Superfluid Bose gas in two dimensions

2008/05/31 by Stefan Floerchinger, S. Floerchinger, C. Wetterich
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Quantum many-body systems #Quantum, superfluid, helium dynamics #cond-mat.supr-con

paper · pdf · doi:10.1103/physreva.79.013601

published as Phys.Rev.A79:013601,2009 · 10 pages, 12 figures, reference added

openalex publication_date 2009/01/05 · arxiv created 2009/01/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We investigate Bose-Einstein condensation for ultracold bosonic atoms in two-dimensional systems. The functional renormalization group for the average action allows us to follow the effective interactions from molecular scales (microphysics) to the characteristic extension of the probe l (macrophysics). In two dimensions the scale dependence of the dimensionless interaction strength \ensuremathλ is logarithmic. Furthermore, for large l the frequency dependence of the inverse propagator becomes quadratic. We find an upper bound for \ensuremathλ, and for large \ensuremathλ substantial deviations from the Bogoliubov results for the condensate depletion, the dispersion relation and the sound velocity. The melting of the condensate above the critical temperature T_c is associated to a phase transition of the Kosterlitz-Thouless type. The critical temperature in units of the density T_c∕n vanishes for l\ensuremath→\ensuremath∞ logarithmically.

Citations

• Two-Dimensional Bose-Einstein Condensate in an Optical Surface Trap
• Existence of Long-Range Order in One and Two Dimensions
• Exact evolution equation for the effective potential
• Dynamics of Bose-Einstein condensates in optical lattices
• Interference of an Array of Independent Bose-Einstein Condensates
• Ordering, metastability and phase transitions in two-dimensional systems
• Universal relaxational dynamics near two-dimensional quantum critical points