arXiv subjects

Huan Yang

Publications and source records attributed to Huan Yang.

At least 73 records · Page 4Linked to original sources

arXiv2025

DreamStory: Open-Domain Story Visualization by LLM-Guided Multi-Subject Consistent Diffusion

Story visualization aims to create visually compelling images or videos corresponding to textual narratives. Despite recent advances in diffusion models yielding promising results, existing methods still struggle to create a coherent sequence of subject-consistent frames based solely on a story. To this end, we propose DreamStory, an automatic open-domain story visualization framework by leveraging the LLMs and a novel multi-subject consistent diffusion model. DreamStory consists of (1) an LLM acting as a story director and (2) an innovative Multi-Subject consistent Diffusion model (MSD) for generating consistent multi-subject across the images. First, DreamStory employs the LLM to generate descriptive prompts for subjects and scenes aligned with the story, annotating each scene's subjects for subsequent subject-consistent generation. Second, DreamStory utilizes these detailed subject descriptions to create portraits of the subjects, with these portraits and their corresponding textual information serving as multimodal anchors (guidance). Finally, the MSD uses these multimodal anchors to generate story scenes with consistent multi-subject. Specifically, the MSD includes Masked Mutual Self-Attention (MMSA) and Masked Mutual Cross-Attention (MMCA) modules. MMSA and MMCA modules ensure appearance and semantic consistency with reference images and text, respectively. Both modules employ masking mechanisms to prevent subject blending. To validate our approach and promote progress in story visualization, we established a benchmark, DS-500, which can assess the overall performance of the story visualization framework, subject-identification accuracy, and the consistency of the generation model. Extensive experiments validate the effectiveness of DreamStory in both subjective and objective evaluations. Please visit our project homepage at https://dream-xyz.github.io/dreamstory.

cs.CV↗

arXiv2025

Vamba: Understanding Hour-Long Videos with Hybrid Mamba-Transformers

State-of-the-art transformer-based large multimodal models (LMMs) struggle to handle hour-long video inputs due to the quadratic complexity of the causal self-attention operations, leading to high computational costs during training and inference. Existing token compression-based methods reduce the number of video tokens but often incur information loss and remain inefficient for extremely long sequences. In this paper, we explore an orthogonal direction to build a hybrid Mamba-Transformer model (VAMBA) that employs Mamba-2 blocks to encode video tokens with linear complexity. Without any token reduction, VAMBA can encode more than 1024 frames (640$\times$360) on a single GPU, while transformer-based models can only encode 256 frames. On long video input, VAMBA achieves at least 50% reduction in GPU memory usage during training and inference, and nearly doubles the speed per training step compared to transformer-based LMMs. Our experimental results demonstrate that VAMBA improves accuracy by 4.3% on the challenging hour-long video understanding benchmark LVBench over prior efficient video LMMs, and maintains strong performance on a broad spectrum of long and short video understanding tasks.

cs.CV↗

arXiv2025

Superconducting gap structure and bosonic mode in La2PrNi2O7 thin films at ambient pressure

The recent discovery of high temperature superconductivity in nickelate systems has generated tremendous interests in the field of superconductivity. The core issue to understand the superconductivity mechanism is about the superconducting gap and its symmetry. By using the substrate of SrLaAlO4(00l), we have successfully synthesized the superconducting thin film of La2PrNi2O7 with Tc(onset) = 41.5 K. Superconducting tunneling spectra are successfully measured on the terraces after we expose the superconducting layer by using the tip-excavation technique. The spectrum shows a two-gap structure with Delta1=19 meV, Delta2=6-8 meV, and fittings based on the Dynes model indicate that the dominant gap should have an anisotropic s-wave structure, this allows us to put the priority in selecting the s+- among the two arguable pairing models: s+- and d-wave. Furthermore, a clear bosonic mode with energy Omega=30+-2 meV is observed, which further supports a sign reversal gap. Our results shed new light in understanding the mystery of superconductivity in bilayer nickelate superconductors.

cond-mat.supr-con↗

arXiv2025

Extreme mass-ratio inspiral within an ultralight scalar cloud I. Scalar radiation

In this work, we study the dynamics of an extreme mass-ratio inspiral (EMRI) embedded within a scalar cloud populated around the massive black hole. This cloud may be generated through the black hole superradiant process if the wavelength of the scalar particle is comparable to the size of the massive black hole. The EMRI motion perturbs the cloud, producing scalar radiation towards infinity and into the black hole horizon. In addition, the backreaction of the scalar radiation onto the orbit modifies the motion of the EMRI and induces an observable gravitational-wave phase shift for a range of system parameters. We quantify the scalar flux and the induced phase shift, as one of the examples of exactly-solvable, environmental effects of EMRIs.

gr-qc↗

arXiv2025

Beijing Normal University 12-meter Interferometric kHz GW Detector Prototype: Design and Scientific Prospects

Current gravitational-wave detectors have achieved remarkable sensitivity around 100 Hz, enabling ground-breaking discoveries. Enhancing sensitivity at higher frequencies in the kilohertz (kHz) range promises access to rich physics, particularly the extreme conditions during the merger stage of binary neutron stars. However, the high-frequency sensitivity of Michelson-based interferometers is fundamentally limited by their linear optical cavities, which are optimized for low-frequency signal enhancement. In [Phys. Rev. X 13, 021019 (2023)], a new configuration employing an L-shaped optical resonator was proposed to overcome this limitation, offering exceptional sensitivity in the kHz band. As a pathfinder, the 12-meter prototype at Beijing Normal University is designed to demonstrate the sensing and control schemes of this new kHz detector configuration and to explore its performance in the high-power regime with suspended optics. Beyond its primary scientific goal, the prototype also offers potential sensitivity in the megahertz (MHz) range, potentially enabling constraints on exotic sources. This paper presents an overview of the prototype, including its optical design and current development status of key components.

physics.optics↗

arXiv2025

Quadratic Mode Couplings in Rotating Black Holes and Their Detectability

Quadratic quasinormal modes encode fundamental properties of black hole spacetimes. They are also one of the key ingredients of nonlinearities of General Relativity in the ringdown stage of binary black hole coalescence. In this work, we classify all possible quadratic coupling channels of quasinormal modes for a generic Kerr black hole, and use a frequency-domain pseudospectral code with hyperboloidal slicing to calculate these couplings. After accounting for all the channels in systems with reflection symmetry, our results become consistent with those extracted from numerical simulations and time-domain fits. This agreement provides a compelling example demonstrating the success of black hole second-order perturbation theory. We also explore potential applications of our calculations in future ringdown data analysis by carrying out a detectability survey for various quadratic modes. We find that a few of them are observationally relevant for third-generation ground-based detectors like Cosmic Explorer, as well as the space-borne detector LISA (Laser Interferometer Space Antenna).

gr-qc↗

arXiv2025

MM-MovieDubber: Towards Multi-Modal Learning for Multi-Modal Movie Dubbing

Current movie dubbing technology can produce the desired speech using a reference voice and input video, maintaining perfect synchronization with the visuals while effectively conveying the intended emotions. However, crucial aspects of movie dubbing, including adaptation to various dubbing styles, effective handling of dialogue, narration, and monologues, as well as consideration of subtle details such as speaker age and gender, remain insufficiently explored. To tackle these challenges, we introduce a multi-modal generative framework. First, it utilizes a multi-modal large vision-language model (VLM) to analyze visual inputs, enabling the recognition of dubbing types and fine-grained attributes. Second, it produces high-quality dubbing using large speech generation models, guided by multi-modal inputs. Additionally, a movie dubbing dataset with annotations for dubbing types and subtle details is constructed to enhance movie understanding and improve dubbing quality for the proposed multi-modal framework. Experimental results across multiple benchmark datasets show superior performance compared to state-of-the-art (SOTA) methods. In details, the LSE-D, SPK-SIM, EMO-SIM, and MCD exhibit improvements of up to 1.09%, 8.80%, 19.08%, and 18.74%, respectively.

cs.MM↗

arXiv2025

KVShare: An LLM Service System with Efficient and Effective Multi-Tenant KV Cache Reuse

Recent advances in long-text understanding have pushed the context length of large language models (LLMs) up to one million tokens. It boosts LLMs's accuracy and reasoning capacity but causes exorbitant computational costs and unsatisfactory Time to First Token (TTFT). KV cache reuse, which reuses the exact same KV cache of prefixes and templates or shares similar ones but with extra selective recomputation, offers a promising way to tackle this issue. However, prior studies overlook the cross-request KV reuse and the attention deviations introduced by new tokens during the decoding stage. In this paper, we present a KV cache management module that shares the KV cache across requests under multi-tenant scenarios without sacrificing model accuracy. Our system, KVShare, enables accurate and efficient LLM serving by 1) a Dual-Stage High Deviation algorithm (DHD) that conditionally selects a small portion of KV cache to be recomputed during both prefill and decode phases, and 2) a cache-aware scheduler that prioritizes requests based on their KV cache hit rates and orchestrates continuous batching to achieve enhanced system efficiency and faster TTFT. Multi-task experiments conducted on models such as Qwen2.5-7B,Llama3.1-8B and Yi1.5-9B demonstrate that KVShare reduces TTFT by up to 9.39x and increases 1.2x of the throughput compared to the full KV recompute. Moreover, KVShare achieves 20.38% boost in terms of accuracy compared to SOTA methods.

cs.CL↗

arXiv2025

Impact of relativistic waveforms in LISA's science objectives with extreme-mass-ratio inspirals

Extreme-Mass-Ratio Inspirals (EMRIs) are one of the key targets for future space-based gravitational wave detectors, such as LISA. The scientific potential of these sources can only be fully realized with fast and accurate waveform models. In this work, we extend the \textsc{FastEMRIWaveform} (\texttt{FEW}) framework by providing fully relativistic waveforms at adiabatic order for circular, equatorial orbits in Kerr spacetime, for mass ratios up to $10^{-3}$. We investigate the significance of including relativistic corrections in the waveform for both vacuum and non-vacuum environments. Specifically, we develop relativistic non-vacuum EMRI waveforms including two different environmental effects in the EMRI waveforms: power-law migration torques, and superradiance scalar clouds. For EMRIs in vacuum, we find that non-relativistic waveforms incorrectly estimate the predicted source's horizon redshift by approximately $35\%$ error. Our analysis shows that incorporating relativistic corrections enhances constraints on accretion disks, modeled through power-law torques, and improves the constraints on disk parameter estimates (error $\simeq 8\%$), representing a significant improvement over previous estimates. Additionally, we assess the evidence for models in a scenario where ignoring the accretion disk biases the parameter estimation (PE), reporting a $\log_{10}$ Bayes factor of $1.1$ in favor of the accretion disk model. In a fully relativistic setup, we also estimate the parameters of superradiant scalar clouds with relative errors $\simeq 0.3\%$ for the scalar cloud's mass. These results demonstrate that incorporating relativistic effects is essential for LISA science objectives with EMRIs.

gr-qc↗

arXiv2025

Density wave order with antiphase feature associated with the pseudogap in cuprate superconductor Bi2+xSr2-xCuO6+delta

The strong correlation effect in cuprate superconductors have greatly enriched the phase diagram showing the co-existence of superconductivity with many intertwined orders. One of the prominent issues concerning the superconductivity mechanism is about the pseudogap phase which behaves either as cooperator or competitor for superconductivity and its fundamental reason remains still elusive. Here we report the measurements of scanning tunneling microscopy/spectroscopy (STM/STS) in the model superconducting system Bi2+xSr2-xCuO6+delta with a transition temperature Tc~7 K. Although this system is supposed to be slightly overdoped, a pseudogap feature can be easily observed in the energy region of about 20-60 meV. A modulation of local density of states (LDOS) with a periodicity of about 4a0/3 (a0: Cu-O-Cu bond length) can be easily observed, which is also supported by the Fourier transformation pattern with wavevectors at about (0,+-3pi/2a0) and (+-3pi/2a0,0). Surprisingly, we find that the LDOS exhibits a clear antiphase feature in the pseudogap energy region below and above the Fermi energy, indicating that it is an intrinsic feature of the pseudogap phase. We interpret this modulation and antiphase feature as a possible consequence of the pair density wave due to the Amperean pairing with finite momentum. Our results give a deep insight on the understanding of the pseudogap phase in cuprate superconductors.

cond-mat.supr-con↗

arXiv2025

Long Video Diffusion Generation with Segmented Cross-Attention and Content-Rich Video Data Curation

We introduce Presto, a novel video diffusion model designed to generate 15-second videos with long-range coherence and rich content. Extending video generation methods to maintain scenario diversity over long durations presents significant challenges. To address this, we propose a Segmented Cross-Attention (SCA) strategy, which splits hidden states into segments along the temporal dimension, allowing each segment to cross-attend to a corresponding sub-caption. SCA requires no additional parameters, enabling seamless incorporation into current DiT-based architectures. To facilitate high-quality long video generation, we build the LongTake-HD dataset, consisting of 261k content-rich videos with scenario coherence, annotated with an overall video caption and five progressive sub-captions. Experiments show that our Presto achieves 78.5% on the VBench Semantic Score and 100% on the Dynamic Degree, outperforming existing state-of-the-art video generation methods. This demonstrates that our proposed Presto significantly enhances content richness, maintains long-range coherence, and captures intricate textual details. More details are displayed on our project page: https://presto-video.github.io/.

cs.CV↗

arXiv2025

Helical edge states and enhanced superconducting gaps in Bi islands on FeTe$_{0.55}$Se$_{0.45}$

By measuring scanning tunneling spectroscopy on some large Bi islands deposited on FeTe$_{0.55}$Se$_{0.45}$ superconductors, we observe clear evidence of topological in-gap edge states with double peaks at about $\pm 1.0$ meV on the spectra measured near the perimeter of the islands. The edge states spread towards the inner side of the islands over a width of 2-3 nm. The two edge-state peaks at positive and negative energies both move to higher values with increase of the magnetic field, and they disappear near the transition temperature $T_\mathrm{c}$ of FeTe$_{0.55}$Se$_{0.45}$. The edge states are interpreted as the counter-propagating topological edge states induced by the strong spin-orbit coupling effect of the Bi island, and the zero-energy mode emerges when the edge states touch each other in some small Bi islands. Meanwhile, enhanced superconducting gaps are observed in the central regions of these Bi islands, which may be induced by the enhanced pair potential of the topological surface state. Our observations provide useful message for the nontrivial topological superconductivity on specific Bi islands grown on FeTe$_{0.55}$Se$_{0.45}$ substrate.

cond-mat.supr-con↗

arXiv2025

Improving Multi-Subject Consistency in Open-Domain Image Generation with Isolation and Reposition Attention

Training-free diffusion models have achieved remarkable progress in generating multi-subject consistent images within open-domain scenarios. The key idea of these methods is to incorporate reference subject information within the attention layer. However, existing methods still obtain suboptimal performance when handling numerous subjects. This paper reveals two primary issues contributing to this deficiency. Firstly, the undesired internal attraction between different subjects within the target image can lead to the convergence of multiple subjects into a single entity. Secondly, tokens tend to reference nearby tokens, which reduces the effectiveness of the attention mechanism when there is a significant positional difference between subjects in reference and target images. To address these issues, we propose a training-free diffusion model with Isolation and Reposition Attention, named IR-Diffusion. Specifically, Isolation Attention ensures that multiple subjects in the target image do not reference each other, effectively eliminating the subject convergence. On the other hand, Reposition Attention involves scaling and repositioning subjects in both reference and target images to the same position within the images. This ensures that subjects in the target image can better reference those in the reference image, thereby maintaining better consistency. Extensive experiments demonstrate that IR-Diffusion significantly enhances multi-subject consistency, outperforming all existing methods in open-domain scenarios.

cs.CV↗

arXiv2025

Extreme Mass-Ratio Inspirals in Active Galactic Nucleus Disks: The Role of Circumsingle Disks

In this work, we numerically explore the dynamics of a point mass (e.g., a stellar-mass black hole) moving within a thin accretion disk of a massive object (i.e., a supermassive black hole) with three dimensional hydrodynamical simulations using \texttt{Athena++}. We are particularly interested in the regime that the Hill radius of the point mass is greater than the disk thickness, but the point mass is not sufficiently massive to open a ``gap" in a high viscosity disk. This parameter regime may be seen for stellar-mass objects moving within thin accretion disks of massive black holes, but less studied for the planet migration scenario in protoplanetary disks. We find that the disk migration may be significantly slower than the type I migration, depending on the surface density gradient of the disk. Furthermore, the circumsingle disk around the point mass plays an important role in damping the orbital eccentricity. If the gravitational interaction between the point mass and circumsingle disk material is turned off, the orbital eccentricity may be pumped to $\mathcal{O}(10^{-2})$ level. Because space-borne gravitational wave detectors such as LISA (Laser Interferometer Space Antenna) is able to measure the eccentricity of extreme mass-ratio inspirals to the level of $\mathcal{O}(10^{-5})$, this finding highlights the importance of understanding stellar-mass black hole feedback mechanisms which will modify the structures of the circumsingle disk, as they will impact LISA observables such as the eccentricity.

astro-ph.HE↗

arXiv2025

"Half-Bogoliubons" as the intermediate states for the phase coherence in underdoped cuprates

Superconductivity is achieved by the pairing of electrons and phase coherence between the Cooper pairs. According to the Bardeen-Cooper-Schrieffer theory, the quasiparticles with Bogoliubov dispersion exists and reveal particle-hole symmetric coherence peaks on the single particle tunneling spectrum. Here we report the observation of two kinds of tunneling spectra showing only one side of the "coherence peak" but with symmetric energies (about +-11 meV) in underdoped cuprate superconductor Bi2Sr2-xLaxCuO6 single crystals (p=0.114) with fractional superconductivity. Merging these two kinds of spectra can mimic the complete Bogoliubov dispersion, thus we name the electronic states associated with these half-peaked spectrum as "half Bogoliubons". In previous studies, it was shown that two doped holes may bind into a local pair within the 4a0 x 4a0 plaquette of CuO bonds (a0: distance between nearest Cu atoms). We attribute the "half-Bogoliubons" to the intermediate states for the phase coherence, and they correspond to the three-hole and one-hole states as the excited ones from the local pairing state of two holes. An entanglement of these two "half-Bogoliubons" would mean the dynamic hopping of charge freedom resulting in the phase coherence between the local paired states. Our results unravel a unique process for establishing the phase coherence through exchanging a charge between the regions with local pairs.

cond-mat.supr-con↗

arXiv2025

Unprecedentedly large gap in HgBa$_2$Ca$_2$Cu$_3$O$_{8+δ}$ with the highest $T_c$ at ambient pressure

In cuprate superconductors, the highest $T_c$ is possessed by the HgBa$_2$Ca$_2$Cu$_3$O$_{8+δ}$ (Hg-1223) system at ambient pressure, but the reason remains elusive. Here we report the scanning tunneling measurements on the Hg-1223 single crystals with $T_c$ = 134 K. The observed gaps determined from the tunneling spectra (STS) can be categorized into two groups: the smaller gap $Δ_1$ ranges from about 45 to 70 meV, while the larger gap $Δ_2$ from about 65 to 98 meV. The STS was measured up to 200 K and the larger gap can persist well above $T_c$, indicating a pseudogap feature which may reflect the strong pairing energy in the inner layer. Interestingly, an extremely strong particle-hole asymmetry is observed in associating with a very robust coherence-like peak at the bias of the larger gap in the hole branch of the Bogoliubov dispersion. We argue that the observed asymmetry results may be from the interplay of a flat band (van Hove singularity) in the electronic spectrum and the large gap in the underdoped (inner) layer. A theoretical approach based on a trilayer model with an interlayer coupling can give a reasonable explanation. Our results provide deep insight into understanding the mechanism of superconductivity in cuprate superconductors.

cond-mat.supr-con↗

arXiv2025

Possible Causes of False General Relativity Violations in Gravitational Wave Observations

General relativity (GR) has proven to be a highly successful theory of gravity since its inception. The theory has thrivingly passed numerous experimental tests, predominantly in weak gravity, low relative speeds, and linear regimes, but also in the strong-field and very low-speed regimes with binary pulsars. Observable gravitational waves (GWs) originate from regions of spacetime where gravity is extremely strong, making them a unique tool for testing GR, in previously inaccessible regions of large curvature, relativistic speeds, and strong gravity. Since their first detection, GWs have been extensively used to test GR, but no deviations have been found so far. Given GR's tremendous success in explaining current astronomical observations and laboratory experiments, accepting any deviation from it requires a very high level of statistical confidence and consistency of the deviation across GW sources. In this paper, we compile a comprehensive list of potential causes that can lead to a false identification of a GR violation in standard tests of GR on data from current and future ground-based GW detectors. These causes include detector noise, signal overlaps, gaps in the data, detector calibration, source model inaccuracy, missing physics in the source and in the underlying environment model, source misidentification, and mismodeling of the astrophysical population. We also provide a rough estimate of when each of these causes will become important for tests of GR for different detector sensitivities. We argue that each of these causes should be thoroughly investigated, quantified, and ruled out before claiming a GR violation in GW observations.

gr-qc↗

arXiv2025

Preformed Cooper Pairs in a Triclinic Iron Pnictide Superconductor

Electron pairing along with phase coherence generates superconductivity below the critical temperature ($T_c$). In underdoped high-$T_c$ cuprates, these two quantum phenomena may occur at separate temperatures, which was lately confirmed in the quasi-two-dimensional (quasi-2D) iron chalcogenide superconductors. Here, we report a systematic investigation on the pre-pairing behavior in a triclinic iron pnictide superconductor (Ca$_{0.85}$La$_{0.15}$)$_{10}$(Pt$_3$As$_8$)(Fe$_2$As$_2$)$_5$ with $T_c \approx $ 30 K, where the superconductivity is quasi-2D manifested by the Berezinskii-Kosterlitz-Thouless behaviors. Inelastic neutron scattering experiments unambiguously reveal a spin resonance peak around $E_R =$ 13 meV in the superconducting state, but its intensity continuously decreases when warming up across $T_c$, accompanied with an anomaly around $T^{*}\approx$ 45 K in spin correlations, and a suppression by an in-plane magnetic field persisting to the same temperature. Below $T^{*}$, a significant Nernst signal and a reduction of density of states at the Fermi level are also observed. These results suggest that the precursor of spin resonance is highly related to the preformed Cooper pairs driven by phase fluctuations, much like the pseudogap case in cuprates.

cond-mat.supr-con↗