On subtle difference between left and right: inducing and probing ultrafast chiral dynamics
Distinguishing left- and right-handed molecular enantiomers is challenging, especially on ultrafast time scale. Traditionally one uses a chiral reagent, an object of known handedness, to determine the unknown handedness of a chiral molecule. In optics, one uses the spatial helix formed by circularly polarized light as a “chiral photonic reagent”. However, in optical domain the pitch of this helix – the light wavelength – does not match the size of the molecule, leading to a very small chiral signal.
I will introduce a concept of efficient chiral measurements, which do not rely on using chiral reagents such as chiral light. They rely on inducing chiral dynamics with non-chiral light and probing it using a chiral experimental setup: a chiral observer is a powerful alternative to a chiral reagent.
However, the chiral observer cannot control the chiral response. To efficiently control chiral optical response in molecules, one needs a chiral reagent of appropriate size. I will introduce a new concept of locally chiral electric fields, which serve as such photonic reagent. I will show how this chiral photonic reagent can be tuned to “react” with the desired enantiomer of a chiral molecule and not with its mirror twin, achieving the ultimate limit in efficiency of chiral discrimination. The simplicity of generating such “locally chiral light” in a laboratory opens a broad field of shaping and controlling chiral matter with light.