Quantum Monte Carlo Simulations of Bose and Fermi Superfluids

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). TECHNICAL SUMMARYThis award from the Condensed Matter and Materials Theory program supports research and education in theoretical condensed matter, atomic, and optical physics. The central core of the proposed effort will seek an improved understanding of the phases, excitations, and phase transitions in strongly correlated and disordered Bose and Fermi systems in cold atoms and condensed matter contexts. Most of the research is concerned with bosons in optical lattices and mapping the finite temperature phase diagram of the Bose-Hubbard model, including issues related with thermometry, momentum distribution function and spectral function near the superfluid (SF)-Mott quantum phase transition using the largest quantum Monte Carlo (QMC) simulations in a trap to-date. The challenge of explaining the puzzles in the Fe-based superconductors with their inherent complexity of multiple bands and intermediate strength correlations will also be tackled.The research program addresses questions of fundamental significance in condensed matter physics. The proposed research program is strongly motivated by current experiments and has the potential to guide future ones. Ultimately, the goal is to establish new paradigms for strongly correlated systems with and without disorder.Some of the major goals of the research include mapping the first finite temperature phase diagram of a model showing a quantum phase transition both theoretically and experimentally, providing a unified understanding of novel superconductivity in cuprates and Fe-based arsenides with an aim to enhancing the transition temperature, and developing a QMC code for bosons in optical lattices with a confining potential using the worm algorithm for system sizes that are comparable to cold atom experiments.Both undergraduate and graduate students will be trained to work on the proposed projects, providing them with a solid grounding in basic condensed matter physics. Women and minority students will be encouraged and specially mentored. The proposal involves national and international collaborations, and involves physicists as well as applied mathematicians, in an effort to generate large scale simulation codes that are at the cutting edge of research today. The different numerical techniques are applicable to diverse materials and systems and beneficial to a larger community of scientists. A sequel to the 2007 Festival of Physics held at the Columbus Science Museum will be organized by the PI. The previous Festival, with a theme centered around superconductivity and over 2000 attendees ,was also organized by the PI, was attended by over 2000 people. It showcased a home-built levitated train, many demo carts, public lectures by scientists, including the PI, and a choreographed superconducting dance.NONTECHNICAL SUMMARYThis award from the Condensed Matter and Materials Theory program supports research and education in theoretical condensed matter, atomic, and optical physics. The research program addresses questions of fundamental significance in condensed matter physics, is strongly motivated by current experiments, and has the potential to guide future experimental efforts. Ultimately, the goal is to establish new paradigms for systems where the interactions of electrons need to be included in the quantum mechanical description of systems with and without disorder, with superconducting materials being a technologically important example of this type of system.Both undergraduate and graduate students will be trained to work on the proposedprojects, providing them with a solid grounding in basic condensed matter physics. Women and minority students will be encouraged and specially mentored. The proposal involves national and international collaborations, and involves physicists as well as applied mathematicians, in an effort to generate large scale simulation codes that are at the cutting edge of research today. The different numerical techniques are applicable to diverse materials and systems and beneficial to a larger community of scientists. A sequel to the 2007 Festival of Physics held at the Columbus Science Museum will be organized by the PI. The previous Festival, with a theme centered around superconductivity and over 2000 attendees ,was also organized by the PI, was attended by over 2000 people. It showcased a home-built levitated train, many demo carts, public lectures by scientists, including the PI, and a choreographed superconducting dance.