Stochastic resonance, where noise synchronizes a system’s response to an external drive, is a phenomenon that occurs in a wide variety of noisy systems ranging from the dynamics of neurons to the periodicity of ice ages. This talk will present theory and experiments on a quantum system that exhibits stochastic resonance — the quantum tunneling of the magnetization of a single Fe atom measured using spin-polarized scanning tunneling microscopy. Stochastic resonance is shown deep in the quantum regime, where fluctuations are driven by tunneling of the magnetization, as well as in a semi-classical crossover region where thermal excitations set in. Combining theory and experiment enables one to probe the dynamics on time scales shorter than can be resolved experimentally.
Professor Susan Coppersmith is a theoretical condensed matter physicist who has made substantial contributions to the understanding of a broad range of subjects, including glasses, biominerals, granular materials, and quantum computers. Her honors include fellowship in the Australian Academy of Science, the Australian Institute of Physics, and the Royal Society of New South Wales, as well as the American Physical Society, the American Association for the Advancement of Science, and the American Academy of Arts and Sciences, and membership in the National Academy of Sciences of the United States.