Quantum sensing using coherent control of near-field polarization of quantum dot-metallic nanoparticle molecules

We theoretically study the impact of quantum coherence on the states of polarization of the plasmonic fields of a quantum dot-metallic nanoparticle system. Via tracing Stokes parameters we predict that, depending on the refractive index of the environment, such a system can pass through different states of polarization with certain ellipticity and handedness. We demonstrate that this allows the nanoparticle system to act as a quantum sensor, wherein ultrasmall changes in the refractive index can lead to distinct changes in the time-dependent evolution of states of polarization (Stokes vector) of the plasmonic fields. Our numerical analysis also shows how these states can become strongly dependent on the intensity and frequency of the laser field responsible for the generation of quantum coherence. Possible applications for high resolution investigation of conformational dynamics and structures of biological molecules are discussed. Published by AIP Publishing.