Quantum dot-phonon interactions in semiconductor quantum optics.

摘要

We analyze the role of QD-phonon interactions in two mesoscopic semiconductor realizations of the Jaynes-Cummings model. The first part of this dissertation focuses on a quantum dot strongly coupled to a single high finesse optical microcavity mode. There we study the effect of exciton-phonon coupling on the reversible interaction between the quantum-dot and the optical cavity without applying the usual Born-Markov approximation. The analysis is based on two related techniques that take into account the relevant multiphonon processes and have been used to study the “spin boson” Hamiltonian: non-interacting blip approximation and polaron operator perturbation theory. Observability of vacuum-Rabi splitting depends on the strength and the frequency dependence of the spectral density function characterizing the interactions with phonons and can be affected by phonon confinement. In the second part of this dissertation we study a semiconductor beam nano-structure with an embedded quantum dot. We show there that it is possible to cool a mechanical resonance of this nano-structure to its motional ground state. The proposed laser cooling technique is based on resonant laser excitation of a phonon sideband of an embedded quantum dot. The strength of the sideband coupling is determined directly by the difference between the electron-phonon couplings of the initial and final states of the quantum dot optical transition.