Quantum many-body systems, as they appear in different branches of physics and chemistry, are very hard to simulate. The number of parameters defining their quantum states grows exponentially with the number of constituents. This prevents us from exploring and investigating relevant problems involving relatively small numbers of subsystems even with the help of the most powerful supercomputers. Richard Feynman already noticed this difficulty back in 1981 when he wrote his visionary paper “Simulating Physics with Computers” [Int. J. Theor. Phys. 21:6/7, 467 (1982)]. There, he proposed to use quantum systems (as opposed to classical computers) to perform the simulation and in this way to circumvent the need to store and compute a colossal number of parameters, necessary to describe the pertaining superpositions. What was a visionary idea at that time has become a very active field of research in the last few years. The extraordinary progress of both theoretical and experimental research in quantum physics allows us now to tame, control, and manipulate various quantum systems with unprecedented precision. Laser, magnetic, electronic and other technologies enable us to arrange quantum subsystems in different geometries, modify their interactions, and detect them. This allows us to engineer Hamiltonians and emulate systems displaying some of the most intriguing quantum phenomena. This tremendous progress is, to a large extent, due to the pioneering work of many researchers during the last twenty to thirty years. Here, the investigations of basic phenomena with one or few atoms or photons were of particular impact. The degree of control achieved in the experiments has enabled the observation of mind-boggling quantum effects, related to the superposition principle or to entangled states, and their disappearance due to decoherence. In fact, the 2012 Nobel Prize has been awarded to two scientists, S. Haroche and D. Wineland, for such ground-breaking experiments. Such experiments, often in combination with laser cooling of atoms or ions and Bose-Einstein condensation, have formed one of the pillars on which the field of quantum simulations is being established. Quantum simulations with cold atoms, either in magnetic traps or in optical lattices, with trapped ions, with photons, with superconducting devices, with quantum dots, etc., have been theoretically proposed and experimentally considered by many researchers. Most of the proposals so far deal with problems in condensed matter physics that are either difficult to tackle with modern supercomputers or are difficult to observe in solid state systems. This has established a very close link between different disciplines, like atomic, molecular, and optical (AMO) physics, and condensed matter physics. Although some of the experiments are still in their infancy, and a lot of research is still needed, the extraordinary progress made in all these research areas during the last few years makes us feel confident that in the not too distant future quantum simulators will provide a key tool to investigate many-body quantum systems. Furthermore, we also expect that quantum simulators will help quantum physicists to establish new and fruitful links to other scientific communities, like high-energy physics or quantum chemistry. The present special issue contains various review papers as well as research papers on quantum simulations. It starts out with two papers written by last year's Nobel Prize winners describing their foundational work (Wineland, p. 739 and Haroche, p. 763). The issue continues with three thorough, invited review papers covering different topics on quantum simulations. The first one reviews recent theoretical proposals to use cold atoms in optical lattices to simulate lattice gauge theories of the sort that appear in high-energy physics (U.-J. Wiese, p. 783). The second covers both theoretical proposals and experimental demonstrations of cold-atom systems to simulate the physics of matter in the presence of gauge fields, displaying so-called topological phenomena, which so far have only been observed in solid-state systems (I. Spielman, p. 794). The third one contains an extensive overview and new proposals to perform a broad range of quantum simulations using quantum dot systems (P. Barthelmy et al., p. 813). The issue also includes six original papers with a variety of theoretical proposals as well as the introduction of novel theoretical techniques related to the field of quantum simulation. The field of quantum simulations is just starting, but we are confident that it will soon generate an even larger plethora of new ideas and discoveries, trigger interdisciplinary research, and lead us to the adventure of describing and understanding the quantum world. We hope that this special issue will help future researchers in such an exciting adventure. Rainer Blatt received his PhD degree in physics from the University of Mainz in 1981. As a postdoctoral fellow he worked on atomic beam cooling in Boulder, CO and later as a research assistant in Hamburg with single trapped ions. In 1995 he accepted a chair in experimental physics at the University of Innsbruck working on quantum information processing with trapped ions. Since 2003 he is also scientific director at the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences. Immanuel Bloch received his PhD degree in physics from the Ludwig Maximilians University of Munich in 2000. As a junior group leader, he continued in Munich starting his work on ultracold quantum gases in optical lattices. In 2008 he was appointed scientific director of the newly founded division on Quantum Many-Body Systems at the Max Planck Institute of Quantum Optics. Since 2009 he also holds a chair in quantum optics at the Ludwig-Maximilians University of Munich. Ignacio Cirac received his PhD degree in physics from the Universidad Complutense de Madrid in 1991. He was professor at the Universities of Castilla-La Mancha and Innsbruck from 1991–1996 and 1996–2001, respectively. In 2001 he joined the Max-Planck Institute of Quantum Optics, where he leads the Theory Division. His current research interests include quantum information theory and quantum optics. Peter Zoller obtained his doctorate from the University of Innsbruck in 1977. He was Max Kade Fellow at the University of Southern California from 1978/79, and was JILA visiting Fellow 1981/82 and 1988. In 1990 he became JILA Fellow and professor of physics at the University of Colorado. At the end of 1994, he accepted a chair at the University of Innsbruck, where he has worked ever since. Since 2003, he has also held the position of Scientific Director at the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences.
As a postdoctoral student at the Massachusetts Institute of Technology in 1978, I trolled the literature, seeking inspiration for my career as an experimental physicist. One article that caught my attention described the first laser-cooling experiment. David Wineland et al. at the National Bureau of Standards (NBS, now the National Institute of Standards and Technology) in Boulder, CO, had trapped a cloud of hot (about 700 K) ions and cooled them to near absolute zero (T < 40 K) by shining light on them (1). (See also ref. 2, which reports an independent and nearly simultaneous demonstration of laser cooling of ions.) Later that year, I was hired by NBS in Gaithersburg, MD and, inspired by Wineland’s landmark experiment, began to work on laser-cooling of neutral atoms.
Nothing is achieved alone.I am what and where I am because of all of those who crossed my path.Without all the good and the bad, I would not be here.I want to deeply thank all of those who joined me in this amazing experience.More specifically... To my mother who have always supported me in every decision I made, who let me walk on my own, but made me sure she was always there for what I needed.To my father, that always taught me the value of education and dedication.To my brother, to all the coffee and many gestures of love and appreciation.I hope I can inspire you, the same way you inspire me.À minha avó, que não somente me ensinou a ler, mas também com quem aprendi muito sobre amor, família e perseverança.To my friends who have been with me throughout all these years, sharing dreams, wins, loses but always there for each other.Specifically, those who started with me this journey in Physics, Rafael e Vitória, and are a fundamental part of my trajectory.Also, all my colleagues from the Quantum Adventures group, that quickly became a second family.To my friend and advisor, Thiago.It was out of pure chance I ended up in that interview and sent you an email.Now, two years later, I can see the difference it has made and how much you helped me through all of it, not only academically.It was a pleasure share these last two years.And hopefully, many to come. At last, I want to thank my beloved girlfriend Clara.There is no overstating the importance you have in my life.A great part of what I am, is due to you.And that part is certainly the best of me.Love you dearly.
I would first like to thank my advisor, Jeff Kimble, for the wonderful opportunities of the past six years. I am deeply grateful for the chance to work in such an exciting field, and I have learned a great deal both from him and from the diverse group of researchers he has assembled. His vision of what it means to be a scientist and his enthusiasm for pursuing challenging research problems have been an inspiring part of my education. The strong sense of community within the Quantum Optics group has been an important part of my time at Caltech, and I would like to express my thanks to all of the group members. I have worked with an amazing set of colleagues on the cavity QED experiments: Kevin Birnbaum, Andreea Boca, David Boozer, Theresa Lynn, Russell Miller, and Dalziel Wilson. They have taught me by example how to be an experimentalist — and to have a lot of fun in the process, even on experiments that have sometimes seemed overwhelming. I want to stress that the recent achievements in lab 11 would not have been possible without Dave’s insight and analysis. Outside the lab, I am grateful to a circle of friends who have made southern
The development of quantum electrodynamics (QED), which studies the light-matter interaction in quantum level, has been accompanied by the enhancement of the coupling strength g between an atom (matter) and an electromagnetic (EM) field (light).With the introduction of a cavity, forming a cavity QED system, the coupling strength reached weak coupling (WC) and strong coupling (SC) regime.These regimes are defined by the system dissipations, the atom decay rate γ and the cavity decay rate κ, where g ≪ γ, κ for the WC regime and g ≫ γ, κ for the SC regime.Especially for the SC regime, the energy exchange between the atom and the EM field can happen repeatedly before the system losses the energy.This physical property enables quantum state manipulation in First and foremost, I would like to express my sincere appreciation to my principal supervisor, Takao Aoki, for his advice and support during my PhD studies.He is the first person who welcomed me to the field of cavity quantum electrodynamics at the end my third-year as an undergraduate student.Then, when I proposed to go to NICT and study about circuit QED and USC/DSC regimes, he agreed and quickly worked on the joined research contract, which yield the contents of this thesis.I still remember his words, "the Hamiltonian is the same anyway", which he said after agreeing my proposal.I also would like to thank him to allow me to the Leading Graduate Program in Science and Engineering and Power Energy Professional WISE Program.These programs require extra work for some unique curriculums, such as Lab.Rotations, internship and studying abroad.He has been supportive and flexible all the time and gave me full room to what I needed to do.All these works could not be done without support and guidance.Next, I would like to thank the members of Macroscopic Quantum Physics Project, National Institute of Information and Communication Technologies (NICT).I greatly appreciate Kouichi Semba, the leader of the project, letting me join the team and supported my PhD studies.He recommended me to Prof. William D. Oliver at MIT which made my visiting stay at EQuS at MIT become true.I also want to thank you him for applying for the fund by CREST which greatly helped me financially for a period of working at NICT.His advices and supports were not only very helpful for the works but also enriched my life.Fumiki Yoshihara was my mentor all the time during these works.He told me how to design and analyze the circuits, prepare the samples and operate the systems for experiments.He always answered me when I face problems and help me solve them, even they are easy ones.It has to be pointed out that he gave me the idea coupling the qubit to multiple modes in the resonator.This research topic has been tough due to its complicity, yet also been fun to mess around.I also appreciate he invited me to the soccer games during the lunch breaks.The cryostat which I used to cool the circuits was mostly prepared by Tomoko Fuse.She also told me how to prepare the cryostat and manage the cables inside it.Her advices and comments on my works were always greatly helpful.As a theorist Sahel Ashhab supported my works from the basic ideas.His advices helped me a lot to understand what is happening in the systems.He also helped me analyze the multimode circuit QED system by carefully deriving the expressions.I would like to thank the of the group, Sunmi Kim, with the discussions over chip designs and preparation of the Lab.At the end, I thank Akiko Hoshi for dealing all the paper works and Takashi Nakayama for helping me with the coding and equipment preparation.Thirdly, I would like to thank Shiro Saito and Kosuke Kakuyanagi from Superconducting Quantum Circuits Research Group at NTT Basic Research Laboratories.As the co-authors, they fabricated the samples with maximum care.I also appreciate the discussions about the experimental results where they always gave helpful advices and suggestions.I would like to thank all the members for the discussions during my iii internship at the same group.I especially thank Shiro Saito and Satoru Toida, the mentor during the internship, to let me join the group and conduct experiments.It was a great experience to work with the top-level researchers around the globe.I also would like to thank my two supervisors of the two Lab.Rotations, Kazuya Yuasa and Hiroshi Kawarada, for giving me the opportunity to join them.Although they were for a short period of time, the experiences broaden my interests towards science and engineering and will be surely valuable for me.I am deeply grateful to my supervisor of Engineering Quantum Systems group, William D. Oliver, for making me joining with he and the other Laboratory members and hosted my stay.I also appreciate the discussions and works with Roni Winik, who patiently explained his research and brought me in with his research topic.I spent a great time discussing and chatting with the group members and enjoyed working with them.I also want to thank William D. Oliver who applied a