Nanofabrication of photonic components based on dielectric-loaded surface plasmon-polariton waveguides (DLSPPWs) excited by single nitrogen vacancy (NV) centers in nanodiamonds is demonstrated. DLSPPW circuits are built around NV containing nanodiamonds, which are certified to be single-photon emitters, using electron-beam lithography of hydrogen silsesquioxane (HSQ) resist on silver-coated silicon substrates. A propagation length of ~20 {\mu}m for the NV single-photon emission is measured with DLSPPWs. A 5-fold enhancement in the total decay rate and up to 63% coupling efficiency to the DLSPPW mode is achieved, indicating significant mode confinement. Finally, we demonstrate routing of single plasmons with DLSPPW-based directional cou-plers, revealing the potential of our approach for on-chip realization of quantum-optical networks

Monolithic integration of quantum emitters in nanoscale plasmonic circuitry requires low-loss plasmonic configurations capable of confining light well below the diffraction limit. We demonstrated on-chip remote excitation of nanodiamond-embedded single quantum emitters by plasmonic modes of dielectric ridges atop colloidal silver crystals. The nanodiamonds were produced to incorporate single germanium-vacancy (GeV) centres, providing bright, spectrally narrow and stable single-photon sources suitable for highly integrated circuits. Using electron-beam lithography with hydrogen silsesquioxane (HSQ) resist, dielectric-loaded surface plasmon polariton waveguides (DLSPPWs) were fabricated on single crystalline silver plates to contain those of deposited nanodiamonds that are found to feature appropriate single GeV centres. The low-loss plasmonic configuration enabled the 532-nm pump laser light to propagate on-chip in the DLSPPW and reach to an embedded nanodiamond where a single GeV centre was incorporated. The remote GeV emitter was thereby excited and coupled to spatially confined DLSPPW modes with an outstanding figure-of-merit of 180 due to a ~six-fold Purcell enhancement, ~56% coupling efficiency and ~33 μm transmission length, thereby opening new avenues for the implementation of nanoscale functional quantum devices.

This Report presents a nitrogen-doping method by chemically forming self-assembled monolayers on silicon. Van der Pauw technique, secondary-ion mass spectroscopy and low temperature Hall effect measurements are employed to characterize the nitrogen dopants. The experimental data show that the diffusion coefficient of nitrogen dopants is 3.66 × 10−15 cm2 s−1, 2 orders magnitude lower than that of phosphorus dopants in silicon. It is found that less than 1% of nitrogen dopants exhibit electrical activity. The analysis of Hall effect data at low temperatures indicates that the donor energy level for nitrogen dopants is located at 189 meV below the conduction band, consistent with the literature value.

High temporal stability and spin dynamics of individual nitrogen-vacancy (NV) centers in diamond crystals make them one of the most promising quantum emitters operating at room temperature. We demonstrate a chip-integrated cavity-coupled emission into propagating surface plasmon polariton (SPP) modes narrowing NV center's broad emission bandwidth with enhanced coupling efficiency. The cavity resonator consists of two distributed Bragg mirrors that are built at opposite sides of the coupled NV emitter and are integrated with a dielectric-loaded SPP waveguide (DLSPPW), using electron-beam lithography of hydrogen silsesquioxane resist deposited on silver-coated silicon substrates. A quality factor of ~ 70 for the cavity (full width at half maximum ~ 10 nm) with full tunability of the resonance wavelength is demonstrated. An up to 42-fold decay rate enhancement of the spontaneous emission at the cavity resonance is achieved, indicating high DLSPPW mode confinement.Chip-scale, bright and photostable single-photon sources are critical components for quantum cryptography and quantum information processing. 1, 2 Colour centers in diamond are very promising candidates among different emitters that have been considered for quantum optical applications. [2][3][4][5][6][7][8][9][10] The most prominent emitter in diamond is the nitrogen vacancy (NV) center, in which the negatively charged state forms a spin triplet in the orbital ground state, and allows for optical initialization and readout at room temperature. 11 In addition, NV center is a stable single-photon source at room temperature. However, the resonant optical emission of an NV center at a wavelength of 637 nm (zero-phonon line, ZPL) is weak, being less than 4% of total emission even at cryogenic temperatures. The resonant emission is accompanied by a broad phonon sideband ranging from ~ 600 nm up to 800 nm at room temperature. For some quantum optical applications only the photons emitted in the ZPL are useful. [12][13][14][15] To enhance and channel the emission into a narrow band, the environment of an emitter can be engineered. [16][17][18][19][20][21][22] Regarding the emission enhancement at the ZPL, photonic and plasmonic cavities have been employed. [21][22][23][24][25][26][27][28][29] Photonic cavities are diffraction limited, and high quality factors (Q) of the cavity required to reach high Purcell effects ultimately limit the rate of emission. 23,25 Plasmonic cavities, on the other hand, feature only moderate Q due to absorption losses, but small volumes can be achieved. 23,25 Plasmonic cavities can be used for channelling the emission into a waveguide as well, as has been demonstrated with an NV center coupled to a plasmonic cavity fabricated around a chemically grown silver nanowire. 30 It is however tedious and time consuming to build a circuitry using chemically grown silver nanowires. 31 In this work, we demonstrate a compact plasmonic configuration based on a broadband NV quantum emitter resulting in a narrow-band single-photon source with colours...