Excitonic clusters in coupled quantum dots

We present a first-principles path integral Monte Carlo study of a finite number of strongly correlated electron-hole pairs in two symmetric vertically coupled quantum dots. In this system, the intra- and interdot correlations depend on the distance d between the dots, the density n (strength of confinement potential) and temperature T. For fixed d and T > 0, increasing n leads to four qualitatively different states: an exciton 'liquid', an exciton 'crystal', orientationally decoupled electron and hole 'crystals' and an electron (hole) liquid.