[1] P. Lett, R. Short, and L. Mandel, Phys. Rev. Lett. 52, 341 (1984).
[2] R. Roy, A.-W. Yu, and S. Zhu, Phys. Rev. Lett. 55, 2794 (1985).
[3] S. Zhu, A.-W. Yu, and R. Roy, Phys. Rev. A 34, 4333 (1986).
[4] P. Jung, Th. Leiber, and H. Risken, Z. Phys. B 66, 397 (1987).
[5] Th. Leiber, P. Jung, and H. Risken, Z. Phys. B 68, 123 (1987).
[6] L. Cao, D.-J. Wu, and X.-L. Luo, Phys. Rev. A 47, 57 (1993).
[7] L. Cao and D.-J. Wu, Phys. Lett. A 260, 126 (1999).
[8] Q. Long, L. Cao, D.-J. Wu, and Z.-G. Li, Phys. Lett. A 231, 339 (1997).
[9] Q. Cheng, L. Cao, D. Xu, and D. Wu, Chin. Opt. Lett. 2, 331 (2004).
[10] D. Xu, L. Cao, D. Wu, and Q. Cheng, Chin. Opt. Lett. 3, 348 (2005).
[11] C.-W. Xie and D.-C. Mei, Phys. Lett. A 323, 421 (2004).
[12] S.-Q. Zhu, Phys. Rev. A 47, 2405 (1993).
[13] E. A. Novikov, Zh. Eksp. Teor. Fiz. 47, 1919 (1964).
[14] R. F. Fox, Phys. Rev. A 34, 4525 (1986).
[15] J. M. Noriega, L. Pesquera, M. A. Bodriguez, J. Casademunt, and A. Hernandez-Machado, Phys. Rev. A 44, 2094 (1991).
[16] H. Fujisaka and S. Grossmann, Z. Phys. B 43, 69 (1981).
[17] A. Hernandez-Machado, M. S. Miguel, and J. M. Sancho, Phys. Rev. A 29, 3388 (1984).
[18] S. Faetti, P. Grigolini, and F. Marchesoni, Z. Phys. B 47, 353 (1982).