  The elucidation of nonequilibrium states in strongly correlated systems holds
the key to emergence of novel quantum phases. The nonequilibrium-induced
insulator-to-metal transition is particularly interesting since it reflects the
fundamental nature of competition between itinerancy and localization of the
charge degrees of freedom. We investigate pulse-excited insulator-to-metal
transition of the half-filled one-dimensional extended Hubbard model.
Calculating the time-dependent optical conductivity with the time-dependent
density-matrix renormalization group, we find that strong mono- and half-cycle
pulses inducing quantum tunneling strongly suppress spectral weights
contributing to the Drude weight $\sigma_\text{D}$, even if we introduce a
large number of carriers $\Delta n_\text{d}$. This is in contrast to a metallic
behavior of $\sigma_\text{D}\propto \Delta n_\text{d}$ induced by photon
absorption and chemical doping. The strong suppression of $\sigma_\text{D}$ in
quantum tunneling is a result of the emergence of the Hilbert-space
fragmentation, which makes pulse-excited states glassy.
