Optical control of vibrational coherence triggered by an ultrafast phase transition

Abstract

Femtosecond time-resolved x-ray diffraction is employed to study the dynamics of the periodic lattice distortion (PLD) associated with the charge-density wave in ${\mathrm{K}}_{0.3}{\mathrm{MoO}}_{3}$. Using a multipulse scheme we show the ability to extend the lifetime of coherent oscillations of the PLD about the undistorted structure through reexcitation of the electronic states. This suggests that it is possible to enter a regime where the symmetry of the potential energy landscape corresponds to the high-symmetry phase but the scattering pathways that lead to the damping of coherent dynamics are still controllable by altering the electronic state population. The demonstrated control over the coherence time offers different routes for the manipulation of coherent lattice states.