[1] Inouye S, Chikkatur A P, Stamper-Kurn D M, Stenger J,
Pritchard D E, and Ketterle W 1999 Science 285 571

[2] Kozuma M, Suzuki Y, Torii Y et al 1999 Science
286 2309

[3] Inouye S, Pfau T, Gupta S, Chikkatur A P, GOrlitz A, Pritchard
D E, and Ketterle W 1999 Nature 402 641

[4] Fisher M P A, Weichman P B, Grinstein G and Fisher D S 1989
Phys. Rev. B 40 546

[5] Jaksch D, Bruder C, Cirac J I, Gardiner C W and Zoller P 1998
Phys. Rev. Lett. 81 3108

[6] Zhu Ri 2007 Chin. Phys. Lett. 24 797

[7] Greiner M, Mandel O, Esslinger T, Hansch T W and Bloch I 2002
Nature 415 39

[8] Sheshadri K, Krishnamurthy H R, Pandit R and Ramakrishnan T V
1993 Europhys. Lett. 22 257

[9] Oktel M O, Nita M and Tanatar B 2007 Phys. Rev. B
75 045133

[10] Buonsante P, Penna V and Vezzani A 2004 Phys. Rev. A
70 061603(R)