Theory of a two-level artificial molecule in laterally coupled quantum Hall droplets

We present a theory of laterally coupled quantum Hall droplets with electron numbers (N-1,N-2) at filling factor nu=2. We show that the edge states of each droplet are tunnel-coupled and form a two-level artificial molecule. By populating the edge states with one electron each a two-electron molecule is formed. We predict the singlet-triplet transitions of the effective two-electron molecule as a function of the magnetic field, the number of electrons, and the confining potential using the configuration interaction method coupled with the unrestricted Hartree-Fock basis. In addition to the singlet-triplet transitions of a two-electron molecule involving edge states, triplet transitions involving transfer of electrons to the center of individual dots exist for (N-1 >= 5, N-2 >= 5).