Ultrafast dynamics induced by coherent exciton–plasmon coupling in quantum dot-metallic nanoshell systems

Abstract

We study ultrafast coherent-plasmonic dynamics of hybrid systems consisting of one semiconductor quantum dot and one metallic nanoshell when they interact with a laser field with a step-like amplitude rise. It is shown that such dynamics is generated when quantum coherence in these systems can generate a retarded super-enhanced local field. This process happens in the picosecond range when the applied laser field ceases to be time-dependent. We show such a field generates a strong impulse, leading to a dramatic upheaval of the collective properties of the system. These include ultrafast oscillations of the effective transition energy and linewidth of the quantum dot, and generation of a polarization pulse. Within this pulse the Förster resonance energy transfer from the quantum dot to the nanoshell happens at a significantly high rate, while after that it is blocked nearly completely. We study the collective molecular resonances of this system using Rayleigh scattering and show how the frequency of the field impulse can be tuned. The intrinsic differences between such resonances and those involving spherical metallic nanoparticles are discussed.