Demonstration of a high-performance pulsed optically pumped Rb clock based on a compact magnetron-type microwave cavity

We demonstrate a high-performance pulsed optically pumped (POP) Rb vapor-cell clock based on a magnetron-type microwave cavity of only 44 cm(3) external volume. Using optical detection, an unprecedented 35% contrast of the Ramsey signal has been obtained. Both the signal-to-noise ratio (of 30 000) and the estimated shot-noise limit of 1.7 x 10(-14) tau(-1/2) are at the same level as those found with a bigger cylindrical TE011 cavity (100 cm 3 inner volume) and are sufficient for achieving excellent clock stability. Rabi oscillations are measured and indicate a sufficiently uniform microwave magnetic field distribution inside the cavity. The instability sources for the POP clock's performance are analyzed. A short-term stability of 2.1 x 10(-13) tau(-1/2) is demonstrated which is consistent with the noise budget. (C) 2015 AIP Publishing LLC.