  Modern light generation technology offers extraordinary capabilities for
sculpting light pulses, with full control over individual electric field
oscillations within each laser cycle. These capabilities are at the core of
lightwave electronics - the dream of ultrafast lightwave control over electron
dynamics in solids, on a few-cycle to sub-cycle timescale, aiming at
information processing at tera-Hertz to peta-Hertz rates. Here we show a robust
and general approach to valley-selective electron excitations in
two-dimensional solids, by controlling the sub-cycle structure of non-resonant
driving fields at a few-femtosecond timescale. Bringing the frequency-domain
concept of topological Floquet systems to the few-fsec time domain, we develop
a transparent control mechanism in real space and an all-optical,
non-element-specific method to coherently write, manipulate and read selective
valley excitations using fields carried in a wide range of frequencies, on
timescales that can be much shorter than the valley lifetime, crucial for
implementation of valleytronic devices.
