Localized All-Optical Control of Single Semiconductor Quantum Dots through Plasmon Polariton-Induced Screening

Due to their ability to strongly modify the local optical field through the excitation of surface plasmon polaritons (SPPs), plasmonic nanostructures are often used to reshape the emission direction and enhance the radiative decay rate of quantum emitters, such as semiconductor quantum dots (QDs). These features are essential for quantum information processing, nanoscale photonic circuitry, and optoelectronics. However, the modification and enhancement demonstrated thus far have typically led to drastic alterations of the local energy density of the emitters, and hence their intrinsic optical properties, leaving little room for active control. Here, dynamic tuning of the energy states of a single semiconductor QD is demonstrated by optically modifying its local dielectric environment with a nearby plasmonic structure, instead of directly coupling it to the QD. This technique leaves intact the intrinsic optical properties of the QD, while enabling a reversible all-optical control mechanism that operates below the diffraction limit at low power levels.