Improved frequency stability of the dual-noble-gas maser

Abstract

We report improved frequency stability of the dual-noble-gas maser. This recently developed device can measure very small changes in the Zeeman transition frequencies of cohabitating ensembles of ${}^{129}\mathrm{Xe}$ and ${}^{3}\mathrm{He}$ atoms, and thus may be useful for symmetry tests and precision measurements such as a search for a permanent electric dipole moment of the ${}^{129}\mathrm{Xe}$ atom. Using the dual-noble-gas maser, we measured the frequency stability (i.e., the Allan deviation) of the ${}^{3}\mathrm{He}$ Zeeman transition to be approximately 100 nHz in 6000 s of data acquisition. This Zeeman frequency stability is an order of magnitude improvement over our previous report [R. E. Stoner et al., Phys. Rev. Lett. 77, 3971 (1996)].