Fast quantum state transfer in hybrid quantum dot-metal nanoparticle systems by shaping ultrafast laser pulses

Abstract

Semiconductor quantum dots (SQDs) have relatively short decoherence times, but have the potential for extremely fast operations implemented by femto-second laser pulses, making them a possible candidate for very high speed quantum information processing. These operations are enhanced by positioning a metal nano-particle (MNP) near to the SQD which significantly increases the strength of electric fields applied to it. Here we consider an SQD with three-levels in a Lambda configuration, and explore the requirements for implementing a transfer from one ground state to the other via the upper level. A recently developed optimization method allows us to fix the energy of the laser pulse while satisfying the requirement that the pulse has no DC component. We show that the use of carefully shaped pulses significantly reduces the required laser power. We also determine the dependence of the pulse power on the distance between the SQD and the MNP, and explore the degree to which the process follows the pulse area theorem for first-order perturbative processes.