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Angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution ({\mu}-ARPES), has become a powerful tool for studying quantum materials. To achieve sub-micrometer or even nanometer-scale spatial resolution, it is important to focus the incident light beam (usually from the synchrotron radiation) using X-ray optics such as the zone plate or ellipsoidal capillary mirrors. Recently, we developed a laser-based {\mu}-ARPES with spin-resolution (LMS-ARPES). The 177 nm laser beam is achieved by frequency doubling a 355 nm beam using a KBBF crystal and subsequently focused using an optical lens with a focal length of about 16 mm. By characterizing the focused spot size using different methods and performing spatial-scanning photoemission measurement, we confirm the sub-micron spatial resolution of the system. Compared with the {\mu}-ARPES facilities based on synchrotron radiation, our LMS-ARPES system is not only more economical and convenient but also with higher photon flux (> 5E13 photons/s), thus enabling the high-resolution and high-statistics measurements. Moreover, the system is equipped with a two-dimensional spin detector based on exchange scattering at a surface-passivated iron film grown on a W(100) substrate. We investigate the spin structure of the prototype topological insulator Bi2Se3 and reveal a high spin-polarization rate, confirming its spin-momentum locking property. This lab-based LMS-ARPES will be a powerful research tool for studying the local fine electronic structures of different condensed matter systems, including topological quantum materials, mesoscopic materials and structures, and phase-separated materials., Comment: To appear in RSI

As a novel X-ray focusing technology, lobster eye micro-pore optics (MPO) feature both a wide observing field of view and true imaging capability, promising sky monitoring with significantly improved sensitivity and spatial resolution in soft X-rays. Since first proposed by Angel (1979), the optics have been extensively studied, developed and trialed over the past decades. In this Letter, we report on the first-light results from a flight experiment of the Lobster Eye Imager for Astronomy ($LEIA$), a pathfinder of the wide-field X-ray telescope of the Einstein Probe mission. The piggyback imager, launched in July 2022, has a mostly un-vignetted field of view of $18.6^\circ \times 18.6^\circ $. Its spatial resolution is in the range of 4$-$7 arcmin in FWHM and the focal spot effective area is 2$-$3 cm$^2$, both showing only mild fluctuations across the field of view. We present images of the Galactic center region, Sco X-1 and the diffuse Cygnus Loop nebular taken in snapshot observations over 0.5$-$4 keV. These are truly wide-field X-ray images of celestial bodies observed, for the first time, by a focusing imaging telescope. Initial analyses of the in-flight data show excellent agreement between the observed images and the on-ground calibration and simulations. The instrument and its characterization are briefly described, as well as the flight experiment. The results provide a solid basis for the development of the present and proposed wide-field X-ray missions using lobster eye MPO., Comment: 11 pages, 4 figures. Accepted for publication in Astrophysical Journal Letter

Medical data mainly includes various types of biomedical signals and medical images, which can be used by professional doctors to make judgments on patients' health conditions. However, the interpretation of medical data requires a lot of human cost and there may be misjudgments, so many scholars use neural networks and deep learning to classify and study medical data, which can improve the efficiency and accuracy of doctors and detect diseases early for early diagnosis, etc. Therefore, it has a wide range of application prospects. However, traditional neural networks have disadvantages such as high energy consumption and high latency (slow computation speed). This paper presents recent research on signal classification and disease diagnosis based on a third-generation neural network, the spiking neuron network, using medical data including EEG signals, ECG signals, EMG signals and MRI images. The advantages and disadvantages of pulsed neural networks compared with traditional networks are summarized and its development orientation in the future is prospected.

We report the phase-connected timing ephemeris, polarization pulse profiles, Faraday rotation measurements, and Rotating-Vector-Model (RVM) fitting results of twelve millisecond pulsars (MSPs) discovered with the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal radio Astronomy FAST survey (CRAFTS). The timing campaigns were carried out with FAST and Arecibo over three years. Eleven of the twelve pulsars are in neutron star - white dwarf binary systems, with orbital periods between 2.4 and 100 d. Ten of them have spin periods, companion masses, and orbital eccentricities that are consistent with the theoretical expectations for MSP - Helium white dwarf (He WD) systems. The last binary pulsar (PSR J1912$-$0952) has a significantly smaller spin frequency and a smaller companion mass, the latter could be caused by a low orbital inclination for the system. Its orbital period of 29 days is well within the range of orbital periods where some MSP - He WD systems have shown anomalous eccentricities, however, the eccentricity of PSR J1912$-$0952 is typical of what one finds for the remaining MSP - He WD systems., Comment: 11 pages, 5 figures, MNRAS accepted

Object detection in autonomous driving applications implies that the detection and tracking of semantic objects are commonly native to urban driving environments, as pedestrians and vehicles. One of the major challenges in state-of-the-art deep-learning based object detection are false positives which occur with overconfident scores. This is highly undesirable in autonomous driving and other critical robotic-perception domains because of safety concerns. This paper proposes an approach to alleviate the problem of overconfident predictions by introducing a novel probabilistic layer to deep object detection networks in testing. The suggested approach avoids the traditional Sigmoid or Softmax prediction layer which often produces overconfident predictions. It is demonstrated that the proposed technique reduces overconfidence in the false positives without degrading the performance on the true positives. The approach is validated on the 2D-KITTI objection detection through the YOLOV4 and SECOND (Lidar-based detector). The proposed approach enables interpretable probabilistic predictions without the requirement of re-training the network and therefore is very practical., Comment: This work has been accepted for publication as a REGULAR PAPER in the Transactions on Intelligent Transportation Systems-ITS

Charge exchange between highly charged ions and neutral atoms and molecules has been considered as one of the important mechanisms controlling soft X ray emissions in many astrophysical objects and environments. However, for modeling charge exchange soft X ray emission, the data of n and l resolved state selective capture cross sections are often obtained by empirical and semiclassical theory calculations. With a newly built cold target recoil ion momentum spectroscopy (COLTRIMS) apparatus, we perform a series of measurements of the charge exchange of Ne(8,9)+ ions with He and H2 for collision energy ranging from 1 to 24.75 keV/u. n resolved state selective capture cross-sections are reported. By comparing the measured state selective capture cross sections to those calculated by the multichannel Landau Zener method (MCLZ), it is found that MCLZ calculations are in good agreement with the measurement for the dominant n capture for He target. Furthermore, by using nl resolved cross sections calculated by MCLZ and applying l distributions commonly used in the astrophysical literature to experimentally derived n resolved cross sections, we calculate the soft X ray emissions in the charge exchange between 4 keV/u Ne8+ and He by considering the radiative cascade from the excited Ne7+ ions. Reasonable agreement is found in comparison to the measurement for even and separable models, and MCLZ calculations give results in a better agreement.

The recent discovery of superconductivity in doped infinite-layer nickelates has stimulated intensive interest, especially for similarities and differences compared to that in cuprate superconductors. In contrast to cuprates, although earlier magnetization measurement reveals a Curie-Weiss-like behavior in undoped infinite-layer nickelates, there is no magnetic ordering observed by elastic neutron scattering down to liquid helium temperature. Until now, the nature of the magnetic ground state in undoped infinite-layer nickelates was still elusive. Here, we perform a nuclear magnetic resonance (NMR) experiment through 139La nuclei to study the intrinsic spin susceptibility of infinite-layer LaNiO2. First, the signature for magnetic ordering or freezing is absent in the 139La NMR spectrum down to 0.24 K, which unambiguously confirms a paramagnetic ground state in LaNiO2. Second, a pseudogap-like behavior instead of Curie-Weiss-like behavior is observed in both the temperature-dependent Knight shift and nuclear spin-lattice relaxation rate (1/T1), which is widely observed in both underdoped cuprates and iron-based superconductors. Furthermore, the scaling behavior between the Knight shift and 1/T1T has also been discussed. Finally, the present results imply a considerable exchange interaction in infinite-layer nickelates, which sets a strong constraint for the proposed theoretical models., Comment: 14 pages, 4 figures, accepted by Physical Review Letters

Recently, competing electronic instabilities, including superconductivity and density-wave-like order, have been discovered in vanadium-based kagome metals AV3Sb5 (A = K, Rb, Cs) with a nontrivial band topology. This finding stimulates wide interests to study the interplay of these competing electronic orders and possible exotic excitations in the superconducting state. Here, in order to further clarify the nature of density-wave-like transition in these kagome superconductors, we performed 51V and 133Cs nuclear magnetic resonance (NMR) measurements on the CsV3Sb5 single crystal. A first-order phase transition associated with orbital ordering is revealed by observing a sudden splitting of orbital shift in 51V NMR spectrum at the structural transition temperature Ts ~ 94 K. In contrast, the quadrupole splitting from a charge-density-wave (CDW) order on 51V NMR spectrum only appears gradually below Ts with a typical second-order transition behavior, suggesting that the CDW order is a secondary electronic order. Moreover, combined with 133Cs NMR spectrum, the present result also confirms a three-dimensional structural modulation with a 2ax2ax2c period. Above Ts, the temperature-dependent Knight shift and nuclear spin-lattice relaxation rate (1/T1) further indicate the existence of remarkable magnetic fluctuations from vanadium 3d orbitals, which are suppressed due to orbital ordering below Ts. The present results strongly support that, besides CDW order, the previously claimed density-wave-like transition also involves a dominant orbital order, suggesting a rich orbital physics in these kagome superconductors., Comment: 13 pages, 4 figures, supplementary information available upon request

The non-collinear antiferromagnetic (AFM) structure makes Mn3Sn exhibit exotic properties. At present, it has been found that both the hydrostatic pressure and the strain introduced by interstitial N atoms have a great influence on this magnetic structure. Here, the effect of the residual strain (RS) on it is investigated. AC and DC magnetic measurement results suggest that Mn3Sn without RS has the non-collinear AFM structure only in the temperature range of 285 K to 400 K; while Mn3Sn with RS has a non-coplanar AFM structure in the entire temperature range from 5 K to 400 K. Both anomalous Hall effect and topological Hall effect appears in Mn3Sn with RS, supporting the anticipated non-coplanar AFM structure. Our findings point out a method to realize the chiral non-coplanar AFM structure through the engineering, thereby providing a path for the construction of topological antiferromagnets., Comment: 18 pages, 5 figures

We consider the problem of unsupervised domain adaptation for image classification. To learn target-domain-aware features from the unlabeled data, we create a self-supervised pretext task by augmenting the unlabeled data with a certain type of transformation (specifically, image rotation) and ask the learner to predict the properties of the transformation. However, the obtained feature representation may contain a large amount of irrelevant information with respect to the main task. To provide further guidance, we force the feature representation of the augmented data to be consistent with that of the original data. Intuitively, the consistency introduces additional constraints to representation learning, therefore, the learned representation is more likely to focus on the right information about the main task. Our experimental results validate the proposed method and demonstrate state-of-the-art performance on classical domain adaptation benchmarks. Code is available at https://github.com/Jiaolong/ss-da-consistency., Comment: ICPR 2020

By means of quantum tensor network calculations, we investigate the large Purcell effect experienced by an organic molecule placed in the vicinity of a plasmonic nanostructure. In particular, we consider a donor-{\pi} bridge-acceptor dye at the gap of two Ag nanospheres. Our theoretical approach allows for a realistic description of the continua of both molecular vibrations and optical nanocavity modes. We analyze both the exciton dynamics and the corresponding emission spectrum, showing that these magnitudes are not accurately represented by the simplified models used up to date. By disentangling the molecule coupling to radiative and non-radiative plasmonic modes, we also shed light into the quenching phenomenology taking place in the system.

Here, by conducting a systematic $^{89}$Y NMR study, we explore the nature of the magnetic ground state in a newly discovered iron-based superconductor YFe$_2$Ge$_2$. An incoherent-to-coherent crossover due to the Hund's coupling induced electronic correlation is revealed below the crossover temperature $T^*\sim 75\pm15\,\mathrm{K}$. During the electronic crossover, both the Knight shift ($K$) and the bulk magnetic susceptibility ($\chi$) exhibit a similar nonmonotonic temperature dependence, and a so-called Knight shift anomaly is also revealed by a careful $K$-$\chi$ analysis. Such an electronic crossover has been also observed in heavily hole-doped pnictide superconductors \emph{A}Fe$_2$As$_2$ (\emph{A} = K, Rb, and Cs), which is ascribed to the Hund's coupling induced electronic correlation. Below $T^*$, the spin-lattice relaxation rate divided by temperature $(1/T_1T)$ shows a similar suppression as the Knight shift, suggesting the absence of critical spin fluctuations. This seems to be in conflict with a predicted magnetic quantum critical point (QCP) near this system. However, considering a $\mathbf{q}$-dependent "filter" effect on the transferred hyperfine field, a predominant spin fluctuation with A-type correlation would be perfectly filtered out at $^{89}$Y sites, which is consistent with the recent inelastic neutron scattering results. Therefore, our results confirm that, through a Hund's coupling induced electronic crossover, the magnetic ground state of YFe$_2$Ge$_2$ becomes close to an itinerant magnetic QCP with A-type spin fluctuations. In addition, the possible superconducting pairing due to spin fluctuations is also discussed., Comment: 6 pages, 4 figures, supplementary information available upon request

Superconductivity arises from two distinct quantum phenomena: electron pairing and long-range phase coherence. In conventional superconductors, the two quantum phenomena generally take place simultaneously, while the electron pairing occurs at higher temperature than the long-range phase coherence in the underdoped high-Tc cuprate superconductors. Recently, whether electron pairing is also prior to long-range phase coherence in single-layer FeSe film on SrTiO3 substrate is under debate. Here, by measuring Knight shift and nuclear spin-lattice relaxation rate, we unambiguously reveal a pseudogap behavior below Tp ~ 60 K in two layered FeSe-based superconductors with quasi-two-dimension. In the pseudogap regime, a weak diamagnetic signal and a remarkable Nernst effect are also observed, which indicate that the observed pseudogap behavior is related to superconducting fluctuations. These works confirm that strong phase fluctuation is an important character in the two-dimensional iron-based superconductors as widely observed in high-Tc cuprate superconductors., Comment: 18 pages, 4 figures, supplementary materials available upon request

Scene recognition model based on the DNN and game theory with its applications in human-robot interaction is proposed in this paper. The use of deep learning methods in the field of scene recognition is still in its infancy, but has become an important trend in the future. As the innovative idea of the paper, we propose the following novelties. (1) In this paper, the image registration problem is transformed into a problem of minimum energy in Markov Random Field to finalize the image pre-processing task. Game theory is used to find the optimal. (2) We select neighboring homogeneous sample features and the neighboring heterogeneous sample features for the extracted sample features to build a triple and modify the traditional neural network to propose the novel DNN for scene understanding. (3) The robot control is well combined to guide the robot vision for multiple tasks. The experiment is then conducted to validate the overall performance.

The mechanism of spontaneous exchange bias (SEB) and the dominant factor of its blocking temperature are still unclear in Heusler alloys. Here, the related investigations are performed in Mn2Ni1.5Al0.5 Heusler alloys with SEB. The results of both magnetic measurements and first-principles calculations confirmed that spin frustrated and unfrustrated antiferromagnetic (AFM) states coexist there and they have different magnetic anisotropies, which are essential for SEB. Based on a series of measurement strategies, we demonstrate that the frustrated AFM state undergoes a first-order magnetic transition to the superferromagnet (SFM) state with the help of an external magnetic field, and SFM is retained due to the first-order property of the magnetic transition. SEB originates from the interface coupling of multiple sublattices between the unfrustrated AFM state and SFM state. By analyzing the Arrott plot using the Landau model, we found that the internal field of the system dominates the blocking temperature of SEB, which paves the way for improving the blocking temperature.

The Cold-target recoil-ion momentum spectroscopy (COLTRIMS) has been employed to study the single-electron capture processes in collisions of N3+ ions with He atoms at an impact energy of 30 keV. The relative differential cross sections for the capture to different orbitals of N3+ ions are obtained and are compared with other experiments at low energy. The predictions of the molecular Columbic barrier model have been made. From the longitudinal momentum spectrum of recoil ions, the different electronic configuration was identified and the metastable projectile ions were distinguished. The single electron capture into the N2+ (1s22s22p 2P) state from the ground state N3+ (1s22s2 1S) projectile is the dominant reaction channel. The fraction of the metastable state N3+(2s2p 3P) of the incident projectile beam is about 46%.

The importance of the spin-orbit coupling (SOC) effect in Fe-based superconductors (FeSCs) has recently been under hot debate. Considering the Hund's coupling-induced electronic correlation, the understanding of the role of SOC in FeSCs is not trivial and is still elusive. Here, through a comprehensive study of 77Se and 57Fe nuclear magnetic resonance, a nontrivial SOC effect is revealed in the nematic state of FeSe. First, the orbital-dependent spin susceptibility, determined by the anisotropy of the 57Fe Knight shift, indicates a predominant role from the 3dxy orbital, which suggests the coexistence of local and itinerant spin degrees of freedom (d.o.f.) in the FeSe. Then, we reconfirm that the orbital reconstruction below the nematic transition temperature (Tnem ~ 90 K) happens not only on the 3dxz and 3dyz orbitals but also on the 3dxy orbital, which is beyond a trivial ferro-orbital order picture. Moreover, our results also indicate the development of a coherent coupling between the local and itinerant spin d.o.f. below Tnem, which is ascribed to a Hund's coupling-induced electronic crossover on the 3dxy orbital. Finally, due to a nontrivial SOC effect, sizable in-plane anisotropy of the spin susceptibility emerges in the nematic state, suggesting a spin-orbital-intertwined nematicity rather than simply spin- or orbital-driven nematicity}. The present work not only reveals a nontrivial SOC effect in the nematic state but also sheds light on the mechanism of nematic transition in FeSe., Comment: 11 pages, 5 figures, supplementary information available upon request

In low-dimensional metallic systems, lattice distortion is usually coupled to a density-wave-like electronic instability due to Fermi surface nesting (FSN) and strong electron-phonon coupling. However, the ordering of other electronic degrees of freedom can also occur simultaneously with the lattice distortion thus challenges the aforementioned prevailing scenario. Recently, a hidden electronic reconstruction beyond FSN was revealed in a layered metallic compound BaTi2As2O below the structural transition temperature Ts ~ 200 K. The nature of this hidden electronic instability is under strong debate. Here, by measuring the local orbital polarization through 75As nuclear magnetic resonance experiment, we observe a p-d bond order between Ti and As atoms in BaTi2As2O single crystal. Below Ts, the bond order breaks both rotational and translational symmetry of the lattice. Meanwhile, the spin-lattice relaxation measurement indicates a substantial loss of density of states and an enhanced spin fluctuation in the bond-order state. Further first-principles calculations suggest that the mechanism of the bond order is due to the coupling of lattice and nematic instabilities. Our results strongly support a bond-order driven electronic reconstruction in BaTi2As2O and shed light on the mechanism of superconductivity in this family., Comment: 7 pages, 4 figures, supplemental material available upon request