[1] Yuen H P. Two-photon coherent states of the radiation field [J]. Phys. Rev.,1976,A13(6): 2226

[2] Walls D F,Zoller P. Reduced quantum fluctuations in resonance fluorescence [J]. Phys. Rev. Lett.,1981,47:709

[3] Ficek Z,Tanas T,Kielich S. Amplitude-squared squeezing in two-atom resonance fluorescence [J]. Opt. Commun.,1988,69(1): 20

[4] Wódkiewicz K et al. Squeezing and superposition states [J]. Phys. Rev.,1987,A35(6): 2567