Generation, Characterization and Application of Chiral Attosecond Pulses

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High harmonic generation is the enabling technology for table-top sources of bright coherent extreme ultraviolet and soft x-ray pulses with durations on attosecond (1 as = 10E−18s) time-scale, the time-scale of electronic response in matter. This proposal addresses the key aspect in  generation, characterization, and application of such pulses: flexible control over their polarization properties.  Availability of circularly polarized attosecond pulses would be indispensable for tracking ultrafast electronic dynamics, from helical charge flows in chiral molecules to ultrafast magneto-optical spectroscopy, with table-top setup. Our joint theoretical and experimental project will develop and demonstrate new schemes for i) generating chiral attosecond pulses, isolated and trains, ii) fully characterizing their polarization state, including pulses where helicity changes on few ten as time-scale, and ii) use them to perform experiments on imaging chiral charge flow in molecules on the electronic time-scale. We will also use the frequency up-conversion process, the high harmonic generation, to visualize how spin-orbit interaction rotates the spin and angular momentum in valence shells of atomic ions, and to time resolve the recapture of electrons, liberated from atoms by intense light fields, into highly excited but stable orbits.