Abstract:We demonstrate a method to probe the local density of states of surface plasmon polaritons using single quantum dots. We attain better than 10 nm spatial precision, and directly observe image dipole interference. The ability to position nanoscopic objects at precise locations on a surface is essential for a broad range of applications in the areas of quantum optics, sub-wavelength imaging, and biological sensing. In this talk I will describe a method we have developed for manipulating particles with nanometer accuracy by controlling the flow of the surrounding liquid [1][2][3]. This technique can manipulate a single pre-selected quantum dot to better than 45 nm accuracy and use it as a near field optical sensor that can probe nanoscale photonic structures. As a demonstration, we use this technique to map the local density of states of a silver nanowire with spatial precision of better than 10 nm [4]. By tracking the particle along two polarizations, we are also able to directly observe interference between an emitter and its image dipole on the surface of the nanowire [5]. We show that this effect can significantly distort particle tracking and sensing applications, and demonstrate a method to correct for it by using polarization-resolved tracking. I will conclude by describing our recent demonstration of a microfluidic magnetometer using a diamond nanocrystal. By applying flow control, we use this sensor to map out the local magnetic field of a magnetic nanoparticle with nanometer accuracy [6]. These results provide a novel toolbox of capabilities for manipulating, assembling, and probing nanoscale systems in a microfluidic device.
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