Quench dynamics of superconducting fluctuations and optical conductivity in a disordered system

Abstract: There has been significant interest in the generation of very short-lived superconducting states in solid-state films. Here we consider the role of non-equilibrium superconducting fluctuations in such systems, generated by an interaction quench, considering the limit of large static disorder. In particular, we argue that because of critical slowing down, the regime of the fluctuation dominated \emph{normal state} is more important than might be na\"ively thought. We show how such a state might appear in the optical conductivity, and give the appropriate non-equilibrium generalization of the Azlamazov-Larkin and Maki-Thompson fluctuation corrections to the optical conductivity. For a quench to the superconducting critical point, we show that the fluctuation corrections lead to power-law aging behavior in the optical conductivity. The power-law aging from Azlamazov-Larkin and Maki-Thompson terms are qualitatively different, despite the effect of the two being similar in dc measurements in thermal equilibrium. These signatures provide a road-map for experiments to identify the role of superconducting fluctuations in a transient state.