Raman-Ramsey CPT with a grating magneto-optical trap

Elvin, Rachel and Hoth, Gregory W. and Wright, Michael W. and McGilligan, James P. and Arnold, Aidan S. and Griffin, Paul F. and Riis, Erling; (2018) Raman-Ramsey CPT with a grating magneto-optical trap. In: 2018 European Frequency and Time Forum (EFTF). IEEE, ITA, pp. 61-64. ISBN 9781538656204 (https://doi.org/10.1109/EFTF.2018.8408998)

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We describe an experiment which combines cold 87Rb atoms from a grating magneto-optical trap (GMOT) with Lin-perp-Lin coherent population trapping (CPT) and pulsed Ramsey interrogation. The bichromatic fields required for Lin-perp-Lin are generated by combining light from a single external cavity diode laser (ECDL) with an electro-optic modulator (EOM) and an acousto-optic modulator (AOM). With this laser system and the GMOT, we are able to produce Raman-Ramsey fringes using either the F' = 1 or the F' = 2 excited states of the 87 Rb D1 line. As a step towards realising a frequency standard based on the GMOT, we measure the Ramsey fringe amplitude as a function of the magnetic bias field and the excited state. We observe dark state interference with F' = 1 and show that this interference is suppressed with F' = 2, as expected from prior work on CPT with 87Rb in thermal vapour cells.