1203.3254 (Chih-Chun Chien et al.)

A unified description of pairing effects, BKT physics, and superfluidity
of 2D interacting Bose gases    [PDF]

Chih-Chun Chien, Jianhuang She, Fred Cooper

We develop a unified description for two-dimensional (2D) interacting Bose gases at arbitrary temperatures. The genuine Bose-Einstein condensation with long-range coherence only survives at zero temperature. At finite temperatures, many-body pairing effects introduce a finite amplitude of the pairing density, which results in a finite superfluid density. The superfluid phase is only stable below the Berenzinskii-Kosterlitz-Thouless (BKT) temperature due to phase fluctuations. We present a finite-temperature phase diagram of 2D Bose gases. One salient signature of the finite amplitude of the pairing density field is a two-peak structure in the single-particle spectral function, resembling that of the pseudogap phase in 2D attractive Fermi gases.

View original: http://arxiv.org/abs/1203.3254