We analyze theoretically and experimentally the electronic structure and charging diagram of three coupled lateral quantum dots filled with electrons. Using the Hubbard model and real-space exact diagonalization techniques we show that the electronic properties of this artificial molecule can be understood using a set of topological Hunds rules. These rules relate the multielectron energy levels to spin and the interdot tunneling $t$, and control charging energies. We map out the charging diagram for up to $N=6$ electrons and predict a spin-polarized phase for two holes. The theoretical charging diagram is compared with the measured charging diagram of the gated triple-dot device.

• Received 5 October 2006

DOI:https://doi.org/10.1103/PhysRevB.75.115301