[1] Prentiss M, Cable A, Chu S and Pritchard D E 1987
Phys. Rev. Lett. 59 2631

[2] Li K, Wang X R, He L X, Zhan M S and Lu B L 2007
Chin. Phys. Lett. 24 2562

[3] Zhao P Y, Xiong Z X, Liang J and He L X and Lu B L 2008
Chin. Phys. Lett. 25 3631

[4] Li X L, Ke M, Tang J Y, Zhou S Y, Zhou S Y and Wang Y Z
2005 Chin. Phys. Lett. 22 2526

[5] Fu J X, Chen X Z, Li Y M, Yang H D and Wang Y Q 1999
Chin. Phys. Lett. 16 805

[6] Boyd M B, Ludlow A D, Blatt S, Foreman S M, Ido T,
Zelevinsky T and Ye J 2007 Phys. Rev. Lett. 98 083002

[7] Santos F P D, Marion H, Bize S, Sortais Y, Clairon A and
Salomon C 2002 Phys. Rev. Lett. 89 233004

[8] Davis K B, Mewes M O, Andrews M R, Druten N J V, Durfee D
S, Kurn D M and Ketterle W 1995 Phys. Rev. Lett. 75 3969

[9] Xiong D Z, Chen H X, Wang P J, Yu X D, Gao F and Zhang J
2008 Chin. Phys. Lett. 25 843

[10] Qu Q Z, Zhou S Y, Long Q, Xu Z, Liu L and Wang Y Z 2007
Chin. Phys. Lett. 24 3396

[11] Chanelie`re T, Matsukevich D N, Jenkins S D, Lan S Y,
Kennedy T A B and Kuzmich A 2005 Nature 438 833

[12] Lett P D, Jessen P S, Phillips W D, Rolston S L,
Westbrook C I and Gould P L 1991 Phys. Rev. Lett. 67
2139

[13] Gibble K E, Kasapi S and Chu S 1992 Opt. Lett.
17 526

[14] Ketterle W, Davis K B, Joffe M A, Martin A and Prichard D
E 1993 Phys. Rev. Lett. 70 2253

[15] Pradhan S, Gaur S J, Manohar K G and Jagatap B N 2005
Phys. Rev. A 72 053407

[16] Lindquist K, Stephens M and Wieman C 1992 Phys.
Rev. A 46 4082

[17] Braje D A, Balic V, Goda S, Yin G Y and Harris S E
Phys. Rev. Lett. 93 183601

[18] Matsukevich D N, Chaneli\`ere T, Bhattacharya M, Lan S Y,
Jenkins S D, Kennedy T A B and Kuzmich A 2005 Phys. Rev. Lett.
95 040405

[19] Bali\'c V, Braje D A, Kolchin P, Yin G Y and Harris S E
2005 Phys. Rev. Lett. 94 183601

[20] Chen Y A, Chen S, Zhen S Y, Zhao B, Chuu C S,
Schmiedmayer J and Pan J W Nature 4 103

[21] Duan L M, Cirac J I and Zoller P 2002 Phys. Rev. A
66 023818

[22] Yan M, Rickey E G and Zhu Y F 2001 J. Opt. Soc. Am.
B 18 1057

[23] Chen Y C, Lin C W and Yu I A 2000 Phys. Rev. A
61 053805

[24] Wang J, Zhu Y F, Jiang K J and Zhan M S 2003 Phys.
Rev. A 68 063810

[25] Han Y X, Wang B, Ma J, Xiao J T and Wang H 2007 Acta
Sin. Quantum Opt. 13 30

[26] Labeyrie G, Delande D, Muller C A, Miniatura C and Kaiser
R 2004 Opt. Commun. 243 157

[27] Brzozowski T M, Maczynska M, Zawada M, Zachorowski J and
Gawlik W 2002 J. Opt. B 4 62