We propose the measurement of cavity-enhanced parity-nonconserving (PNC) optical rotation in several transitions of metastable Xe and Hg, including Xe ${(}^2{P}_{3/2}^o)6s{}^2[3/2{]}_2^o\to {(}^2{P}_{1/2}^o)6s{}^2[1/2{]}_1^o$ and Hg $6s6p{}^{3}P_2^o\to 6s6p{}^{1}P_1^o$, with calculated amplitude ratios of $E_1^{\mathrm{PNC}}/M1=11\times {10}^{-8}$ and $10\times {10}^{-8}$, respectively. We demonstrate the use of a high-finesse bow-tie cavity with counterpropagating beams and a longitudinal magnetic field, which allows the absolute measurement of chiral optical rotation, with a path length enhancement of about ${10}^4$, necessary for PNC measurement from available column densities of ${10}^{14}{\mathrm{cm}}^{-2}$ for metastable Xe or Hg. Rapid PNC-signal reversal, allowing robust background subtraction, is achieved by shifting the cavity resonance to an opposite polarization mode or by inverting the magnetic field. The precise measurement of isotope and nuclear-spin dependent $E_1^{\mathrm{PNC}}$ amplitudes provides a sensitive low-energy test of the standard model.

• Received 7 December 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.210801