THz pump-THz probe Cooper pair dynamics in MgB$_{2}$

THz pump-THz probe spectroscopy is used to study non-equilibrium superconducting carrier dynamics in MgB$_{2}$ thin films. An intense THz pump pulse resonantly breaks Cooper pairs, exciting quasiparticles across the lowest energy superconducting gap (2$\Delta _{\mathrm{0}}\approx $3.6meV corresponding to $\sim$ 0.8THz). The condensate and quasiparticle dynamics are temporally resolved by measuring the real and imaginary part of THz conductivity. Following THz excitation, the condensate density is strongly suppressed on a picosecond time scale coinciding with the emergence of a Drude peak. These results are compared with optical pump-THz probe experiments where, consistent with previous measurements, much slower Copper pair-breaking dynamics are observed.