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Ying Gu

Publications and source records attributed to Ying Gu.

At least 19 recordsLinked to original sources
arXiv2026

Theory of Deterministic Photon-Loss Subspaces for Quantum Interferences

Quantum coherence, quantum decoherence, and photon number reduction are coexistent in linear lossy optical systems. However, how these three elements combine together to determine the evolution of the quantum light remains unclear. Here, based on singular value decomposition (SVD), we propose the theory of deterministic photon-loss subspace (DPLS) for quantum interferences in lossy systems. By performing an SVD of scattering matrices with singular values either 0 or 1, a series of completely lossy and lossless input modes are first defined. According to n_1,...,n_i photons in the first,..., i-th lossy modes, the Hilbert space of the input states can be decomposed into a set of orthogonal subspaces H_((n_1,...,n_i ))^in, i.e., deterministic photon-loss subspaces (DPLSs). When the concept of DPLS is established, the input state can be projected onto these DPLSs. In each DPLS, the photons in lossy modes will be completely dissipated, while those in lossless modes experience a unitary evolution. The output state is a statistical mixture of the evolved outcomes of all projections, since decoherence is a concurrent process. Then, based on the DPLS theory, we not only revisited Anti-HOM interference and the distillation of quantum states, but also demonstrate a robust W-state generation for various input states in a three-port lossy system with one-dimensional DPLSs. Through investigating the loss-induced subspace structure of the system, our general theory for analyzing quantum state evolution in lossy systems explicitly reveals the interplay among quantum coherence, quantum decoherence, and photon number reduction. By engineering the loss, the constructed DPLSs can be used to precisely control quantum interferences in dissipative systems, with potential applications in quantum state preparation, quantum logic operations, and other quantum information processes.

quant-ph↗
arXiv2026

AT2019ijn: a fast-rising, slow-decaying blue optical transient with exceptionally bright radio emission

We report the discovery of a peculiar optical transient, AT2019ijn, occurred in the nuclear region of a dwarf galaxy at z=0.273. It rises rapidly to peak at a luminosity of Mg=-21.1 in 5 days, followed by a slow decline over more than a month, during which the optical emission has a persistently high blackbody temperature of T_BB~1.5-1.6x10^4 K. The radio emission is exceptional which peaks at 640 days after optical discovery with a high luminosity of 2x10^31 erg/s/Hz. The peak radio luminosity is at least two orders of magnitude brighter than known radio-bright fast blue optical transients and supernova explosions at similar epochs, but comparable to jetted tidal disruption events. The luminous and long-lasting radio emission with a late-time peak can be explained by an off-axis relativistic jet with a viewing angle of ~40 deg. We discuss possible origins for AT2019ijn and favor a jetted tidal disruption event involving an intermediate-mass black hole of ~10^5 Msun, although a jetted magnetar model cannot be fully ruled out. AT2019ijn represents a new class of relativistic optical transients that highlights the importance of radio surveys for discovering off-axis jetted events.

astro-ph.HE↗
arXiv2026

Signatures of Two Distinct Epochs of FRB 20240114A from January to August 2024 Based on its Energy and Waiting Time Analysis

A comprehensive analysis of the energy and waiting time distributions of the bursts from FRB 20240114A detected by the Five-hundred-meter Aperture Spherical Radio Telescope between 28 January and 29 August 2024 is presented. For the full sample, its energy distribution cannot be fitted with the simple power-law (SPL),bent power-law (BPL), thresholded power-law (TPL) or Band function models, and its waiting time distribution excluding intervals shorter than 0.5 s cannot be fitted with the Poisson or Weibull models. Nevertheless, for the subsamples with more than 50 bursts in single-day observations, their energy distributions can be fitted with the BPL or TPL models, and their waiting time distributions are better described by a Weibull model. It is noted that the best-fitting BPL parameter $\beta$ is approximately invariant within the epochs before and after 21 March 2024, with an average of $\bar \beta_b = 1.006 \pm 0.074$ and $\bar \beta_a = 1.236 \pm 0.183$ (one standard deviation), respectively. Most subsamples from the later epoch have a smaller burst rate parameter $r$ in the Weibull model than those from the earlier epoch. The majority of bursts with $E>10^{39}$ erg occurred in the earlier epoch. The energy distributions in the high-energy range ($> 6\times10^{37}$ erg) differ significantly between the two epochs, and power-law fits to $dN/dE$ yield indices of $-1.97_{-0.02}^{+0.02}$ and $-2.34_{-0.06}^{+0.06}$, respectively. The median of the waiting time distribution of the later epoch is larger than that in the earlier epoch. These results suggest that the two epochs may be dominated by different types of bursts, possibly attributed to changes in the physical properties of the emission region.

astro-ph.HE↗
arXiv2026

Physics-informed neural networks for quantitative assessment of cancellous bone microstructure from photoacoustic signals

Artificial intelligence (AI) empowers innovative diagnostic tools for common diseases, yet its clinical application in skeletal health evaluation is constrained by unsatisfactory accuracy, owing to the inherent porous and poroelastic biophysical features of bone. To address such bottlenecks amid global population aging, this study targets skeletal health and develops a reliable AI framework for precise bone microstructural characterization. We proposed Biot-PINN, a physics-informed neural network embedded with Biot's poroelasticity theory to characterize mechanical responses and wave propagation in poroelastic bone tissues. By decoding photoacoustic signals encoding bone mineral and microstructural features, the framework enables automatic bone microstructural grading. Experimental results reveal that Biot-PINN reaches an accuracy of 97%, markedly surpassing traditional data-driven approaches and providing a robust solution for early skeletal health diagnosis.

physics.med-ph↗
arXiv2026

Two-Phonon Resonance Drives Multicomponent Mechanical Cat States

Using quadratic optomechanical coupling to prepare high-purity mechanical cat states is not feasible as its strength is several orders weaker than linear optomechanical coupling. Here, using only linear coupling in a multimode system, we achieve strong interaction between photons and two phonons, enabling the deterministic generation of high-purity multicomponent mechanical cats. Mediated by an auxiliary supermode, when other two optical supermodes satisfy the two-phonon resonance condition, the process whereby the annihilation of a high-frequency photon accompanied by the creation of a low-frequency photon and two phonons is strongly enhanced. Such resonant two-phonon process drives multiple rotations and interferences of mechanical coherent states, deterministically generating a multicomponent mechanical cat immune to both mechanical and optical losses. Our work provides an universal strategy for enhancing high-order phonon nonlinearities, paving the way for quantum state engineering, quantum precision measurement and fault-tolerant quantum computation.

quant-ph↗
arXiv2026

Towards Annotation-Free Validation of MLLMs: A Vision-Language Logical Consistency Metric

Dominant accuracy evaluation might reward unwarranted guessing of Large Language Models, and it might not be applicable to novel tasks for model validation without ground-truth (gt) annotation. Based on basic logic principle, we propose a novel framework to evaluate the vision-language logical consistency of MLLMs on both sufficient and necessary cause-effect relations. We define Vision-Language Logical Consistency Metric (VL-LCM) on traditional MC-VQA tests, and recent NaturalBench tests without the need for gt annotation. Through systematic experiments on representative VL benchmark MMMU and recent VL challenges like NaturalBench, we evaluated 11 recent open-source MLLMs from 4 frontier families. Our findings reveal that, despite significant progress of recent MLLMs on accuracy, logical consistency lags behind significantly. Extensive evaluations on the correlations of VL-LCM with metrics on gt, the reliability of LCM, and the relation of VL-LCM with response distribution justify the validity and applicability of VL-LCM even without gt annotation. Our findings suggest that, beyond accuracy, logical consistency could be employed for both accuracy and reliability. VL-LCM can also be employed for MLLM selection, validation, and reliable answer justification in novel tasks without gt annotation.

cs.AI↗
arXiv2026

PRBench: End-to-end Paper Reproduction in Physics Research

AI agents powered by large language models exhibit strong reasoning and problem-solving capabilities, enabling them to assist scientific research tasks such as formula derivation and code generation. However, whether these agents can reliably perform end-to-end reproduction from real scientific papers remains an open question. We introduce PRBench, a benchmark of 30 expert-curated tasks spanning 11 subfields of physics. Each task requires an agent to comprehend the methodology of a published paper, implement the corresponding algorithms from scratch, and produce quantitative results matching the original publication. Agents are provided only with the task instruction and paper content, and operate in a sandboxed execution environment. All tasks are contributed by domain experts from over 20 research groups at the School of Physics, Peking University, each grounded in a real published paper and validated through end-to-end reproduction with verified ground-truth results and detailed scoring rubrics. Using an agentified assessment pipeline, we evaluate a set of coding agents on PRBench and analyze their capabilities across key dimensions of scientific reasoning and execution. The best-performing agent, OpenAI Codex powered by GPT-5.3-Codex, achieves a mean overall score of 34%. All agents exhibit a zero end-to-end callback success rate, with particularly poor performance in data accuracy and code correctness. We further identify systematic failure modes, including errors in formula implementation, inability to debug numerical simulations, and fabrication of output data. Overall, PRBench provides a rigorous benchmark for evaluating progress toward autonomous scientific research.

cs.CL↗
arXiv2026

From Human Interfaces to Agent Interfaces: Rethinking Software Design in the Age of AI-Native Systems

Software systems have traditionally been designed for human interaction, emphasizing graphical user interfaces, usability, and cognitive alignment with end users. However, recent advances in large language model (LLM)-based agents are changing the primary consumers of software systems. Increasingly, software is no longer only used by humans, but also invoked autonomously by AI agents through structured interfaces. In this paper, we argue that software engineering is undergoing a paradigm shift from human-oriented interfaces to agent-oriented invocation systems. We formalize the notion of agent interfaces, introduce invocable capabilities as the fundamental building blocks of AI-oriented software, and outline design principles for such systems, including machine interpretability, composability, and invocation reliability. We then discuss architectural and organizational implications of this shift, highlighting a transition from monolithic applications to capability-based systems that can be dynamically composed by AI agents. The paper aims to provide a conceptual foundation for the emerging paradigm of AI-native software design.

cs.SE↗
arXiv2026

Explicit Logic Channel for Validation and Enhancement of MLLMs on Zero-Shot Tasks

Frontier Multimodal Large Language Models (MLLMs) exhibit remarkable capabilities in Visual-Language Comprehension (VLC) tasks. However, they are often deployed as zero-shot solution to new tasks in a black-box manner. Validating and understanding the behavior of these models become important for application to new task. We propose an Explicit Logic Channel, in parallel with the black-box model channel, to perform explicit logical reasoning for model validation, selection and enhancement. The frontier MLLM, encapsulating latent vision-language knowledge, can be considered as an Implicit Logic Channel. The proposed Explicit Logic Channel, mimicking human logical reasoning, incorporates a LLM, a VFM, and logical reasoning with probabilistic inference for factual, counterfactual, and relational reasoning over the explicit visual evidence. A Consistency Rate (CR) is proposed for cross-channel validation and model selection, even without ground-truth annotations. Additionally, cross-channel integration further improves performance in zero-shot tasks over MLLMs, grounded with explicit visual evidence to enhance trustworthiness. Comprehensive experiments conducted for two representative VLC tasks, i.e., MC-VQA and HC-REC, on three challenging benchmarks, with 11 recent open-source MLLMs from 4 frontier families. Our systematic evaluations demonstrate the effectiveness of proposed ELC and CR for model validation, selection and improvement on MLLMs with enhanced explainability and trustworthiness.

cs.AI↗
arXiv2026

Wavefront Control and Intensity Modulation of Third Harmonic Generation in Nonlocal Metasurfaces

Metasurfaces have emerged as a promising platform for integrated nonlinear optics. Nonlocal metasurfaces enable high nonlinear conversion efficiency, while the local ones can offer versatile wavefront control, yet achieving both within a single metasurface remains challenging. Here, using a nonlocal phase gradient metasurface, we firstly demonstrate efficient third harmonic generation (THG) with polarization-dependent wavefront control. Leveraging nonlocal nonlinear geometric phase existing at resonance, the third harmonic light with distinct polarizations is deflected into $\pm$ 2nd and $\pm$ 4th diffraction orders, simultaneously achieving a conversion efficiency up to $1.45\times 10^{-4}$ under a pump intensity of $1 GW/cm^{2}$. Then, by introducing a secondary fundamental beam, whose generated third harmonic light overlaps with that of the first beam, the intensity modulation of THG is obtained. The THG efficiency can be tuned from $3.9 \times 10^{-9}$ to $5.5 \times 10^{-3}$ by varying the relative phase, polarization and intensity of two fundamental beams. Through utilizing the advantages of both local and nonlocal metasurfaces, our results effectively pave the way to on-chip nonlinear photonic devices and signal processing.

physics.optics↗
arXiv2025

Efficient Waveform Capture without Absorption with Synthesis of Complex Frequencies

A optical waveform can be synthesized by complex-frequency waves as well as by real-frequency harmonic waves. While single complex-frequency wave with exponentially rising waveform can be perfectly absorbed in lossless structures. Here, we propose that diverse optical waveforms can be captured without any absorption through the synthesis of complex frequencies in a lossless system. The scattering matrix zeros of the system correspond to a set of complex frequencies with exponentially rising waveforms, each of which can be virtually and perfectly absorbed. Thus, an input waveform, decomposed into these complex frequencies automatically, can be captured without any absorption. Then, in a well-designed coupled cavity system, various waveforms such as exponentially decaying, Gaussian, rectangular, triangular, and randomly generated piecewise-linear profiles, are captured with high efficiency. The proposed mechanism has potential applications in enhancing light-matter interactions and optical energy storage.

physics.optics↗
arXiv2025

AGN-Driven Biconical Outflows as the Origin of the Double-Peaked [O~{\sc iii}] doublet in SDSS J134733.36+121724.27

In this manuscript, we recheck the spectroscopic properties of SDSS J134733.36+121724.27 (4C+12.50), confirming the presence of the double-peaked [O~{\sc iii}]$\lambda\lambda4959,5007$\AA\ doublet and a broad H$\alpha$. The former likely results from AGN-driven biconical outflows, while the absence of a broad H$\beta$ supports a classification of the source as a Type-1.9 AGN. We analyze its high-quality Sloan Digital Sky Survey (SDSS) optical spectrum after robustly subtracting host galaxy and AGN continuum contributions through a simple stellar population fitting method employing 39 templates and a power-law continuum. Each narrow line of the [O~{\sc iii}]$\lambda\lambda4959,5007$\AA\ doublet is better described by two Gaussian components (blue-shifted and red-shifted) than by a single Gaussian, as confirmed by the F-test. Broad components are included for both H$\alpha$ and H$\beta$, but only H$\alpha$ reveals a significant detection, further supported by a comparison between the SDSS spectrum and that previously reported. These results support that the object is highly consistent with a Type-1.9 AGN classification, and the double-peaked [O~{\sc iii}] profiles are most likely produced by AGN-driven biconical outflows rather than by a rotating narrow-line region or a dual AGN merger system. Additional observations are still needed to strengthen these conclusions.

astro-ph.GA↗
arXiv2025

Time-Dependent obscuration of a tidal disruption event candidate in the active galactic nucleus CSS100217

CSS100217 is considered a peculiar tidal disruption event (TDE) candidate occurring in an active galactic nucleus (AGN). Unlike typical TDEs, where the post-flare luminosity is equal to that pre-flare, CSS100217 decayed to $\sim$ 0.4 magnitudes fainter than its pre-flare V band level. In this manuscript, we propose an obscured TDE model to explain the light curve of CSS100217. Assuming that the time-dependent obscuration, caused by the TDE unbound stellar debris, or by nuclear clouds moving around the supermassive black hole (SMBH), follows a Weibull distribution, we find that the light curve of CSS100217 can be described by the tidal disruption of a $4.6_{-0.9}^{+0.9}{\rm M_\odot}$ main-sequence star by a $3.3_{-0.3}^{+0.3}\times10^7{\rm M_\odot}$ black hole. The total energy of the event derived from our fit is $7.23\times10^{53}$ ergs and about 1.38 ${\rm M_\odot}$ of debris mass is accreted by the central SMBH. The model indicates that the contribution of the host galaxy to the observed pre-flare optical luminosity is not-significant compared to that of the AGN, which is consistent with the results of the spectral analysis. These results suggest that obscuration may play an important role in explaining the unusual TDE-like variability observed in CSS100217.

astro-ph.HE↗
arXiv2025

An improved Seyfert-LINER classification line in the [N~{\sc ii}] BPT diagram

In this manuscript, an improved Seyfert-LINER classification line (= S-L line) is proposed in the [N~{\sc ii}] BPT diagram, based on a sample of 47,968 low redshift narrow emission line galaxies from SDSS DR16, motivated by different S-L lines reported in the [N~{\sc ii}] BPT diagram through different methods. The method proposed by Kewley et al. in 2006 is firstly applied, however, the method cannot lead to an accepted S-L line in the [N~{\sc ii}] BPT diagram. Meanwhile, the S-L lines proposed by Schawinski et al. in 2007 and Cid Fernandes et al. in 2010 in the [N~{\sc ii}] BPT diagram are different from each other. Therefore, it is meaningful to check which proposed S-L line is better or to determine an improved one in the [N~{\sc ii}] BPT diagram by a new method. In this manuscript, Seyferts and LINERs that have already been classified in the [S~{\sc ii}] and/or [O~{\sc i}] BPT diagrams can be visualized in the [N~{\sc ii}] BPT diagram, leading the intersection boundary of the two contour maps to be considered as the S-L line in the [N~{\sc ii}] BPT diagram. Rather than the previously proposed S-L lines, the new S-L line can lead to more efficient and harmonious classifications of Seyferts and LINERs, especially in the composite galaxy region, in the [N~{\sc ii}] BPT diagram. Furthermore, based on the discussed S-L lines, the number ratio of Type-2 Seyferts to Type-2 LINERs differs significantly from that of Type-1 Seyferts to Type-1 LINERs in the [N~{\sc ii}] BPT diagram, suggesting that about 90$\%$ of Type-2 LINERs are non-AGN-related objects, true Type-2 AGNs, or objects exhibiting both Seyfert and LINER characteristics.

astro-ph.GA↗
arXiv2025

Conversion of photon temporal shape using single gradient metasurface

By applying phase modulation across different frequencies, metasurfaces possess the ability to manipulate the temporal dimension of photons at the femtosecond scale. However, there remains a fundamental challenge to shape the single wavepacket at the nanosecond scale by using of metasurfaces. Here, we propose that the single photon temporal shape can be converted through the multi-photon wavepacket interference on a single metasurface. By selecting appropriate input single-photon temporal shapes and metasurfaces beam splitting ratio, controllable photon shape conversion can be achieved with high fidelity. For examples, photons with an exponentially decaying profile can be shaped into a Gaussian profile; by tuning the relative time delays of input photons, Gaussian-shaped photons can be transformed into exponentially decaying or rising profiles through the same metasurface. The proposed mechanism provides a compact way for solving the temporal shape mismatch issues in quantum networks, facilitating the realization of high-fidelity on-chip quantum information processing.

quant-ph↗
arXiv2025

The orbital kinematics of kpc-scale dual-core systems with double-peaked narrow emission lines

In this manuscript, based on SDSS photometry and spectroscopy, a method is proposed to test the hypothesis that the orbital kinematics of kpc-scale dual-core systems can lead to double-peaked narrow emission lines (DPNELs), through analyzing a sample of seven kpc-scale dual-core systems by comparing the upper limits of their orbital velocities (calculated using total stellar mass and projected distance) with the velocity separation of DPNELs (peak separation). To determine accurate total stellar masses, GALFIT is applied to consider the effects of the overlapping components on the photometric images to obtain accurate magnitudes. Then, based on the correlation between absolute Petrosian magnitudes and total stellar masses, the individual masses of the galaxies are determined. Therefore, the maximum orbital velocities can be calculated by combining the projected distance. Meanwhile, the peak separation can be accurately measured after subtracting the pPXF determined host galaxy contributions. Finally, four objects exhibit peak separations almost consistent with their respective maximum orbital velocities under the assumption of a circular orbit, while the remaining three objects display peak separations larger than the maximum orbital velocities. A larger sample will be given later to further test whether DPNELs can arise from kpc-scale dual-core systems.

astro-ph.GA↗
arXiv2024

A central tidal disruption event candidate in high redshift quasar SDSS J000118.70+003314.0

We report a high-redshift ($z=1.404$) tidal disruption event (TDE) candidate in SDSS J000118.70+003314.0 (SDSS J0001), which is a quasar with apparent broad Mg~{\sc ii} emission line. The long-term variability in its nine-year photometric $ugriz$-band light curves, obtained from the SDSS Stripe82 and the PHOTOOBJALL databases, can be described by the conventional TDE model. Our results suggest that the TDE is a main-sequence star with mass of $1.905_{-0.009}^{+0.023}{\rm M_\odot}$ tidally disrupted by a black hole (BH) with mass {$6.5_{-2.6}^{+3.5}\times10^7{\rm M_\odot}$}. The BH mass is about 7.5 times smaller than the virial BH mass derived from the broad Mg~{\sc ii} emission line, which can be explained by non-virial dynamic properties of broad emission lines from TDEs debris. Furthermore, we examine the probability that the event results from intrinsic variability of quasars, which is about $0.009\%$, through applications of the DRW/CAR process. Alternative explanations for the event are also discussed, such as the scenarios of dust obscurations, microlensing and accretion. Our results provide clues to support that TDEs could be detectable in broad line quasars as well as in quiescent galaxies, and to indicate the variability of some active galactic nuclei may be partly attributed to central TDEs.

astro-ph.GA↗
arXiv2024

Near-symmetric multiport beam splitting for high-NOON state preparation on nonlocal metasurface

Polarization beam splitting (BS) has been implemented on gradient metasurface with local response for entanglement manipulation and state reconstruction. To realize more degrees of light modulation, nonlocal modes, manifested as wavelength and momentum selectivity, should be applied into metasurface BS. Here, we demonstrate that single nonlocal phase gradient metasurface(NPGM) can function as a series of independent near-symmetric multiport BS,constructed by its momentum-polarization mode subspaces.Then, using any of above BS with simultaneous multiphoton interference, high-photon NOON states are prepared with high success probability and fidelity. For example,four-mode four-photon NOON state is obtained with 34.8% success probability and fidelity of 99.9%, greatly higher than those previously reported.With unique capability of multiphoton interference, this multiport BS on single NPGM can be directly used in the on-chip quantum photonics. Also, the efficient generation of high-photon NOON states with above BS has potential applications in quantum precision measurement.

quant-ph↗