Tracking interacting dark states through higher order absorption resonances
LAMP Group, Raman Research Institute, Sadashivnagar, 560 080, Bangalore, Karnataka, India
Corresponding author: a email@example.com
Revised: 20 April 2010
Published online: 8 September 2010
A three photon resonance arising due to coherent population trapped (CPT) states in multi-level systems, is experimentally shown to be a powerful spectral marker to detect interacting CPT states. In systems showing N type or double Λ type level configurations, these absorption resonances can be used to identify spectral positions of maximal interactions between competing CPT ground states. The contrast of the absorption resonance serves to identify even partially destructive interactions between the CPT states, eliminating the need for strong resonant changes of ground state coherence for identification. We demonstrate this effect in a room temperature, gaseous collection of 87Rb. atoms. Three laser fields interact with a double Λ configuration in the Zeeman degenerate levels of the ground state 5, F = 1 and those of the excited states 5, F = 0,1, around the D2 line. The three-photon resonance is studied in the counter-propagating third field when the other two co-propagating fields satisfy the two-photon resonance condition necessary for creation of CPT states. We envisage that this absorption feature in the third field, can become a veritable tool to quantify degradation of CPT induced effects in engineered quantum states using multi-level systems.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2010