Optical-pumping enantio-conversion of chiral mixtures in presence of tunneling between chiral states

Abstract

Enantio-conversion of chiral mixtures has become an important research topic in chemical and biological fields. Here we propose a scheme for enantio-conversion of chiral mixtures via optical pumping based on a four-level model of chiral molecules composed of two chiral ground states and two achiral excited states, in which there exists a tunneling interaction between the chiral states. By eliminating one of the achiral excited states in the case of large detuning and well designing the detuning and coupling strengths of the electromagnetic fields, the induced indirect tunneling interaction between the chiral ground states can be cancelled with the direct tunneling interaction, and the induced indirect interaction between the left-handed chiral state and the remained achiral excited state can be cancelled with the direct one between them. Hence, the left-handed ground state is unchanged and the right-handed one can be excited to an achiral excited state, i.e., establishing chiral-state-selective excitations. By numerically calculating the populations of two chiral ground states, we find that the high enantiomeric excess can be achieved with almost only the left-handed ground state being populated. That means the high-efficiency enantio-conversion of chiral mixtures is realized under the combining effect of the system dissipation and the chiral-stateselective excitations.