Parity Violation Measurements With Ramsey-type Matter-wave Interferometry

Parity Violation measurements with Ramsey-type matter-wave interferometry

Marie-Anne Bouchiat
Ecole Normale Superieure

Aomic Parity Violation experiments provide a test of the Standard Model through the measurement of the weak nuclear charge. We present new strategies for improving the accuracy of its measurement, hence the quality of this test. It would be highly desirable as well to measure the nuclear anapole moment in conditions where its effect is the dominant source of parity violation. While the method so far was based on left-right asymmetry measurements of the transition rates, our goal is now to rely on frequency shifts measured by atom interferometry which has demonstrated unprecedented accuracy.

We study the light-shifts of alkali atoms placed in crossed electric and magnetic dc fields when they are dressed with circularly polarized photons. We point out the existence of a linear Stark shift of the hyperfine and Zeeman transition frequencies, which involves the mixed product of the two fields and the photon angular momentum, a pseudoscalar quantity with a well-defined signature. We discuss the detuning of the dressing beam, the magnitude of the shifts in realistic conditions and a calibration procedure. We conclude that the powerful techniques developed for high precision frequency measurements with cold atoms, which can be applied to small atomic samples, should be appropriate for measuring the weak charge of cesium or that of francium, about 20 times larger. With a different dressing beam, the nuclear anapole moment can also be measured by atomic interferometry.