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- 摘要
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Toward Valleya??Coupled Spin Qubits
摘要： The bid for scalable physical qubits has attracted many possible candidate platforms. In particular, spin-based qubits in solid-state form factors are attractive as they could potentially benefit from processes similar to those used for conventional semiconductor processing. However, material control is a significant challenge for solid-state spin qubits as residual spins from substrate, dielectric, electrodes, or contaminants from processing contribute to spin decoherence. In the recent decade, valleytronics has seen a revival due to the discovery of valley-coupled spins in monolayer transition metal dichalcogenides. Such valley-coupled spins are protected by inversion asymmetry and time reversal symmetry and are promising candidates for robust qubits. In this report, the progress toward building such qubits is presented. Following an introduction to the key attractions in fabricating such qubits, an up-to-date brief is provided for the status of each key step, highlighting advancements made and/or outstanding work to be done. This report concludes with a perspective on future development highlighting major remaining milestones toward scalable spin-valley qubits.
关键词： valleytronics,qubits,quantum information,transition metal dichalcogenides,quantum dots
更新于2025-09-23 15:21:01
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Higha??temperature droplet epitaxy of symmetric GaAs/AlGaAs quantum dots
摘要： We introduce a high–temperature droplet epitaxy procedure, based on the control of the arsenization dynamics of nanoscale droplets of liquid Ga on GaAs(111)A surfaces. The use of high temperatures for the self-assembly of droplet epitaxy quantum dots solves major issues related to material defects, introduced during the droplet epitaxy fabrication process, which limited its use for single and entangled photon sources for quantum photonics applications. We identify the region in the parameter space which allows quantum dots to self–assemble with the desired emission wavelength and highly symmetric shape while maintaining a high optical quality. The role of the growth parameters during the droplet arsenization is discussed and modeled.
关键词： GaAs/AlGaAs,quantum photonics,arsenization dynamics,high–temperature droplet epitaxy,quantum dots
更新于2025-09-23 15:21:01
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Bright Blue Light Emission of Ni2+ ions doped CsPbClxBr3-x Perovskite Quantum Dots Enabling Efficient Light-Emitting Devices
摘要： In recent years, significant advances have been achieved in the red and green perovskite quantum dots（PQDs）based light-emitting diodes (LEDs). However, the performances of the blue perovskite LEDs are still seriously lagging behind that of the green and red counterparts. Herein, we successfully developed Ni2+ ions doped CsPbClxBr3-x PQDs through the room-temperature supersaturated recrystallization synthetic approach. We simultaneously realized the doping of various concentrations of Ni2+ cations, and modulated the Cl/Br element ratios through introducing different amount of NiCl2 solution in the reaction medium. By the synthetic method, not only the emission wavelength from 508 to 432 nm of Ni2+ ions doped CsPbClxBr3-x QDs was facially adjusted, but also the photoluminescence quantum yield (PLQY) of PQDs was greatly improved due to efficiently removing the defects of the PQDs. Thus, the blue emission at 470 nm with PLQY of 89% was achieved in 2.5% Ni2+ ions doped CsPbCl0.99Br2.01 QDs, which increased nearly three times over that of undoped CsPbClBr2 QDs, and was the highest for the CsPbX3 PQDs with blue emission that fulfilling the NTSC standards. Benefiting from the high luminous Ni2+ ions doped PQDs, the blue emitting LED at 470 nm was obtained, exhibiting an external quantum efficiency (EQE) of 2.4% and a maximum luminance of 612 cd/m2, which surpassed the best performance reported previously for the corresponding blue-emitting PQDs based LED.
关键词： perovskite QD-LEDs,Ni2+ ion doping,blue emission,anion exchange,perovskite quantum dots
更新于2025-09-23 15:21:01
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A universal growth strategy for DNA-programmed quantum dots on graphene oxide surfaces
摘要： The emerging materials of semiconductor quantum dots/graphene oxide (QDs/GO) hybrid composites have recently attracted intensive attention in materials science and technology due to their potential applications in electronic and photonic devices. Here, a simple and universal strategy to produce DNA-programmed semiconductor quantum dots/graphene oxide (QDs/GO) hybrid composites with controllable sizes, shapes, compositions, and surface properties is reported. This proof-of-concept work successfully demonstrates the use of sulfhydryl modi?ed single-stranded DNA (S-ssDNA) as a ‘universal glue’ which can adsorb onto GO easily and provide the growth sites to synthesize CdS QDs, CdSe QDs, CdTe QDs and CdTeSe QDs with distinctive sizes, shapes and properties. Also, adapting this method, other graphene oxide-based hybrid materials which are easily synthesized in aqueous solution, including oxides, core–shell structure QDs and metal nanocrystals, would be possible. This method provided a universal strategy for the synthesis and functional realization of graphene -based nanomaterials.
关键词： quantum dots/graphene oxide,DNA,two-dimensional materials,graphene -based nanomaterials
更新于2025-09-23 15:21:01
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Preparation of ZnO-carbon quantum dot composite thin films with superhydrophilic surface
摘要： Carbon quantum dots (CQDs)-ZnO composite thin films were prepared via ultrasonic mist vapour deposition (UMVD) method. The effect of different CQDs concentrations (C), substrate temperatures (Ts), nozzle-substrate distances and also post-annealing process on the thin film structure were considered and examined systematically. The effects of these parameters on optical, morphological and surface properties of the layers as well as their wettability were carefully investigated and discussed. It was found that for low Ts and short ‘d’, CQDs diffuse inside the layer during deposition and then were evaporated after annealing process making drastic changes in layer morphology and optical transmittance. On the other hand, for high Ts and long ‘d’, most of CQDs inside mist vapour drops are evaporated during deposition process. Therefore, the layer transmittance and morphology did not change notably after annealing. Interestingly, the layer prepared with C = 5 volume %, Ts = 470 °C and d = 9 cm was turned to super-hydrophilic surface after annealing process with contact angle of , 3o. Such a super-hydrophilic CQDS-ZnO thin film is highly beneficial for a wide range of applications which high wettability is required.
关键词： mist vapour deposition,super-hydrophilic,ZnO thin film,Carbon quantum dots
更新于2025-09-23 15:21:01
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Paired electron motion in interacting chains of quantum dots
摘要： We study the motion of a pair of electrons along two separate parallel chains of quantum dots. The electrons that are released from the central dot of each chain tend to accompany and not avoid each other. The correlated electron motion involves entanglement of the wave functions which is generated in time upon release of the initial con?nement. Observation of the simultaneous presence of electrons at the same side of the chain can provide a ?ngerprint of the paired electron motion.
关键词： electron motion,correlated motion,quantum dots,entanglement
更新于2025-09-23 15:21:01
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valley of (In,Al)As/AlAs quantum dots
摘要： The electron-nuclei hyperfine interaction of electrons in indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment has been experimentally studied by measuring the polarization degree of the photoluminescence in a transverse magnetic field (Hanle effect) and the polarization recovery in a longitudinal magnetic field. The different symmetries of the X valley electron Bloch amplitudes at the As, In, and Al nuclei strongly affect the hyperfine interaction. The hyperfine constants corresponding to these nuclei have been determined.
关键词： X valley,hyperfine constants,Bloch amplitudes,Hanle effect,polarization recovery,photoluminescence,quantum dots,electron-nuclei hyperfine interaction
更新于2025-09-23 15:21:01
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Mercaptoalkanoic Acida??Induced Band Gap Attenuation of Copper Selenide Quantum Dot
摘要： Copper selenide quantum dot (CuSeQD) materials functionalised with mercaptoalkanoic acids {3-mercaptopropionic acid (3-MPA), 6-mercaptohexanoic acid (6-MHA) and mercaptosuccinic acid (MSA)} were synthesized by a reproducible aqueous colloidal technique at room temperature. The impact of the capping agents on the size and the crystallinity of the CuSeQD materials, were investigated by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) spectroscopic techniques, respectively. SAXS results confirmed that 6-MHA-CuSeQD had the smallest average particle core size when dried, whereas MSA-CuSeQD had the smallest size in aqueous solution, though with a tendency to aggregate. Dynamic light scattering (DLS) measurements indicated strong bonding of the capping agents to CuSe particles, with MSA being the weakest binding agent, confirmed by low Zeta potential(ζ = (cid:0) 31.1 mV) and high polydispersity index (0.469) values. UV-Vis absorption studies confirmed a large blue shift of the band gap for the QD compared to the bulk material, with characteristic absorption band (λ) and direct band gap (Egd) values being (λ = 435 nm, Egd = 5.6 eV) and (λ = 400 nm, Egd = 8.0 eV), (λ = 340 nm, Egd = 4.0 eV), for 6-MHA-CuSeQD, 3-MPA-CuSeQD and MSA-CuSeQD, respectively. As supported by the formal potential values for 6-MHA-CuSeQD (E0’ ? 120 mV), 3-MPA-CuSeQD (E0’ ? 159 mV) and MSA-CuSeQD (E0’ ? 183 mV), the smaller the particle size, the lower the potential required for the application of the quantum dots in an electron transfer process.
关键词： Cyclic Voltammetry,biocompatible,copper selenide,Aqueous synthesis,quantum dots
更新于2025-09-23 15:21:01
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Effect of Concentration on the Spectrala??Luminescent Properties of Quantum Dots in Colloidal Solutions
摘要： The effect the concentration of double-shell CdSe/CdS/ZnS semiconductor colloidal quantum dots has on the measured parameters of the absorption and luminescence spectra of a solutions of these quantum dots in toluene is studied via optical spectroscopy. Possible mechanisms of the effect the concentration of quantum dots in the solutions has on the characteristics of the luminescence spectra are analyzed.
关键词： optical spectroscopy,colloidal solutions,concentration,quantum dots,spectral-luminescent properties
更新于2025-09-23 15:21:01
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Graphene Quantum Dots with High Yield and High Quality Synthesized from Low Cost Precursor of Aphanitic Graphite
摘要： It is di?cult to keep the balance of high quality and high yield for graphene quantum dots (GQDs). Because the quality is uncontrollable during cutting large 2D nanosheets to small 0D nanodots by top-down methods and the yield is low for GQDs with high quality obtained from bottom-up strategy. Here, aphanitic graphite (AG), a low-cost graphite contains a large amount of small graphite nanocrystals with size of about 10 nm is used as the precursor of graphene oxide quantum dots (GO-QDs) for the ?rst time. GO-QDs with high yield and high quality were successfully obtained directly by liquid phase exfoliating AG without high strength cutting. The yield of these GO-QDs can reach up to 40 wt. %, much higher than that obtained from ?ake graphite (FG) precursor (less than 10 wt. %). The size of GO-QDs can be controlled in 2–10 nm. The average thickness of GO-QDs is about 3 nm, less than 3 layer of graphene sheet. Graphene quantum dots (GQDs) with di?erent surface properties can be easily obtained by simple hydrothermal treatment of GO-QDs, which can be used as highly e?cient ?uorescent probe. Developing AG as precursor for GQDs o?ers a way to produce GQDs in a low-cost, highly e?ective and scalable manner.
关键词： high yield,high quality,low cost precursor,aphanitic graphite,graphene quantum dots
更新于2025-09-23 15:21:01