Recoilless optical absorption and Doppler sidebands of a single trapped ion

Abstract

Spectroscopic measurements of the electric-quadrupole-allowed 5${d}^{10}$6s ${\mathrm{}}^{2}$${S}_{1/2}$ to 5${d}^{9}$6${s}^{2}$ ${\mathrm{}}^{2}$${D}_{5/2}$ transition near 282 nm on a single, laser-cooled ${\mathrm{Hg}}^{+}$ ion give a recoil-free absorption line (carrier) and well-resolved motional sidebands. From the intensity ratio of the sidebands to the carrier, the effective temperature of the ${\mathrm{Hg}}^{+}$ ion was determined to be near the theoretical minimum of 1.7 mK. A fractional resolution of better than 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}11}$ for this ultraviolet transition is achieved.