Reduced Limit on the Permanent Electric Dipole Moment of $^{199}$Hg

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This paper describes the results of the most recent measurement of the permanent electric dipole moment (EDM) of neutral $^{199}$Hg atoms.

• Fused silica vapor cells containing enriched $^{199}$Hg are arranged in a stack in a common magnetic field.
• Optical pumping is used to spin-polarize the atoms orthogonal to the applied magnetic field, and the Faraday rotation of near-resonant light is observed to determine an electric-field-induced perturbation to the Larmor precession frequency.
• Our results for this frequency shift are consistent with zero; we find the corresponding $^{199}$Hg EDM $d_{Hg} = (2.20 \pm 2.75_{stat} \pm 1.48_{syst}) \times 10^{-30} e\cdot \text{cm}$.