Plasmon-Induced Trap State Emission from Single Quantum Dots.

Charge carriers trapped at localized surface defects play a crucial role in quantum dot (QD) photophysics. Surface traps offer longer lifetimes than band-edge emission, expanding the potential of QDs as nanoscale light-emitting excitons and qubits. Here, we demonstrate that a nonradiative plasmon mode drives the transfer from two-photon-excited excitons to trap states. In plasmonic cavities, trap emission dominates while the band-edge recombination is completely suppressed. The induced pathways for excitonic recombination not only shed light on the fundamental interactions of excitonic spins, but also open new avenues in manipulating QD emission, for optoelectronics and nanophotonics applications.