Two-dimensional spectroscopy of superconductors*

Recent progress in the generation of coherent terahertz pulses allows probing several many-body phenomena, providing unique fingerprints of exotic excitations. In higher-dimensional spectroscopy, terahertz pulses delayed in time are irradiated to the sample and the corresponding nonlinear response functions are measured. In this talk, we present theoretical results on the two-dimensional spectroscopy of clean and dirty superconductors. We show how higher-order optical responses of disordered superconductors can quantify the effects of impurities and provide fingerprints about the scattering and lifetime of Bogoliubons. For clean superconductors, we study the multi-band case and address the possibility of resolving the orbital content and the gap symmetry.