Nanofiber Photonics and Quantum Optics – Niels Bohr Institute - University of Copenhagen

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Nanofiber Photonics and Quantum Optics

Recently, optical nanofibers with diameters smaller than the wavelength of the guided light have attracted considerable interest in the field of quantum optics due to their high potential for efficiently interfacing light and matter. In my talk I will report on two experiments using such nanofiber-optical interfaces. In the first experiment, we perform ultra-sensitive spectroscopic measurements on 3,4,9,10-perylene-tetracarboxylic dianhydride molecules (PTCDA) deposited on the fiber surface at ambient conditions. We use the guided mode of the nanofiber both for excitation of the molecules and for fluorescence collection and we show that surface coverages as small as 1 ‰ of a compact monolayer still give rise to absorption and fluorescence spectra with a good signal to noise ratio. In the second experiment, we trap about 2000 cold neutral cesium atoms close to the surface of an optical nanofiber using the optical dipole force exerted by the evanescent field of the nanofiber guided light. The atoms are probed with a weak resonant field which is sent through the nanofiber and which interfaces with the atoms via the evanescent field. Remarkably, the atomic ensemble almost entirely absorbs this probe field, yielding an optical depth of up to 18. This opens the route towards non-linear optics and quantum communication applications with fiber-coupled atomic ensembles.