Amplification of electroweak left-right asymmetry in atoms by stimulated emission

Abstract

This work describes quantitatively the amplification of the electroweak left-right asymmetry, a remarkable and attractive feature of the experiment in progress on the 6S1/2 → 7S1/2 cesium transition using detection by stimulated emission on the 7S1/2 → 6P3/2 transition. The process relies on the optical anisotropy of the atomic medium resulting from the 7S1/2 alignment created by excitation with linearly polarized light. The crucial parameter (α⊥−α∥)/α∥ involves the amplification coefficients for the probe field oriented in a direction either parallel or perpendicular to the alignment axis. Explicit computations are done by a semiclassical approach (classical for the field, quantum mechanical for the atomic states). The larger the optical anisotropy and the optical density, the stronger the asymmetry amplification; among all hyperfine components of the 7S1/2 → 6P3/2 transition, the ΔF=0 ones and more particularly the 4 → 4 offer the largest anisotropy. It is also predicted that saturation of the probe transition by the optical field should provide manifestation of the effect at lower optical densities and notwithstanding at larger fluxes of transmitted photons. Indirect production of 6P3/2 atoms by the excitation pulse does not reduce the left-right asymmetry, neither its amplification which then appears at lower effective optical densities.