Atoms irradiated with combined femtosecond laser and extreme ultraviolet (XUV) fields ionize through
multiphoton processes, even when the energy of the XUV photon is below the ionization potential.
However, in the presence of two different XUV photons and an intense laser field, it is possible to induce
full electromagnetic transparency. Taking helium as an example, the laser field modifies its electronic
structure, while the presence of two different XUV photons and the laser field leads to two distinct
ionization pathways that can interfere destructively. This work demonstrates a new approach for coherent
control in a regime of highly excited states and strong optical fields.
sildes here: http://charles.qols.ph.ic.ac.uk/~twitting/consJCDM/material/20120221_Simon/Journal%20Club%20IC%20Feb21%202012.pptx