Enantioselective Topological Frequency Conversion.

Two molecules are enantiomers if they are nonsuperimposable mirror images of each other. Electric dipole-allowed cyclic transitions |1⟩ → |2⟩ → |3⟩ → |1⟩ obey the symmetry relation OR=-OS, where OR,S = (µ21R,SE21)(µ13R,SE13)(µ32R,SE32) and R and S label the two enantiomers. Herein, we generalize the concept of topological frequency conversion to an ensemble of enantiomers. We show that, within a rotating-frame, the pumping power between fields of frequency ω1 and ω2 is sensitive to enantiomeric excess, P2→1 = ℏ[ω1ω2CLR/(2π)](NR - NS), where Ni is the number of enantiomers i and CLR is an enantiomer-dependent Chern number. Connections with chiroptical microwave spectroscopy are made. Our work provides an underexplored and fertile connection between topological physics and molecular chirality.