Quantum control of electron dynamics in the continuum

The entangled light-matter character of autoionizing states in the presence of laser fields, which makes them polaritons, forms a relatively unexplored topic. We report the study of multiple radiatively coupled autoionizing light-induced states in argon, as well as evidence of their stabilization, thus confirming a long standing prediction. XUV absorption measurements were conducted in the presence of a tunable light fields and the non-linear light-matter interactions were interepreted with ab initio simulations. We demonstrated optical control over the formation of autoionizing polaritons and their decay rate into different channels. This is achieved by arranging destructive interferences between the interfering Auger decay and radiative ionization paths, which leads to the stabilization of the system against the ionization. We also investigated the avoided crossings between the bright states and light induced autoionizing states. The application of tunable attosecond transient absorption and multi-wave-mixing between XUV and IR fields offers new insights into the properties of autoionizing states, and provides tools for the control of polyelectronic metastable systems, opening the doors for implementation of quantum control protocols in the continuum.