Structuring light's chirality, enantio-sensitive light bending, and the chiral double slit experiment

Structured light, which exhibits nontrivial intensity, phase, and polarization patterns in space, has key applications ranging from imaging and 3D micromanipulation to classical and quantum communication [J. Opt. 19, 013001]. However, to date, its application to molecular chirality [J. Phys. Chem. A, 118, 3472] has been limited by the weakness of magnetic interactions. Here we show how to lift this limitation by structuring light's local chirality – a new type of chirality effective within the electric-dipole approximation [Nat. Phot. 13, 866]. We introduce and realize an enantio-sensitive interferometer for efficient chiral recognition without magnetic interactions, which can be seen as a chiral version of Young's double slit experiment. We show that if the distribution of light's handedness breaks left-right symmetry, the interference of chiral and achiral parts of the molecular response leads to unidirectional bending of the emitted light, in opposite directions in media of opposite handedness. Our work introduces the concepts of polarization of chirality and chirality-polarized light, exposes the immense potential of sculpting light's local chirality to control the molecular response, and offers novel opportunities for efficient chiral discrimination, optical molecular fingerprinting, and imaging on ultrafast time scales using intense light.