Condensed Matter/Materials & Biological Physics Seminar with Liang Tan on Ion Dynamics in the Photoexcited State

The coupling between light, electrons, and phonons is responsible for rich phenomena, relevant in applications from energy transport and harvesting, to the quantum information sciences. Here we discuss recent developments in the theory of the bulk photovoltaic effect, which is the generation of current in the absence of interfaces.  We discuss how phonon-induced interactions give rise to large photocurrents, and show that
strong photocurrent enhancements are possible when the system is driven into a hidden phase transition. These observations show that non-perturbative effects are powerful tools for controlling the bulk photovoltaic effect in systems with strongly-coupled charge, spin, and lattice degrees of freedom.

In quantum defect systems, phonon- and strain-induced dephasing are critical processes that control quantum-coherent applications. Silicon-based quantum emitters have emerged as strong candidates for these applications due to their favorable coherence properties and the technological relevance of the host material. We apply first-principles methods to study loss mechanisms of these new quantum defects, showing that a quantitative understanding of these mechanisms is the key to improving the performance of quantum emitters for quantum information science applications.