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Increasing coupling efficiency. In order to increase coupling efficiency of the NV emitter to the guided mode in the waveguide, a structure with a thinner supporting membrane (m = 100 nm) is proposed, enabling better access to the evanescent field. The field profile ( $| E{| }^{2}$ ) of the guided TE and TM mode for two different optimized designs is shown. With the traditional rib design in (a) and (b) the β factor can be increased to 15 % and 10 %. In (c) and (d) a slot of width ws = 50 nm is added and the β factor can be increased to 65 % and 32 % for the TE and TM mode coupling to a vertical and horizontal emitter, respectively.
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One important building block for future integrated nanophotonic devices is the scalable on-chip interfacing of single photon emitters and quantum memories with single optical modes. Here we present the deterministic integration of a single solid-state qubit, the nitrogen-vacancy (NV) center, with a photonic platform consisting exclusively of SiO 2...
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Integrating fluorescent nanoparticles with high-Q, small mode volume cavities is indispensable for nanophotonics and quantum technologies. To date, nanoparticles have largely been coupled to evanescent fields of cavity modes, which limits the strength of the interaction. Here, we developed both a cavity design and a fabrication method that enable e...
Citations
... Hybrid quantum photonics [7,8] offers a unique route to efficiently interface stationary to flying qubits, by combining individually optimized photonic and quantum systems, therefore inheriting the advantages of each of its constituents. These hybrid systems can be assembled using pick and place transfer [9] or lithographic positioning [10] and can be categorized into evanescent [11,12] and embedded optical coupling strategies, where embedding the quantum system has reached high photonic enhancements in photonic crystal cavities (PCCs) and ring resonators [13,14]. However, until today access to stationary qubits was not demonstrated in coherent hybrid quantum photonics. ...
Hybrid quantum photonic systems connect classical photonics to the quantum world and promise to deliver efficient light-matter quantum interfaces while leveraging the advantages of both, the classical and the quantum, subsystems. However, combining efficient, scalable photonics and solid-state quantum systems with desirable optical and spin properties remains a formidable challenge. In particular, the access to individual spin states and coherent mapping to photons remains unsolved for hybrid systems. In this paper, we demonstrate all-optical initialization and readout of the electron spin of a negatively charged silicon-vacancy center in a nanodiamond coupled to a silicon nitride photonic crystal cavity. We characterize relevant parameters of the coupled emitter-cavity system and determine the silicon-vacancy center’s spin-relaxation and spin-decoherence rate. Our results mark a key step towards the realization of a hybrid spin-photon interface based on silicon nitride photonics and the silicon-vacancy center’s electron spin in nanodiamonds with potential use for quantum networks, quantum communication, and distributed quantum computation.
Published by the American Physical Society 2024
... Notably, linear optics quantum computation (LOQC) requires triggered single-photon sources, which supply photons into photonic circuit [3]. Recently, several groups have achieved direct on chip integration of single photon source [4][5][6][7][8]. Realizing non classical light source working at room temperature is a hot topic and colloidal QDs are among the candidates thanks to their engineerable optical properties [9]. ...
Integrated quantum photonic circuits require the efficient coupling of photon sources to photonic waveguides. Hybrid plasmonic/photonic platforms are a promising approach, taking advantage of both plasmon modal confinement for efficient coupling to a nearby emitter and photonic circuitry for optical data transfer and processing. In this work, we established directional quantum dot (QD) emission coupling to a planar TiO2 waveguide assisted by a Yagi-Uda antenna. Antenna on waveguide is first designed by scaling radio frequency dimensions to nano-optics, taking into account the hybrid plasmonic/photonic platform. Design is then optimized by full numerical simulations. We fabricate the antenna on a TiO2 planar waveguide and deposit a few QDs close to the Yagi-Uda antenna. The optical characterization shows clear directional coupling originating from antenna effect. We estimate the coupling efficiency and directivity of the light emitted into the waveguide.
... Coupling the emission of ND-CCs with waveguides is necessary to realize the efficient transfer of photons and provide an interface to other photonic elements [175]. Deterministic integration of NV-NDs with free-standing dielectric rib waveguides, with a coupling efficiency of ∼ 5%, has been shown on a silica-on-silicon platform [219]. Waveguide embedded nanoresonators with ND-CCs have been explored for realizing on-chip photonic integrated circuits [220,221]. ...
Optically active color centers in nanodiamonds offer unique opportunities for generating and manipulating quantum states of light. These mechanically, chemically, and optically robust emitters can be produced in mass quantities, deterministically manipulated, and integrated with a variety of quantum device geometries and photonic material platforms. Nanodiamonds with deeply sub-wavelength sizes coupled to nanophotonic structures feature a giant enhancement of light-matter interaction, promising high bitrates in quantum photonic systems. We review the recent advances in controlled techniques for synthesizing, selecting, and manipulating nanodiamond-based color centers for their integration with quantum nanophotonic devices.
... However, along with deterministic on-chip integration of quantum emitters, efficient collection and routing of emitted single photon is also necessary to direct application in quantum information processing [20]. Some of the prior approaches on building chip-compatible single photon emitters involved fabrication of an embedded nano emitter adjacent to low-loss photonic substrate/waveguide to let the SPP coupled fluorescence out-couple to guided modes in the dielectric [21][22][23]. Such approaches involve refractive optics based free space excitation lacking the flexibility of remote operation and incompatible for integrated networks. ...
To address the challenges of developing a scalable system of an on-chip integrated quantum emitter, we propose to leverage the loss in our hybrid plasmonic-photonic structure to simultaneously achieve Purcell enhancement as well as on-chip maneuvering of nanoscale emitter via optical trapping with guided excitation-emission routes. In this report, we have analyzed the feasibility of the functional goals of our proposed system in the metric of trapping strength (∼8KBT), Purcell factor (>1000∼), and collection efficiency (∼10%). Once realized, the scopes of the proposed device can be advanced to develop a scalable platform for integrated quantum technology.
... This could be relevant because the technique of tapered fibers or direct coupling of on-chip waveguides is already very mature for silicon-based photonics, even though the method is probably limited to positionable nanoparticles or structures. An experimental implementation utilized an under-etched freestanding rib waveguide, tapered in two dimensions in the coupling region [186]. Pre-selected NV emitters were placed in the coupling region using an atomic force microscope, and coupling to a lensed SMF was achieved by implementing a mode-size inverter at one end of the waveguide to ensure high mode overlap. ...
Photonic quantum technology is essentially based on the exchange of individual photons as information carriers. Therefore, the development of practical single-photon sources that emit single photons on-demand is a crucial contribution to advance this emerging technology and to promoting its first real-world applications. In the last two decades, a large number of quantum light sources based on solid state emitters have been developed on a laboratory scale. Corresponding structures today have almost ideal optical and quantum-optical properties. For practical applications, however, one crucial factor is usually missing, namely direct on-chip fiber coupling, which is essential, for example, for the direct integration of such quantum devices into fiber-based quantum networks. In fact, the development of fiber-coupled quantum light sources is still in its infancy, with very promising advances having been made in recent years. Against this background, this review article presents the current status of the de-velopment of fiber-coupled quantum light sources based on solid state quantum emitters and discusses challenges, technological solutions and future prospects. Among other things, the numerical optimiza-tion of the fiber coupling efficiency, coupling methods, and important realizations of such quantum devices are presented and compared. Overall, this article provides an important overview of the state of the art and the performance parameters of fiber-coupled quantum light sources that have been achieved so far. It is aimed equally at experts in the scientific field and at students and newcomers who want to get an overview of the current developments.
... Similar work was carried out on SiV-NDs on a metallic bullseye design, where it was possible to saturate optical transitions with a low NA objective of 0.25 [ Fig. 7(c)] [218]. In a simulation, combining plasmonic resonators with bullseye antennas [217,219] leads to high directionalities of about ~85% for a 0.9 NA objective. ...
... Coupling the emission of ND-CCs with waveguides is necessary to realize the efficient transfer of photons and provide an interface to other photonic elements [175]. Deterministic integration of NV-NDs with free-standing dielectric rib waveguides, with a coupling efficiency of ~0.05, has been shown on a silica-on-silicon platform [219]. Waveguide embedded nanoresonators with ND-CCs have been explored for realizing on-chip photonic integrated circuits [220,221]. ...
Optically active color centers in nanodiamonds offer unique opportunities for generating and manipulating quantum states of light. These mechanically, chemically, and optically robust emitters can be produced in mass quantities, deterministically manipulated, and integrated with a variety of quantum device geometries and photonic material platforms. Nanodiamonds with deeply sub-wavelength sizes coupled to nanophotonic structures feature a giant enhancement of light-matter interaction, promising high bitrates in quantum photonic systems. We review the recent advances in controlled techniques for synthesizing, selecting, and manipulating nanodiamond-based color centers for their integration with quantum nanophotonic devices.
... Far-field coupling was recently considered for NV centers in diamond, however, using a black-box optical imaging system for coupling the emitted far-field to the optical fiber [31]. Moreover, the approach of fiber coupling by means of a tapered fiber has been investigated by numerical simulations for different types of emitters, including quantum dots formed at the apex of a pyramidal structure [32], NV centers [33] and for 2D emitters [34]. ...
We perform extended numerical studies to maximize the overall photon coupling efficiency of fiber-coupled quantum dot single-photon sources emitting in the near-infrared and O-band and C-band. Using the finite element method, we optimize the photon extraction and fiber-coupling efficiency of quantum dot single-photon sources based on micromesas, microlenses, circular Bragg grating cavities and micropillars. The numerical simulations which consider the entire system consisting of the quantum dot source itself, the coupling lens, and the single-mode fiber, yield overall photon coupling efficiencies of up to 83%. Our work provides objectified comparability of different fiber-coupled single-photon sources and proposes optimized geometries for the realization of practical and highly efficient quantum dot single-photon sources.
... Since the emission and manipulation of single photons is often associated with single atomic and molecular radiation, such devices often must include single nano-objects such as quantum dots or nanoantennas, etc. Therefore, many devices for nano-photonic, nano-plasmonic and nano-optical technologies include single quantum nano-objects or individual nano-devices [16,18,[21][22][23][24][25][26]. The creation of such devices is also impossible with the help of planar top down technologies, which cannot manipulate single nano-objects, those are the building blocks in such technologies. ...
... These technologies do not provide the possibility of 3D nanomanipulation with nano-objects, that is, they also work in a planar manner, which greatly limits their functionality. Pick up and place mechanical nano-assembling methods are implemented in AFM [24,25], SEM [27][28][29][30], TEM [31], FIB [24,25], confocal microscope [25] and other microscopes [32]. In some cases, SEM uses micro-grippers [27][28][29][30], the use of which is not technologically advanced due to their relatively large sizes both in relation to the captured objects and the surveillance camera. ...
... These technologies do not provide the possibility of 3D nanomanipulation with nano-objects, that is, they also work in a planar manner, which greatly limits their functionality. Pick up and place mechanical nano-assembling methods are implemented in AFM [24,25], SEM [27][28][29][30], TEM [31], FIB [24,25], confocal microscope [25] and other microscopes [32]. In some cases, SEM uses micro-grippers [27][28][29][30], the use of which is not technologically advanced due to their relatively large sizes both in relation to the captured objects and the surveillance camera. ...
The numerous 1-D and 2-D nanomaterials: nanotubes, nanowires (NWs), graphene, etc. were discovered, synthesized and intensively studied in the past decades. These nanomaterials had appeared to reveal the unique physical and functional properties allowing constructing the large number of nanodevice based on single nanoobjects. Recently many studies have led to a wide range of proof-of-concept of individual nanoscale devices including nanolasers, nanosensors, field-effect transistors (nanoFETs) and many others based on NWs, carbon nanotubes (CNT) and many other nanoobjects. Such nanodevices represent attractive building blocks for hierarchical assembly of microscale and macroscopic devices which are attractive for creating of micro-and –macro-devices and arrays by the bottom-up and hybrid paradigm. In this paper the conceptual survey is given of nowadays achievements in the field of mechanical bottom-up nanoassembling. We emphasize on the system based on smallest and the fastest in the World nanotweezer developed on the base of the new smart materials with shape memory effect for nanomanipulation of real nanoobjects. We discuss the recent experiments on nanomanipulation, nanoassembling and nanomanufacturing of nanoand micro-devices using this method, which in many cases can replaced very expensive “top-down” technologies.
... Evanescent coupling of the color center in NDs to waveguides can offer coupling on the single photon level. 12 Nevertheless, an emitter inside the waveguide can show stronger coupling due to better electric field overlap. We perform FDTD simulations based on the software MEEP 22 in order to show the dependence of the coupling strength on the emitter position. ...
Spin-based, quantum-photonics promise to realize distributed quantum computing and quantum networks. The performance depends on an efficient entanglement distribution where cavity quantum electrodynamics could boost the efficiency. The central challenge is the development of compact devices with large spin-photon coupling rates and a high operation bandwidth. Photonic crystal cavities comprise strong field confinement but require highly accurate positioning of atomic systems in mode field maxima. Negatively charged silicon-vacancy centers in diamond emerged as promising atom-like systems. Spectral stability and access to long-lived, nuclear-spin memories enabled elementary demonstrations of quantum network nodes, including memory-enhanced quantum communication. In a hybrid approach, we deterministically place SiV-containing nanodiamonds inside one hole of one-dimensional, freestanding, Si3N4-based photonic crystal cavities and coherently couple individual optical transitions to cavity modes. We optimize light–matter coupling utilizing two-mode composition, waveguiding, Purcell-enhancement, and cavity-resonance tuning. The resulting photon flux increases by 14 compared to free space. Corresponding lifetime-shortening below 460 ps puts potential operation bandwidth beyond GHz rates.
... In the hybrid case, the coupling efficiency can vary depending on the shape and the refractive index of the hybrid material. In this study, a rectangular block with 200 nm (width) × 200 nm (length) × 100 nm (height) with the same refractive index as the waveguide is simulated, where β reaches 0.04, which is on par with related works on hybrid coupled schemes 43 . The grating coupler used in this simulation extracts more than 30 percent of light into free space, with specific values for η of 0.32, 0.33, and 0.35 for the hybrid, surface, and monolithic cases, respectively. ...
Hexagonal boron nitride (hBN) is gaining interest for potential applications in integrated quantum nanophotonics. Yet, to establish hBN as an integrated photonic platform several cornerstones must be established, including the integration and coupling of quantum emitters to photonic waveguides. Supported by simulations, we study the approach of monolithic integration, which is expected to have coupling efficiencies that are 4 times higher than those of a conventional hybrid stacking strategy. We then demonstrate the fabrication of such devices from hBN and showcase the successful integration of hBN single photon emitters with a monolithic waveguide. We demonstrate coupling of single photons from the quantum emitters to the waveguide modes and on-chip detection. Our results build a general framework for monolithically integrated hBN single photon emitter and will facilitate future works towards on-chip integrated quantum photonics with hBN.
