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Optical Fredkin gate assisted by quantum dot within optical cavity under vacuum noise and sideband leakage
摘要： We propose a deterministic fredkin gate which can accomplish controlled-swap operation between three-qubit states. the proposed fredkin gate consists of a photonic system (single photon) and quantum dots (QDs) confined in single-sided cavities (two electron spin states). In our scheme, the control qubit is the polarization state of the single photon, and two electron spin states in QDs play the role of target qubits (swapped states by control qubit). the interaction between a photon and an electron of QD within the cavity (QD-cavity system) significantly affects the performance of Fredkin gate. Thus, through the analysis of the QD-cavity system under vacuum noise and sideband leakage, we demonstrate that reliable interaction and performance of the QD-cavity system with photonic state (photon) can be acquired in our scheme. Consequently, the Fredkin gate proposed in this paper can be experimentally implemented with high feasibility and efficiency.
关键词： quantum dot,Fredkin gate,sideband leakage,optical cavity,vacuum noise
更新于2025-09-23 15:19:57
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CdS quantum dots modified surface oxygen vacancy defect ZnO1-x-TiO2-x solid solution sphere as Z-Scheme heterojunctions for efficient visible light-driven photothermal-photocatalytic performance
摘要： CdS quantum dots (QDs) modified surface oxygen vacancy defect ZnO1-x-TiO2-x solid solution spheres were prepared by using a hydrothermal, chemical reduction and electroless plating strategy, which have sufficient negative conduction band potential while having a photoresponse in visible light region. According to the band energy alignment, Z-scheme structure is formed, which favors spatial charge separation. The obtained CdS QDs/ZnO1-x-TiO2-x heterojunctions with the gap of ~2.09 eV exhibit excellent photothermal performance and photocatalytic degradation of bisphenol A (~99.5%), 2,6-dichlorophenol (~99.1%), and 2,4,5-trichlorophenol (~98.9%). It can be attributed to the following reasons: (1) a solid solution strategy can be used to enhance the photocatalytic activity of a given semiconductor photocatalyst. (2) The presence of oxygen defects can extend the photoresponse to visible light region. (3) TiO2-x-ZnO1-x and CdS QDs can form Z-Scheme heterojunctions to increase the spatial separation of photogenerated electron-holes, which can promote photocatalytic performance. After recycle test, the resultant catalysts show high stability, which has superiority in practical application. So this novel CdS QDs modified surface oxygen vacancy defect ZnO1-x-TiO2-x solid solution sphere will have potential applications in environmental fields.
关键词： Photothermal-photocatalytic,Solid solution,Oxygen vacancy defect,Z-Scheme heterojunction,Quantum dot
更新于2025-09-23 15:19:57
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Enhanced efficiency of quantum dot light-emitting diode by sol-gel derived Zn1-xMgxO electron transport layer
摘要： In this study, sol-gel derived Zn1-xMgxO (ZMO) is proposed as an electron transport layer (ETL) for solution-processed quantum-dot light-emitting diodes (QLEDs). It is demonstrated that the increase of Mg content in Zn1-xMgxO films from 0% to 20% causes a dramatic suppression of electron current, which is attributed to the lifting of conduction band minimum and reduction of electron mobility. As a result of Mg-doping, the charge carrier balance might be achieved in the QLED with the Zn0.85Mg0.15O layer resulting in maximum external quantum efficiency of 5.74% and current efficiency of 18 cd·A-1, which are over 3-fold higher than in the case of the device with ZnO layer. Improved device performance is further explained by reduced exciton quenching at QDs/ZMO interface, which is confirmed by time-resolved PL experiments. Obtained results indicate that sol-gel derived ZMO is a promising candidate for ETL in quantum-dot based optoelectronic devices.
关键词： quantum dot,doped zinc oxide,sol-gel process,light-emitting diode,electron transport layer
更新于2025-09-23 15:19:57
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Solution-processed blue quantum-dot light-emitting diodes based on double hole transport layers: Charge injection balance, solvent erosion control and performance improvement
摘要： Solution processed quantum-dot based light emitting diodes (QLEDs) usually suffer from the issues of imbalanced carrier injection (especially for blue QLEDs) and solvent erosion, which prevents these devices from reaching high performance. Here we report a simple and effective method of promoting hole injection and mitigating solvent erosion simultaneously for fabricating high-performance blue QLEDs. Poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(p-butylphenyl))-diphenylamine)] (TFB)/Lithium bis(trifluoromethanesulfonimide) (Li-TFSI)-doped poly(9-vinlycarbazole) (PVK) bi-layers with smooth surfaces/interfaces, prepared via a solution-process by utilizing 1,4-dioxane as the solvent for PVK, were used as hole transport layers (HTLs) for improving the performance of blue QLEDs. The TFB/Li-doped PVK based QLED records 5829 cd/m2 of maximum brightness and 5.37% of peak EQE, which represents 1.1-fold increase in brightness and ~11.5-fold increase in EQE as compared with the devices based on TFB-only HTLs. The enhanced performance for these TFB/Li-doped PVK based QLEDs can be ascribed to more efficient hole injection offered by Li-doped bilayer HTLs with smooth surfaces/interfaces and stepwise energy level alignment. The CIE 1931 color coordinates (0.15, 0.03) for these TFB/Li-doped PVK based QLEDs are close to the National Television System Committee (NTSC) standard blue CIE coordinates, showing promise for use in next-generation full-color displays. This work provides a facile solution method of fabricating TFB/Li-doped PVK bi-layers with smooth surfaces/interfaces and proves the superiority of these TFB/Li-doped PVK bi-layered HTLs in hole transport and injection for high-performance blue QLEDs.
关键词： double hole transport layers,blue quantum-dot light-emitting diodes,charge injection；Lithium salt doped hole transport layer,solvent erosion,solution processability
更新于2025-09-23 15:19:57
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Influence of Group Modification at the Edges of Carbon Quantum Dots on Fluorescent Emission
摘要： We present a detailed investigation on the effect of functional group modulation at the edges of carbon quantum dots (CQDs) on the fluorescence from the CQDs. The CQDs attached by N, S, and P elements are synthesized via pyrolysis of a mixture of citric acid and NH3H2O, H2SO4, and H3PO4, respectively. Thus, part of –COOH at the edges of CQDs can be converted into –C=O and functional groups such as –NH2, –SO2, –HSO3, and –H2PO4 can connect to the carbon bonds. We find that the formation of the N/S/P-CQDs can reduce the amount of –COOH that attaches to the edges of sp2-conjugated π-domains located at centers of these CQDs. This effect can result in the reduction of the non-radiative recombination for electronic transition in these CQDs. As a result, the quantum yield (QY) for fluorescence from the CQDs can be efficiently enhanced. We demonstrate experimentally that the QYs for N/S/P-CQDs can reach up to 18.7%, 29.7%, and 10.3%, respectively, in comparison to 9% for these without functional group modulation. This work can provide a practical experimental approach in improving the optical properties of fluorescent CQDs.
关键词： Functional group modulation,Carbon quantum dot,Fluorescent emission
更新于2025-09-23 15:19:57
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Immunochromatographic assay for melamine based on luminescent quantum dot beads as signaling probes
摘要： To screen and detect the harmful substance melamine (MEL), a quantum-dot-bead-based immunochromatographic assay (QB-ICA) was formulated. After optimization, calibration was performed within the linear range from 0.06 to 0.28 ng mL?1, with limit of detection (LOD) of 0.04 ng mL?1. The LOD was 35 times lower than that of ICA that used colloidal gold nanoparticles (LOD ? 1.4 ng mL?1) and 40 times lower than that of the assay based on quantum dots (LOD ? 1.6 ng mL?1). In the detection of MEL in spiked pure milk using the proposed QB-ICA strategy, the LOD (LOD ? 0.19 ng mL?1) of the samples with the proposed pretreatment was 18.4 times lower than those of the samples without pretreatment (LOD ? 3.5 ng mL?1). The performance and practicability of the proposed QB-ICA system was validated; the obtained results reveal that QB-ICA is comparable with the conventional enzyme-linked immunosorbent assay (ELISA) method, but with enhanced applicability. Given its high sensitivity and practicability, the QB-ICA strategy could become a worthwhile alternative for the rapid, sensitive, and quantitative onsite detection of harmful substances, facilitating food safety monitoring.
关键词： melamine,quantum-dot-bead-based immunochromatographic assay,sensitivity,rapid detection,food safety
更新于2025-09-23 15:19:57
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Photon-Assisted Heat Generation by Electric Current in a Quantum Dot Attached to Ferromagnetic Leads
摘要： Heat generated by electric current in a quantum dot device contacting a phonon bath is studied using the non-equilibrium Green function technique. Spin-polarized current is generated owing to the Zeeman splitting of the dot level. The current’s strength and the spin polarization are further manipulated by changing the frequency of an applied photon field and the ferromagnetism on the leads. We find that the associated heat by this spin-polarized current emerges even if the bias voltage is smaller than the phonon energy quanta and obvious negative differential of the heat generation develops when the photon frequency exceeds that of the phonon. It is also found that both the strength and the resonant peaks’ position of the heat generation can be tuned by changing the value and the arrangement configurations of the magnetic moments of the two leads, and then provides an effective method to generate large spin-polarized current with weak heat. Such a result may be useful in designing low energy consumption spintronic devices.
关键词： quantum dot,heat generation,ferromagnetic leads,photon-assisted tunneling,spin-polarized current
更新于2025-09-23 15:19:57
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Study of nanometer-scale structures and electrostatic properties of InAs quantum dots decorating GaAs/AlAs core/shell nanowires
摘要： The configurations of core/shell nanowires (NWs) and quantum dots (QDs) decorating NWs have found great applications in forming optoelectronic devices thanks to their superior performances, and the combination of the two configurations would expect to bring more benefits. However, the nanometer-scale electrostatic properties of the QD/buffer layer/NW heterostructures are still un-revealed. In this study, the InAs QDs decorating GaAs/AlAs core/shell NWs are systemically studied both experimentally and theoretically. The layered atomic structures, chemical information, and anisotropic strain conditions are characterized by comprehensive transmission electron microscopy (TEM) techniques. Quantitative electron holography analyses show large number of electrons accumulating in the InAs QD especially at the dot apex, and charges of reversed signs and similar densities are observed to distribute at the sequential interfaces, leaving great amount of holes in the NW core. Theoretical calculations including simulated heterostructural band structures, interfacial charge transfer, and chemical bonding analysis are in good accordance with the experimental results, and prove the important role of AlAs buffer layer in adjusting the heterostructural band structure as well as forming stable InAs QDs on the NW surfaces. These results could be significant for achieving related optoelectronic devices with better stability and higher efficiency.
关键词： quantum dot,transmission electron microscopy,atomic structure,core/shell nanowire,electrostatic property
更新于2025-09-23 15:19:57
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CdTe and CdTe@ZnS quantum dots induce IL-1??-mediated inflammation and pyroptosis in microglia
摘要： CdTe quantum dots (QDs) are still widely considered as excellent fluorescent probes because of their far more superior optical performance and fluorescence efficiency than non?cadmium QDs. Thus, it is important to find ways to control their toxicity. In this study, CdTe QDs and CdTe@ZnS QDs both could cause IL-1?-mediated inflammation following with pyroptosis in BV2 cells, but the toxic effects caused by CdTe@ZnS QDs was weaker than CdTe QDs, which demonstrated the partial protection of ZnS shell. When investigating the molecular mechanisms of QDs causing the inflammatory injury, the findings suggested that cadmium-containing QDs exposure activated NF-κB that participated in the NLRP3 inflammasome priming and pro-IL-1? expression. After that, QDs-induced excessive ROS generation triggered the NLRP3 inflammasome activation and resulted in active caspase-1 to process pro-IL-1? into mature IL-1? release and inflammatory cell death, i.e. pyroptosis. Fortunately, the inhibitions of caspase-1, NF-κB and ROS or knocking down of NLRP3 all effectively attenuated the increases in the IL-1? secretion and cell death caused by QDs in BV2 cells. This study provided two methods to alleviate the toxicity of cadmium-containing QDs, in which one is to encapsulate bare-core QDs with a shell and the other is to inhibit their toxic pathways. Since the latter way is more effective than the former one, it is significant to evaluate QDs through a mechanism-based risk assessment to identify controllable toxic targets.
关键词： Interleukin-1?,Quantum dot,NLRP3 inflammasome,Pyroptosis,BV2 cells
更新于2025-09-23 15:19:57
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SiRNA-directed self-assembled quantum dot biosensor for simultaneous detection of multiple microRNAs at the single-particle level
摘要： MicroRNAs are essential post-transcriptional regulators and may act as the noninvasive biomarker for disease diagnosis. Sensitive and multiplexed detection of microRNAs may facilitate the accurate and early clinical diagnosis, but the available methods are usually compromised by using organic dyes as the signal probes, laborious chemical and enzymatic manipulations, and the complicated reaction schemes. Here we reported a siRNA-directed self-assembled quantum dot (QD) biosensor for facile and simultaneous detection of multiple microRNAs. In this biosensor, the binding of microRNA targets with corresponding QD nanoprobes leads to the formation of siRNA duplexes, which not only induces the spectrally resolved coding of microRNAs, but also facilitates the assembly of QDs:magnetic nanoparticle bioconjugates for the isolation and enrichment of target microRNAs. The disassembled QDs can be sensitively detected by single-molecule detection, enabling quantitatively sensing of microRNAs at the single-particle level. This biosensor employs only QDs as the signal reporters, which can simultaneously detect multiple microRNAs from the same sample and achieves femtomolar sensitivity and single-base mismatch selectivity without the involvement of any target labeling and amplification steps. Moreover, it can be successfully applied for simultaneous detection of circulating microRNAs in clinical serum samples, holding great potential in non-invasive early diagnosis and biomedical researches.
关键词： Quantum dot,SiRNA,Fluorescent biosensor,MicroRNA,Single-particle detection
更新于2025-09-23 15:19:57