共查询到20条相似文献，搜索用时 15 毫秒
1.
Lucas Bremer Sarah Fischbach Suk‐In Park Sven Rodt Jin‐Dong Song Tobias Heindel Stephan Reitzenstein 《Advanced Quantum Technologies》2020,3(2)
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. 相似文献
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Julian Maisch Hüseyin Vural Michael Jetter Peter Michler Ilja Gerhardt Simone Luca Portalupi 《Advanced Quantum Technologies》2020,3(2)
Full control of single photons is important in quantum information and quantum networking. In particular, controlling the photon–atom interaction can be an appealing means to realize more complex quantum experiments. As a matter of example, the storage of photons into atomic media represents one key approach to memory‐assisted quantum communication and computing. Here it is shown that the propagation of single photons from a semiconductor quantum dot can be deliberately controlled by an atomic vapor under the application of an external magnetic field. The present results enable the use of an atomic vapor as a precise and reliable wavelength selective delay and allows for routing the single photons according to their polarization and the external magnetic field. With an overall delay of 25 ns, it is possible to fine‐tune the arrival time of the photons by more than 600 ps which matches the scale of the quantum dot's lifetime. The experimental data are fully reproduced by a theoretical model. 相似文献
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Khaled Mnaymneh Dan Dalacu Joseph McKee Jean Lapointe Sofiane Haffouz John F. Weber David B. Northeast Philip J. Poole Geof C. Aers Robin L. Williams 《Advanced Quantum Technologies》2020,3(2)
A method to integrate nanowire‐based quantum dot single photon sources on‐chip using evanescent coupling is demonstrated. By deterministically placing an appropriately tapered III‐V nanowire, containing a single quantum dot, on top of a silicon‐based ridge waveguide, the quantum dot emission directed toward the taper can be transferred to the ridge waveguide with calculated efficiencies close to 100%. As the evanescent coupling is bidirectional, the source can be optically pumped in both free‐space and through the ridge waveguide. The latter configuration paves the way toward a self‐contained, all‐fiber, plug‐and‐play solution for applications requiring a bright on‐demand single photon source. Using InAsP quantum dots embedded in InP nanowire waveguides, coupling efficiencies to a SiN ridge waveguide of 74% with a single photon purity of 97% are demonstrated. The technique to demonstrate deterministic placement of single quantum emitters onto pre‐fabricated waveguides is used, an important step toward the fabrication of complex quantum photonic circuits. 相似文献
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利用应力释放模型计算了 Zn Cd Se/Ga As间的临界厚度 ,并以该临界厚度为基础 ,用 MOVCD设备在Stranski-Krastanow (S-K)生长模式下 ,外延生长了 Zn Cd Se量子点。用原子力显微镜和光谱测量的方法研究了量子点的演化过程。随着时间的推移 ,量子点发生了两种变化 ,即 Ostwald熟化过程和量子点的生成过程。另外 ,量子点由尖塔状逐渐演化为圆顶状。这种形状的变化可以用晶体生长模型进行解释。通过分析量子点样品的发光光谱 ,发现了两种发光机制 ,一种是零维量子点激子的发光 ,另一种是二维激子的发光。随着量子点生长完毕与加盖层之间间隔时间的增加 ,零维激子对二维激子发光的比值增加 ,且发光峰位明显红移。这从另一方面验证了由原子力显微镜直接观测到的量子点的演化过程 相似文献
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Lingqiao Kong Yujin Ji Zhenzhen Dang Junqing Yan Ping Li Youyong Li Shengzhong Liu 《Advanced functional materials》2018,28(22)
Black phosphorus (BP) is an interesting two‐dimensional material with low‐cost and abundant metal‐free properties and is used as one cocatalyst for photocatalytic H2 production. However, the BP quantum dot (BPQD) is not studied. Herein, for the first time, BPQD is introduced as a hole‐migration cocatalyst of layered g‐C3N4 for visible‐light‐driven photocatalytic hydrogen generation. A high‐vacuum stirring method is developed for BPQD loading without the dissociation of BP. The layered BPQD is coupled on the layered g‐C3N4 surface to form a heterojunction structure. The 7% BPQD–C3N4 samples show similar time‐resolved photoluminescence curves as 0.5% Pt–C3N4. The optimum hydrogen rates of the modified sample (7% BPQD–C3N4) are 190, 133, 90, and 10.4 µmol h?1 under simulated sunlight, LED‐405, LED‐420, and LED‐550 nm irradiation, respectively, which are 3.5, 3.6, and 3 times larger than that of the pristine g‐C3N4. Such low‐cost layered system not only optimizes the optical, electrical, and texture properties of the hybrid materials for photocatalytic water splitting to generate hydrogen but also provides ideas for designing novel or easily oxidized candidates by incorporating different available materials with given carriers. 相似文献
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Xin Zhou Imgon Hwang Ondřej Tomanec Dominik Fehn Anca Mazare Radek Zboril Karsten Meyer Patrik Schmuki 《Advanced functional materials》2021,31(30):2102843
Single atom (SA) catalysis, over the last 10 years, has become a forefront in heterogeneous catalysis, electrocatalysis, and most recently also in photocatalysis. Most crucial when engineering a SA catalyst/support system is the creation of defined anchoring points on the support surface to stabilize reactive SA sites. Here, a so far unexplored but evidently very effective approach to trap and stabilize SAs on a broadly used photocatalyst platform is introduced. In self-organized anodic TiO2 nanotubes, a high degree of stress is incorporated in the amorphous oxide during nanotube growth. During crystallization (by thermal annealing), this leads to a high density of Ti3+-Ov surface defects that are hardly present in other common titania nanostructures (as nanoparticles). These defects are highly effective for SA iridium trapping. Thus a SA-Ir photocatalyst with a higher photocatalytic activity than for any classic co-catalyst arrangement on the semiconductive substrate is obtained. Hence, a tool for SA trapping on titania-based back-contacted platforms is provided for wide application in electrochemistry and photoelectrochemistry. Moreover, it is shown that stably trapped SAs provide virtually all photocatalytic reactivity, with turnover frequencies in the order of 4 × 106 h−1 in spite of representing only a small fraction of the initially loaded SAs. 相似文献
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Rui Tang Shujie Zhou Caixia Li Ran Chen Luyuan Zhang Zhiwei Zhang Longwei Yin 《Advanced functional materials》2020,30(19)
MXene materials have attracted increasing attention in electrochemical energy‐storage applications while MXene also becomes photo‐active at the quantum dot scale, making it an alternative for solar‐energy‐conversion devices. A Janus‐structured cobalt‐nanoparticle‐coupled Ti3C2 MXene quantum dot (Co‐MQD) Schottky catalyst with tunable cobalt‐loading content serving as a photoelectrochemical water oxidation photoanode is demonstrated. The introduction of cobalt triggers concomitant surface‐plasmon effects and acts as a water oxidation center, enabling visible‐light harvesting capability and improving surface reaction kinetics. Most importantly, due to the rectifying effects of Co‐MQD Schottky junctions, photogenerated carrier separation/injection efficiency can be fundamentally facilitated. Specifically, Co‐MQD‐48 exhibits both superior photoelectrocatalysis (2.99 mA cm?2 at 1.23 V vs RHE) and charge migration performance (87.56%), which corresponds to 194% and 236% improvement compared with MQD. Furthermore, excellent photostability can be achieved with less than 6.6% loss for 10 h cycling reaction. This fills in gaps in MXene material research in photoelectrocatalysis and allows for the extension of MXene into optical‐related fields. 相似文献
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The effects of hydrogen incorporation in dilute nitride semiconductors, specifically GaAs1‐xNx, are discussed. The remarkable consequences of hydrogen irradiation include tuneable and reversible changes in the electronic, optical, structural, and electrical properties of these materials. The highly trapping‐limited diffusion of H atoms in dilute nitrides results in the formation of extremely sharp heterointerfaces between H‐containing and H‐free regions of the crystals. This, in turn, offers an unprecedented possibility to tailor the physical properties of a semiconductor chip in its growth plane with nanometer precision. A number of examples are presented and discussed. 相似文献
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Cameron Jennings Xiangyu Ma Thushan Wickramasinghe Matthew Doty Michael Scheibner Eric Stinaff Morgan Ware 《Advanced Quantum Technologies》2020,3(2)
Coupled quantum dots (CQDs) that consist of two InAs QDs stacked along the growth direction and separated by a relatively thin tunnel barrier have been the focus of extensive research efforts. The expansion of available states enabled by the formation of delocalized molecular wavefunctions in these systems has led to significant enhancement of the already substantial capabilities of single QD systems and have proven to be a fertile platform for studying light–matter interactions, from semi‐classical to purely quantum phenomena. Observations unique to CQDs, including tunable g‐factors and radiative lifetimes, in situ control of exchange interactions, coherent phonon effects, manipulation of multiple spins, and nondestructive spin readout, along with possibilities such as quantum‐to‐quantum transduction with error correction and multipartite entanglement, open new and exciting opportunities for CQD‐based photonic quantum technologies. This review is focused on recent CQD work, highlighting aspects where CQDs provide a unique advantage and with an emphasis on results relevant to photonic quantum technologies. 相似文献
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Jonathan Wyrick Xiqiao Wang Ranjit V. Kashid Pradeep Namboodiri Scott W. Schmucker Joseph A. Hagmann Keyi Liu Michael D. Stewart Curt A. Richter Garnett W. Bryant Richard M. Silver 《Advanced functional materials》2019,29(52)
Atomically precise fabrication has an important role to play in developing atom‐based electronic devices for use in quantum information processing, quantum materials research, and quantum sensing. Atom‐by‐atom fabrication has the potential to enable precise control over tunnel coupling, exchange coupling, on‐site charging energies, and other key properties of basic devices needed for solid‐state quantum computing and analog quantum simulation. Using hydrogen‐based scanning probe lithography, individual dopant atoms are deterministically placed relative to atomically aligned contacts and gates to build single electron transistors, single atom transistors, and gate‐controlled quantum sensing devices. The key steps required to fabricate and demonstrate the essential building blocks needed for spin selective initialization/readout and coherent quantum manipulation are described. 相似文献
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Zhiping Zeng Yibo Yan Jie Chen Ping Zan Qinghua Tian Peng Chen 《Advanced functional materials》2019,29(2)
MXene quantum dots (QDs) are emerging 0D nanomaterials. Here, a new heterostructure is developed based on a 1D photoactive semiconductor and a 0D MXene QD for improved photocatalytic reduction of CO2 into methanol. Specifically, Ti3C2 QDs are incorporated onto Cu2O nanowires (NWs) through a simple self‐assembly strategy. It is demonstrated that Ti3C2 QDs not only significantly improve the stability of Cu2O NWs but also greatly improve their photocatatlytic performance by enhancing charge transfer, charge transport, carrier density, light adsorption, as well as by decreasing band bending edge and charge recombination. The energy level diagram derived from both experimental measurements and theoretical calculations provide further insights of such hierarchical photocatalysis system. 相似文献
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Optoelectronic and photocatalytic properties of I–III–VI QDs: Bridging between traditional and emerging new QDs 
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下载免费PDF全文 Yanhong Liu Fenghua Li Hui Huang Baodong Mao Yang Liu Zhenhui Kang 《半导体学报》2020,41(9):091701-091701-13
Due to the quantum size effect and other unique photoelectric properties, quantum dots (QDs) have attracted tremendous interest in nanoscience, leading a lot of milestone works. Meantime, the scope and scientific connotation of QDs are constantly expanding, which demonstrated amazing development vitality. Besides the well-developed Cd-containing II–VI semiconductors, QDs of environmentally friendly I–III–VI (I = Cu, Ag; III = Ga, In; VI = S, Se) chalcogenides have been a hot spot in the QDs family, which are different from traditional II–VI QDs in terms of multi-composition, complex defect structure, synthetic chemistry and optical properties, bringing a series of new laws, new phenomena and new challenges. The composition of I–III–VI chalcogenides and their solid solutions can be adjusted within a very large range while the anion framework remains stable, giving them excellent capability of photoelectric property manipulation. The important features of I–III–VI QDs include wide-range bandgap tuning, large Stokes shift and long photoluminescence (PL) lifetime, which are crucial for biological, optoelectronic and energy applications. This is due to the coexistence of two or more metal cations leading to a large number of intrinsic defects within the crystal lattice also known as deep-donor-acceptor states, besides the commonly observed surface defects in all QDs. However, a profound understanding of their structure and optoelectronic properties remains a huge challenge with many key issues unclear. On one hand, the achievements and experience of traditional QD research are expected to provide vital value for further development of I–III–VI QDs. On the other hand, the understanding of the emerging new QDs, such as carbon and other 2D materials, are even more challenging because of the dramatically different composition and structure from II–VI semiconductors. For this, I–III–VI QDs, as a close relative to II–VI QDs but with much more complex composition and structure variation, provide a great opportunity as a gradual bridge to make up the big gap between traditional QDs and emerging new QDs, such as carbon dots. Here, we hope to compare the research progress of I–III–VI QDs and II–VI QDs, in an effort to comprehensively understand their structure, synthetic chemistry, optical electronic and photocatalytic properties. We further give insights on the key potential issues of I–III–VI QDs from the perspective of bridging between traditional QDs and emerging carbon dots, especially the profound principles behind synthetic chemistry, PL mechanism and optoelectronic applications. 相似文献
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Shunxing Li Dejian Chen Fengying Zheng Haifeng Zhou Shaoxiong Jiang Yijin Wu 《Advanced functional materials》2014,24(45):7133-7138
Here, a new class of quantum dots, that is, sulphur quantum dots (SQDs), which are synthesized by the phase interfacial reaction, is reported. The prepared SQDs are monodisperse with a narrow size distribution (average 1.6 nm in size), excellent aqueous dispersibility, ultrahigh photostability, and lowly toxicity. Because of abundant oxidized sulphur species on the surface of SQDs, the incorporation of TiO2 with SQDs results in a synergistic effect for the TiO2‐based photocatalysts offering more effective environmental applications. It is demonstrated that SQDs‐TiO2 nanocomposite can enhance the photocatalytic activity of producing hydrogen (enhancement factor for 191) in methanol‐water system. The SQDs also can used as fluorescent probe for highly selective quantitative detection Fe3+ in an aqueous solution contained various metal ions. 相似文献
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Xu Wang Lei Xu Yun Jiang Zhouyang Yin Christopher C. S. Chan Chaoyong Deng Robert A. Taylor 《半导体学报》2019,40(7):071906-071906-12
Single-photon emitters (SPEs) are one of the key components in quantum information applications. The ideal SPEs emit a single photon or a photon-pair on demand, with high purity and distinguishability. SPEs can also be integrated in photonic circuits for scalable quantum communication and quantum computer systems. Quantum dots made from III–V compounds such as InGaAs or GaN have been found to be particularly attractive SPE sources due to their well studied optical performance and state of the art industrial flexibility in fabrication and integration. Here, we review the optical and optoelectronic properties and growth methods of general SPEs. Subsequently, a brief summary of the latest advantages in III–V compound SPEs and the research progress achieved in the past few years will be discussed. We finally describe frontier challenges and conclude with the latest SPE fabrication science and technology that can open new possibilities for quantum information applications. 相似文献
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《Advanced functional materials》2018,28(13)
Anisotropic Ag2S‐edged Au‐triangular nanoprisms (TNPs) are constructed by controlling preferential overgrowth of Ag2S as plasmonic photocatalysts for hydrogen generation. Under visible and near‐infrared light irradiation, Ag2S‐edged Au‐TNPs exhibit almost fourfold higher efficiency (796 µmol h−1 g−1) than those of Ag2S‐covered Au‐TNPs (216 µmol h−1 g−1) and pure Au‐TNPs in hydrogen generation. A single‐particle photoluminescence study demonstrates that the plasmon‐induced hot electrons transfer from Au‐TNPs to Ag2S for hydrogen generation. Finite‐difference‐time‐domain simulations verify that the corners/edges of Au‐TNPs are high‐curvature sites with maximum electric field distributions facilitating hot electron generation and transfer. Therefore, Ag2S‐edged Au‐TNPs are efficient plasmonic photocatalyst with the desired configurations for charge separation boosting hydrogen generation. 相似文献
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Pawan Kumar Abdelrahman Askar Jiu Wang Soumyabrata Roy Srinivasu Kancharlapalli Xiyang Wang Varad Joshi Hangtian Hu Karthick Kannimuthu Dhwanil Trivedi Praveen Bollini Yimin A. Wu Pulickel M. Ajayan Michael M. Adachi Jinguang Hu Md Golam Kibria 《Advanced functional materials》2024,34(29):2313793
Many industrial processes such transesterification of fatty acid for biodiesel production, soap manufacturing and biosynthesis of ethanol generate glycerol as a major by-product that can be used to produce commodity chemicals. Photocatalytic transformation of glycerol is an enticing approach that can exclude the need of harsh oxidants and extraneous thermal energy. However, the product yield and selectivity remain poor due to low absorption and unsymmetrical site distribution on the catalyst surface. Herein, tellurium (Te) nanorods/nanosheets (TeNRs/NSs) wrapped potassium-doped carbon nitride (KCN) van der Waal (vdW) heterojunction (TeKCN) is designed to enhance charge separation and visible-NIR absorption. The iridium (Ir) single atom sites decoration on the TeKCN core-shell structure (TeKCNIr) promotes selective oxidation of glycerol to glyceraldehyde with a conversion of 45.6% and selectivity of 61.6% under AM1.5G irradiation. The catalytic selectivity can reach up to 88% under 450 nm monochromatic light. X-ray absorption spectroscopy (XAS) demonstrates the presence of undercoordinated IrN2O2 sites which improved catalytic selectivity for glycol oxidation. Band energies and computational calculations reveal faile charge transfer in the TeKCNIr heterostructure. EPR and scavenger tests discern that superoxide (O2•−) and hydroxyl (•OH) radicals are prime components driving glycerol oxidation. 相似文献