Experimental realization of coherent dark-state magnetometersA. Nagel, L. Graf, A. Naumov, E. Mariotti, V. Biancalana, D. Meschede and R. WynandsEurophys. Lett., 44 1 (1998) 31-36DOI: https://doi.org/10.1209/epl/i1998-00430-0