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The local interaction of charges and light in organic solids is the basis of distinct and fundamental effects. We here observe, at the single molecule scale, how a focused laser beam can locally shift by hundreds-time their natural linewidth and in a persistent way the transition frequency of organic chromophores, cooled at liquid helium temperatures in different host matrices. Supported by quantum chemistry calculations, the results are interpreted as effects of a photo-ionization cascade, leading to a stable electric field, which Stark-shifts the molecular electronic levels. The experimental method is then applied to a common challenge in quantum photonics, i.e. the independent tuning and synchronization of close-by quantum emitters, which is desirable for multi-photon experiments. Five molecules that are spatially separated by about 50 microns and originally 20 GHz apart are brought into resonance within twice their linewidth. Combining this ability with an emission linewidth that is only limited by the spontaneous decay, the system enables fabrication-free, independent tuning of multiple molecules integrated on the same photonic chip., Comment: 15 pages, 5 figures. Supplementary Informations 23 pages, 13 figures

Plasmonic waveguides are key elements in nanophotonic devices serving as optical interconnects between nanoscale light sources and detectors. Multimode operation in plasmonic two-wire transmission lines promises important degrees of freedom for near-field manipulation and information encoding. However, highly confined plasmon propagation in gold nanostructures is typically limited to the near-infrared region due to ohmic losses, excluding all visible quantum emitters from plasmonic circuitry. Here, we report on top-down fabrication of complex plasmonic nanostructures in single-crystalline silver plates. We demonstrate controlled remote excitation of a small ensemble of fluorophores by a set of waveguide modes and emission of the visible luminescence into the waveguide with high efficiency. This approach opens up the study of nanoscale light-matter interaction between complex plasmonic waveguides and a large variety of quantum emitters available in the visible spectral range.