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The Enhanced Electrons and Holes Separation for Bi2MoO6/TiO2 Z-scheme Heterojunction by Ag Loading

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Journal of Wuhan University of Technology(Materials science) 2023年第5期38卷 996-1002页

作者：阮辰亮 WANG Wei 戴振翔郑赣鸿 school of physics and Materials science Anhui University school of physics and Optoeletronics Engineering Anhui University

The Bi2Mo O6/Ti O2and Bi2Mo O6/Ag/Ti O2composites were solvothermally synthesized and characterized by X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),and (high resolution)transmission electron microscopy ((HR)TEM).The Bi2Mo O6/Ti O2and Bi2Mo O6/Ag/Ti O2composites exhibited higher photocatalytic activity than pure Bi2Mo O6.100%of the Rh B dye molecules could be decomposed over Bi2Mo O6/Ag/Ti O2composite in 120 min.The enhanced photocatalytic activity of Bi2Mo O6/Ti O2and Bi2Mo O6/Ag/Ti O2composite was attributed to the efficient separation of photoinduced electrons and holes.The mechanism for the enhanced photocatalytic activity is discussed.

关键词： photocatalysis Ag heterojunction Bi 2 MoO 6 /TiO 2 photocatalytic activity

Morphology Study for GeV Emission of Nearby Supernova Remnant G332.5-5.6

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Research in Astronomy and Astrophysics 2024年第4期24卷 134-140页

作者： Ming-Hong Luo Qing-Wen Tang Xiu-Rong Mo Department of physics School of Physics and Materials ScienceNanchang UniversityNanchang 330031China

A spatial template is important to study nearby supernova remnants(SNRs).For SNR G332.5-5.6,we report a Gaussian disk with a radius of about 1°.06 to be a potential good spatial model in the γ-ray band.Employing this new Gaussian disk,its GeV lightcurve shows a significant variability of about seven sigma.The γ-ray observations of this SNR could be explained well either by a leptonic model or a hadronic model,in which a flat spectrum for the ejected electrons/protons is required.

关键词： ISM:supernova remnants gamma rays:ISM

Observation of Giant Topological Hall Effect in Room-Temperature Ferromagnet Cr_(0.82)Te

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Chinese physics Letters 2024年第6期41卷 128-140页

作者：苗伟婷甄伟立陆振王恒宁王杰牛群田明亮 Anhui Key Laboratory of Low-energy Quantum Materials and Devices High Magnetic Field LaboratoryHFIPSChinese Academy of SciencesHefei 230031China science Island Branch Graduate School of University of Science and Technology of ChinaHefei 230026China school of physics and Optoelectronic Engineering Anhui UniversityHefei 230601China

Novel magnetic materials with non-trivial magnetic structures have led to exotic magnetic transport properties and significantly promoted the development of spintronics in recent years.Among them is the Crx Tey family,the magnetism of which can persist above room temperature,thus providing an ideal system for potential spintronic applications.Here we report the synthesis of a new compound,Cr_(0.82)Te,which demonstrates a record-high topological Hall effect at room temperature in this family.Cr_(0.82)Te displays soft ferromagnetism below the Curie temperature of 340 K.The magnetic measurement shows an obvious magneto-crystalline anisotropy with the easy axis located in the ab plane.The anomalous Hall effect can be well explained by a dominating skew scattering mechanism.Intriguing,after removing the normal Hall effect and anomalous Hall effect,a topological Hall effect can be observed up to 300 K and reaches up to 1.14μΩ·cm at 10 K,which is superior to most topological magnetic structural materials.This giant topological Hall effect possibly originates from the noncoplanar spin configuration during the spin flop process.Our work extends a new Cr_(x)Te_(y)system with topological non-trivial magnetic structure and broad prospects for spintronics applications in the future.

关键词： mechanism. process. topological

An evolutionary ensemble learning for diagnosing COVID-19 via cough signals

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Intelligent Medicine 2023年第3期3卷 200-212页

作者： Mohammad Hassan Tayarani Najaran University of Hertfordshire school of physics Engineering and Computer science HatfieldUnited Kindom

Objective The spread of the COVID-19 disease has caused great concern around the world and detecting the positive cases is crucial in curbing the pandemic.One of the symptoms of the disease is the dry cough it causes.It has previously been shown that cough signals can be used to identify a variety of diseases including tuberculosis,asthma,etc.In this paper,we proposed an algorithm to diagnose the COVID-19 disease via cough signals.Methods The proposed algorithm was an ensemble scheme that consists of a number of base learners,where each base learner used a different feature extractor method,including statistical approaches and convolutional neural networks(CNNs)for automatic feature extraction.Features were extracted from the raw signal and some transforms performed it,including Fourier,wavelet,Hilbert-Huang,and short-term Fourier transforms.The outputs of these base-learners were aggregated via a weighted voting scheme,with the weights optimised via an evolutionary paradigm.This paper also proposed a memetic algorithm for training the CNNs in the base-learners,which combined the speed of gradient descent(GD)algorithms and global search space coverage of the evolutionary algorithms.Results Experiments were performed on the proposed algorithm and different rival algorithms which included a number of CNN architectures in the literature and generic machine learning algorithms.The results suggested that the proposed algorithm achieves better performance compared to the existing algorithms in diagnosing COVID-19 via cough signals.Conclusion COVID-19 may be diagnosed via cough signals and CNNs may be employed to process these signals and it may be further improved by the optimization of CNN architecture.

关键词： Optimization Evolutionary algorithms COVID-19

Low-Voltage IGZO Field-Effect Ultraviolet Photodiode

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Chinese physics Letters 2024年第6期41卷 156-161,I0001-I0003页

作者：宋双梁会力霍文星张广张永晖王绩梅增霞 Songshan Lake Materials Laboratory Dongguan 523808China Institute of physics Chinese Academy of SciencesBeijing 100190China College of physics Liaoning UniversityShenyang 110036China Department of Instruments science and Technology School of Precision Instrument and Opto-electronics EngineeringTianjin UniversityTianjin 300072China National Key Laboratory of Scattering and Radiation Beijing 100039China school of physics and Optoelectronic Engineering Shandong University of TechnologyZibo 255000China

In the era of Internet of Things(Io Ts),an energy-efficient ultraviolet(UV)photodetector(PD)is highly desirable considering the massive usage scenarios such as environmental sterilization,fire alarm and corona discharge monitoring.So far,common self-powered UV PDs are mainly based on metal-semiconductor heterostructures or p–n heterojunctions,where the limited intrinsic built-in electric field restricts further enhancement of the photoresponsivity.In this work,an extremely low-voltage field-effect UV PD is proposed using a gatedrain shorted amorphous IGZO(a-IGZO)thin film transistor(TFT)architecture.A combined investigation of the experimental measurements and technology computer-aided design(TCAD)simulations suggests that the reverse current(ⅠR)of field-effect diode(FED)is highly related with the threshold voltage(Vth)of the parental TFT,implying an enhancement-mode TFT is preferable to fabricate the field-effect UV PD with low dark current.Driven by a low bias of-0.1 V,decent UV response has been realized including large UV/visible(R_(300)/R_(550))rejection ratio(1.9×10^(3)),low dark current(1.15×10^(-12)A)as well as high photo-to-dark current ratio(PDCR,~10^(3))and responsivity(1.89 A/W).This field-effect photodiode provides a new platform to construct UV PDs with well-balanced photoresponse performance at a low bias,which is attractive for designs of large-scale smart sensor networks with high energy efficiency.

关键词： IGZO attractive ultraviolet

Collective radiance of giant atoms in non-Markovian regime

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science China(physics,Mechanics & Astronomy) 2023年第2期66卷 79-86页

作者： Qing-Yang Qiu Ying Wu Xin-You Lü school of physics Huazhong University of Science and TechnologyWuhan 430074China

We investigate the non-Markovian dynamics of two giant artificial atoms interacting with a continuum of bosonic modes in a onedimensional(1D) waveguide.Based on the diagrammatic method,we present the exact analytical solutions,which predict the rich phenomena of collective radiance.For the certain collective states,the decay rates are found to be far beyond that predicted in the the Dicke model and standard Markovian framework,which indicates the occurrence of super-superradiance.The superadiance-to-subradiance transition could be realized by adjusting the exchange symmetry of giant atoms.Moreover,there exist multiple bound states in continuum(BICs),with photons/phonons bouncing back and forth in the cavity-like geometries formed by the coupling points.The trapped photons/phonons in the BICs can also be re-released conveniently by changing the energy level splitting of giant atoms.The mechanism relies on the joint effects of the coherent time-delayed feedback and the interference between the coupling points of giant atoms.This work fundamentally broadens the fields of giant atom collective radiance by introducing non-Markovianity.It also paves the way for a clean analytical description of the nonlinear open quantum system with more complex retardation.

关键词： collective symmetry conveniently

Learning from crowds with robust support vector machines

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science China(Information sciences) 2023年第3期66卷 133-149页

作者： Wenjun YANG Chaoqun LI Liangxiao JIANG school of Mathematics and physics China University of Geosciences school of Computer science China University of Geosciences

Crowdsourcing system provides an easy way to obtain labeled training data. However, the labels provided by non-expert labelers often appear low quality. So in practice, each sample usually obtains a multiple label set from multiple different labelers. Learning-from-crowds(LFC) aims to design ground truth inference algorithms to infer the unknown true labels of data from multiple label sets. Despite their proper statistical foundations, the existing ground truth inference algorithms show limited performance when the number of labelers is small. However, more labelers mean higher costs. This paper tries to propose a novel ground truth inference algorithm which can maintain moderate performance and simultaneously reduce labeling costs. This paper addresses LFC from a point of view of robust classifiers and presents a new label noise robust support vector machine inference(RSVMI) algorithm. We prove that only one convex quadratic programming problem needs to be solved to build a robust support vector machine. Furthermore,in order to apply the robust support vector machine to crowdsourced data, two methods are proposed to estimate the noise level of integrated labels. By transforming the original LFC problem into a robust classifier learning problem, our algorithm shows good performance when the number of labelers is very small. In our experiments, the minimum number of labelers is set to 3. In terms of both label quality and model quality,the experimental results on benchmark data sets and real-world data sets show the effectiveness of RSVMI.

关键词： crowdsourcing learning ground truth inference integrated labels label noise robust support vector machines

Effects of cross-Kerr coupling on transmission spectrum of double-cavity optomechanical system

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Chinese physics B 2024年第6期33卷 390-396页

作者：陈立滕秦立国田立君黄接辉周南润龚尚庆 school of Mathematics Physics and StatisticsShanghai University of Engineering ScienceShanghai 201620China Department of physics Shanghai UniversityShanghai 200444China school of Electrical Engineering Shanghai University of Engineering ScienceShanghai 201620China school of physics East China University of Science and TechnologyShanghai 200237China

We theoretically study the transmission spectrum of the cavity field in a double-cavity optomechanical system with cross-Kerr(CK) effect. The system consists of two tunneling coupling optomechanical cavities with a mechanical resonator as a coupling interface. By doping CK medium into the mechanical resonator, CK couplings between the cavity fields and the mechanical resonator are introduced. We investigate the effects of CK coupling strength on the transmission spectrum of the cavity field, including the transmission rate, nonreciprocity and four-wave mixing(FWM). We find that the transmission spectrum of the probe field can show two obvious transparent windows, which can be widened by increasing the CK coupling strength. For the transmission between the two cavity fields, the perfect nonreciprocity and reciprocity are present and modulated by CK coupling and phase difference between two effective optomechanical couplings. In addition, the effects of the optomechanical and CK couplings on FWM show that the single peak of FWM is split into three symmetrical peaks due to the introduction of the CK effect.

关键词： cross-Kerr transmission rate nonreciprocity four-wave mixing

Dynamical switchable quantum nonreciprocity induced by off-resonant chiral two-photon driving

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science China(physics,Mechanics & Astronomy) 2024年第6期67卷 31-37页

作者： Da-Wei Liu Zi-Hao Li Shi-Lei Chao Ying Wu Liu-Gang Si school of physics and Institute for Quantum science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

Optical nonreciprocity,which refers to the direction-dependent emission,scattering and absorption of photons,plays a very important role in quantum engineering and quantum information processing.Here,we propose an all-optical approach to achieve the optical dynamical switchable quantum nonreciprocity by an off-resonant chiral two-photon driving in a single microring cavity,which differs from the conventional nonreciprocal schemes.It is shown that the optical field with time-dependent statistical properties can be generated and the nonreciprocity flips periodically,with switchable photon blockade and photon-induced tunneling effects.We find that the dynamical system is robust and immune to the parameter variations,which loosens the parameter range of system.Meanwhile,the time window for one-way quantum information is sufficiently wide and tunable.Our work opens a new idea for the current quantum nonreciprocal research,which can facilitate a memory functionality and be used for future inmemory superconducting quantum compute.The other nonreciprocal quantum devices,i.e.,dynamical switchable nonreciprocal squeezing and entanglement,may be inspired by our method,which is expected to have important applications in future quantum technology.

关键词： dynamical switchable nonreciprocity single-photon source chiral two-photon driving