indeed with the quantum mechanical understanding of the structure and properties of matter that physicists and engineers were able to invent and develop the transistor and the laser – two key technologies that now permit the high-bandwidth circulation of information, as well as many other scientific and commercial applications. After such an accumulation of conceptual – and eventually technological – successes, one might think that by 1960 all the interesting questions about quantum mechanics had been raised and answered. However, in his now-famous paper of 1964 – one of the most remarkable papers in the history of physics – John Bell drew the attention of physicists to the extraordinary features of entanglement: quantum mechanics describes a pair of entangled objects as a single global quantum system, impossible to be thought of as two individual objects, even if the two components are far apart.
We are currently in the midst of a second quantum revolution. The first quantum revolution gave us new rules that govern physical reality. The second quantum revolution will take these rules and use them to develop new technologies. In this review we discuss the principles upon which quantum technology is based and the tools required to develop it. We discuss a number of examples of research programs that could deliver quantum technologies in coming decades including: quantum information technology, quantum electromechanical systems, coherent quantum electronics, quantum optics and coherent matter technology.
The National Aeronautics and Space Administration (NASA) develops a broad range of technologies to support space-based quantum sensing and communications, uses the space environment to study fundamental quantum processes to advance our knowledge of physics, and develops algorithms to attack complex science problems that might be solved using quantum computing. This paper describes quantum sensors that NASA has flown on space missions, investments that NASA is making to develop quantum sensors, and possible approaches to employ quantum sensing to study the attributes of distant stars and planets, the Sun, Earth, and fundamental properties of matter.
The difficulties of the old quantum theory were largely dispelled by the development of quantum mechanics in the 1920s. First Heisenberg (1925) developed the rather abstract matrix mechanics and soon after Schro¨dinger (1926; see also Eckart, 1926) developed the physically more appealing wave mechanics. Subsequently he showed them to be mathematically equivalent. The physicists were greatly relieved; now they had once again a mathematical formalism that enabled the results of experiments to be calculated. It was possible to move forward. It is certainly a very elegant and indeed beautiful formalism, and does enable the results of many physical measurements to be calculated with great accuracy. It is used daily by atomic and nuclear physicists; there is no other way to make calculations. From the earliest days there has been intense debate about the interpretation of quantum mechanics, and it shows no signs of being settled; if anything it is becoming more intense over the years. As Penrose has remarked, no one understands quantum mechanics. Feynman (1967; see also Sykes, 1994) also admitted that ‘nobody understands quantum mechanics’, and Einstein once remarked: ‘I have thought a hundred times as much about the quantum problems as I have about general relativity theory’ (Pais, 1994, p. 57). It should therefore be evident that the most that can be done here is to try to show where the real difficulties lie, and how the failure to recognize that quantum mechanics is an essentially statistical theory has led to a series of confusing quantum paradoxes. It is just these paradoxes that have often been used to support theological speculations. It is useful to ask what ‘understanding quantum mechanics’ actually means. Certainly it means being able to calculate the results of many measurements. The same applies to Newton’s theory of gravitation, which we understand in the sense that we can use it as a basis of calculation, although we do not really understand the gravitational force itself. Very often, especially in modern physics, the mathematical formalism does not give us the sort of intuitive physical feeling for what is going on that we often obtain from classical mechanics. Perhaps we can never achieve more than this for quantum mechanics. In classical mechanics we can assume that a property that is measured objectively exists prior to the interaction of the measuring apparatus with the observed system. Quantum mechanics, however, ‘is incompatible with the proposition that measurement discovers some unknown but pre-existing property’ (Peres, 1997, p. 14). There is an important distinction between mysteries and absurdities. We may be forced to live with mysteries, but there is no reason why we should put up with absurdities such as the wave-particle duality, tunnelling through potential barriers, acausal events and the collapse of the wave function. These are the quantum paradoxes that will be discussed later on. They arise within the Copenhagen interpretation of quantum mechanics and are solved by other interpretations. These alternative interpretations enable us to make conjectures about what is going on, even though we cannot understand it in detail. This is acceptable and a stimulus to further research. It is certainly difficult enough to understand quantum mechanics, but there is no need to try to visualize logical absurdities in the effort to do so. Quantum mechanics is a mathematical formalism that makes it possible to calculate the results of some experiments. Anything more than this, such as questions about the interpretation of what is measured and whether it tells us what is actually going on in the system being studied, belongs to philosophy. Thus we are concerned here with what is essentially a philosophical debate; if it were just a matter of physics the debate would have been settled long ago. One of the difficulties is that it invokes the results of experiments and uses the language of quantum mechanics. Inevitably this language uses philosophical terms and then it is easy to give the impression that the philosophical propositions are in some way entailed by the physical results. These in turn can influence theological thinking. In order to be quite clear which arguments are justified and which are not, it is essential to separate the three levels of discourse: physical, philosophical and theological. Our task is to relate these together, and this immediately raises the traditional problems of the philosophy of science, including the relation of experiment to theory, and of theory to explanation. We begin by discussing experiments, distinguishing between those that are real and those that are imaginary.
2019 promises to be a crucial year for the emerging field of quantum technologies. On the funding side, the Quantum Technologies Flagship of the European Union has kicked off with the first 20 projects,1 and the total funding is expected to reach €1bn over the coming decade.2 Other world regions are not being left behind: In the US, Congress has recently passed the National Quantum Initiative Act, likewise a 10-year program with a budget of $1.3bn. This bold concept is accompanied by further support from government agencies such as the DOE and NSF. Research activities are being intensified not only in academia and research laboratories but also in the R&D centers of giant corporations such as Google, IBM, Microsoft and in many other companies. A key goal is to couple ever more qubits and to demonstrate a working quantum computer that will be able to achieve the ‘holy grail’ of quantum supremacy in computational power – if not yet today or tomorrow, then certainly in the years to come. Last but not least, the Chinese government has announced the provision of no less than $10bn to create a National Laboratory for Quantum Information Sciences. China has already taken crucial steps in creating a quantum network, including satellite-based communication. So, clearly the world is not short of opportunities in pursuing new and exciting quantum science, as well as its applications. On the other hand, it is more than obvious that there are still many fundamental scientific questions to be solved, not to speak of the development of real technologies that are still in their infancy to be implemented on a broader scale. Our journal Advanced Quantum Technologies (QUTE) (www.advquantumtech.com), a young member of the renowned Advanced journal family published by Wiley-VCH, aims to provide a peer-reviewed high quality forum for these topics, ranging from the theoretical basics to future device applications. Key areas include quantum-based communication, computation, control, engineering, information, metrology, optics, sensing and simulation, as well as adjacent areas such as nanophotonics, quasiparticle excitations, topological materials, superconductors, micro- and nano-electromechanical systems, ultracold atoms and others. The first three issues published in 2018 already provided a glimpse of our intended broad topical spectrum, with Reviews on continuous-variable quantum key distribution,3 non-equilibrium Bose–Einstein-like condensation4 and integrated quantum photonics based on diamond,5 accompanied by original research contributions as Communications or Full Papers. Now, what do we have in store for the New Year: The present issue features, for example, a Review on topological insulators and semimetals for magnetoresistive sensors6 and a Progress Report on the Dicke model being relevant for quantum optics.7 Later during 2019, we also plan to present two special issues on the topics of Quantum Machine Learning and Photonic Quantum Technologies that will aim to provide a snapshot of the state-of-the-art in these respective fields. Most importantly, please be reminded that the journal is open for original research submissions at www.editorialmanager.com/advquantumtech as well as your proposals for review-type contributions that you may send to advquantumtech@wiley.com at any time. We will also use forthcoming conference opportunities such as the APS March Meeting in Boston, several DPG (German Physical Society) meetings as well as various events in Asia to meet with you personally to get to know your research, to invite you to submit as well to learn more about the publication needs of the quantum community. Feel free to get in touch with us through any physical or virtual channel! For those of you who might be new to our journals: Online submission and online publication (no print) in QUTE are completely cost-free, and the journal is also free-to-read for anybody during the whole year. If you would like to make use of open-access options, Wiley OnlineOpen with various open access licenses is available through an increasing number of national, consortial or funder agreements (such as the ‘DEAL’ soon to be implemented in Germany8) or via payment of the respective article publication charge by your institution or funder. Details are provided in the ‘Contribute’ section of our homepage. You may also post a preprint of your manuscript to arXiv.org or similar servers, or to a scientific collaboration network that is compliant with the STM sharing principles.9 When doing so, please make sure that the journal reference is always up to date, including the DOI and/or URL of your journal-published article. More information on general article sharing principles is available on howcanishareit.com. These should help you to achieve maximum visibility both of your newest publication and of our young journal, as will news stories on selected top content on our news portal advancedsciencenews.com. We look forward to exciting quantum times and to reading (or hearing) from you! The Editorial Team of Advanced Quantum Technologies