Efficient exciton generation in a semiconductor quantum-dot–metal-nanoparticle composite structure using conventional chirped pulses

Abstract

We consider a nanostructure consisting of a semiconductor quantum dot coupled to a metal nanoparticle, and show with numerical simulations that the exciton state of the quantum dot can be robustly generated from the ground state even for small interparticle distances, using conventional chirped pulses with Gaussian and hyperbolic secant envelopes. The asymmetry observed in the final exciton population with respect to the chirp sign of the applied pulses is explained using the nonlinear density matrix equations describing the system, and is attributed to the real part of the parameter emerging from the interaction between excitons in the quantum dot and plasmons in the metal nanoparticle. The simplicity of the conventional chirped pulses, which can also be easily implemented in the laboratory, make the proposed robust quantum control scheme potentially useful for the implementation of ultrafast nanoswitches and quantum information processing tasks with semiconductor quantum dots.