Measurement of the Hyperfine Quenching Rate of the Clock Transition in ${}^{171}\mathrm{Yb}$

We report the first experimental determination of the hyperfine quenching rate of the $6s^2{}^1{S}_0(F=1/2)-6s6p{}^3{P}_0(F=1/2)$ transition in ${}^{171}\mathrm{Yb}$ with nuclear spin $I=1/2$. This rate determines the natural linewidth and the Rabi frequency of the clock transition of a Yb optical frequency standard. Our technique involves spectrally resolved fluorescence decay measurements of the lowest lying ${}^3{P}_{0,1}$ levels of neutral Yb atoms embedded in a solid Ne matrix. The solid Ne provides a simple way to trap a large number of atoms as well as an efficient mechanism for populating ${}^3{P}_0$. The decay rates in solid Ne are modified by medium effects including the index-of-refraction dependence. We find the ${}^3{P}_0$ hyperfine quenching rate to be $(4.42\pm 0.35)\times 10^{-2}{\mathrm{s}}^{-1}$ for free ${}^{171}\mathrm{Yb}$, which agrees with recent ab initio calculations.

Figure 1

Low-lying atomic levels and transitions of Yb in solid Ne. ${}^3{P}_0$ can be efficiently populated by virtue of an enhanced intersystem crossing ${}^3{D}_1\leftarrow {}^1{P}_1$. The radiative decay of ${}^3{P}_0$ is observed in both ${}^{171}\mathrm{Yb}$ and ${}^{172}\mathrm{Yb}$ samples.

Figure 2

The time-dependent fluorescence intensity of ${}^{171}\mathrm{Yb}$ ${}^3{P}_0$ (red solid circles) and ${}^{172}\mathrm{Yb}$ ${}^3{P}_0$ (blue open circles) in solid Ne near the center of the emission peak. The influence of the HFQ effect is evident.

Figure 3

(a) The ${}^1{S}_0\leftarrow {}^3{P}_0$ emission spectrum of ${}^{171}\mathrm{Yb}$ (red solid circles) and ${}^{172}\mathrm{Yb}$ (blue open circles) in solid Ne after the 385 nm LED is switched off. The peak is shifted from the vacuum position at 578.4 nm. The spectra are separately normalized so that the peaks appear to have similar height. (b) The decay rate of ${}^{171}\mathrm{Yb}$ ${}^3{P}_0$ (red solid circles) and ${}^{172}\mathrm{Yb}$ ${}^3{P}_0$ (blue open circles), and the difference of the decay rates between the two isotopes (purple solid triangles) at select wavelengths. The error bars are about the size of the markers.

Figure 4

(a) The ${}^1{S}_0\leftarrow {}^3{P}_1$ emission spectrum of Yb in solid Ne induced by the 543 nm laser. The peak is shifted from the vacuum position at 555.8 nm. (b) The decay rate of ${}^3{P}_1$ at select wavelengths in solid Ne (green circles). The error bars are about the size of the markers. The decay rate in vacuum, $1.162\times {10}^6{\mathrm{s}}^{-1}$, is off the scale. The black square with an error bar indicates the predicted ${}^3{P}_1$ decay rate in solid Ne using the RC model and the frequency cube dependence.