We theoretically investigate the transient spectral function during the photoinduced melting of charge order in a correlated electron system, to unravel the dynamical processes triggered by different initial excitations. We employ a one-dimensional interacting spinless fermion model introducing a pulsed laser light, and perform a comparative study by the Hartree-Fock approximation and by the exact diagonalization method to numerically solve the time-dependent Schrödinger equation. We find characteristic behavior in the transient spectral function, whose features strongly depend on the pump light frequency ${\omega }_p$. When ${\omega }_p$ is resonant with the collective phase mode of frequency ${\mathrm{\Omega }}_c\simeq {\mathrm{\Delta }}_{\mathrm{CO}}/2$, where ${\mathrm{\Delta }}_{\mathrm{CO}}$ is the charge gap, the transient spectral function exhibits a photoinduced in-gap weight that triggers large responses. With increasing laser intensity, the development of in-gap weight directly turns into the collapse of the gap. This charge-order destabilization process is in sharp contrast to the case of ${\omega }_p>{\mathrm{\Delta }}_{\mathrm{CO}}$, where the photoirradiation induces interband electron-hole excitations giving rise to a shrinkage of the gap. The impact of quantum fluctuations and spatial inhomogeneity on the photoinduced dynamics is also discussed.

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• Metal-insulator transition
• Photoinduced effect
• Collective dynamics
• Strongly correlated systems
• Exact diagonalization
• Hubbard model
• Mean field theory
• Schroedinger equation