Quantum information science (QIS) is the interdisciplinary field that investigates how to use systems obeying the laws of quantum mechanics to perform information-processing tasks. This research project establishes and provides the core funding for a new center, the Center for Quantum Information and Control (CQuIC), based at the University of New Mexico (UNM), with a major component of experimental research at the University of Arizona (UA). CQuIC brings a quantum-information perspective to physics-based research. In particular, research within CQuIC applies the new ideas and techniques of QIS to the state-of-the-art laboratory tasks of controlling the behavior of quantum systems, so these systems can be made to do what scientists want them to do, instead of doing just what comes naturally, and of making high-precision measurements.
CQuIC specializes in the training of graduate students and postdoctoral fellows for research careers in QIS. Students at UNM and UA are exposed to a full range of courses and other activities, which provide an interdisciplinary integration of information-theoretic and physics perspectives. CQuIC partners with four external institutions, the Joint Quantum Institute at the University of Maryland, the quantum information and quantum nanoscience groups at the University of Queensland, Sandia National Laboratory, and Los Alamos National Laboratory. These partnerships focus on a two-way flow of ideas and people, thus expanding the theoretical and experimental capabilities available to CQuIC and the partnering institutions. CQuIC is the administrative home for the Southwest Quantum Information and Technology (SQuInT) Network, which promotes QIS research at about 20 institutions located mainly in the US Southwest.
Quantum information science (QIS) is the interdisciplinary field that investigates how to use systems obeying the laws of quantum mechanics to perform information-processing tasks. This NSF award was the founding grant for the Center for Quantum Information and Control (CQuIC), which is based at the University of New Mexico (UNM), with an experimental-physics research node at the Optical Sciences Center of the University of Arizona (UA). The award began on August 1, 2009, and was scheduled to run for three years; a one-year no-cost extension brought it to a close on July 31, 2013. Quantum mechanics is the framework within which the behavior of all physical systems is described, but the odd effects of quantum mechanics manifest themselves mainly in the behavior of systems at the atomic scale. Larger systems, often called classical systems, tend to behave in ways that are consistent with what is called classical physics, which is a set of rules that are consistent with what we experience in our everyday lives. Systems that behave according to the rules of quantum mechanics act quite differently from what we would expect from ordinary experience. The last two decades has seen an explosion of ideas for how to use the odd behavior of quantum systems to perform information-processing tasks that cannot be done in a classical world. Research at CQuIC focuses on harnessing the new ideas and new techniques of QIS to the physics tasks of controlling the behavior of quantum systems and measuring that behavior precisely to determine that the system has done what is desired and to detect external influences on the system. Research under this award focused on three major questions: 1. Physical foundations of quantum information. These are theoretical investigations into the basis of the information-processing power of quantum systems. 2. Control of quantum systems and dynamics. These are theoretical and laboratory investigations of how to make quantum systems do what we want instead of what comes naturally. 3. High-precision measurements and quantum metrology. These are investigations of how to use quantum systems to make the best measurements allowed by quantum mechanics to determine quantities of physical interest. In addressing these questions, the explicit objective of research at CQuIC is to integrate fundamental theoretical ideas in QIS with state-of-the-art laboratory techniques for control and metrology. An award of this size has numerous outcomes, far more than can be described here, so this report is limited to the most important outcomes, one for each of the three questions. One of the most important questions in quantum information theory is which of the odd aspects of quantum mechanics powers the information-processing power of quantum systems. With this question in mind, we investigated and categorized various ways of quantifying the properties of correlations between quantum systems. One such measure is called quantum discord, and we formulated an operational interpretation of discord, i.e., an information-theoretic task for which the amount of discord tells one how well the task can be performed. Experimental investigations at UA under this award focused on controlling the internal quantum state of cesium atoms brought to a standstill and trapped in an optical lattice. The difficulty of a quantum-control task is typically characterized by the dimension of the quantum Hilbert space in which the quantum state exists. During this award, the UA group, supported by theoretical investigations carried on at UNM, achieved full quantum control of the sixteen-dimensional cesium hyperfine ground manifold, both in terms of creating and verifying arbitrary quantum states and of implementing arbitrary state transformations. The level of control in these experiments at UA is the most precise and most ambitious in terms of Hilbert-space dimension achieved anywhere in the world. This award saw the first derivation of the fundamental quantum-mechanical limitation on estimating a time-dependent signal (waveform). This fundamental quantum limit has immediate implications for detection of forces that act on linear systems, as in a gravitational-wave detector or in the new generation of miniaturized opto-mechanical force sensors. We showed that the fundamental force-estimation limit can be attained by a new force-detection strategy called quantum noise cancellation, and we unified all the various techniques for high-precision force detection in terms of what we called a quantum-mechanics free subsystem. CQuIC is the administrative home for the Southwest Quantum Information and Technology (SQuInT) network, a consortium of research groups at 24 institutions, located mainly in the US Southwest. The main activity of the SQuInT network is an Annual Workshop, a three-day conference held every February which places a premium on participation by PhD students and postdoctoral fellows from the node institutions. During the lifetime of this award, CQuIC sponsored four Annual Workshops, attended by between 150 and 250 researchers, and hosted two of those Workshops in Albuquerque.
