[1] Wang X B and Keiji M 2002 Phys. Rev. B 65
172508

[2] Blais A and Zagoskin A M 2000 Phys. Rev. A 61
042308

[3] Yang C P, Chu S I and Han S 2004 Phys. Rev. Lett.
92 117902.

[4] Zhou Z, Chu S I and Han S 2002 Phys. Rev. B
66 054527

[5] Amin M H S, Smirnov A Y and Brink A M 2003 Phys. Rev.
B 67 100508

[6] Yang C P and Han S 2004 Phys. Lett. A 32 273

[7] Song K H, Zhou Z W and Guo G C 2005 Phys. Rev. A
71 052310

[8] Xue Z Y et al2006 Eur. Phys. J. B 52 333

[9] Yang $C$ P and Han S 2005 Phys. Rev. A 72
032311

[10] Zhang A S et al 2007 Chin. Phys. Lett. 24
2489

[11] ZHeng A S, Wan Z Z and Bi J 2006 Chin. Phys. Lett
23 3267

[12] Han S, Rouse R and Lukens J E 1996 Phys. Rev. Lett.
76 3404

[13] Yang $C$ P and Cun S I 2003 Phys. Rev. A 67
042311

[14] Yu Y et al 2002 Science 296 889

[15] Chiorescu I et al 2003 Science 299 1896

[16] Yu Y et al 2004 Phys. Rev. Lett. 92 117904