Attosecond Clocking and Control of Strong Field Quantum Trajectories

We introduce a quantum trajectory selector method capable of resolving individual quantum trajectories responsible for strong-field phenomena in real time, revealing the dependence of the electron dynamics on the ionization time. Using an attosecond extreme ultraviolet pulse train, we select the moment of ionization and measure the rates of rescattered electron emission and double ionization driven by a phase locked near IR (1.77 or 2.4  μm) field. We show that there is an intensity-dependent shift in the ionization time associated with double ionization, and we clock this shift as it varies by 250 as. The quantum trajectory selector provides a new attosecond paradigm for expanding our understanding of recollision-driven physics.