Entanglement optimization in plasmonically coupled quantum dots

Abstract

Although the enhanced near fields produced by plasmon resonances in metal nanoparticles can enable strong local light-matter interactions, the strong dissipation of plasmon resonances would seem to be incompatible with quantum-mechanical phenomena such as entanglement. Counter to this intuition, the dissipation can in fact lead to the production of transient entanglement between the occupation states of dots coupled to a common plasmonic system. Building on previous results that showed entanglement between pairs of dots, we scale to larger systems of two, three, and more closely spaced dots. Moreover, we show that tuning the degree of coupling between each dot and the common plasmonic nanostructure enables entanglement to be created in the case where the entire system begins in its ground state and is excited by a single laser pulse. Entanglement is achieved without the need for the dots to be individually addressable, and without the need for controlled quantum gates, postselective measurements, or engineering of the dissipative environment. Through analytical solutions and numerical simulation of a model Hamiltonian based on a cavity-quantum-electrodynamics approach, we determine system configurations that maximize pairwise entanglement among the quantum dots, illustrating in principle the potential for true “quantum plasmonics.