Quantum information science (QIS) is devoted to understanding how the fundamental laws of quantum physics might be harnessed to dramatically improve the acquisition, transmission, and processing of information. The potential scientific and technological payoff from QIS is vast, but many deep and fundamental problems must be solved before that potential can be fulfilled. These advances will require contributions from scientists trained in a variety of subjects who are bold enough to disregard the traditional boundaries between disciplines and to pool their efforts in building an important new field. With this need in mind, the Institute for Quantum Information (IQI) was founded at Caltech in September 2000, supported by a five-year $5M Information Technology Research (ITR) award from NSF. Since September 2005, the IQI has been supported by a three-year award sponsored jointly by the Physics at the Information Frontier program (PIF) in MPS/PHY, the Emerging Models and Technologies for Computation Cluster (EMT) in CISE/CCF, and the Office of Multidisciplinary Activities (OMA). The IQI, led by a multidisciplinary team of five Caltech professors, is devoted to building the theoretical foundations of quantum information science across a broad front encompassing quantum algorithms, quantum cryptography, quantum information theory, fault-tolerant quantum information processiThe research accomplishments of the IQI have clear intellectual merit. Since September 2000, IQI participants have produced 282 publications covering all aspects of theoretical QIS; of these 86 were generated since the onset of our current award in September 2005. Some noteworthy achievements during the past two years are: (1) Progress in quantum algorithms, such as the discovery of an exponential speedup for finding hidden nonlinear structures. (2) Insights into quantum communication, such as a proof of the quantum channel capacity theorem based on decoupling of the environment. (3) Studies of quantum entanglement, such as a characterization of the monogamy of nonlocal correlations. (4) Tools for fault-tolerant quantum computation, such as a scheme for protecting against highly biased noise. (5) Proposals for quantum hardware, such as a protected qubit based on a superconducting current mirror. (6) Connections between quantum information theory and quantum many-body theory, such as new proposals for experiments that probe the non-abelian statistics of quantum Hall quasiparticles. The broader impact of the IQI also has many facets. With the end of scalability of conventional siliconbased information technology on the horizon, it is vitally important to explore aggressively new paradigms for information technology. IQI contributions are broadening the nation's technical base, ensuring US leadership in the future development of quantum science and technology. The IQI has attracted and trained top postdoctoral scholars, 16 of whom have moved on to faculty positions (or the equivalent) elsewhere, thus significantly strengthening the world effort in QIS. The IQI has also trained many Ph.D. students who are still working in the field, and we have sponsored a variety of undergraduate research projects. A particularly important aspect of the IQI?s broader impact is a vibrant visitor program.
Since 2000, we have sponsored 120 visits by senior and postdoctoral scholars, and 70 visits by graduate students from other institutions. The visitor program fuels intellectual excitement,facilitates collaborations and exchanges of scientific ideas, and performs a highly valued service for the international QIS community. The IQI can best ensure its continued success by nurturing its distinctive qualities: a focus on interdisciplinary research, an emphasis on fostering the career development of world-class postdoctoral talent, and devotion to an active visitor program. At the same time, in response to new scientific opportunities, the mission of the IQI will evolve in important ways over the next several years. Two increasingly prominent themes will be the exciting interface of QIS with condensed matter physics, and the daunting challenge of closing the considerable gap between the theory and experimental practice of QIS and physical implementations of quantum computing. Basic advances in all of these areas are needed to bring revolutionary quantum technologies closer to realization.
(IQI), established in 2000, is an NSF-supported collaboration which carries out and facilitates research in theoretical quantum information science, an inter-disciplinary field addressing how fundamental physical laws can be harnessed to dramatically improve the acquisition, transmission, and processing of information. The IQI is led by four faculty members drawn from Caltech’s Division of Physics, Mathematics, and Astronomy and Division of Engineering and Applied Science: John Preskill (Director and PI, Feynman Professor of Theoretical Physics), Alexei Kitaev (co-PI, Linde Professor of Theoretical Physics and Mathematics), Leonard Schulman (co-PI, Professor of Computer Science), and Gil Refael (co-PI, Professor of Theoretical Physics). Our current award, the third from NSF supporting the IQI, began on 1 September 2008. The IQI has attracted and trained some of the world's top postdoctoral scholars, many of whom have moved on to faculty positions elsewhere and are emerging leaders among the scientists working on quantum computing. During the 6 years covered by this report, there have been 25 IQI postdoctoral scholars appointed for terms of one, two, or three years. Of these 25, 13 moved to faculty positions after departing Caltech; all of the rest are still engaged doing fundamental quantum information research, either at Caltech or elsewhere. At this stage, 34 former IQI postdoctoral scholars have moved on to faculty positions or staff scientist positions at national laboratories since the IQI was founded fourteen years ago (13 in the US, 6 in Canada, 9 in Europe, 2 in Asia, 2 in Australia, and 2 in the Middle East). Another central component of the IQI is a vibrant visitor program. Short-term visitors include senior scientists, postdoctoral scholars, and graduate students, with a typical visit lasting one week or more. During this award period there were nearly 200 such visits by senior and postdoctoral scholars and by graduate students from other institutions. The visitor program sparked and facilitated many collaborations of Caltech personnel with researchers from all over the world. During this award period, 11 graduate students received financial support from NSF, of whom 7 have received PhD degrees. In addition the IQI sponsors summer research projects under the auspices of the Caltech Summer Undergraduate Research Fellowship (SURF) program, a total of 20 such projects during the award period, with postdocs participating actively as project mentors. Research at the IQI covers five broad areas: (1) Quantum algorithms that achieve speedups relative to classical algorithms, and limits on such algorithms. (2) Quantum protocols and quantum entanglement. (3) Protection of quantum information using quantum error correcting codes, fault-tolerant protocols for quantum information processing, and control of quantum systems. (4) Theory and practice regarding physical implementations of quantum information processing. (5) Connections between quantum information science and other aspects of fundamental physics. IQI participants produced 240 publications during the award period, of which we will mention only a few. Large scale quantum computers, when available, will be able to solve hard problems which are intractable for conventional digital computers. We showed that a quantum computer can be used to simulate high-energy collisions between strongly interacting elementary particles, like the collisions studied at accelerator laboratories. Quantum states can be very complex, making it difficult for experimental physicists to identify such states, or to verify the success of a state preparation procedure. We showed that in some cases of interest quantum states have a special structure, allowing the identification or verification of the state to be performed quite efficiently. Quantum states are very fragile, easily damaged by unavoidable interactions between a quantum system and its unobserved environment. We discovered new kinds of quantum codes which can be used to protect quantum states from damage. These codes realize a new exotic type of order in quantum systems, not previously known to be mathematical possible. Future quantum computers may exploit particles called anyons, which can be used for robust storage and processing of quantum data. We discovered that anyons can be physically realized in networks of superconducting wires fashioned from suitable materials. In the midst of this award, the IQI underwent a major transition -- a new NSF Physics Frontiers Center was established at Caltech, the Institute for Quantum Information and Matter (IQIM). Our Quantum Information research effort became one of four Major Activities within the IQIM, along with Quantum Many-Body Systems, Quantum Optics, and Quantum Mechanics of Mechanical Systems. Since 2011, funding from the IQI award has been pooled with other funding from NSF and the Gordon and Betty Moore Foundation for IQIM, which is now managed as one unified Center. Thus the IQI(M) still lives on as one of the world’s leading centers for quantum information research, thanks to the NSF’s generous support.
