Search for a frequency difference in the spectrum of the enantiomers of chiral molecules: How to reach a sensitivity better than 10-14?

A series of two searches of a frequency difference in the vibrational spectrum of the enantiomers of CHFClBr by using Fabry-Perot cavities is presented. No difference is observed within the present sensitivity of 10-13. This experiment is limited by pressure shifts induced by uncontrolled impurities of the samples. We propose to use a two-photon Ramsey fringes scheme with a molecular beam to push the relative sensitivity much below 10-14 in the range where the effect is expected.