A look at the crossover region between BCS superconductivity and Bose Einstein Condensation

TL;DR

This paper investigates the transition from BCS superconductivity to Bose-Einstein condensation, emphasizing the importance of pair fluctuations and introducing a self-consistent method for calculating pair susceptibility.

Contribution

It provides a comprehensive analysis of pair fluctuations across the crossover and presents a new self-consistent scheme for pair susceptibility calculation.

Findings

Pair fluctuations are significantly enhanced in both 2D and 3D.

Mean field theory is inadequate in the crossover regime.

A self-consistent scheme for pair susceptibility is proposed.

Abstract

Pair fluctuation theory has been used to study the crossover from the weak coupling BCS theory to the strong coupling Bose Einstein Condensation. The effect of fluctuations has been studied over the whole crossover regime. It has been shown that the pair fluctuations are enhanced considerably in both two and three dimensions and hence mean field theory is inadequate to study the physical properties in this regime. A self consistent scheme for calculating the pair susceptibility is given.