  The many-body state of carriers confined in a quantum dot is controlled by
the balance between their kinetic energy and their Coulomb correlation. In
coupled quantum dots, both can be tuned by varying the inter-dot tunneling and
interactions. Using a theoretical approach based on the diagonalization of the
exact Hamiltonian, we show that transitions between different quantum phases
can be induced through inter-dot coupling both for a system of few electrons
(or holes) and for aggregates of electrons and holes. We discuss their
manifestations in addition energy spectra (accessible through capacitance or
transport experiments) and optical spectra.
