Lindsay LeBlanc – University of Alberta
Title: Light-matter interactions in cold and ultracold neutral atomic gases: Applications to quantum memory and holonomic quantum operations

Abstract: Neutral atomic gases provide fantastic opportunities for studying and controlling quantum phenomena, ranging from many-body physics to quantum computers. In our research, we use the well-known interactions between cold gases and electromagnetic radiation to harness various quantum degrees of freedom. Quantum memories, used for storing and manipulating photonic signals, will be a key component in quantum communications systems, especially in realizing critical quantum repeater infrastructure. Cold atoms have significant potential as high performance spin-wave quantum memories, due to the long storage times associated with low temperature and slow thermal diffusion. In our work, we demonstrate two memory protocols in ultracold (sometimes Bose-condensed) atoms, which hold the potential for high-performance light storage: the Autler-Townes splitting (ATS) and superradiant approaches. These methods provide a path towards practical implementations in both ground- and satellite-based quantum communications systems, and we are working on both increasing performance and developing practical implementations. In a separate direction, our lab also uses ultracold ensembles to study unconventional quantum gates for quantum computing. In our work on holonomic operations, we engineer degeneracies into our system through Floquet driving, with the goal of realizing non-Abelian geometric phases. Our experiments reveal that we indeed rotate quantum states in this degenerate manifold, though we find that the naive expectation of geometric robustness to fluctuations is less resilient to real experimental issues than expected. We fully characterize our system in terms of its performance in realistic conditions and propose a path forward for working with holonomic operations on a variety of quantum platforms.

Speaker bio: Lindsay LeBlanc is an experimental atomic physicist working with ultracold atoms and quantum technologies. Lindsay earned her BSc in Engineering Physics from the University of Alberta in 2003 and her Ph.D. in Physics from the University of Toronto in 2011, after which she joined the Joint Quantum Institute in Maryland in 2013 as a postdoctoral fellow, before returning to join the University of Alberta where she is Canada Research Chair in Ultracold Quantum Gases and Associate Professor in Physics.