Doppler-free spectroscopy of the 1S0-3P0 optical clock transition in laser-cooled fermionic isotopes of neutral mercury

M. Petersen (1) , R. Chicireanu (1) , S.T. Dawkins (1) , D.V. Magalhães (1, 2) , C. Mandache (1, 3) , Y. Lecoq (1) , A. Clairon (1) , S. Bize (1)

1 SYRTE - Systèmes de Référence Temps Espace
2 IFSC-USP - Instituto de Física de São Carlos
3 INFLPR - National Institute for Laser, Plasma and Radiation Physics

We have performed for the first time direct laser spectroscopy of the 1S0-3P0 optical clock transition at 265.6 nm in fermionic isotopes of neutral mercury laser-cooled in a magneto-optical trap. Spectroscopy is performed by measuring the depletion of the magneto-optical trap induced by the excitation of the long-lived 3P0 state by a probe at 265.6 nm. Measurements resolve the Doppler-free recoil doublet allowing for a determination of the transition frequency to an uncer- tainty well below the Doppler-broadened linewidth. We have performed absolute measurement of the frequency with respect to an ultra-stable reference monitored by LNE-SYRTE fountain pri- mary frequency standards using a femtosecond laser frequency comb. The measured frequency is 1128575290808 +/- 5.6 kHz in 199Hg and 1128569561140 +/- 5.3 kHz in 201Hg, more than 4 orders of magnitude better than previous indirect determinations. Owing to a low sensitivity to blackbody radiation, mercury is a promising candidate for reaching the ultimate performance of optical lattice clocks.

Mots clés: time and frequency; ultraviolet spectra; laser cooling of atoms; laser spectroscopy; optical lattice clocks

Domaines: Physique Quantique [quant-ph]

M. Petersen, R. Chicireanu, S.T. Dawkins, D.V. Magalhães, C. Mandache, et al.. Doppler-free spectroscopy of the 1S0-3P0 optical clock transition in laser-cooled fermionic isotopes of neutral mercury. 2008. ⟨hal-00303326⟩