Excitons and polaritons in quasi-molecular eigenbasis of the excitation hopping system interacting with a photon field.

We report studies of excitons and polaritons in the quasi-molecular eigenbasis of a nano-aggregate, in the model of excitation transfer with, or without, photon-exciton coupling. We evaluate the effective interaction between quasi-molecular subsystems in quasi-molecular eigenbasis representation, with its eigenenergies and eigenstates. From the analysis of the effective interaction Hamiltonian in the quasi-molecular eigenbasis representation, we see that the effective interaction between subsystems in quasi-molecular eigenbasis representation gives fertile points of view to understand the given system, and the dynamics of excitons and polaritons becomes simpler to understand, or to deal with, depending on the division of the whole system into specified subsystems.

Excitonic quantum interference in a quantum dot chain with rings.

We demonstrate excitonic quantum interference in a closely spaced quantum dot chain with nanorings. In the resonant dipole-dipole interaction model with direct diagonalization method, we have found a peculiar feature that the excitation of specified quantum dots in the chain is completely inhibited, depending on the orientational configuration of the transition dipole moments and specified initial preparation of the excitation. In practice, these excited states facilitating quantum interference can provide a conceptual basis for quantum interference devices of excitonic hopping.