Electronic and fluctuation dynamics following a quench to the superconducting phase
Christopher Stahl, Martin Eckstein
Abstract
We investigate the dynamics of superconducting fluctuations in the attractive three-dimensional Hubbard model after a quench from the disordered phase to the ordered regime. While the long-time evolution is well understood in terms of dissipative time-dependent Ginzburg-Landau models with unstable potentials, early times are more demanding due to the inseparable dynamics of the pairing fluctuations and the electronic quasiparticles. Our simulation using the time-dependent fluctuation exchange approximation treats both degrees of freedom on the same footing and reveals a nonthermal electronic regime causing a nonmonotonous growth of the fluctuations. This feature is not directly captured by the Ginzburg-Landau theory but nevertheless remains observable beyond the thermalization time of the electrons. We further explore how the growth of the order parameter fluctuations leads to an opening of a pseudogap in the electronic spectrum and identify Andreev reflections as the dominant mechanism behind the gap opening.