A proposed experiment to measure the parity-violating energy difference between enantiomers from the optical rotation of chiral ammonia-like “cat” molecules

Abstract

We propose a novel method to measure the parity-violating energy difference (PVED) between enantiomers using chiral ammonia-like molecules with tunnelling between L and D. The eigenstates of such molecules are Schrödinger's cat-type coherent superpositions of the L and D forms, but due to the PVED these “cat” states are slightly unequal superpositions of L and D, and therefore show a small electroweak optical rotation that is a direct measure of the PVED. We show that the rotational states of these “cat” molecules can be separated by applying an inhomogeneous electric field to a molecular beam. We calculate the optical rotations of the separated states, and show that they are measurable by state-of-the-art polarimeters for molecules with tunnelling times between 10 −7 and 10 −2 s.