[1] [1] Walls D F,Zoller P.Reduced quantum fluctuations in resonance fluorescence [J].Phys.Rev.Lett.,1981,47(10):709-711.

[2] [2] Ficek Z,Tonas R.,Kielich S.Amplitude-squared squeezing in two-atom resonance fluorescence [J].Opt.Commun.,1988,69(1):20-24.

[3] [3] Wodkiewicz K,Knight P L,et al.Squeezing and superposition states [J].Phys.Rev.,1987,A35(6):2567-2577.

[11] [11] Hou Bangpin.Sum and two-atom dipole squeezing in a system of a two-mode vacuum field interacting with two coupled atoms [J].Chinese Physics,2002,11(1):30-34.

[15] [15] Zhang Z M,Lei X,Chai J L,et al.A new kind of higher-order squeezing of radiation field [J].Phys.Lett.,1990,150A:27-32.