# Real single-loop cyclic three-level configuration of chiral molecules. (arXiv:1802.00576v1 [quant-ph])

Single-loop cyclic three-level ($\Delta$-type) configuration of chiral
molecules was used for enantio- separation in many theoretical works based on
the electric-dipole coupling with three microwave fields. Considering the
molecular rotation, this simple single-loop model is generally replaced by a
complicated multiple-loop one containing multi degenerated magnetic sub-levels
and the ability of the enantio-separation methods is suppressed. For chiral
molecules of asymmetric top, we propose a real single-loop $\Delta$-type
configuration by applying three microwave fields with appropriate polar-
izations and frequencies to resonantly couple respectively with the transitions
among three single rotational levels, where each of the levels does not involve
multi degenerated magnetic sub-levels. With our scheme, the previous
theoretical proposals for enantio-separation based on single-loop $\Delta$-type
configuration can be experimentally realized when the molecular rotation is
considered.