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Abstract:
Monolayer graphene provides an ideal material to explore one of the fundamental light-field driven interference effects: Landau-Zener-Stfickelberg interference. However, direct observation of the resulting interference patterns in momentum space has not proven possible, with Landau-Zener-Stuckelberg interference observed only indirectly through optically induced residual currents. Here we show that the transient electron momentum density (EMD), an object that can easily be obtained in experiment, provides an excellent description of momentum resolved charge excitation. We employ state-of-the-art time-dependent density function theory calculations, demonstrating by direct comparison of EMD with conduction band occupancy, obtained from projecting the time propagated wave function onto the ground state, that the two quantities are in excellent agreement. For even the most intense laser pulses we find the electron dynamics to be almost completely dominated by the pi band, with transitions to other bands strongly suppressed. Simple model based tight-binding approaches can thus be expected to provide an excellent description for the laser induced electron dynamics in graphene.
