Crossover between the Dense Electron-Hole Phase and the BCS Excitonic   Phase in Quantum Dots
  Second order perturbation theory and a Lipkin-Nogami scheme combined with an exact Monte Carlo projection after variation are applied to compute the ground-state energy of $6\le N\le 210$ electron-hole pairs confined in a parabolic two-dimensional quantum dot. The energy shows nice scaling properties as N or the confinement strength is varied. A crossover from the high-density electron-hole phase to the BCS excitonic phase is found at a density which is roughly four times the close-packing density of excitons. 
Boris A. Rodriguez (1), Augusto Gonzalez (1), Luis Quiroga (3),   Roberto Capote (4) and Ferney Rodriguez (3) ((1) Universid...