Ultra-high contrast coherent population trapping resonances in a cold-atom microwave clock
Xiaochi Liu, V. I. Yudin, A. V. Taichenachev, John E. Kitching, Elizabeth A. Donley
A cold-atom coherent population trapping clock can achieve a better long-term frequency stability than similar clocks based on vapor cells, since long interrogation periods are possible without introducing systematic frequency shifts from buffer gases. Here we demonstrate a cold-atom CPT clock based on ς+–ς-; interrogation realized by counter-propagating optical fields of opposite circular polarization. Because the system is based on cold atoms and there is very little relaxation, nearly complete dark states are created and CPT resonances with maximum contrast are observed. A fractional frequency stability of 1.3×^-11/√τ is achieved, which averages down to 2×10^-13 after a 40,000 s integration period.
, Yudin, V.
, Taichenachev, A.
, Kitching, J.
and Donley, E.
Ultra-high contrast coherent population trapping resonances in a cold-atom microwave clock, Applied Physics Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923695
(Accessed September 17, 2021)