Ultrafast optical excitation of coherent phonons in a one-dimensional metal at the photoinduced insulator-metal transition

Photoinduced insulator-metal transition from the charge-density wave (CDW) ground state in a one-dimensional electron system is studied within the nonadiabatic theory of electron-phonon coupling. Ultrafast melting and partial recovery of the CDW and its critical slowing down are found to accompany the cooperative lattice response by an electron-phonon energy transfer on the subpicosecond time scale, which is read out by the nonadiabatic depopulation and repopulation of coherent phonons. Further, electron correlation is described in a self-consistent mean-field theory. In the strong electron correlation, the spin-density wave competes with the CDW and the photoinduced responses of the lattice is found to undergo the nonadiabatic-adiabatic transition.