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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) - Interaction of Topological States of Sounds and Light with Solid-State Emitters as a Quantum Hybrid Platform
摘要： A large set of physically different platforms are still in the race, as promising quantum systems, to perform efficient quantum information processing. Each of them offer particular figures of merit and weaknesses. An important paradigm for quantum computation is to consider hybrid systems where the strengths of different systems can be harvested while mitigating their weaknesses [1]. Meanwhile, increasing efforts are being devoted to topological phases of matter in bosonic systems to perform robust manipulation of quantum information, where topologically protected edge states can be utilized as quantum channels [2]. In this work, we propose a two-dimensional array of driven optomechanical nano-cavities coupled to Silicon-Vacancy (SiV) centres as a versatile quantum hybrid system where a rich set of topological phases for sound and light is present. More precisely, we consider the well-established snowflake architecture where strongly interacting photonic and acoustic modes can be localised in any crystalline arrangement on a free-standing micro-scale chip [3]. The novel element of this work is the addition of the nonlinear system in the SiV centres coupled to the cavities vibrational modes via strain-coupling [4]. Such defects play the role of highly tunable spin qubits that efficiently couple to the propagating acoustic modes within the array. The topological states of joint mechanical and optical modes (polaritons) can open channels for robust transport between distant SiV centres while offering a way to optically probe the dynamics during the transport. For example, regimes in which the acoustic and optical modes are weakly coupled allow the generation of chiral and robust phononic edge states where one could tune in time their coupling to the SiV defects, leading to a single-mode phononic network. In this case, we describe high-fidelity state transfer between distant centres for experimentally relevant parameter regimes. In addition to robust state transfer between distant qubits, we investigate the effects of the nonlinearity generated by the defects on the topological phases of the polaritonic modes. In this context, we describe the topological phases in different regimes of experimental relevance.
关键词： optomechanical nano-cavities,sound and light,solid-state emitters,quantum hybrid platform,Silicon-Vacancy centres,topological states
更新于2025-09-16 10:30:52
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Amorphous ZnO/PbS quantum dots heterojunction for efficient responsivity broadband photodetectors
摘要： The integration of lead sulfide quantum dots (QDs) with high conductivity material that is compatible with a scalable fabrication is an important route for the applications of QDs based photodetectors. Herein, we firstly developed a broadband photodetector by combining amorphous ZnO and PbS QDs forming a heterojunction structure. The photodetector showed detectivities up to 7.9x1012 jones and 4.1x1011 jones under 640 nm and 1310 nm illumination, respectively. The role of oxygen background pressure on the electronic structure of ZnO films grown by pulsed laser deposition was systematically studied, and it was found to play an important role on the conductivity, associated to the variation of oxygen vacancy concentration. By increasing the oxygen vacancy concentration, the electron mobility of amorphous ZnO layers dramatically increased and work function decreased, which were beneficial for the photocurrent enhancement of ZnO/PbS QDs photodetectors. Our results provide a simple and highly scalable approach to develop broadband photodetectors with high performance.
关键词： oxygen vacancy,amorphous ZnO,broadband photodetector,mobility,heterojunction
更新于2025-09-16 10:30:52
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Vacancy defect modulation in hot-casted NiO film for efficient inverted planar perovskite solar cell
摘要： Nickel oxide (NiOx) has exhibited great potential as an inorganic hole transport layer (HTL) in perovskite solar cells (PSCs) due to its wide optical bandgap and superior stability. In this study, we have modulated the Ni2+ vacancies in NiOx film by controlling deposition temperature in a hot-casting process, resulting the change of coordination structure and charge state of NiOx. Moreover, the change of the HOMO level of NiOx makes it more compatible with perovskite to decrease energy losses and enhance hole carrier injection efficiency. Besides, the defect modulation in the electronic structure of NiOx is beneficial for increasing the electrical conductivity and mobility, which are considered to achieve the balance of charge carrier transport and avoid charge accumulation at the interface between the perovskite and HTL effectively. Both experimental analyses and theoretical calculations reveal the increase of nickel vacancy defects change the electronic structure of NiOx by increasing the ratio of Ni3+/Ni2+ and improving the p-type characteristics. Accordingly, an optimal deposition temperature of the NiOx film at 120 °C enabled a 36.24% improvement in the power conversion efficiency compared to that deposited at room temperature (25 °C). Therefore, this work provides a facile method to manipulate the electronic structure of NiOx to improve the charge carrier transport and photovoltaic performance of related PSCs.
关键词： Electronic structure,Vacancy,Hole transport layer,Conductivity,Energy level,Mobility
更新于2025-09-16 10:30:52
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High-efficiency Posture Pre-alignment Method for Large Component Assembly via iGPS and Laser Ranging
摘要： A model for controlling the two-dimensional distribution of negatively charged nitrogen-vacancy (NV?) fluorescent centers near the surface of a diamond crystal is presented, using only a microwave plasma-assisted chemical vapor deposition (CVD) method. In this approach, a CVD diamond layer is homoepitaxialy grown via microwave plasma-assisted CVD using an isotopically enriched methane (12CH4 ), hydrogen (H2 ), and nitrogen (N2 ) gas mixture on patterned diamond (0 0 1). When the surface is imaged by means of confocal microscope photoluminescence mapping, fine grooves are observed to have been generated artificially on the diamond surface. NV? centers are found to be distributed selectively into these grooves. These results demonstrate an effective means for the formation of NV? centers of selectable size and density via microwave plasma-assisted CVD, with potential application in the production of diamond quantum sensors.
关键词： doping,nitrogen-vacancy centers,homoepitaxial,groove structure,Diamond,microwave plasma-assisted chemical vapor deposition
更新于2025-09-16 10:30:52
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Interfacial Lattice‐Strain‐Driven Generation of Oxygen Vacancies in an Aerobic‐Annealed TiO <sub/>2</sub> (B) Electrode
摘要： Oxygen vacancies play crucial roles in defining physical and chemical properties of materials to enhance the performances in electronics, solar cells, catalysis, sensors, and energy conversion and storage. Conventional approaches to incorporate oxygen defects mainly rely on reducing the oxygen partial pressure for the removal of product to change the equilibrium position. However, directly affecting reactants to shift the reaction toward generating oxygen vacancies is lacking and to fill this blank in synthetic methodology is very challenging. Here, a strategy is demonstrated to create oxygen vacancies through making the reaction energetically more favorable via applying interfacial strain on reactants by coating, using TiO2(B) as a model system. Geometrical phase analysis and density functional theory simulations verify that the formation energy of oxygen vacancies is largely decreased under external strain. Benefiting from these, the obtained oxygen-deficient TiO2(B) exhibits impressively high level of capacitive charge storage, e.g., ≈53% at 0.5 mV s?1, far surpassing the ≈31% of the unmodified counterpart. Meanwhile, the modified electrode shows significantly enhanced rate capability delivering a capacity of 112 mAh g?1 at 20 C (≈6.7 A g?1), ≈30% higher than air-annealed TiO2 and comparable to vacuum-calcined TiO2. This work heralds a new paradigm of mechanical manipulation of materials through interfacial control for rational defect engineering.
关键词： aerobic-annealing,oxygen vacancy,pseudocapacitive charge storage,lithium-ion batteries,interfacial lattice strain
更新于2025-09-12 10:27:22
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Quantitative Mapping of the Charge Density in a Monolayer of MoS <sub/>2</sub> at Atomic Resolution by Off-Axis Electron Holography
摘要： The electric potential, electric field and charge density of a monolayer of MoS2 has been quantitatively measured at atomic scale resolution. This has been performed by off-axis electron holography using a double aberration-corrected transmission electron microscope operated at 80 kV and a low electron beam current density. Using this low dose rate and acceleration voltage, the specimen damage is limited during imaging. In order to improve the sensitivity of the measurement, series of holograms have been acquired. Instabilities of the microscope such as the drifts of the specimen, biprism and optical aberrations during the acquisition have been corrected by data processing. Phase images of the MoS2 monolayer have been acquired with a sensitivity of 2π/698 rad associated to a spatial resolution of 2.4 ?. The improvement in the signal-to-noise ratio allows the charge density to be directly calculated from the phase images using Poisson’s equation. Density functional theory simulations of the potential and charge density of this MoS2 monolayer were performed for comparison to the experiment. The experimental measurements and simulations are consistent with each other and notably, the charge density in a sulphur mono-vacancy (VS) site is shown.
关键词： MoS2,high-resolution,charge density,electric potential,electric field,electron holography,sulphur vacancy
更新于2025-09-12 10:27:22
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Oxygen non-stoichiometry in TiO2 and ZnO nano rods: Effect on the photovoltaic properties of dye and Sb2S3 sensitized solar cells
摘要： Rutile TiO2 (TiO2-NR) and ZnO (ZnO-NR) in nanorod microstructural forms are synthesized by hydrothermal route. The oxides are grown directly on fluorine doped SnO2 coated glass, and annealed in air (AA) and hydrogen (HA) atmosphere for 3 h at 450 °C. A detailed structural, optical, and microstructural study confirms the phase formation in the AA and stability in HA samples. EPR signal with g-values of ~1.99 and ~1.95 from TiO2-NR and ZnO-NR photoanodes respectively confirms the presence of oxygen vacancy (OV) related defects. The EPR signals are stronger in TiO2-NR-HA compared to TiO2-NR-AA and is absent in ZnO-NR-AA suggesting increased defect concentration on hydrogenation. Further this leads to two order increase in photoconductivity for hydrogenated TiO2-NR-HA and ZnO-NR-HA photoanodes when measured under 1 Sun illumination compared to AA photoanodes. Photovoltaic power conversion efficiency for both dye and Sb2S3 sensitized solar cells are found to increase by 2 to 3 times in hydrogenated ZnO-NR. In contrast, TiO2-NR show two-fold decrease in efficiency on hydrogenation. The efficiency change is consistent with the change in interface impedance, which increases for dye or Sb2S3 sensitized TiO2-NR-HA photoanode, whereas, decreases for sensitized ZnO-NR-HA photoanode. These studies show that despite of one to two to three order increase in photoconductivity, the sensitizer/photoanode interface impedance play a significant role in deciding the efficiency.
关键词： Oxygen vacancy,Nanorod,Photoanode,Efficiency,ZnO,Solar cell,TiO2
更新于2025-09-12 10:27:22
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Evidence for vacancy trapping in Au-hyperdoped Si following pulsed laser melting
摘要： Nanosecond pulsed laser melting can be used to rapidly recrystallize ion-implanted Si through liquid phase epitaxy. The rapid resolidification that follows the melting results in a supersaturation of impurities and hyperdopes the Si, inducing novel optoelectronic properties with a wide range of applications. In this work, structural changes in the Si lattice in Au-hyperdoped Si are studied in detail. Specifically, we show that the local skewing of the lattice observed previously in regions of extremely high Au concentrations (>1.4 at. %) can be related to the displacement of Au from perfect lattice positions. Surprisingly, although the incorporation of the larger Au atoms into Si is expected to cause swelling of the lattice, reciprocal space mapping shows that a small amount (0.3 at. %) of lattice contraction (decrease in lattice parameter) is present in the hyperdoped layer. Furthermore, positron annihilation spectroscopy shows an elevated concentration of vacancies in the hyperdoped layer. Based on these observations and with the aid of density functional theory, we propose a phenomenological model in which vacancies are kinetically trapped into lattice sites around substitutional Au atoms during resolidification. This vacancy trapping process is hypothesized to occur as a means to minimize lattice strain and may be universal in pulsed laser melted Si systems.
关键词： vacancy trapping,lattice contraction,positron annihilation spectroscopy,density functional theory,pulsed laser melting,Au-hyperdoped Si
更新于2025-09-12 10:27:22
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Hybrid spin-superconducting quantum circuit mediated by deterministically prepared entangled photonic states
摘要： In hybrid quantum systems, a controllable coupling can be obtained by mediating the interactions with dynamically introduced photons. We propose a hybrid quantum architecture consisting of two nitrogen vacancy center ensembles coupled to a tunable flux qubit, which is contained on the transmission line of a multimode nonlinear superconducting coplanar waveguide resonator with an appended Josephson mixing device. We discuss the use of entangled propagating microwaves photons, which through our nonlinear wave-mixing procedure are made into macroscopically distinct quantum states. We use these states to steer the system and show that, with further amplification, we can create a similar photonic state, which has a more distinct reduction of its uncertainty. Furthermore, we show that all of this leads to a lengthened coherence time, a reasonable fidelity that decays to 0.94 and then later increases upward to stabilize at 0.6, as well as a strengthened entanglement.
关键词： squeezed Schr?dinger cat state,entangled microwaves photons,Schr?dinger cat state,flux qubit,nitrogen vacancy center ensembles,superconducting coplanar waveguide resonator,hybrid quantum systems
更新于2025-09-12 10:27:22
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First-principle study of SO2 adsorption on Fe/Co-doped vacancy defected single-walled (8, 0) carbon nanotubes in sensor applications
摘要： To explore the excellent sensor for detecting the pollution gas SO2, the adsorptions of SO2 molecule on the surfaces of Fe/Co-doped carbon nanotubes (CNTs) and single vacancy defected (8, 0) CNTs were investigated by using density functional theory (DFT). In addition, the adsorption energies, geometries, energy gaps and electronic structures were analyzed. The results showed that Fe/Co-doping and single-vacancy-defected can improve the adsorption and sensitiveness of CNTs toward SO2. Considering the changes of energy gap before and after the SO2 molecule adsorbed on each modiˉed CNTs and its adsorption strength, Fe-doped CNTs (Fe-CNTs) and Co-doped site-2 single-vacancy-defected CNTs performed better for detecting SO2 molecule. With the decreasing number of electrons of the doped atom (Fe, Co, Ni), the adsorption became more stable. The results of this paper are profound and meaningful for designing SO2 sensing devices.
关键词： SO2,adsorption,carbon nanotubes,co-doping,vacancy,Fe-doping
更新于2025-09-12 10:27:22