The performance of space cold atom clocks（SCACs） should be improved thanks to the microgravity environment in space.The microwave interrogation cavity is a key element in a SCAC.In this paper,we develop a microwave interrogation cavity especially for the rubidium SCAC.The interrogation cavity has two microwave interaction zones with a single feedin source,which is located at the center of the cavity for symmetric coupling excitation and to ensure that the two interaction zones are in phase.The interrogation cavity has a measured resonance frequency of 6.835056471 GHz with a loaded quality factor of nearly 4200,which shows good agreement with simulation results.We measure the Rabi frequency of the clock transition of the rubidium atom in each microwave interaction zone,and subsequently demonstrate that the distributions of the magnetic field in the two interaction zones are the same and meet all requirements of the rubidium SCAC.
A high-performance transportable fountain clockis attractive for use in laboratories with high-precisiontime-frequency measurement requirements. This Letterreports the improvement of the stability of atransportable rubidium-87 fountain clock because of anoptimization of temperature characteristics. This clockintegrates its physical packaging, optical benches,microwave frequency synthesizers, and electronic controlsonto an easily movable wheeled plate. Two optical bencheswith a high-vibration resistance are realized in thiswork. No additional adjustment is required after movingthem several times. The Allan deviation of the fountainclock frequency was measured by comparing it with that ofthe hydrogen maser. The fountain clock got a short-termstability of 2.3×10^-13 at 1 s and long-term stabilityon the order of 10-16 at 100,000 s.
We report a novel nonresonant magneto-optical effect in cold atoms and present the optimized parameters of the biased magnetic field, the incident probe light intensity, and the probe detuning to obtain the maximal signal of the magneto-optical rotation. This detection scheme may further improve the stability of the cold atom clock.
