Transient Higgs Spectroscopy

We investigate the time evolution of superconducting order in the cuprate high-Tc La_2-xSr_xCuO₄ under photodoping. We probe the superconducting condensate in the framework of Higgs spectroscopy: A high-field multicycle THz-pulse drives superconducting Higgs modes that leads to a characteristic third harmonic generation (THG) signal. In the present work we extend this scheme into a pump-drive spectroscopy and analyze the transient THG signal. Using methods from 2D spectroscopy allows us distinguishing hot quasiparticles contributions due to the pair breaking dynamics from the transient superconducting order parameter dynamics of the condensate. Thus, we can establish transient THG spectroscopy as powerful method for investigating light-driven superconductors and propose probing and characterizing transient Higgs modes as novel criterion for non-equilibrium superconductivity.

Min-Jae Kim et al., Tracing the dynamics of superconducting order via transient terahertz third- harmonic generation Science Advances 10, eadi7598 (2024)