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Improving indistinguishability of single photons from colloidal quantum dots using nanocavities
摘要： Colloidal quantum dots have garnered active research interest as quantum emitters due to their robust synthesis process and straightforward integration with nanophotonic platforms. However, obtaining indistinguishable photons from the colloidal quantum dots at room temperature is fundamentally challenging because they suffer from an extremely large dephasing rate. Here we propose an experimentally feasible method of obtaining indistinguishable single photons from an incoherently pumped solution-processed colloidal quantum dot coupled to a system of nanocavities. We show that by coupling a colloidal quantum dot to a pair of silicon nitride cavities, we can obtain comparable performance of a single photon source from colloidal quantum dots as other leading quantum emitters like defect centers and self-assembled quantum dots.
关键词： Colloidal quantum dots,Nanocavities,Indistinguishable single photon source
更新于2025-09-16 10:30:52
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Fabrication and optical characterization of photonic crystal nanocavities with electrodes for gate-defined quantum dots
摘要： Among various solid-state systems, gate-defined quantum dots (QD) with high scalability and controllability for single electron spin qubits are promising candidates to realize quantum spin-photon interface. The efficiency of the spin-photon interface is expected to be significantly enhanced by optical coupling of gate-defined QDs with photonic crystal (PhC) nanocavities. As the first step towards this optical coupling, we designed and experimentally demonstrated a PhC nanocavity with electrodes. The electrodes, which can form a single QD, were introduced on the top surfaces of two-dimensional PhC nanocavities with a position accuracy of a few tens of nanometers. Despite the electrodes, a resonant mode was confirmed for the PhC nanocavities through micro-photoluminescence spectroscopy. This work marks a crucial step towards optical coupling between gate-defined QDs and PhC nanocavities.
关键词： optical coupling,quantum spin-photon interface,quantum dots,photonic crystal nanocavities
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Seoul, Korea (South) (2019.1.27-2019.1.31)] 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS) - Diversified and Precise Plasmonic Color Tuning by Three-Dimensional Air-Gap Nanocavities
摘要： We report a new arrayed three-dimensional (3D) air-gap nanocavities with multiple tunable geometrical parameters. Light is tightly confined into the nanocavities and strong surface-plasmon coupling is introduced, realizing narrow band resonance. Vivid plasmonic colors are generated, and can be tuned by multiple geometrical parameters of the 3D nanocavities, including shapes, separations, and heights. What’s more, the surface-plasmon coupling resonance has different dependence on different variable geometrical parameters. So, multi-dimensional color tuning with different spectral sensitivities is realized by proper and precise structural design, leading to both broad gamut and sophisticated plasmonic color printing at the optical diffraction limit.
关键词： plasmonic color tuning,surface-plasmon coupling,color printing,optical diffraction limit,3D air-gap nanocavities
更新于2025-09-12 10:27:22
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Carbon nanotube color centers in plasmonic nanocavities: A path to photon indistinguishability at telecom bands
摘要： Indistinguishable single photon generation at telecom wavelengths from solid-state quantum emitters remains a significant challenge to scalable quantum information processing. Here we demonstrate efficient generation of indistinguishable single photons directly in the telecom O-band from aryl-functionalized carbon nanotubes by overcoming the emitter quantum decoherence with plasmonic nanocavities. With an unprecedented single-photon spontaneous emission time down to 10 ps (from initially 0.7 ns) generated in the coupling scheme, we show a two-photon interference visibility at 4 K reaching up to 0.79, even without applying post selection. Cavity-enhanced quantum yields up to 74% and Purcell factors up to 415 are achieved with single-photon purities up to 99%. Our results establish the capability to fabricate fiber-based photonic devices for quantum information technology with coherent properties that can enable quantum logic.
关键词： Plasmonic nanocavities,indistinguishable single photons,telecommunication bands,carbon nanotubes
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) - Collective Laser Emission in Coupled Hybrid InP-on-SOI Nanocavities
摘要： Coupled optical micro/nanocavities have raised large attention over the last decades as their use has triggered breakthroughs in photonics such as the exploitation of electromagnetically induced transparency (EIT) effect for delaying or storing light [1]. More recently, research was initiated on the coupling between micro/nano cavities including an active medium, in order to develop optical memories [2] or to study more fundamental physical effects such as spontaneous mirror-symmetry breaking [3]. This work is focused on coupled nanolasers made of photonic crystals onto a silicon optical platform. The development of ultra-compact and power efficient laser sources on this type of platform is crucial to enable the deployment of on chip optical interconnects. We already demonstrated an electrically powered single nanolaser integrated on SOI (Silicon-On-Insulator) [4]. To go beyond, we present here the study of the collective laser emission arising from the coupling of two identical photonic crystal nanobeam cavities made of InP materials through a SOI wire. The coupled system is fabricated by bonding a III-V semiconductor heterostructure onto a SOI optical waveguide circuitry. The InP-based slab is then patterned using electron beam lithography followed by inductively coupled plasma etching [Fig. 1]. We show that this hybrid platform is very versatile to change at will, both the coupling strength and phase. Indeed, the coupling strength can easily be tuned by changing the SOI wire width. Regarding the coupling phase, it is controlled by varying the relative distance of the 2 cavities made atop the SOI waveguides [Fig. 2]. We demonstrate that collective laser emission is obtained at 1.55μm at room temperature by CW optically pumping at 1180nm. It is obtained when the coupling phase is near a multiple of π. Compared to stand alone structures, this coupled configuration results in a drastic reduction of the laser threshold and an improvement of the slope efficiency [Fig. 3], due to the control of the coupling phase to reduce the losses in the coupled system. This is an unprecedented manner to achieve simultaneously low threshold and high coupling efficiency to the SOI waveguide circuitry. In the same time, this configuration allows to investigate interesting fundamental physical effects, such as superradiance, lasing effect without inversion of population [5], but also to study the existence of exceptional points [6] and dark modes [7] in this kind of coupled system.
关键词： silicon optical platform,coupled optical micro/nanocavities,collective laser emission,photonic crystals,SOI waveguide circuitry
更新于2025-09-12 10:27:22
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Nanocavities cause a stir
摘要： Reactions between gases and liquids are important in industry but are typically slow and difficult to monitor in situ. Elevated temperatures and pressures are often required to increase the efficiency of reactions between immiscible gases and liquids. Now, reporting in Angewandte Chemie International Edition, Xing Yi Ling and colleagues introduce a platform composed of an array of solid nanoparticles coated in a metal–organic framework (MOF) that substantially increases gas–liquid reaction efficiency owing to the formation of interfacial nanocavities. The platform can also be adapted for the in situ monitoring of reactions.
关键词： nanocavities,gas–liquid reactions,metal–organic frameworks,in situ monitoring,solid@MOF
更新于2025-09-09 09:28:46
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Optimization of photonic crystal nanocavities based on deep learning
摘要： An approach to optimizing the Q factors of two-dimensional photonic crystal (2D-PC) nanocavities based on deep learning is hereby proposed and demonstrated. We prepare a data set consisting of 1000 nanocavities generated by randomly displacing the positions of many air holes in a base nanocavity and calculate their Q factors using a first-principles method. We train a four-layer neural network including a convolutional layer to recognize the relationship between the air holes’ displacements and the Q factors using the prepared data set. After the training, the neural network is able to estimate the Q factors from the air holes’ displacements with an error of 13% in standard deviation. Crucially, the trained neural network can estimate the gradient of the Q factor with respect to the air holes’ displacements very quickly using back-propagation. A nanocavity structure with an extremely high Q factor of 1.58 × 109 was successfully obtained by optimizing the positions of 50 holes over ~106 iterations, taking advantage of the very fast evaluation of the gradient in high-dimensional parameter spaces. The obtained Q factor is more than one order of magnitude higher than that of the base cavity and more than twice that of the highest Q factors reported so far for cavities with similar modal volumes. This approach can optimize 2D-PC structures over a parameter space of a size unfeasibly large for previous optimization methods that were based solely on direct calculations. We believe that this approach is also useful for improving other optical characteristics.
关键词： nanocavities,deep learning,photonic crystal,Q factors,optimization
更新于2025-09-09 09:28:46