Manipulation of Superconductivity through Parametric Driven Phonons*

Photoinduced superconductivity has attracted much attention in the past decade, due to the possibility of dramatically enhancing the transition temperature and finally creating a room-temperature superconductor. One promising realization of nonequilibrium superconducting states is achieved via pumping mid-infrared phonons. In this work, we perform a numerical study of an electron-phonon system after dynamically squeezing the phonons, which mimics the leading impact of the infrared pump. Using a variational non-Gaussian wavefunction, we are able to evaluate not only the superconducting order parameter, but also the time-resolved optical and ARPES spectroscopies. By comparing with optical probes, we identify the physical order parameter as a pair of dressed quasiparticles. Driving the system at different frequencies we observe that superconductivity can be either persistently enhanced or suppressed, depending on the resonant characteristic excitations. Revealing the dynamics of the parametric phonon pump, this work enables the design of conventional non-equilibrium superconductors.