Photon statistics and absorption spectrum in cooperative resonance fluorescence

Abstract

Analytic results for the absorption spectrum in cooperative resonance fluorescence are presented. An initial broad-band absorption spectrum on the cooperative branch develops a sharp spike as the instability point is approached. The usual one-atom absorption spectrum is regained on the non-cooperative branch. The photon statistics of the scattered light are studied through a calculation of the second-order correlation function g⁽²⁾(0). On the cooperative branch the value of g⁽²⁾(0) is unity reflecting the coherent scattering from the cooperative atomic state. On the non-cooperative branch the value of g⁽²⁾(0) jumps to two, reflecting the incoherent scattering from independently scattering atoms.