Lee-Yang cluster expansion approach to the BCS-BEC crossover: BCS and BEC limits

作者：Sakumichi Naoyuki^*; Nishida Yusuke; Ueda Masahito

来源：Physical Review A, 2014, 89(3): 033622.

DOI：10.1103/PhysRevA.89.033622

It is shown that a cluster expansion technique, which is usually applied in the high-temperature regime to calcutate virial coefficients, can be applied to evaluate the superfluid transition temperature of the Bardeen-Cooper-Schrieffer (BCS)-Bose-Einstein condensation (BEC) crossover a la Lee and Yang. The transition temperature is identified with the emergence of the singularity in the sum of a certain infinite series of cluster functions. In the weak-coupling limit, we reproduce the Thouless criterion and the number equation of Nozieres and Schmitt-Rink, and hence the transition temperature of the BCS theory. In the strong-coupling limit, we reproduce the transition temperature of BEC of noninteracting tightly bound dimers.

• 出版日期2014-3-14
• 单位RIKEN