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Pumping and decay rates of cold atoms dark states



Moshe Shuker, Juniper Pollock, V. I. Yudin, John Kitching, Elizabeth Donley


Coherent dark states in atoms, created by simultaneous interaction of two coherent light fields with an atom, are of prime importance in quantum state manipulation. They are used extensively in quantum sensing and quantum information applications to build atomic clocks, magnetometers, atomic interferometers and more. Here we study the formation and decay of coherent dark-states in an ensemble of laser-cooled free-falling atoms. We first measure the optical-pumping rate into the dark-state in the $\sigma ^+-\sigma ^-$ polarization configuration. We find that the pumping rate is linear with the optical field intensity, but about an order-of-magnitude slower than the commonly used, but simplistic, three-level analytic formula. Using the numerical model we demonstrate that this discrepancy is due to the multi-level Zeeman manifold. Taking into account the slower pumping rate we explain quantitatively the dependence of the light-shift on the dark-state pumping duration in Ramsey spectroscopy. We also measure the decay of the dark- state coherence and find that in our apparatus it is dominated by the mechanical motion of the atoms out of the probing region, while the atomic decoherence is negligible.
Physical Review A


Coherent population trapping, Dark states, decay processes, light-shifts, optical pumping


Shuker, M. , Pollock, J. , Yudin, V. , Kitching, J. and Donley, E. (2019), Pumping and decay rates of cold atoms dark states, Physical Review A (Accessed April 15, 2024)
Created September 9, 2019, Updated March 25, 2024