Figure 1

Three-level coherence in neutral ${}^{88}\mathrm{Sr}$. The two clock levels are $5s^2{}^{1}S_0$ and $5s5p{}^{3}P_0$. By applying the probe and the dressing laser as shown, a coherent coupling is established between the clock levels, mediated by the $5s5p{}^{1}P_1$ level.Reuse & Permissions

Figure 2

Absorption rate from the ground state of ${}^{88}\mathrm{Sr}$ in the presence of the two laser frequencies indicated in Fig. 1. The laser-induced width, $\tilde{\gamma }$, is $2\pi \times 1\mathrm{mHz}$. (a) Loss of phase coherence between levels 1 and 2 is neglected, ${\gamma }_c=0$. Note that the curves for ${\delta }_d=0$ and ${\delta }_d=0.01\times \gamma =2\pi \times 320\mathrm{kHz}$ are virtually indistinguishable. (b) Macroscopic decoherence and laser-induced decay are comparable, ${\gamma }_c=\tilde{\gamma }$.Reuse & Permissions

Figure 3

(a) Lattice-confined atoms for use in the EIT clock scheme. The ac Stark shift due to the dressing laser on the clock transition is shown, as are the level shifts associated with the lattice trapping field. The expanded view of the ${}^{1}P_1$ state compares the lattice-induced level shift versus the linewidth $\gamma$. Atoms are cooled to the Lamb-Dicke regime, predominantly occupying the ground vibrational level in the lattice. (b) Experimental implementation of the EIT-based optical clock. A prestabilized narrow-linewidth local oscillator at 698 nm establishes a tight frequency track between the probe and dressing lasers. This enables a probe of the narrow EIT resonance, which in turn provides a long-term clock reference for the 698 nm local oscillator.Reuse & Permissions