Dynamics of open quantum systems excitons, cavities and surface plasmons

Resumo

This Thesis is devoted to the interplay between coherence and decoherence in open quantum optical systems. Coherence in these systems is given by the interaction of matter with diferent kind of electromagnetic modes. In particular, in this Thesis we focus on photonic modes in semiconductor microcavities and surface plasmons in metallic structures. Unfortunately, these systems have an unavoidable coupling with the environment that tends to destroy coherence. A deep understanding of this competition is needed to evaluate the possibilities of these systems in future quantum technologies. The first part of the Thesis is focused on the so-called semiconductor cavity QED systems. They typically consists of a single quantum dot embedded inside a microcavity, where the exciton and cavity mode interact. Through the appropriate inclusion of a new Lindblad term in the Master Equation, we study how decoherence induced by the phonon modes of the solid-state matrix affects the observation of strong-coupling in the non-linear regime. Importantly, we are able to predict a new kind of spectral structures, namely triplets, due to the interplay between interaction and decoherence. These triplets have already been observed experimentally but attributed to different origins. Moreover, we are able to characterize the eficiency of these systems to generate identical and simultaneous photon pairs. Another important landmark developed within this Thesis is a new method to eficiently compute frequency and time resolved photon correlations. Our method overcomes the computational dificulties of the standard theory, being able to predict a new zoology of processes completely hidden in usual spectroscopy. In the second part, metallic nanostructures are studied within an open quantum system formalism. Through this formalism we are able to characterize the strong-coupling between one or many quantum emitters interacting with surface plasmon modes of low dimensional structures. By tracing out the plasmonic degrees of freedom in one-dimensional systems, we find that they can induce a controllable coherent and incoherent coupling between emitters. Together with a continuous excitation, we show that this coupling can lead to entanglement generation between two or many quantum emitters.