Two-particle pairing in 2D Bose gases

Chih-Chun Chien, Jian-Huang She, Fred Cooper

Deke Li, Dun Zhao

Dmitry Borzov, Mohammad Sadegh Mashayekhi, Jean-Sébastien Bernier +2 more

B. Laburthe-Tolra, Kenneth M. O’Hara, J. H. Huckans +4 more

Hongwei Xiong, Shujuan Liu, Guoxiang Huang

The analytical probability distributions of the quasi-two-dimensional (quasi-2D) (and purely 2D) ideal and interacting Bose gases are investigated by using a canonical ensemble approach. Using the analytical probability distribution of the condensate, the statistical properties such as the mean occupation number and particle number fluctuations of the condensate are calculated. Research shows that there is a continuous crossover of the statistical properties from a quasi-2D to a purely 2D ideal gas or interacting gas. In contrast to the case of a 3D Bose gas, the interaction between atoms changes, in a deep way, the nature of the particle number fluctuations.

Senne Van Loon, C. A. R. Sá de Melo

We investigate the effects of quantum fluctuations on the low-energy collective modes of two-dimensional (2D) s-wave Fermi superfluids from the BCS to the Bose limit. We compare our results to recent Bragg scattering experiments in 2D box potentials, with very good agreement. We show that quantum fluctuations in the phase and modulus of the pairing order parameter are absolutely necessary to give physically acceptable chemical potential and dispersion relation of the low-energy collective mode throughout the BCS to Bose evolution. Furthermore, we demonstrate that the dispersion of the collective modes change from concave to convex as interactions are tuned from the BCS to the Bose regime, and never crosses the two-particle continuum, because arbitrarily small attractive interactions produce bound states in two dimensions.