Issue
EPL
Volume 83, Number 6, September 2008
Article Number 64007
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
DOI http://dx.doi.org/10.1209/0295-5075/83/64007
Published online 15 September 2008
EPL, 83 (2008) 64007
DOI: 10.1209/0295-5075/83/64007

Critical fluctuations of an attractive Bose gas in a double-well potential

P. 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

pazin@fuw.edu.pl

received 13 June 2008; accepted in final form 11 August 2008; published September 2008
published online 15 September 2008

Abstract
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.

PACS
47.20.Ky - Nonlinearity, bifurcation, and symmetry breaking.
68.35.Rh - Phase transitions and critical phenomena.
67.85.Jk - Other Bose-Einstein condensation phenomena.

© EPLA 2008