Physics Colloquium: Towards chiral attosecond science

Abstract:

Attosecond science - where the dynamics of electrons in atoms, in molecules and in solids, is probed and steered at attosecond time resolution - is primarily based on light attosecond pulses. The polarization of these attosecond pulses is linear, because attosecond pulses with polarization other than linear (e.g. circular) do not yet exist. Consequently, features such as chirality, magnetism, spin and orbital angular momentum, cannot be directly probed with attosecond pulses. The reason there has not been any experimental progress in controlling the polarization of attosecond pulses is a direct consequence of a similar limitation over the process in which attosecond pulses are produced: High Harmonic Generation (HHG).

I will present our recent demonstration of a method for generation of intense high-order harmonics with fully controlled polarization, from circular through elliptic to linear. I will also present applications of circularly polarized high harmonics and our roadmap towards generation of attosecond pulses with circular polarization.