Microwave Pulse-Coherent Technique Based Clock with A Novel Magnetron-type Cavity

We report a high-performance pulsed optically pumped (POP) Rb clock based on a novel magnetron-type microwave cavity. The cavity has a volume of 30 mL, enabling a highly homogenous microwave field distribution. With the laser frequency tuning to the ground-state hyperfine level ${F}= {2}$ of the ${D}_{{2}}$ line, we observe a Ramsey fringe contrast of 52% in terms of optical absorption detection. The resultant shot noise limit is estimated to be ${1.6} \,\times \, {10}^{-{14}}{\tau }^{-\text {1/2}}$ . The clock frequency stability is measured as ${2.3}\,\times \, {10}^{-{13}}\tau ^{-\text {1/2}}$ (1–100 s), which is limited by the relative intensity noise of the light.