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Further miniaturization of funcionalized quantum optical systems down to nm-dimensions and their integration
into fibre optical networks is a major challange for future implementations of quantum information, quantum
communication and quantum processing applications. Furthermore, scalability, long-term stability and room- as
well as liquid helium temperature operation are benchmarking properties of such systems.
In this paper, we present the realizations of fiber-coupled diamond-based single photon systems. First, an
alignment free, μm-scale single photon source consisting of a single nitrogen vacancy center facet coupled to
an optical fiber operating at room temperature is presented. Near-field coupling of the single nitrogen vacancy
center is realized by placing a pre-selected nanodiamond directly on the fiber facet in a bottom-up approach.
Its photon collection efficiency is comparable to a far-field collection via an air objective with a numerical
aperture of 0.82. As the system can be simultaneously excited and its photons be recollected through the
fiber, it can be used as a fiber-connected single quantum sensor that allows optical near-field probing on the
quantum level. Secondly single nanodiamonds that contain nitrogen vacancy defect centers, are near-field coupled
to a tapered fiber of 300 nanometer in diameter. This system provides a record-high number of 97 kcps single
photons from a single defect center into a single mode optical fiber. The entire system can be cooled to liquid
Helium temperatures and reheated without breaking. Furthermore, the system can be evanescently coupled to
various nanophotonic structures, e.g. microresonators. The system can also be applied for integrated quantum
transmission experiments and the realization of two-photon interference. It can be used as a quantum-randomnumber
generator as well as a probe for nano-magnetometry.
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