Fluctuating Nature of Light-Enhanced $d$-Wave Superconductivity: A Time-Dependent Variational Non-Gaussian Exact Diagonalization Study

TL;DR

This study uses a time-dependent variational non-Gaussian exact diagonalization method to explore light-induced $d$-wave superconductivity, revealing enhancement of pairing correlations but suppression of correlation length, indicating a fluctuating nature.

Contribution

It introduces a novel application of the variational non-Gaussian exact diagonalization method to investigate light-enhanced superconductivity in strongly correlated systems.

Findings

Laser pulses can enhance $d$-wave pairing correlations.

Pairing correlation length is suppressed by the pump pulse.

Light-enhanced superconductivity may be inherently fluctuating.

Abstract

Engineering quantum phases using light is a novel route to designing functional materials, where light-induced superconductivity is a successful example. Although this phenomenon has been realized experimentally, especially for the high-$T_c$ cuprates, the underlying mechanism remains mysterious. Using the recently developed variational non-Gaussian exact diagonalization method, we investigate a particular type of photoenhanced superconductivity by suppressing a competing charge order in a strongly correlated electron-electron and electron-phonon system. We find that the $d$-wave superconductivity pairing correlation can be enhanced by a pulsed laser, consistent with recent experiments based on gap characterizations. However, we also find that the pairing correlation length is heavily suppressed by the pump pulse, indicating that light-enhanced superconductivity may be of fluctuating nature. Our findings also imply a general behavior of nonequilibrium states with competing orders, beyond the description of a mean-field framework.