Proposal for high-precision atomic-parity-violation measurements by amplification of the asymmetry by stimulated emission in a transverse electric and magnetic field pump-probe experiment

Abstract

Amplification by stimulated emission of radiation provides an intriguing means for increasing the sensitivity of Atomic Parity Violation (APV) measurements in a pump-probe configuration well adapted to the 6S − 7S cesium transition. It takes advantage of the large number of atoms excited along the path of the pump beam. In the longitudinal E-field configuration currently exploited in an ongoing APV measurement, this number is limited only by the total voltage sustainable by the Cs vapor. In order to overcome this limit, we consider, both theoretically and experimentally, the possibility of performing the measurements in a transverse E-field configuration requiring a much lower voltage. We discuss the necessarily different nature of the observable and the magnetoelectric optical effects entering into play. They condition modifications of the experimental configuration with, in particular, the application of a transverse magnetic field. We suggest the possibility of rotating the transverse direction of the fields so as to suppress systematic effects. With a long interaction length, a precision reaching 0.1% in a quantum noise limited measurement can be expected, now limited only by the necessity of operating below the threshold of spontaneous superradiant emission of the excited medium. If we approached this limit, however, we could greatly amplify the asymmetry using triggered superradiance.

Measurement of the parity violating6S−7Stransition amplitude in cesium achieved within2×10−13Guéna1, Lintz2, Bouchiat3 2005Phys. Rev. A903660View full textAdd to dashboardCite

“…We have already discussed the noise-equivalent-angle and shown [16,42] that, for a given number of incident probe photons, n in , the quantum noise limited SNR per excitation pulse,…”

Pump-probe measurement of atomic parity violation in cesium with a precision of 2.6%

“…Hence, the PV asymmetry is an increasing function of the applied electric field. One important consequence is the considerable enhancement of sensitivity that can be foreseen in an experiment with a transverse electric field and a longer interaction length [12]. Despite the transverse field configuration, a special multi-electrode design can "restore cylindrical symmetry", which helps in tracking and rejecting systematic effects [27].…”

Alkali-vapor cell with metal coated windows for efficient application of an electric field

“…3. Such a cell has been considered 31 for APV measurements in cesium vapor, using a transverse electric field, where one could benefit from larger excited-state atom numbers, and hence a larger amplification of the left-right asymmetry to be detected. The quantum shot noise limited precision for an APV measurement in transverse E field could reach the 10 -3 level, and systematic effects would become a crucial issue.…”

“…The reason for the design of Fig. 3 is that it would allow easy rotation of the direction of the transverse electric field by steps of 45°, so as to suppress some possible sources of systematic effects on the APV measurement 31 .…”