Eur. Phys. J. D (2012) 66: 131
https://doi.org/10.1140/epjd/e2012-20715-3

Regular Article

Linear susceptibilities of a single two-level atom and two two-level atoms inside a coupled resonator waveguide: Green function approach

¹ Department of Physics, Faculty of Science, University of Isfahan, Hezar Jerib, 81746-73441 Isfahan, Iran
² Quantum Optics Group, Department of Physics, Faculty of Science, University of Isfahan, Hezar Jerib, 81746-73441 Isfahan, Iran

^a e-mail: mhnaderi@phys.ui.ac.ir

Received: 8 December 2011
Received in final form: 19 March 2012
Published online: 23 May 2012

Abstract

In this paper, we use the Green function method to determine the linear quantum mechanical susceptibilities of a single two-level atom and two two-level atoms located inside a coupled-resonator optical waveguide (CROW). We first calculate the susceptibility of a single atom in a CROW which has the same form as that of a single atom in free space, except for the modification of the atomic decay rate and the frequency shift. Then, we consider two non-identical, non-interacting two-level atoms inside two separate cavities of the CROW. We find that the susceptibility of this system contains not only the contributions of the two individual atoms, but also the contribution arising from the atom-atom correlation due to the CROW field. This additional contribution leads to an electromagnetically induced transparency-like (EIT-like) phenomenon. Furthermore, we find that the optical response of the atomic systems under consideration can be controlled by tuning the atomic transition frequency. Finally, we study the effects of the dissipation processes, i.e., the spontaneous emission of the atoms and the photon leakage from the CROW, on the optical susceptibility.