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The capability to embed self-assembled quantum dots (QDs) at predefined positions in nanophotonic structures is key to the development of complex quantum-photonic architectures. Here, we demonstrate that QDs can be deterministically positioned in nanophotonic waveguides by pre-locating QDs relative to a global reference frame using micro-photoluminescence (mu PL) spectroscopy. After nanofabrication, mu PL images reveal misalignments between the central axis of the waveguide and the embedded QD of only (9 +/- 46) nm and (1 +/- 33) nm for QDs embedded in undoped and doped membranes, respectively. A priori knowledge of the QD positions allows us to study the spectral changes introduced by nanofabrication. We record average spectral shifts ranging from 0.1 nm to 1.1 nm, indicating that the fabrication-induced shifts can generally be compensated by electrical or thermal tuning of the QDs. Finally, we quantify the effects of the nanofabrication on the polarizability, the permanent dipole moment, and the emission frequency at vanishing electric field of different QD charge states, finding that these changes are constant down to QD-surface separations of only 70 nm. Consequently, our approach deterministically integrates QDs into nanophotonic waveguides whose light-fields contain nanoscale structure and whose group index varies at the nanometer level.

Light is a union of electric and magnetic fields, and nowhere is the complex relationship between these fields more evident than in the near fields of nanophotonic structures. There, complicated electric and magnetic fields varying over subwavelength scales are generally present, which results in photonic phenomena such as extraordinary optical momentum, superchiral fields, and a complex spatial evolution of optical singularities. An understanding of such phenomena requires nanoscale measurements of the complete optical field vector. Although the sensitivity of near-field scanning optical microscopy to the complete electromagnetic field was recently demonstrated, a separation of different components required a priori knowledge of the sample. Here, we introduce a robust algorithm that can disentangle all six electric and magnetic field components from a single near-field measurement without any numerical modeling of the structure. As examples, we unravel the fields of two prototypical nanophotonic structures: a photonic crystal waveguide and a plasmonic nanowire. These results pave the way for new studies of complex photonic phenomena at the nanoscale and for the design of structures that optimize their optical behavior., QN/Quantum Nanoscience

Coherent light-matter interactions are key to a range of quantum optical technologies and experiments. We present measurements showing near-life-time limited transitions, for quantum dots embedded in nanoguides, demonstrating the robust suppression of environmental decoherence processes.

The first solid state structures for cavity quantum electrodynamic studies were realized analog to established designs from the field of trapped atom or ions: Single emitters (e.g. semiconductor quantum dots) were place in optical resonators with small mode volumes and a large quality factors. These devices have allowed the demonstration of effects that were already observed for atom/ion systems, like the strong coupling of a single emitter to an optical cavity mode [1,2]. However, a solid state platform offers much more control over the optical density of states than the open resonators used in quantum optics experiments with atoms or ions. Modern nano-fabrication tools can be used to pattern the dielectric environment of the emitters with nanometer precision, opening completely new possibility to tailor their photonic environment. This has led to the development of alternative structures, e.g. for single photon sources. Cavity based single photon sources rely on the Purcell effect to direct the spontaneous emission into a defined optical mode. However, it is also possible to collect a large fraction of the emitted photons in a single mode when the emission into other modes is suppressed. This can be achieved by embedding the quantum dots in photonic crystal waveguides [3] or nanowires [4]. A big advantage of these structures is their broadband operation that is not limited by the bandwidth of a cavity resonance.