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.
Highlights
Understanding, controlling, and designing functional quantum phases are major goals and challenges in modern condensed matter physics [1,2]
For the nonequilibrium superconductivity in this paper, we focus on the zero-temperature dynamics, and fluctuations may arise from quantum instead of thermal origins
It does not rule out other interpretations, our result reflects that the light-induced Cooper pairs may be spatially local
Summary
Understanding, controlling, and designing functional quantum phases are major goals and challenges in modern condensed matter physics [1,2]. The occurrence of the Cooper pairs above Tc (reflected by the Josephson plasma resonance in experiments), as a signature of light-induced superconductivity, is observed when these materials are stimulated by a near-infrared pulse laser. The resonance and gap in the transient optical conductivity may cause a misassignment of the long-range superconductivity [36,37,38] Both observations raise the necessity to further investigate the coherence of superconductivity induced by light in a quantum many-body model. As an extension of the equilibrium NGSED [43], this timedependent method provides an accurate description of far-from-equilibrium states through the Krylov-subspace method and the Kählerization of the solvers These advances of the numerical method allow the simulation of light-induced dynamics in quantum materials with both electronic correlations and electron-phonon couplings.
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