Optical scattering imaging with sub-nanometer precision based on position-ultra-sensitive giant Lamb shift

The Lamb shift of a quantum emitter in close proximity to a plasmonic nanostructure can be three or more orders of magnitude larger than that in the free space and is ultra-sensitive to the emitter position and polarization. We demonstrate that this large Lamb shift can be sensitively observed from the scattering or absorption spectrum dip shift of the coupled system when the plasmonic nanoparticle or tip scans the emitter. Using these observations, we propose a scanning optical scattering imaging method based on the plasmonic-enhanced Lamb shift with achieves sub-nanometer resolution. Our method is based on the scattering or absorption spectrum of the plasmon-emitter coupling system, which is free of the fluorescence quenching problem and easier to implement in a plasmon-emitter coupling system. In addition, our scheme works even if the quantum emitter is slightly below the dielectric surface, which can bring about broader applications, such as detecting atoms and molecules or quantum dots above or under a surface.