Narrow-line Cooling and Determination of Magic Wavelength of Cd

TL;DR

This paper reports the experimental and theoretical determination of the magic wavelength of the $^{111}$Cd clock transition, demonstrating narrow-line cooling and low blackbody radiation sensitivity for potential optical lattice clock applications.

Contribution

The study provides the first precise measurement of the magic wavelength for cadmium's clock transition and details narrow-line cooling techniques to enable high-precision optical lattice clocks.

Findings

Magic wavelength of 419.88(14) nm and 420.1(7) nm determined.

Cadmium's blackbody shift is significantly smaller than Sr and Yb.

Atoms cooled to 6 μK and loaded into an optical lattice.

Abstract

We experimentally and theoretically determine the magic wavelength of the (5$s^2$)$^{1}S_{0}$$-$(5$s$5$p$)$^{3}P_{0}$ clock transition of $^{111}$Cd to be 419.88(14) nm and 420.1(7) nm. To perform Lamb-Dicke spectroscopy of the clock transition, we use narrow-line laser cooling on the $^{1}S_{0}$$-$$^{3}P_{1}$ transition to cool the atoms to 6 $\mu$K and load them into an optical lattice. Cadmium is an attractive candidate for optical lattice clocks because it has a small sensitivity to blackbody radiation and its efficient narrow-line cooling mitigates higher order light shifts. We calculate the blackbody shift, including the dynamic correction, to be fractionally 2.83(8)$\times$10$^{-16}$ at 300 K, an order of magnitude smaller than that of Sr and Yb. We also report calculations of the Cd $^1P_1$ lifetime and the ground state $C_6$ coefficient.