Hydrodynamic nonlinear response of interacting integrable systems

Studying the response of a system to external fields yields information on its macroscopic order as well as its microscopic properties. While working to linear order in field strength often suffices to describe experiments, recent advances allow measurements to probe beyond the linear regime. Understanding nonlinear response functions could significantly advance the characterization of exotic phases of matter, but little is known theoretically about their properties in interacting many-body systems. We introduce a framework for computing nonlinear responses in a class of exactly solvable one-dimensional quantum systems. We show that nonlinear response exhibits clear signatures of interaction effects, in contrast to linear response in similar settings.