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Advanced Silicon Carbide Devices and Processing || Silicon Carbide for Novel Quantum Technology Devices
摘要： Silicon carbide (SiC) has recently been investigated as an alternative material to host deep optically active defects suitable for optical and spin quantum bits. This material presents a unique opportunity to realise more advanced quantum-based devices and sensors than currently possible. We will summarise key results revealing the role that defects have played in enabling optical and spin quantum measurements in this material such as single photon emission and optical spin control. The great advantage of SiC lies in its existing and well-developed device processing protocols and the possibilities to integrate these defects in a straightforward manner. There is particular current interest in nanomaterials and nanophotonics in SiC that could, once realised, introduce a new platform for quantum nanophotonics and in general for photonics. We will summarise SiC nanostructures exhibiting optical emission due to multiple polytypic bandgap engineering and deep defects. The combination of nanostructures and in-built paramagnetic defects in SiC could pave the way for future single-particle and single-defect quantum devices and related biomedical sensors with single-molecule sensitivity. We will review relevant classical devices in SiC (photonic crystal cavities, microdiscs) integrated with intrinsic defects. Finally, we will provide an outlook on future sensors that could arise from the integration of paramagnetic defects in SiC nanostructures and devices.
关键词： Optical-detected magnetic resonance,Single-photon sources,Silicon carbide deep defects,Paramagnetic properties
更新于2025-09-23 15:22:29
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Improving photon antibunching with two dipole-coupled atoms in whispering-gallery-mode microresonators
摘要： In the two-atom or multiatom system, the atoms can interact with each other through exchange of virtual photon. This kind of energy exchange is often referred as the dipole-dipole interaction (DDI). Here we consider this DDI system consisting of a pair of two-level atoms strongly coupled with a bimodal whispering-gallery-mode (WGM) microresonator which is driven by an external laser field. Our aim is to explore the photon correlation characteristics of the proposed architecture using realistic experimental parameter values. We compare in detail the quality of photon antibunching (i.e., the smallness of the second-order correlation function) from three involved configurations in cavity quantum electrodynamics (QED): (i) only one two-level atom, (ii) two far apart two-level atoms without DDI, and (iii) two DDI (dipole-coupled) two-level atoms are respectively coupled to the driven WGM microresonator through the evanescent field. We clearly show that the DDI between both atoms can distinctly enhance the photon antibunching even in the weak-coupling regime in configuration (iii) with feature-rich line shapes. We also find that the photon antibunching can be modulated by properly adjusting the atom-cavity coupling strength. In addition, we display that this strong photon antibunching is robust against the cooperative atomic decay. Our DDI-based cavity QED scheme may provide an alternative way to the construction of integrated on-chip single-photon sources.
关键词： photon antibunching,whispering-gallery-mode microresonators,single-photon sources,dipole-dipole interaction,cavity quantum electrodynamics
更新于2025-09-19 17:13:59
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Cesium‐Vapor‐Based Delay of Single Photons Emitted by Deterministically Fabricated Quantum Dot Microlenses
摘要： Quantum light sources are key building blocks of photonic quantum technologies. For many applications, it is of interest to control the arrival time of single photons emitted by such quantum devices, or even to store single photons in quantum memories. In situ electron beam lithography is applied to realize InGaAs quantum dot (QD)-based single-photon sources, which are interfaced with cesium (Cs) vapor to control the time delay of emitted photons. Via numerical simulations of the light–matter interaction in realistic QD-Cs-vapor configurations, the influence of the vapor temperature and spectral QD-atom detuning is explored to maximize the achievable delay in experimental studies. As a result, this hybrid quantum system allows to trigger the emission of single photons with a linewidth as low as 1.54 GHz even under non-resonant optical excitation and to delay the emission pulses by up to (15.71 ± 0.01) ns for an effective cell length of 150 mm. This work can pave the way for scalable quantum systems relying on a well-controlled delay of single photons on a time scale of up to a few tens of nanoseconds.
关键词： quantum dots,atomic vapors,single-photon sources,deterministic fabrication,delays
更新于2025-09-19 17:13:59
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Nonclassical Light Sources Based on Selectively Positioned Deterministic Microlens Structures and (111) In(Ga)As Quantum Dots
摘要： The results of investigations of the optical characteristics of nonclassical light sources based on selectively positioned microlens structures and single (111) In(Ga)As quantum dots grown on a (111) BGaAs substrate are presented. The single-photon nature of the radiation is confirmed by measuring and analyzing second-order correlation functions g(2)(τ); g(2)(0) = 0.07. The fine structure of the exciton states of (111) In(Ga)As quantum dots is investigated. It is shown that, in the energy range of 1.320–1.345 eV, the splitting of exciton states is comparable to the natural width of the exciton lines, which is of interest for developing photon-pair emitters based on them.
关键词： quantum dots,single-photon sources,fine structure of exciton states,photon-pair sources
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Scanning Resonant Nano-Antenna High Resolution Imaging and Emission Control of hBN Defect Photon Emission
摘要： Single atomic defects in hexagonal boron nitride (hBN) are particularly interesting due to their stability of emission and absence of blinking and bleaching, at ambient conditions. Furthermore, they show exceptional robustness of emission, even at high temperatures of operation. Therefore, hBN defects have emerged as promising candidates for novel robust single photon sources. Several attempts have been done to induce hBN defects in a controlled manner. Because of their ease of accessibility and, due to the nanometer scale thickness of the hBN flakes, these defects are attractive to couple to plasmonic structures in order to increase their photon emission. However efficient coupling requires a high precision of positioning (<20 nm) and so far the methods adopted lack this level of control, both in assembling and imaging. Also, they present static configurations of coupled emitter-particles and no strategy is adopted in order to discern between the photons emitted by the hBN defects and the luminescence of the metallic particles. Here we present first systematic and simultaneous coupling and imaging of hBN emission centers with resonant optical antennas, with nanometer control and optical resolution of 45 nm. We show the capability of nano-antennas to manipulate hBN defects by depleting their emission 30-70%. Our setup is a near-field microscope working in scattering configuration, where we fabricate a single dipolar nano-antenna as a near-field probe that we can independently scan over hBN defects controlling the coupling and the fluorescence emission with nanometer resolution. We employ a photon time-gating technique in order to discriminate the light emitted by the metallic antenna by the one radiated by the hBN emitters. Finally, we report on a lifetime shortening of 2x, due to coupling emitter--antenna.
关键词： nano-antennas,single photon sources,plasmonic structures,near-field microscope,hBN defects
更新于2025-09-16 10:30:52
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<i>In situ</i> wavelength tuning of quantum-dot single-photon sources integrated on a CMOS-processed silicon waveguide
摘要： Silicon quantum photonics provides a promising pathway to realize large-scale quantum photonic integrated circuits (QPICs) by exploiting the power of complementary-metal-oxide-semiconductor (CMOS) technology. Toward scalable operation of such silicon-based QPICs, a straightforward approach is to integrate deterministic single-photon sources (SPSs). To this end, hybrid integration of deterministic solid-state SPSs, such as those based on InAs/GaAs quantum dots (QDs), is highly promising. However, the spectral and spatial randomness inherent in the QDs poses a serious challenge for scalable implementation of multiple identical SPSs on a silicon CMOS chip. To overcome this challenge, we have been investigating a hybrid integration technique called transfer printing, which is based on a pick-and-place operation and allows for the integration of the desired QD SPSs on any locations on the silicon CMOS chips at will. Nevertheless, even in this scenario, in situ fine tuning for perfect wavelength matching among the integrated QD SPSs will be required for interfering photons from dissimilar sources. Here, we demonstrate in situ wavelength tuning of QD SPSs integrated on a CMOS silicon chip. To thermally tune the emission wavelengths of the integrated QDs, we augmented the QD SPSs with optically driven heating pads. The integration of all the necessary elements was performed using transfer printing, which largely simplified the fabrication of the three-dimensional stack of micro/nanophotonic structures. We further demonstrate in situ wavelength matching between two dissimilar QD sources integrated on the same silicon chip. Our transfer-printing-based approach will open the possibility for realizing large-scale QPICs that leverage CMOS technology.
关键词： wavelength tuning,transfer printing,quantum photonics,single-photon sources,silicon CMOS,quantum dots
更新于2025-09-16 10:30:52
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Design of Quantum Dot-Nanowire Single-Photon Sources that are Immune to Thermomechanical Decoherence
摘要： Nanowire antennas embedding a single quantum dot (QD) have recently emerged as versatile platforms to realize bright sources of quantum light. In this theoretical work, we show that the thermally driven, low-frequency vibrations of the nanowire have a major impact on the QD light emission spectrum. Even at liquid helium temperatures, these prevent the emission of indistinguishable photons. To overcome this intrinsic limitation, we propose three designs that restore photon indistinguishability thanks to a specific engineering of the mechanical properties of the nanowire. We anticipate that such a mechanical optimization will also play a key role in the development of other high-performance light-matter interfaces based on nanostructures.
关键词： single-photon sources,photon indistinguishability,quantum dot,nanowire,thermomechanical decoherence
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Udine, Italy (2019.9.4-2019.9.6)] 2019 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Simulation of quantum dot based single-photon sources using the Schr?dinger-Poisson-Drift-Diffusion-Lindblad system
摘要： The device-scale simulation of electrically driven quantum light sources based on semiconductor quantum dots requires a combination of the (semi-)classical semiconductor device equations with cavity quantum electrodynamics. We present a comprehensive quantum-classical simulation approach that self-consistently couples the (semi-)classical drift-diffusion system to a Lindblad-type quantum master equation. This allows to describe the spatially resolved carrier transport in complex, multi-dimensional device geometries along with the fully quantum-mechanical light-matter interaction in the quantum dot-cavity system. The latter gives access to important quantum optical figures of merit, in particular the second-order correlation function of the emitted radiation. In order to account for the quantum confined Stark effect in the device’s internal electric field, the system is solved along with a Schr?dinger–Poisson problem, that describes the envelope wave functions and energy levels of the quantum dot carriers. The approach is demonstrated by numerical simulations of a single-photon emitting diode.
关键词： quantum-confined Stark effect,device simulation,Single-photon sources,quantum-classical coupling
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Planar Optical Antennas as Efficient Single-Photon Sources for Free-Space and Fiber-Based Operation in Quantum Optics and Metrology
摘要： Practical implementations of quantum technologies, ranging from optical quantum computing to metrological measurements, suffer from the lack of high-rate, on-demand sources of indistinguishable single photons. We will discuss a simple and versatile planar optical antenna, showing both theoretical and experimental evidence of low-loss (< 20%) beaming of the radiation from a single quantum emitter into a narrow cone of solid angles in free space, which allows in principle up to 50% coupling into a single-mode fiber. In particular, we will first present an experimental implementation of the design operated at room temperature, exploiting Dibenzoterrylene molecules (DBT) hosted in a crystalline anthracene matrix (Ac) [1]. The DBT:Ac system is particularly suitable for this task, due to its outstanding photo-physical properties (i.e. long-term photostability both at room and cryogenic temperature, lifetime-limited emission at cryogenic temperatures, 780 nm operating wavelength) demonstrated in 50 nm-thick crystals [2] and recently also in nanocrystals [3]. Moreover, single photons from DBT molecules and similar [4] result very appealing concerning quantum communication and computation protocols which involve quantum memories, due to the unmatched stability and narrowness of their spectrum (below 100 MHz). Then we will report on our theoretical study to determine the ultimate performances attainable with such design in case of operation in cryogenic environment, exploring materials and fine tuning of geometrical parameters. We will finally discuss our recent results about a single-mirror antenna operating at cryogenic temperature. We demonstrate a photon flux in the Fourier-limited line higher than 1MHz at detectors, and coupling of fluorescence into single-mode fibers up to 46%. These results open to the deploiment of our system both in quantum optics experiments requiring deterministic single-photon sources and in metrology, in particular for a new operative definition of the candela, as recently proposed in the EMPIR project 'SIQUST' [5].
关键词： Quantum Optics,Single-Photon Sources,Dibenzoterrylene molecules,Metrology,Planar Optical Antennas,Crystalline anthracene matrix
更新于2025-09-12 10:27:22
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Strain-induced control of a pillar cavity-GaAs single quantum dot photon source
摘要： Herein, we present the calculated strain-induced control of single GaAs/AlGaAs quantum dots (QDs) integrated into semiconductor micropillar cavities. We show precise energy control of individual single GaAs QD excitons under multi-modal stress fields of tailored micropillar optomechanical resonators. Further, using a three-dimensional envelope-function model, we evaluated the quantum mechanical correction in the QD band structures depending on their geometrical shape asymmetries and, more interestingly, on the practical degree of Al interdiffusion. Our theoretical calculations provide the practical quantum error margins, obtained by evaluating Al-interdiffused QDs that were engineered through a front-edge droplet epitaxy technique, for tuning engineered QD single-photon sources, facilitating a scalable on-chip integration of QD entangled photons.
关键词： single-photon sources,quantum dots,micropillar cavities,strain-induced control,quantum computation
更新于2025-09-12 10:27:22