Fig. 3: Input power requirements.

Required input optical power as a function of cavity round-trip length and finesse \({{{{{{{\mathcal{F}}}}}}}}\). The cavity baseline is fixed at 1 km, and the maximum pulse duration, minimizing power requirements, is selected. This is the limiting value for the pulses to avoid spatial overlap at the atoms; see Methods. The parameters used throughout are indicated by the red dot.