Abstract In this paper, we investigate the condensate fraction (CF) of fermionic pairs in the BCS–BEC crossover for three-component Fermi gas with both asymmetric interactions and unequal chemical potentials in two-dimensional free space. By using the functional-path-integral method, we have analytically derived the number densities and bound-state energy, from which the off-diagonal long-range order is analyzed in terms of the asymptotic behavior of the two-body density matrix. The explicit formula of CF is obtained as a function of the bound-state energy and population imbalance. It is demonstrated that the CF spectrum with respect to the bound-state energy can be used to characterize the quantum phase transition between the two kinds of Sarma phases as well as the transition from three-component to two-component superfluid. Moreover we obtain the same analytic formula of CF in the BCS superfluid phase as that of homogeneous Fermi gas with equal chemical potentials.
Fund: Project supported by the Graduate Outstanding Innovation Item of Shanxi Province, China (Grant No. 20123005) and the National Natural Science Foundation of China (Grant Nos. 11075099 and 11275118).
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