The 2^nd harmonic signal in vapor-cell clocks error-signal quality: Does S2 imply dS1/d#x0394;?

摘要

How does one directly assess the quality of a Rb atomic clock signal remotely and in real time? Typically, one monitors the clock's 2^nd harmonic signal, S2, which in the quasi-static approximation is a measure of the correction signal's slope, dS1/dΔ. Unfortunately, in real vapor-cell clocks the quasi-static approximation is not valid, and the physics relating S2 to dS1/dΔ is complicated and not well understood. We have begun a series of studies aimed at elucidating the relationship between S2 and dS1/dΔ, and here we present our preliminary results.