During the past decade the minimum duration of optical pulses has fallen from 5 femtoseconds to less then 100 attoseconds. The processes involved in the creation of these pulses will be explored.
Intense femtosecond laser pulses drove this advance by forcing electron wave packets to (1) tunnel from the atom or molecules, (2) move under the force of the time dependent electric field and (3) reunite with the parent orbital, thereby converting many photons into one. I will describe how this process maps onto an electron interferometry. Attosecond XUV pulses are a by-product of this interference (or collision).
This three-step process can be readily manipulated, allowing us to measure the attosecond pulse as it is born – and much more. We image orbitals, measure attosecond electronic wave packet motion created by tunnelling and follow chemical dynamics, all while generating high harmonics of the fundamental.