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Joint Conference of the IEEE International Frequency Control Symposium and International Symposium on Applications of Ferroelectrics (IFCS-ISAF)

Stability Budget for Thermal Calcium-Beam Optical Clock

Bryan Hemingway, Thomas G. Akin, Jennifer A. Taylor, Steven Peil

Published Jul 1, 2020• 4 citations
Publisher

Abstract

We assess the limits to long-term frequency stability of a thermal calcium-beam optical clock from a variety of experimental parameters by measuring the change in clock frequency with changes in that parameter's value. Required regulation of the parameters to keep the contributed instability at the 10-17level are extracted from these measurements and the implications discussed.

DOI
10.1109/ifcs-isaf41089.2020.9234909

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The optical frequency transitions with long-lifetime spin triplet states produced by the two valence electrons in the outermost layer of alkaline earth atoms make calcium atom a promising quantum frequency reference. Electron-shelving detection improves the signal-to-noise ratio of the clock transition spectrum, enabling a calcium atomic beam optical frequency standard. This scheme employs the 1S0-1P1 transition at 423 nm to detect the 1S0-3P1 transition at 657 nm, emphasizing the importance of 423 nm laser stability. While the performance of these clocks is well-studied, research on the atomic beam itself is limited. This study investigates frequency shifts in neutral calcium atoms’ 1S0-1P1 transition at 423 nm and their 1S0-3P1 transition at 657 nm. We measure the frequency shift caused by temperature, laser power, and laser alignment, providing insights to optimize the design of the calcium beam’s physical apparatus.