Critical fluctuations of an attractive Bose gas in a double-well potentialP. Ziń 1, J. Chwedeńczuk2, B. Oleś3, K. Sacha3 and M. Trippenbach1, 2
1 Soltan Institute for Nuclear Studies - Hoża 69, 00-681 Warsaw, Poland, EU
2 Institute for Theoretical Physics - Warsaw University, Hoża 69, 00-681 Warsaw, Poland, EU
3 Marian Smoluchowski Institute of Physics and Mark Kac Complex Systems Research Centre, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland, EU
received 13 June 2008; accepted in final form 11 August 2008; published September 2008
published online 15 September 2008
We consider a Bose gas with an attractive interaction in a symmetric double-well potential. In the mean-field approximation, the ground-state solution spontaneously breaks the symmetry of the trapping potential above a certain value of the interaction strength. We demonstrate how the Landau-Ginzburg scheme of the second-order phase transition emerges from the quantum model and show the link to the spontaneous symmetry breaking mentioned above. We identify the order parameter, the critical point and analyze quantum fluctuations around it.
47.20.Ky - Nonlinearity, bifurcation, and symmetry breaking.
68.35.Rh - Phase transitions and critical phenomena.
67.85.Jk - Other Bose-Einstein condensation phenomena.
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