Janine Riedrich-Möller

Single photon emission from silicon-vacancy colour centres in chemical vapour deposition nano-diamonds on iridium

We introduce a process for the fabrication of high quality, spatially isolated nano-diamonds on iridium via microwave plasma assisted CVD-growth. We perform spectroscopy of single silicon-vacancy (SiV)-centres produced during the growth of the nano-diamonds. The colour centres exhibit extraordinary narrow zero-phonon-lines down to 0.7 nm at room temperature. Single photon count rates up to 4.8 Mcps at saturation make these SiV-centres the brightest diamond based single photon sources to date. We measure for the first time the fine structure of a single SiV-centre thus confirming the atomic composition of the investigated colour centres.

One- and two-dimensional photonic crystal microcavities in single crystal diamond

Diamond is an attractive material for photonic quantum technologies because its colour centres have a number of outstanding properties, including bright single photon emission and long spin coherence times. To take advantage of these properties it is favourable to directly fabricate optical microcavities in high-quality diamond samples. Such microcavities could be used to control the photons emitted by the colour centres or to couple widely separated spins. Here, we present a method for the fabrication of one- and two-dimensional photonic crystal microcavities with quality factors of up to 700 in single crystal diamond. Using a post-processing etching technique, we tune the cavity modes into resonance with the zero phonon line of an ensemble of silicon-vacancy colour centres, and we measure an intensity enhancement factor of 2.8. The controlled coupling of colour centres to photonic crystal microcavities could pave the way to larger-scale photonic quantum devices based on single crystal diamond.

Deterministic Coupling of a Single Silicon-Vacancy Color Center to a Photonic Crystal Cavity in Diamond

Deterministic coupling of single solid-state emitters to nanocavities is the key for integrated quantum information devices. We here fabricate a photonic crystal cavity around a preselected single silicon-vacancy color center in diamond and demonstrate modification of the emitters internal population dynamics and radiative quantum efficiency. The controlled, room-temperature cavity coupling gives rise to a resonant Purcell enhancement of the zero-phonon transition by a factor of 19, coming along with a 2.5-fold reduction of the emitters lifetime.

Design of photonic crystal microcavities in diamond films

We design photonic crystal microcavities in diamond films for applications in quantum information yielding high quality factors Q>66000 and small mode volume Vap1.1(lambda/n)3. The calculated quality factors show a strong dependence on material absorption.

Modeling of optomechanical coupling in a phoxonic crystal cavity in diamond.

A photonic and phononic crystal (phoxonic crystal PxC) is a periodically patterned material that can at the same time localize optical and mechanical modes. Here we theoretically model one-dimensional PxC in diamond and find high quality mechanical resonances with very high frequencies > 10 GHz and optical properties comparable to those of PxC in other materials. The simultaneous confinement of photons and phonons leads to an optomechanical interaction that we calculate in a perturbation approach. The optomechanical coupling strengths reach values in the MHz range. We identify design rules to simultaneously achieve high optical and mechanical quality factors along with strong optomechanical coupling.

Design of microcavities in diamond-based photonic crystals by Fourier- and real-space analysis of cavity fields

In recent years color centers in diamond have attracted significant interest for applications in quantum information and quantum optics [1] due to their unique properties, such as very long spin lifetimes at room temperature, and their suitability for single photon sources.

Controlled coupling of single color centers to a photonic crystal cavity in monocrystalline diamond

Summary form only given. Deterministic coupling of a single emitter to a photonic crystal cavity is an important step towards the realization of integrated solid-state devices for quantum photonics. As single emitters, color centers in diamond, e.g. the Nitrogen-Vacancy (NV) center or the Silicon-Vacancy (SiV) center have attracted significant interest due to their extraordinary properties like long spin-coherence times or narrowband and bright single photon emission, respectively. For the realization of recent proposals like cavity-enhanced spin measurements or cavity-enhanced single photon sources, it is necessary to couple single color centers to a cavity with small mode volume and high quality factor. Photonic crystal cavities directly fabricated within a monocrystalline diamond membrane are well suited for this task, as they offer tiny mode volumes for efficient emitter-cavity coupling as well as scalable architectures for integrated photonic devices.In order to achieve controlled coupling of a color center to a photonic crystal cavity, several challenges have to be tackled, e.g. exact emitter positioning and alignment of its dipole moment with the cavity electric field as well as the ability for cavity tuning. For deterministic emitter-cavity positioning, two different routes can be pursued: In the first approach, a single emitter is localized within the diamond, its dipole orientation is determined and the cavity is subsequently structured around it. In the second approach, the cavity is fabricated first and a single color center is created within the cavity, e.g. via ion implantion or creation of vacancies. Here we present strategies to realize both methods for deterministic emitter-cavity coupling. For the first approach, we use a monocrystalline diamond film containing single SiV centers. Figure 1a) shows a fluorescence scan of a single SiV center with position markers next to it. The position markers are subsequently used to structure a photonic crystal cavity around the color center using focused ion beam milling [1]. Figures 1b) and c) show SEMimages before and after the cavity fabrication. The photonic crystal lattice constant a ≈ 283nm is chosen such that the cavity modes are red shifted with respect to the SiV emission lines. Using an oxidation tuning method, the cavity modes are tuned into resonance with the zero-phonon line at 740nm of a single SiV center (see Fig. 1d)). On resonance, we measure an intensity enhancement by a factor of 3.8 compared to the off-resonant case.

Photonic crystal microcavities in single crystal diamond for color center coupling

We fabricate photonic crystal microcavities in a single crystal diamond membrane and actively tune the cavity modes into resonance with the emission line of color centers in diamond to enhance the emission rate.

Fabrication and characterization of photonic crystal microcavities in quasi-single crystal diamond films

Single crystal diamond has become an attractive material for quantum information processing [1] due to the extraordinary properties of optically active defect centers, including Silicon (SiV), Nickel and Nitrogen (NV) complexes. The NV-center is the most investigated color center due to its outstanding properties such as very long spin lifetimes at room temperature and its suitability for single photon sources. There have been a number of recent proposals for the employment of color centers as cavity enhanced single photon sources, for cavity enhanced spin measurements or as optical qubits in quantum networks. All these proposals require a direct coupling of an emitter to a cavity with long photon lifetime (high quality factor Q) as well as strong spatial light confinement (small modal volume V). Photonic crystal microcavities etched in a diamond slab are being considered as an attractive architecture to manipulate and control light-matter interaction between an individual defect center and a resonator.

Narrow-bandwidth high-brightness single photon emission from silicon-vacancy colour centres in CVD-nano-diamonds

In recent years, colour centres in diamond have demonstrated the ability to fulfil the requirements for practical single photon sources, such as room temperature operation, photostability and high brightness. Among these single photon sources, Silicon-Vacancy (SiV) centres attracted attention due to their narrow emission, predominantly into a zero-phonon-line (ZPL) at 738 nm of only 5 nm width at room temperature. In previous studies, however, SiV centres suffered from an unfavourable low emission rate of only around 1000 cps [1].