Subcycle pulse-induced nonequilibrium dynamics in one-dimensional Mott insulators

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 [1,2]. Calculating the time-dependent optical conductivity with the time-dependent density-matrix renormalization group, we find that broad mono- and half-cycle pulses inducing quantum tunneling strongly suppress spectral weights contributing to the Drude weight σ_D, even if we introduce a large number of carriers Δn_d [1]. This is in contrast to a metallic behavior of σ_D ∝ Δn_d induced by photon absorption and chemical doping. The strong suppression of σ_D in quantum tunneling is accompanied by electric polarization, which breaks inversion symmetry [2]. The breaking of inversion symmetries in a photoexcited state can be monitored by second harmonic generation. These findings provide a new methodology for designing the localization and symmetry of electronic states and open up a new field of subcycle-pulse engineering.

References:

[1] K. Shinjo, S. Sota, and T. Tohyama, Phys. Rev. Res. 4, L032019 (2022).

[2] K. Shinjo, S. Sota, S. Yunoki, and T. Tohyama, Phys. Rev. B 107, 195103 (2023).