Anharmonicity-assisted multiphonon transitions between distant levels in semiconductor quantum dots

We calculate the multiphonon transition rate from the excited state of a single-occupied two-level quantum dot. The electron interacts with certain optical phonon modes which in turn transfer the transition energy to the bath of other phonon modes decoupled from the electron states. Our theory covers the previously unexplored range of transition energies several times larger than the optical phonon energy and systematically studies the role of quantum interference of the processes involving different virtual polaron states.