Gopalakrishnan Seminar Abstract Feb 3

Dynamical response in many-body localized systems

I will present recent results on the response of many-body localized (MBL) systems to time-dependent external perturbations. First, I will discuss the linear-response optical conductivity and related dynamical response functions, and argue that these fall off as universal power laws of frequency (or time), due to isolated many-body resonances in the MBL phase. Second, I will explore the regime of validity of linear-response theory, arguing that the conductivity has no well-defined d.c. limit, and discussing the crossovers between the linear-response regime and the nonlinear regime in which saturation effects are dominant. I will comment on applications of these ideas to "hole burning" and related spectroscopic probes. If time permits, I will also discuss the dynamics of localized systems subject to external classical noise, and identify regimes of normal and anomalous diffusion in such systems.