[PAST EVENT] Peter Rosenberg: Physics Dissertation Defense
Peter Rosenberg, Final Oral Examination for the Ph.D., Title: "Exotic Phases in Attractive Fermions: Charge Order, Pairing, and Topological Signatures."
Abstract: Strongly interacting many-body systems remain a central challenge of modern physics. Recent developments in the field of ultra-cold atomic physics have opened a new window onto this enduring problem. Experimental progress has revolutionized the approach to studying many-body systems and the exotic behaviors that emerge in these systems. It is now possible to engineer and directly measure a variety of models that can capture the essential features of real materials without the added complexity of disorder, impurities, or complicated or irregular geometries. The parameters of these models can be freely tuned with tremendous precision. These experimental realizations are an ideal setting in which to test and calibrate computational many-body methods that can provide insight and quantitative understanding to many of the open questions in condensed matter and many-body physics. In this thesis we study several models of strongly interacting many-fermion systems using cutting-edge numerical techniques including Hartree-Fock-Bogoliubov (HFB) mean-field theory and auxiliary-field quantum Monte Carlo (AFQMC). We explore the exotic phases and behaviors that emerge in these systems, beginning with finite-momentum pairing states in attractive spin-polarized fermions. We next demonstrate the unique capability of AFQMC to treat systems with spin-orbit coupling (SOC). We obtain high-precision, and in many cases numerically exact, results on SOC systems that can eventually be compared directly to experiment. The first system we highlight is the attractive Fermi gas with Rashba SOC, which displays unconventional pairing, charge, and spin properties. We then study the coexistence of charge and superfluid order, as well as topological signatures, in attractive lattice fermions with Rashba SOC. Our results provide a new, high-accuracy understanding of a strongly interacting many-body system and its exotic behaviors. These techniques can serve as a general framework for the treatment of strong interactions and SOC in many-body systems, and provide a foundation for future work on exotic phases in models and real materials.
Bio: Peter Rosenberg was born and raised in Port Washington, NY. He studied physics and math at the State University of New York at Geneseo, graduating in 2011. His continued interest in physics led him to graduate school at William & Mary, beginning in the fall of 2011. After one year working on lattice QCD, he joined the research group of Professor Shiwei Zhang in the summer of 2013. His research focuses on the development and application of numerical techniques to treat many-body systems, typically in the context of ultra-cold atoms. He will begin work as a Postdoctoral Research Associate in the Condensed Matter Science group at the National High Magnetic Field Lab at Florida State University starting this fall.