Exact-diagonalization treatment of the non-universal transport regime in few-electron quantum dots

Recently, experimental studies\footnote{M. Avinun-Kalish {\it et al.\/}, Nature {\bf 436}, 529 (2005)} have revealed a distinct second transport regime in the behavior of transmission phases obtained via Aharonov-Bohm interferometry using small quantum dots (QDs); namely, a non-universal regime for QDs with $N < 10$ electrons, in addition to the earlier known universal one for larger QDs with $N > 14$. Sophisticated (beyond-the-mean-field) many-body methods are needed for describing this non-universal regime. Here, we study the transport properties of small QDs using exact-diagonalization (EXD) calculations in conjunction with Bardeen's theory of quasiparticle mediated conductance.\footnote{For an adaptation of the formalism to QDs, see S.A. Gurvitz, arXiv:0704.1260v1} We will present EXD calculations\footnote{C. Yannouleas and U. Landman, Rep. Prog. Phys. {\bf 70}, 2067 (2007)} for anisotropic QDs, and for a wide range of anisotropies and strengths of inter-electron repulsion.