The interplay between the superconducting and normal states is essential to understanding the underlying mechanisms of high-temperature superconductivity. Here, photoinduced changes in conductivity of an optimally doped $\mathrm{YB}{\mathrm{a}}_2\mathrm{C}{\mathrm{u}}_3{\mathrm{O}}_{7-\delta }$ superconducting film at temperatures well below the critical temperature ($T_c$) are examined using transient terahertz spectroscopy. The pump-fluence-dependent experiment unveils that the excitations of superfluid and normal fluid lead to distinct nonequilibrium conductivities and recovery dynamics. The selective excitation of the normal fluid below $T_c$ exhibits exceptionally slower recovery dynamics with a bimolecular decay pattern, and the temperature dependence of its recovery time indicates a characteristic divergence at a temperature substantially below $T_c$. The dynamic behaviors of the normal fluid are dramatically different from those in the normal metals. These anomalous dynamic behaviors may suggest the existence of an energy gap for the normal state that displays remarkable likeness to the short-range pair-density-wave state. Our finding sheds light on understanding the dynamic interplay between the coexisting superconducting and nonsuperconducting pairs in cuprate superconductors.

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• Pairing mechanisms
• Superconducting gap
• Superconducting order parameter
• High-temperature superconductors
• Superconductivity
• Terahertz spectroscopy