Wiring up pre-characterized single-photon emitters by laser lithography

Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time

Slow and fast single photons from a quantum dot interacting with the excited state hyperfine structure of the Cesium D1-line

Hybrid interfaces between distinct quantum systems play a major role in the implementation of quantum networks. Quantum states have to be stored in memories to synchronize the photon arrival times for entanglement swapping by projective measurements in quantum repeaters or for entanglement purification. Here, we analyze the distortion of a single-photon wave packet propagating through a dispersive and absorptive medium with high spectral resolution. Single photons are generated from a single In(Ga)As quantum dot with its excitonic transition precisely set relative to the Cesium D1 transition. The delay of spectral components of the single-photon wave packet with almost Fourier-limited width is investigated in detail with a 200 MHz narrow-band monolithic Fabry-Pérot resonator. Reflecting the excited state hyperfine structure of Cesium, “slow light” and “fast light” behavior is observed. As a step towards room-temperature alkali vapor memories, quantum dot photons are delayed for 5 ns by strong dispersion between the two 1.17 GHz hyperfine-split excited state transitions. Based on optical pumping on the hyperfine-split ground states, we propose a simple, all-optically controllable delay for synchronization of heralded narrow-band photons in a quantum network

Scanning single quantum emitter fluorescence lifetime imaging: Quantitative analysis of the local density of photonic states

Their intrinsic properties render single quantum systems as ideal tools for quantum enhanced sensing and microscopy. As an additional benefit, their size is typically on an atomic scale that enables sensing with very high spatial resolution. Here, we report on utilizing a single nitrogen vacancy center in nanodiamond for performing three-dimensional scanning-probe fluorescence lifetime imaging microscopy. By measuring changes of the single emitter's lifetime, information on the local density of optical states is acquired at the nanoscale. Three-dimensional ab initio discontinuous Galerkin time-domain simulations are used in order to verify the results and to obtain additional insights. This combination of experiment and simulations to gather quantitative information on the local density of optical states is of direct relevance for the understanding of fundamental quantum optical processes as well as for the engineering of novel photonic and plasmonic devices

Miniaturized Bragg grating couplers for SiN photonic crystal slabs

We report on an experimental and theoretical investigation of an integrated Bragg like grating coupler for near vertical scattering of light from photonic crystal waveguides with an ultra small footprint of a few lattice constants only. Using frequency resolved measurements, we find the directional properties of the scattered radiation and prove that the coupler shows a good performance over the complete photonic bandgap. The results compare well to analytical considerations regarding 1d scattering phenomena as well as to FDTD simulation

Silica coated Au Ag nanorods with tunable surface plasmon bands for nanoplasmonics with single particles

Abstract We present the synthesis and analysis of silicacoated Au Ag bimetallic nanorods with controlled surface plasmon bands. Depending on the thickness of Ag shell deposited on the Au nanorod surface, there is a blue shift on the longitudinal surface plasmon band of Au nanorods, which can be expressed by an approximate formula derived from the absorption profile of light in Ag films using finite difference time domain simulations. The subsequent coating of silica shell not only enhances the stability of the Au Ag bimetallic nanorods but also provides a mesoporous host for optically active species. Minute red shifts of the longitudinal resonance mode, induced by stepwise increased silica shell volumes, are shown. Application as carrier for fluorescent rhodamine B molecules is demonstrated by photoluminescence analysis. On the single particle level, dark field microscopy of Au Ag silica nanorods was finally employed. This introduces a route towards revealing the relation between structure, shape, and optical plasmonic properties of complex composite metal particles as well as fabrication strategies for nanoassemblies of tailored structures in the field of nanoplasmonic