Microscopic theory of quantum dot interactions with quantum light: Local field effect

Abstract

A theory of both linear and nonlinear electromagnetic responses of a single quantum dot (QD) exposed to quantum light, accounting for depolarization induced local field has been developed. Based on the microscopic Hamiltonian accounting for the electron-hole exchange interaction, an effective two-body Hamiltonian has been derived and expressed in terms of the incident electric field, with a separate term describing the QD depolarization. The quantum equations of motion have been formulated and solved using the Hamiltonian for various types of the QD optical excitation, such as Fock qubit, coherent fields, vacuum state of electromagnetic field, and light with arbitrary photonic state distribution. For a QD exposed to coherent light, we predict the appearance of two oscillatory regimes in the Rabi effect separated by the bifurcation. In the first regime, the standard collapse-revival phenomenon does not reveal itself and the QD population inversion is found to be negative, while in the second one, the collapse-revival picture is found to be strongly distorted as compared to that predicted by the standard Jaynes-Cummings model. For the case of QD interaction with an arbitrary quantum light state in the linear regime, it has been shown that the local field induces a fine structure of the absorbtion spectrum. Instead of a single line with frequency corresponding to the exciton transition frequency, a duplet appears, with one component shifted by the amount of the local field coupling parameter. It has been demonstrated that the strong light--matter coupling regime arises in the weak-field limit. A physical interpretation of the predicted effects has been proposed.