arXiv subjects

Shaofeng Wang

Publications and source records attributed to Shaofeng Wang.

18 recordsLinked to original sources

arXiv2026

Doppler-enhanced superheterodyne Rydberg microwave receiver

We report the enhanced sensitivity of the Rydberg microwave (MW) receiver by exploiting the Doppler effect in a vapor cell. A two-photon Rydberg ladder scheme is implemented via the co-propagation of probe and coupling lasers, which enhances the Doppler effect. When an MW field is applied, microwave dressing modifies the velocity-dependent resonance condition, enabling stronger contributions from atoms with non-zero velocities and leading to an enhancement of the EIT transmission. Based on this mechanism, we achieve a sensitivity of $35.1\ \mathrm{nV\ cm^{-1}\ Hz^{-1/2}}$ using the heterodyne technique, which is 1.5 times better than that obtained in the counter-propagating configuration. Meanwhile, the required local oscillator (LO) field is reduced by a factor of 17.6 compared with the counter-propagating configuration, which is advantageous for applications requiring minimal radiation and low power consumption. Moreover, the co-propagating configuration is more amenable to integration or portable sensing platforms because multiple laser fields can be delivered through a single optical fiber.

physics.atom-ph↗

arXiv2026

TCATSeg: A Tooth Center-Wise Attention Network for 3D Dental Model Semantic Segmentation

Accurate semantic segmentation of 3D dental models is essential for digital dentistry applications such as orthodontics and dental implants. However, due to complex tooth arrangements and similarities in shape among adjacent teeth, existing methods struggle with accurate segmentation, because they often focus on local geometry while neglecting global contextual information. To address this, we propose TCATSeg, a novel framework that combines local geometric features with global semantic context. We introduce a set of sparse yet physically meaningful superpoints to capture global semantic relationships and enhance segmentation accuracy. Additionally, we present a new dataset of 400 dental models, including pre-orthodontic samples, to evaluate the generalization of our method. Extensive experiments demonstrate that TCATSeg outperforms state-of-the-art approaches.

cs.CV↗

arXiv2025

TeethGenerator: A two-stage framework for paired pre- and post-orthodontic 3D dental data generation

Digital orthodontics represents a prominent and critical application of computer vision technology in the medical field. So far, the labor-intensive process of collecting clinical data, particularly in acquiring paired 3D orthodontic teeth models, constitutes a crucial bottleneck for developing tooth arrangement neural networks. Although numerous general 3D shape generation methods have been proposed, most of them focus on single-object generation and are insufficient for generating anatomically structured teeth models, each comprising 24-32 segmented teeth. In this paper, we propose TeethGenerator, a novel two-stage framework designed to synthesize paired 3D teeth models pre- and post-orthodontic, aiming to facilitate the training of downstream tooth arrangement networks. Specifically, our approach consists of two key modules: (1) a teeth shape generation module that leverages a diffusion model to learn the distribution of morphological characteristics of teeth, enabling the generation of diverse post-orthodontic teeth models; and (2) a teeth style generation module that synthesizes corresponding pre-orthodontic teeth models by incorporating desired styles as conditional inputs. Extensive qualitative and quantitative experiments demonstrate that our synthetic dataset aligns closely with the distribution of real orthodontic data, and promotes tooth alignment performance significantly when combined with real data for training. The code and dataset are available at https://github.com/lcshhh/teeth_generator.

cs.CV↗

arXiv2025

Twisted heterobilayer photonic crystal based on stacking and selective etching of 2D materials

Nanophotonic devices with moir\'e superlattice is currently attracting broad interest due to the unique periodicity and high efficiency control of photons. Till now, experimental investigations mainly focus on the single layer device, i.e., two or more layers of photonic crystal patterns are merged and etched in a single layer of material. By comparison, twisted photonic crystal with multilayer materials raises challenges in the nanofabrication technology, because the growth of upper layer material usually requires a smooth bottom layer without nanostructures. Hereby, we fabricate twisted heterobilayer photonic crystal in the graphite/Si$_3$N$_4$ heterostructure. We use dry transfer method to stack the graphite on top of bottom Si$_3$N$_4$ with pre-etched photonic crystal patterns. Selective dry etching recipes are used to etch two photonic crystal layers individually, which improves the quality and accuracy in alignment. The cavity photonic mode at the visible wavelength $\sim 700$ nm arsing from the moir\'e site is clearly observed in experiment. These results reveal the experimental diagram of heterobilayer nanophotonic devices and open the way to design flexibility and control of photons in new degrees of freedom.

physics.optics↗

arXiv2024

Teeth-SEG: An Efficient Instance Segmentation Framework for Orthodontic Treatment based on Anthropic Prior Knowledge

Teeth localization, segmentation, and labeling in 2D images have great potential in modern dentistry to enhance dental diagnostics, treatment planning, and population-based studies on oral health. However, general instance segmentation frameworks are incompetent due to 1) the subtle differences between some teeth' shapes (e.g., maxillary first premolar and second premolar), 2) the teeth's position and shape variation across subjects, and 3) the presence of abnormalities in the dentition (e.g., caries and edentulism). To address these problems, we propose a ViT-based framework named TeethSEG, which consists of stacked Multi-Scale Aggregation (MSA) blocks and an Anthropic Prior Knowledge (APK) layer. Specifically, to compose the two modules, we design 1) a unique permutation-based upscaler to ensure high efficiency while establishing clear segmentation boundaries with 2) multi-head self/cross-gating layers to emphasize particular semantics meanwhile maintaining the divergence between token embeddings. Besides, we collect 3) the first open-sourced intraoral image dataset IO150K, which comprises over 150k intraoral photos, and all photos are annotated by orthodontists using a human-machine hybrid algorithm. Experiments on IO150K demonstrate that our TeethSEG outperforms the state-of-the-art segmentation models on dental image segmentation.

cs.CV↗

arXiv2023

Automatic Tooth Arrangement with Joint Features of Point and Mesh Representations via Diffusion Probabilistic Models

Tooth arrangement is a crucial step in orthodontics treatment, in which aligning teeth could improve overall well-being, enhance facial aesthetics, and boost self-confidence. To improve the efficiency of tooth arrangement and minimize errors associated with unreasonable designs by inexperienced practitioners, some deep learning-based tooth arrangement methods have been proposed. Currently, most existing approaches employ MLPs to model the nonlinear relationship between tooth features and transformation matrices to achieve tooth arrangement automatically. However, the limited datasets (which to our knowledge, have not been made public) collected from clinical practice constrain the applicability of existing methods, making them inadequate for addressing diverse malocclusion issues. To address this challenge, we propose a general tooth arrangement neural network based on the diffusion probabilistic model. Conditioned on the features extracted from the dental model, the diffusion probabilistic model can learn the distribution of teeth transformation matrices from malocclusion to normal occlusion by gradually denoising from a random variable, thus more adeptly managing real orthodontic data. To take full advantage of effective features, we exploit both mesh and point cloud representations by designing different encoding networks to extract the tooth (local) and jaw (global) features, respectively. In addition to traditional metrics ADD, PA-ADD, CSA, and ME_{rot}, we propose a new evaluation metric based on dental arch curves to judge whether the generated teeth meet the individual normal occlusion. Experimental results demonstrate that our proposed method achieves state-of-the-art tooth alignment results and satisfactory occlusal relationships between dental arches. We will publish the code and dataset.

cs.CV↗

arXiv2023

Audience Expansion for Multi-show Release Based on an Edge-prompted Heterogeneous Graph Network

In the user targeting and expanding of new shows on a video platform, the key point is how their embeddings are generated. It's supposed to be personalized from the perspective of both users and shows. Furthermore, the pursue of both instant (click) and long-time (view time) rewards, and the cold-start problem for new shows bring additional challenges. Such a problem is suitable for processing by heterogeneous graph models, because of the natural graph structure of data. But real-world networks usually have billions of nodes and various types of edges. Few existing methods focus on handling large-scale data and exploiting different types of edges, especially the latter. In this paper, we propose a two-stage audience expansion scheme based on an edge-prompted heterogeneous graph network which can take different double-sided interactions and features into account. In the offline stage, to construct the graph, user IDs and specific side information combinations of the shows are chosen to be the nodes, and click/co-click relations and view time are used to build the edges. Embeddings and clustered user groups are then calculated. When new shows arrive, their embeddings and subsequent matching users can be produced within a consistent space. In the online stage, posterior data including click/view users are employed as seeds to look for similar users. The results on the public datasets and our billion-scale data demonstrate the accuracy and efficiency of our approach.

cs.SI↗

arXiv2021

Silicon photonics integrated dynamic polarization controller for continuous-variable quantum key distribution

We designed and demonstrated experimentally a silicon photonics integrated dynamic polarization controller which is a crucial component of a continuous-variable quantum key distribution system. By using a variable step simulated annealing approach, we achieve a dynamic polarization extinction ratio greater than 25 dB. The dynamic polarization controller can be utilized in silicon photonics integrated continuous-variable quantum key distribution system to minimize the size and decrease the cost further.

quant-ph↗

arXiv2018

Quantum improved measurement of time transfer

Accurate time transfer has become a crucial issue for future space experiments which require increasing resolution over large distances. In 2008, a scheme combining homodyne detection and mode-locked femtosecond lasers was proposed that leads to a potential timing precision reaching the yoctosecond range; with a multimode quantum frequency comb as the input field, the sub-shot noise measurement for the time transfer can further improve the timing precision. Based on this scheme and applying the multimode squeezing frequency comb that was measured to have a phase quadrature quantum noise reduction of 1.5 dB at the analyzing frequency 2MHz, the measurable timing fluctuation was reduced from a shot-noise limited value of 8.9E-23s to 7.5E-23s. To our knowledge, this is the first experimental demonstration of the time transfer measurement that achieves a precision beyond the standard quantum limit (SQL).

quant-ph↗

arXiv2016

An efficient source of frequency anti-correlated entanglement at telecom wavelength

We demonstrate an efficient generation of frequency anti-correlated entangled photon pairs at telecom wavelength. The fundamental laser is a continuous-wave high-power fiber laser at 1560 nm, through an extracavity frequency doubling system, a 780-nm pump with a power as high as 742 mW is realized. After single passing through a periodically poled KTiOPO4 (PPKTP) crystal, degenerate down-converted photon pairs are generated. With an overall detection efficiency of 14.8 %, the count rates of the single photons and coincidence of the photon pairs are measured to be 370 kHz and 22 kHz, respectively. The spectra of the signal and idler photons are centered at 1560.23 and 1560.04 nm, while their 3-dB bandwidths being 3.22 nm both. The joint spectrum of the photon pair is observed to be frequency anti correlated and have a spectral bandwidth of 0.52 nm. According to the ratio of the single photon spectral bandwidth to the joint spectral bandwidth of the photon pairs, the degree of frequency entanglement is quantified to be 6.19. Based on a Hong Ou Mandel interferometric coincidence measurement, a frequency indistinguishability of 95 % is demonstrated. The good agreements with the theoretical estimations show that the inherent extra intensity noise in fiber lasers has little influence on frequency entanglement of the generated photon pairs.

quant-ph↗

arXiv2016

Demonstration of quantum synchronization based on second-order quantum coherence of entangled photons

Based on the second-order quantum interference between frequency entangled photons that are generated by parametric down conversion, a quantum strategic algorithm for synchronizing two spatially separated clocks has been recently presented. In the reference frame of a Hong-Ou-Mandel (HOM) interferometer, photon correlations are used to define simultaneous events. Once the HOM interferometer is balanced by use of an adjustable optical delay in one arm, arrival times of simultaneously generated photons are recorded by each clock. The clock offset is determined by correlation measurement of the recorded arrival times. Utilizing this algorithm, we demonstrate a proof-of-principle experiment for synchronizing two clocks separated by 4km fiber link. A minimum timing stability of 0.4 ps at averaging time of 16000 s is achieved with an absolute time accuracy of 59.4 ps. The timing stability is verified to be limited by the correlation measurement device and ideally can be better than 10 fs. Such results shine a light to the application of quantum clock synchronization in the real high-accuracy timing system.

quant-ph↗

arXiv2015

Charge transfer of edge states in zigzag silicene nanoribbons with Stone-Wales defects

Stone-Wales (SW) defects are favorably existed in graphenelike materials with honeycomb lattice structure and potentially employed to change the electronic properties in band engineering. In this paper, we investigate structural and electronic properties of SW defects in bulk silicene and its nanoribbons as a function of their concentration using the methods of periodic boundary conditions with first-principles calculations. We first calculate the formation energy, structural properties, and electronic band structures of SW defects in bulk silicene, with dependence on the concentration of SW defects. Our results show a good agreement with available values from the previous first-principles calculations. The energetics, structural aspects, and electronic properties of SW defects with dependence on defect concentration and location in edge-hydrogenated zigzag silicene nanoribbons are obtained. For all calculated concentrations, the SW defects prefer to locate at the edge due to the lower formation energy. The SW defects at the center of silicene nanoribbons slightly influence on the electronic properties, whereas the SW defects at the edge of silicene nanoribbons split the degenerate edge states and induce a sizable gap, which depends on the concentration of defects. It is worth to find that the SW defects produce a perturbation repulsive potential, which leads the decomposed charge of edge states at the side with defect to transfer to the other side without defect.

cond-mat.mes-hall↗

arXiv2011

First-principles calculations on finite temperature elastic properties of B2-AlRE (RE=Y, Tb, Pr, Nd, Dy) intermetallics

We have investigated the finite temperature elastic properties of AlRE (RE=Y, Tb, Pr, Nd, Dy) with B2-type structures from first principles. The phonon free energy and thermal expansion is obtained from the quasiharmonic approach based on density-functional perturbation theory. The static volume-dependent elastic constants are obtained from energy-strain functions by using the first-principles total-energy method. The comparison between our predicted results and the ultrasonic experimental data for a benchmark material Al provides excellent agreements. At T = 0K, our calculated values of lattice equilibrium volume and elastic moduli of our calculated AlRE (RE=Y, Tb, Pr, Nd, Dy) intermetallics agree well with the previous theoretical results. The temperature dependent elastic constants exhibit a normal behavior with temperature, i.e., decrease and approach linearity at higher temperature and zero slope around zero temperature. Furthermore, the anisotropy ratio and sound velocities as a function of temperature has also been discussed.

cond-mat.mtrl-sci↗

arXiv2011

First-principles calculations of phonon and thermodynamic properties of AlRE (RE= Y, Gd, Pr, Yb) intermetallic compounds

The phonon and thermodynamic properties of rare-earth-aluminum intermetallics AlRE (RE=Y, Gd, Pr, Yb) with B2-type structure are investigated by performing density functional theory and density functional perturbation theory within the quasiharmonic approximation. The phonon spectra and phonon density of states, including the phonon partial density of states and total density of states, have been discussed. Our results demonstrate that the density of states is mostly composed of Al states at the high frequency. The temperature dependence of various quantities such as the thermal expansions, the heat capacities at constant volume and constant pressure, the isothermal bulk modulus, and the entropy are obtained. The electronic contribution to the specific heat is discussed, and the presented results show that the thermal electronic excitation affecting the thermal properties is inessential.

cond-mat.mtrl-sci↗

arXiv2011

The temperature-dependent elastic properties of B2-MgRE intermetallic compounds from first principles

Using the density functional theory (DFT) formulated within the framework of the plane-wave basis projector augmented wave (PAW) method, the temperature-dependent elastic properties of MgRE (RE=Y, Dy, Pr, Sc, Tb) intermetallics with B2-type structure are presented from first-principles. Our calculations are based on the fact that the elastic moduli as a function of temperature mainly results from thermal expansion. The comparison between the predicted results and the available experimental data for a benchmark material NiAl provides good agreements. At $T=0K$, our calculated values of lattice parameter and elastic moduli for MgRE intermetallics show excellent agreement with previous theoretical results and experimental data. While temperature increases, we find that the elastic constants decrease and approach linearity at higher temperature and zero slope around zero temperature.

cond-mat.mtrl-sci↗

arXiv2011

Ab initio study of the thermodynamic properties of rare-earthmagnesium intermetallics MgRE (RE=Y, Dy, Pr, Tb)

We have performed an ab initio study of the thermodynamical properties of rare-earth-magnesium intermetallic compounds MgRE (RE=Y, Dy, Pr, Tb) with CsCl-type B2-type structures. The calculations have been carried out the density functional theory and density functional perturbation theory in combination with the quasiharmonic approximation. The phonon-dispersion curves and phonon total and partial density of states have been investigated. Our results show that the contribution of RE atoms is dominant in phonon frequency, and this character agrees with the previous discussion by using atomistic simulations. The temperature dependence of various quantities such as the thermal expansions, bulk modulus, and the heat capacity are obtained. The electronic contributions to the specific heat are discussed, and found to be important for the calculated MgRE intermetallics.

cond-mat.mtrl-sci↗

arXiv2011

The third-order elastic moduli and pressure derivatives for AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce) intermetallics with B2-structure: A first-principles study

The third-order elastic moduli and pressure derivatives of the second-order elastic constants of novel B2-type AlRE (RE=Y, Pr, Nd, Tb, Dy, Ce) intermetallics are presented from first-principles calculations. The elastic moduli are obtained from the coefficients of the polynomials from the nonlinear least-squares fitting of the energy-strain functions. The calculated second-order elastic constants of AlRE intermetallics are consistent with the previous calculations. To judge that our computational accuracy is reasonable, the calculated third-order constants of Al are compared with the available experimental data and other theoretical results and found very good agreement. In comparison with the theory of the linear elasticity, the third-order effects are very important with the finite strains are lager than approximately 3.5%. Finally, the pressure derivative has been discussed.

cond-mat.mtrl-sci↗

arXiv2011

Edge dislocation core structures in FCC metals determined from ab initio calculations combined with the improved Peierls-Nabarro equation

We have employed the improved Peierls-Nabarro (P-N) equation to study the properties of 1/2<110> edge dislocation in {111} plane in FCC metals Al, Cu, Ir, Pd, and Pt. The generalized-stacking-fault energy (GSFE) surface entering the equation is calculated by using first-principles density functional theory (DFT). The accuracy of the method has been tested by calculating values for various stacking fault energies which favorably compare with the previous theoretical and experimental results. The core structures, including the core widths both of the edge and screw components, dissociation behavior for edge dislocations have been investigated. The dissociated distance between two partials for Al in our calculation agrees well with the values obtained from the numeric simulation with DFT and molecular dynamics simulation, as well as experiment. Our calculations show that it is preferred to create partial dislocation in Cu, and to be easily observed full dislocation in Al, Ir, Pd, and especially Pt.

cond-mat.mtrl-sci↗