We study the spectra of collective low excitations of two atomic ensembles which couple with a single-mode cavity field. When the left ensemble is driven with an external optical field, its corresponding response spectrum to the incident optical light shows an electromagnetically-induced-transparency–like (EIT-like) phenomenon when the layers are arranged in the sequence of node antinode but not in the sequence of antinode node. In the case of antinode-antinode sequence, the response spectrum shows an EIT-like phenomenon with two transparent windows. We also investigate the fluctuation spectra of the atomic collective excitation modes and show similar EIT-like phenomena.

• Received 21 April 2013

DOI:https://doi.org/10.1103/PhysRevA.88.053827