Weyl semimetals in ultrafast laser fields

We study theoretically the interaction of topological Weyl semimetals with an ultrafast optical pulse. The electron dynamics in such material is coherent and highly anisotropic. For some directions of pulse polarization, the electric dynamics is irreversible, which means that the residual electron conduction-band population after the pulse is comparable to the maximum conduction-band population during the pulse. For other directions of polarization, the electron dynamics is highly reversible and, after the pulse, the electron system returns to its initial state with almost zero conduction-band population. Such high anisotropy in electron dynamics is related to anisotropy in interband dipole matrix elements. In the reciprocal space, the electron conduction-band population density shows hot spots near the Weyl points. The optical pulse also causes net charge transfer through the system. The direction of transfer is the same as the direction of the field maximum. The transferred charge has highly anisotropic dependence on polarization direction with almost zero transferred charge for some directions.