Andreev reflection off a fluctuating sup

This study investigates Andreev reflection between a normal metal and a fluctuating superconductor, focusing on the effects of quantum phase fluctuations on the system's behavior. The objective is to explore how these fluctuations influence the differential conductance and other physical properties of the junction. To achieve this, the authors employ a non-perturbative approach within the framework of the tunneling Hamiltonian, which enables the analysis across a broad range of voltage biases, including those up to the superconducting gap amplitude. Results are illustrated through a one-dimensional Josephson junction array model, allowing for a direct comparison to previous work done on rigid BCS superconductors. The findings reveal significant modifications to the current's noise spectrum due to phase fluctuations, and the second derivative of the Andreev current with respect to frequency emerges as a valuable tool for probing these fluctuations. This research adds to the understanding of transport phenomena in superconductors exhibiting dynamic order parameters and could have implications for future studies in high-temperature superconducting materials.