Dynamics of the superconducting order parameter through ultrafast normal-to-superconducting phase transition in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ from multi-pulse polarization-resolved transient optical reflectivity

A systematic temperature dependent study of the femtosecond optical superconducting (SC) state destruction and recovery in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ cuprate superconductor by means of the all-optical polarization-sensitive multi-pulse spectroscopy is presented. At low temperatures and a partial SC state suppression an anisotropic SC-gap recovery-timescale is suggested by the data. The SC state destruction and recovery dynamics are compared to the recent TR-ARPES-inferred SC-gap dynamics and a qualitative agreement is found. Using a phenomenological response function the experimental data are also compared to time dependent Ginzburg-Landau model simulations.