2005/01/31 by A. Perali, P. Pieri, G. C. Strinati
Physics and Astronomy · #cond-mat.supr-con #cond-mat.other
paper · pdf · doi:10.1103/physrevlett.95.010407
published as Phys. Rev. Lett. 95, 010407 (2005) · 4 pages, 4 figures
arxiv created 2005/04/21 · arxiv updated 2009/12/01
A debated issue in the physics of the BCS-BEC crossover with trapped Fermi atoms is to identify characteristic properties of the superfluid phase. Recently, a condensate fraction was measured on the BCS side of the crossover by sweeping the system in a fast (nonadiabatic) way from the BCS to the BEC sides, thus ``projecting'' the initial many-body state onto a molecular condensate. We analyze here the theoretical implications of these projection experiments, by identifying the appropriate quantum-mechanical operator associated with the measured quantities and relating them to the many-body correlations occurring in the BCS-BEC crossover. Calculations are presented over wide temperature and coupling ranges, by including pairing fluctuations on top of mean field.