New Manifestation of Atomic Parity Violation in Cesium: A Chiral Optical Gain Induced by Linearly Polarized $6S\mathrm{\text{−}}7S$ Excitation

We have detected, by using stimulated emission, an atomic parity violation (APV) in the form of a chiral optical gain of a cesium vapor on the $7S\mathrm{\text{−}}6P_{3/2}$ transition, consecutive to linearly polarized $6S\mathrm{\text{−}}7S$ excitation. We demonstrate the validity of this detection method of APV, by presenting a 9% accurate measurement of expected sign and magnitude. We stress several advantages of this new approach which fully exploits the cylindrical symmetry of the setup. Future measurements at the percent level will provide an important cross-check of an existing more precise result obtained by a different method.

Figure 1

Schematic of the experiment showing the two orthogonal symmetry planes defined by the electric field ${\overrightarrow{E}}_l$ and the linear excitation polarization ${\widehat{ϵ}}_{\mathrm{e}\mathrm{x}}$. APV gives rise to a tilt ${\theta }^{\mathrm{p}\mathrm{v}}$ of the optical axes of the excited vapor out of those planes. The incoming probe polarization ${\widehat{ϵ}}_{\mathrm{p}\mathrm{r}}$ provides a superposition of the right- and left-handed ${\widehat{ϵ}}_{\mathrm{e}\mathrm{x}},{\widehat{ϵ}}_{\mathrm{p}\mathrm{r}},{\overrightarrow{E}}_l$ configurations analyzed. The probe amplification difference is directly extracted from the optical signals $S_1,S_2$, recorded in each channel of the PBS. Inset: timing of the experiment repeated at 100 Hz.

Figure 2

Experimental values of ${\theta }_{\exp }^{\mathrm{p}\mathrm{v}}(\mu \mathrm{r}\mathrm{a}\mathrm{d})$ obtained in successive runs with experimental conditions kept as constant as possible. The solid (respectively, dashed) line represents the mean (respectively, the statistical error on this mean).