Attosecond control of tunneling ionization and electron trajectories

We demonstrate the control of electron tunneling in the highorder armonic generation process and subsequent positive-energy wavepacket ropagation until recollision with the unprecedented precision of about 10 attoseconds. This is accomplished with waveforms synthesized from a fewcycle near-infrared pulse and its second harmonic. The presented attosecond control of few-cycle-driven high harmonics permits the generation of tunable isolated attosecond pulses, opening the prospects for a new class of attosecond pump-probe experiments.