分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The past decade has witnessed a booming development of topological photonics, which revolutionizes the methodology for controlling the behavior of light. A gigantic achievement is to engineer robust confined modes localized at interfaces between topologically distinct regions, where the optical context can trigger exotic topological phenomena exclusive to photons. Here, we provide an experimentally flexible approach to engineering topologically induced interface states in the visible regime via a unique design of complex superlattice formed by connecting two component superlattices of distinguished topological phases. Assisted by the intrinsic pseudospin degree due to the splitting between TM and TE polarized modes, we attain a precise manipulation of the spin-dependent topological interface states that can manifest themselves straightforwardly through transmission spectra. More specifically, since these topological localized modes stem from the hybridization of artificial photonic orbitals that are of topological origin as well, they are deemed as a novel topological effect and thus named as the secondary topological interface states. Our work develops an innovative and productive strategy to tune topologically protected localized modes, based on which various applications such as selective local enhancement can be exploited.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Suppressing the interference of atmospheric turbulence and obtaining observation data with a high spatial resolution is an issue to be solved urgently for ground observations. One way to solve this problem is to perform a statistical reconstruction of short-exposure speckle images. Combining the rapidity of Shift-Add and the accuracy of speckle masking, this paper proposes a novel reconstruction algorithm-NASIR (Non-rigid Alignment based Solar Image Reconstruction). NASIR reconstructs the phase of the object image at each frequency by building a computational model between geometric distortion and intensity distribution and reconstructs the modulus of the object image on the aligned speckle images by speckle interferometry. We analyzed the performance of NASIR by using the correlation coefficient, power spectrum, and coefficient of variation of intensity profile (CVoIP) in processing data obtained by the NVST (1m New Vacuum Solar Telescope). The reconstruction experiments and analysis results show that the quality of images reconstructed by NASIR is close to speckle masking when the seeing is good, while NASIR has excellent robustness when the seeing condition becomes worse. Furthermore, NASIR reconstructs the entire field of view in parallel in one go, without phase recursion and block-by-block reconstruction, so its computation time is less than half that of speckle masking. Therefore, we consider NASIR is a robust and high-quality fast reconstruction method that can serve as an effective tool for data filtering and quick look.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： How to utilize topological microcavities to control quantum emission is one of the ongoing research topics in the optical community. In this work, we investigate the emission of quantum emitters in doubly-resonant topological Tamm microcavity, which can simultaneously achieve dual resonances at two arbitrary wavelengths according to the needs of practical application. To achieve the enhancement of quantum emission in such cavities, we have exploited the tunable doubly-resonant modes, in which one of resonant modes corresponds to the pump laser wavelength and the other one is located at the emission wavelength of quantum emitters. Both theoretical and experimental results demonstrate that the pump excitation and emission efficiencies of quantum emitters are greatly enhanced. The main physical mechanism can be explained by the doubly-resonant cavity temporal coupled-mode theory. Furthermore, we observe the faster emission rate and the higher efficiency of unidirectional quantum emission, which have promising applications in optical detection, sensing, filtering, and light-emitting devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Recent experimental advances in Floquet engineering and controlling dissipation in open systems have brought about unprecedented flexibility in tailoring novel phenomena without any static and Hermitian analogues. It can be epitomized by the various Floquet and non-Hermitian topological phases. Topological classifications of either static/Floquet Hermitian or static non-Hermitian systems based on the underlying symmetries have been well established in the past several years. However, a coherent understanding and classification of Floquet non-Hermitian (FNH) topological phases have not been achieved yet. Here we systematically classify FNH topological bands for 54-fold generalized Bernard-LeClair (GBL)symmetry classes and arbitrary spatial dimensions using $K$-theory. The classification distinguishes two different scenarios of the Floquet operator's spectrum gaps [dubbed as Floquet operator (FO) angle-gapped and FO angle-gapless]. The results culminate into two periodic tables, each containing 54-fold GBL symmetry classes. Our scheme reveals FNH topological phases without any static/Floquet Hermitian and static non-Hermitian counterparts. And our results naturally produce the periodic tables of Floquet Hermitian topological insulators and Floquet unitaries. The framework can also be applied to characterize the topological phases of bosonic systems. We provide concrete examples of one and two-dimensionalfermionic/bosonic systems. And we elucidate the meaning of the topological invariants and their physical consequences. Our paper lays the foundation for a comprehensive exploration of FNH topological bands. And it opens a broad avenue toward uncovering unique phenomena and functionalities emerging from the synthesis of periodic driving, non-Hermiticity, and band topology.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： One of the most fascinating aspects of quantum fields in curved spacetime is the Unruh effect. The direct experimental detection of Unruh temperature has remained an elusive challenge up to now. Gradient optical waveguides manipulating the dispersion of photons are assumed to realize the great acceleration of effective particles, leading to a high effective Unruh temperature. However, experimentally achieving this optical waveguide has not yet been reported. In this work, we exploit a tapered fiber to simulate the accelerated motion of effective particles and obtain an effective Unruh temperature. When light propagating in a tapered fiber is affected by the external high refractive index medium, a leaky phenomenon akin to bremsstrahlung will be observed, and the pattern of leaky radiation is dependent on the acceleration of photons. During the experiments, different accelerations corresponding to different Unruh temperatures are achieved by controlling the shape of the tapered waveguide.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A perturbation on the background inflaton potential can lead inflation into the ultraslow-roll stage and can thus remarkably enhance the power spectrum ${\cal P}_{\cal R}(k)$ of the primordial curvature perturbation on small scales. Such an enhanced ${\cal P}_{\cal R}(k)$ will result in primordial black holes (PBHs), contributing a significant fraction of dark matter, and will simultaneously generate sizable scalar-induced gravitational waves (SIGWs) as a secondorder effect. In this work, we calculate the PBH abundances $f_{\rm PBH}(M)$ and SIGW spectra $\Omega_{\rm GW}(f)$ in peak theory. We obtain the PBHs with desirable abundances in one or two typical mass windows at $10^{-17}\, M_\odot$, $10^{-13}\, M_\odot$, and $30\, M_\odot$, respectively. At the same time, the relevant SIGWs are expected to be observed by the next-generation gravitational wave detectors, without spoiling the current constraint. Especially, the SIGW associated with the PBH of $30\, M_\odot$ can also interpret the potential isotropic stochastic gravitational wave background from the NANOGrav 12.5-year dataset.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A perturbation on the background inflaton potential can lead inflation into the ultraslow-roll stage and can thus remarkably enhance the power spectrum ${\cal P}_{\cal R}(k)$ of the primordial curvature perturbation on small scales. Such an enhanced ${\cal P}_{\cal R}(k)$ will result in primordial black holes (PBHs), contributing a significant fraction of dark matter, and will simultaneously generate sizable scalar-induced gravitational waves (SIGWs) as a secondorder effect. In this work, we calculate the PBH abundances $f_{\rm PBH}(M)$ and SIGW spectra $\Omega_{\rm GW}(f)$ in peak theory. We obtain the PBHs with desirable abundances in one or two typical mass windows at $10^{-17}\, M_\odot$, $10^{-13}\, M_\odot$, and $30\, M_\odot$, respectively. At the same time, the relevant SIGWs are expected to be observed by the next-generation gravitational wave detectors, without spoiling the current constraint. Especially, the SIGW associated with the PBH of $30\, M_\odot$ can also interpret the potential isotropic stochastic gravitational wave background from the NANOGrav 12.5-year dataset.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Light scattering within scattering media presents a substantial obstacle to optical transmission. A speckle pattern with random amplitude and phase distribution is observed when coherent light travels through strong scattering media. Fortunately, wavefront shaping has been successfully employed with a spatial light modulator to recover intensity targets after scattering media, such as a sharp focus point or specified two-dimensional patterns. There have, however, been few studies that attempted to separately manipulate the amplitude and phase of the focusing field. In this paper, we propose a feedback-based wavefront shaping method to generate complex optical fields through scattering medium. A reliable phase retrieval approach is introduced to provide the complex feedback information, i.e., the amplitude and phase of the focusing field. Accordingly, in order to modulate the speckle field into a desired complex structured optical field, a multi-objective genetic algorithm is used to find the best phase map. To demonstrate the proposed method's high performance, experimental tests have been carried out. High fidelity is demonstrated in the generation of diverse complex light fields, both in amplitude and phase. Our findings may facilitate the manipulation of light field through scattering medium, and are anticipated to further promote future applications such as optogenetics, vortex optical communication, and optical trapping through scattering media.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In this study, we propose and experimentally demonstrate a novel kind of Tamm plasmon topological superlattice (TTS) by engineering Tamm photonic crystals (TPCs) belonging to a different class of topology. Utilizing specifically designed double-layer metasurfaces etching on planar multilayered photonic structures, the TPC that supports the Tamm plasmon photonic bandgap is realized in the visible regime. Through the coupling of topological interface states existing between different TPCs, hybrid topological interface states of Tamm plasmon, called supermodes, are obtained that can be fully described by a tight-binding model. Meanwhile, we can achieve a tunable bandwidth of supermodes via varying the etching depth difference between double-layer metasurfaces. We show that the bandwidth decreases with the increase of etching depth difference, resulting in a nearly flat dispersion of supermodes with strong localization regardless of excitation angles. All the results are experimentally verified by measuring angular-resolved reflectance spectra. The TTS and supermodes proposed here open a new pathway for the manipulation of Tamm plasmons, based on which various promising applications such as integrated photonic devices, optical sensing, and enhancing light-matter interactions can be realized.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Recent advances in iterative wavefront shaping (WFS) techniques have made it possible to manipulate the light focusing and transport in scattering media. To improve the optimization performance, various optimization algorithms and improved strategies have been utilized. Here, a novel guided mutation (GM) strategy is proposed to improve optimization efficiency for iterative WFS. For both phase modulation and binary amplitude modulation, considerable improvements in optimization effect and rate have been obtained using multiple GM-enhanced algorithms. Due of its improvements and universality, GM is beneficial for applications ranging from controlling the transmission of light through disordered media to optical manipulation behind them.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Although general relativity (GR) has been precisely tested at the solar system scale, precise tests at a galactic or cosmological scale are still relatively insufficient. Here, in order to test GR at the galactic scale, we use the newly compiled galaxy-scale strong gravitational lensing (SGL) sample to constrain the parameter $\gamma_{PPN}$ in the parametrized post-Newtonian (PPN) formalism. We employ the Pantheon sample of type Ia supernovae observation to calibrate the distances in the SGL systems using the Gaussian Process method, which avoids the logical problem caused by assuming a cosmological model within GR to determine the distances in the SGL sample. Furthermore, we consider three typical lens models in this work to investigate the influences of the lens mass distributions on the fitting results. We find that the choice of the lens models has a significant impact on the constraints on the PPN parameter $\gamma_{PPN}$. We use the Bayesian information criterion as an evaluation tool to make a comparison for the fitting results of the three lens models, and we find that the most reliable lens model gives the result of $\gamma_{PPN}=1.065^{+0.064}_{-0.074}$, which is in good agreement with the prediction of $\gamma_{PPN}=1$ by GR. As far as we know, our 6.4% constraint result is the best result so far among the recent works using the SGL method.
分类： 物理学 >> 核物理学 提交时间： 2023-12-13
摘要： Simulating the total ionizing dose (TID) of an electrical system using transistor-level models can be difficult and expensive, particularly for digital integrated circuits (ICs). In this study, a method for modeling TID effects in complementary metal-oxide semiconductor (CMOS) digital ICs based on the input/output buffer information specification (IBIS) was proposed. The digital IC was first divided into three parts based on its internal structure: the input buffer, output buffer, and functional area. Each of these three parts was separately modeled. Using the IBIS model, the transistor V-I characteristic curves of the buffers were processed, and the physical parameters were extracted and modeled using VHDL-AMS. In the functional area, logic functions were modeled in VHDL according to the data sheet. A golden digital IC model was developed by combining the input buffer, output buffer, and functional area models. Furthermore, the golden ratio was reconstructed based on TID experimental data, enabling the assessment of TID effects on the threshold voltage, carrier mobility, and time series of the digital IC. TID experiments were conducted using a CMOS noninverting multiplexer, NC7SZ157, and the results were compared with the simulation results, which showed that the relative errors were less than 2% at each dose point. This confirms the practicality and accuracy of the proposed modeling method. The TID effect model for digital ICs developed using this modeling technique includes both the logical function of the IC and changes in electrical properties and functional degradation impacted by TID, which has potential applications in the design of radiation-hardening tolerance in digital ICs.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The past decade has seen a proliferation of topological materials for both insulators and semimetals in electronic systems and classical waves. Topological semimetals exhibit topologically protected band degeneracies, such as nodal points and nodal lines. Dirac nodal line semimetals (DNLS), which own four-fold line degeneracy, have drawn particular attention. DNLSs have been studied in electronic systems but there is no photonic DNLS. Here in this work, we provide a new mechanism which is unique for photonic systems to investigate a stringent photonic DNLS. When truncated, the photonic DNLS exhibits double-bowl states (DBS), which comprises two sets of perpendicularly polarized surface states. In sharp contrast to nondegenerate surface states in other photonic systems, here the two sets of surface states are almost degenerate over the whole spectrum range. The DBS and the bulk Dirac nodal ring (DNR) dispersion along the relevant directions, are experimentally resolved.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Yibo Wang
Ning Jiang
Tinggui Wang
Jiazheng zhu
LiMing Dou
Zheyu Lin
LuMing Sun
Hui Liu
Zhenfeng Sheng
摘要： We hereby report the discovery of ATLAS17jrp as an extraordinary TDE in star-forming galaxy SDSSJ162034.99+240726.5 in our recent sample of mid-infrared outbursts in nearby galaxies. Its optical/UV light curves rise to a peak luminosity $\sim1.06\times10^{44}\rm\,erg\,s^{-1}$ in about a month and then decay as $\rm t^{-5/3}$ with a roughly constant temperature around 19000~K, and the optical spectra show a blue continuum and very broad Balmer lines with FWHM$\sim$15000 km/s which gradually narrowed to 1400 km/s within 4 years, all agreeing well with other optical TDEs. A delayed and rapidly rising X-ray flare with a peak luminosity $\rm \sim 1.27\times10^{43}\,erg\,s^{-1}$ was detected at $\rm \sim$ 170 days after the optical peak. The high MIR luminosity of ATLAS17jrp ($\sim2\times10^{43} \rm\,erg\,s^{-1}$) has revealed a distinctive dusty environment with covering factor as high as $\sim0.2$, that is comparable with that of torus in active galactic nuclei but at least one order of magnitude higher than normal optical TDEs. Therefore, ATLAS17jrp turns out to be one of the rare unambiguous TDE found in star-forming galaxies and its high dust covering factor implies that the dust extinction could play an important role in the absence of optical TDEs in star-forming galaxies.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Topological photonics, featured by stable topological edge states resistant to perturbations, has been utilized to design robust integrated devices. Here, we present a study exploring the intriguing topological rotated Weyl physics in a 3D parameter space based on quaternary waveguide arrays on lithium niobate-on-insulator (LNOI) chips. Unlike previous works that focus on the Fermi arc surface states of a single Weyl structure, we can experimentally construct arbitrary interfaces between two Weyl structures whose orientations can be freely rotated in the synthetic parameter space. This intriguing system was difficult to realize in usual 3D Weyl semimetals due to lattice mismatch. We found whether the interface can host gapless topological interface states (TISs) or not, is determined by the relative rotational directions of the two Weyl structures. In the experiment, we have probed the local characteristics of the TISs through linear optical transmission and nonlinear second harmonic generation. Our study introduces a novel path to explore topological photonics on LNOI chips and various applications in integrated nonlinear and quantum optics.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The New Vacuum Solar Telescope (NVST) has been releasing its novel winged Ha data (WHD) since April 2021, namely the Ha imaging spectroscopic data. Compared with the prior released version, the new data are further co-aligned among the off-band images and packaged into a standard solar physics community format. In this study, we illustrate the alignment algorithm used by the novel WHD, which is mainly based on the optical flow method to obtain the translation offset between the winged images. To quantitatively evaluate the alignment results of two images with different similarities, we calculate the alignment accuracies between the images of different off-band and line center, respectively. The result shows that our alignment algorithm could reach up to the accuracy of about 0.1 "when the off-band of winged image is lower than 0.6 \.A. In addition, we introduce the final product of the WHD in detail, which can provide convenience for the solar physicists to use high-resolution H{\alpha} imaging spectroscopic data of NVST.
分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2023-12-15 合作期刊: 《Research in Astronomy and Astrophysics》
摘要： The Tian-ma Radio Telescope (TMRT) applies an Active Surface System (ASFS), which corrects for large-scale deformations due to gravity and thermal on the primary reflector. The centralized and automated management of the ASFS using software has become a challenge, for which we have developed the TMRT Active Surface System Control Software (TASCS). This paper describes the design and implementation of TASCS for device control, status monitoring, human-computer interaction, and data management functionalities. TASCS adopts the open-source Tango Controls framework and distributes middleware technology to realize real-time automated adjustment of the primary reflector through remote centralized control of a large number of actuators. At present, it has been successfully deployed on the TMRT and has played an important role in Event Horizon Telescope observations.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jia-Xing Wen
Xu-Tao Zheng
Jian-Dong Yu
Yue-Peng Che
Dong-Xin Yang
Huai-Zhong Gao
Yi-Fei Jin
Xiang-Yun Long
Yi-Hui Liu
Da-Cheng Xu
Yu-Chong Zhang
Ming Zeng
Yang Tian
Hua Feng
Zhi Zeng
Ji-Rong Cang
Qiong Wu
Zong-Qing Zhao
Bin-Bin Zhang
Peng An
摘要： Gamma-Ray Integrated Detectors (GRID) mission is a student project designed to use multiple gamma-ray detectors carried by nanosatellites (CubeSats), forming a full-time all-sky gamma-ray detection network that monitors the transient gamma-ray sky in the multi-messenger astronomy era. A compact CubeSat gamma-ray detector, including its hardware and firmware, was designed and implemented for the mission. The detector employs four Gd2Al2Ga3O12 : Ce (GAGG:Ce) scintillators coupled with four silicon photomultiplier (SiPM) arrays to achieve a high gamma-ray detection efficiency between 10 keV and 2 MeV with low power and small dimensions. The first detector designed by the undergraduate student team onboard a commercial CubeSat was launched into a Sun-synchronous orbit on October 29, 2018. The detector was in a normal observation state and accumulated data for approximately one month after on-orbit functional and performance tests, which were conducted in 2019.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Yuzhu Cui
Kazuhiro Hada
Motoki Kino
Bong Won Sohn
Jongho Park
Hyun Wook Ro
Satoko Sawada-Satoh
Wu Jiang
Lang Cui
Mareki Honma
Zhi Qiang Shen
Fumie Tazaki
Tao An
Ilje Cho
Guang Yao Zhao
Xiao Peng Cheng
Kotaro Niinuma
Kiyoaki Wajima
Ying Kang Zhang
Noriyuki Kawaguchi
摘要： The East Asian very-long-baseline interferometry (VLBI) Network (EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China, Japan, and Korea. EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions. After the combination of the Korean VLBI Network (KVN) and the VLBI Exploration of Radio Astrometry (VERA) into KaVA, further expansion with the joint array in East Asia is actively promoted. Here we report the first imaging results (at 22 and 43 GHz) of bright radio sources obtained with KaVA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China. To test the EAVN imaging performance for different sources, we observed four active galactic nuclei (AGN) having different brightness and morphology. As a result, we confirmed that Tianma 65-m Radio Telescope (TMRT) significantly enhances the overall array sensitivity, a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of KaVA only. The addition of Nanshan 26-m Radio Telescope (NSRT) further doubled the east-west angular resolution. With the resulting high-dynamic-range, high-resolution images with EAVN (KaVA+TMRT+NSRT), various fine-scale structures in our targets, such as the counter-jet in M87, a kink-like morphology of the 3C273 jet and the weak emission in other sources, are successfully detected. This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general. Ongoing expansion of EAVN will further enhance the angular resolution, detection sensitivity and frequency coverage of the network.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
JUNO Collaboration
Jie Zhao
Baobiao Yue
Haoqi Lu
Yufeng Li
Jiajie Ling
Zeyuan Yu
Angel Abusleme
Thomas Adam
Shakeel Ahmad
Rizwan Ahmed
Sebastiano Aiello
Muhammad Akram
Abid Aleem
Tsagkarakis Alexandros
Fengpeng An
Qi An
Giuseppe Andronico
Nikolay Anfimov
Vito Antonelli
摘要： The physics potential of detecting $^8$B solar neutrinos is exploited at the Jiangmen Underground Neutrino Observatory (JUNO), in a model independent manner by using three distinct channels of the charged-current (CC), neutral-current (NC) and elastic scattering (ES) interactions. Due to the largest-ever mass of $^{13}$C nuclei in the liquid-scintillator detectors and the potential low background level, $^8$B solar neutrinos would be observable in the CC and NC interactions on $^{13}$C for the first time. By virtue of optimized event selections and muon veto strategies, backgrounds from the accidental coincidence, muon-induced isotopes, and external backgrounds can be greatly suppressed. Excellent signal-to-background ratios can be achieved in the CC, NC and ES channels to guarantee the $^8$B solar neutrino observation. From the sensitivity studies performed in this work, we show that one can reach the precision levels of 5%, 8% and 20% for the $^8$B neutrino flux, $\sin^2\theta_{12}$, and $\Delta m^2_{21}$, respectively, using ten years of JUNO data. It would be unique and helpful to probe the details of both solar physics and neutrino physics. In addition, when combined with SNO, the world-best precision of 3% is expected for the $^8$B neutrino flux measurement.
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