arXiv subjects

Hongwei Yu

Publications and source records attributed to Hongwei Yu.

At least 55 records · Page 3Linked to original sources

arXiv2025

Significant circular Unruh effect at small acceleration

We study the transition rates of an atom rotating in a circular orbit, which is coupled with fluctuating electromagnetic fields in vacuum. We find that when the rotational angular velocity exceeds the transition frequency of the atom, the excitation rate can reach the same order of magnitude as the emission rate, even with an extremely low centripetal acceleration resulting from a very small orbital radius. For experimentally accessible centripetal accelerations, the excitation rate of centripetally accelerated atoms can be $10^{272,878}$ times greater than that of linearly accelerated atoms with the same magnitude of acceleration. Our result suggests that the circular version of the Unruh effect can be significant even at very small centripetal accelerations, contrary to the common belief that a large Unruh effect requires large acceleration. This finding sheds new light on the experimental detection of the circular Unruh effect.

gr-qc↗

arXiv2025

Constraining inflation with nonminimal derivative coupling with the Parkes Pulsar Timing Array third data release

We study an inflation model with nonminimal derivative coupling that features a coupling between the derivative of the inflaton field and the Einstein tensor. This model naturally amplifies curvature perturbations at small scales via gravitationally enhanced friction, a mechanism critical for the formation of primordial black holes and the associated production of potentially detectable scalar-induced gravitational waves. We derive analytical expressions for the primordial power spectrum, enabling efficient exploration of the model parameter space without requiring computationally intensive numerical solutions of the Mukhanov-Sasaki equation. Using the third data release of the Parkes Pulsar Timing Array (PPTA DR3), we constrain the model parameters characterizing the coupling function: $ϕ_c = 3.7^{+0.3}_{-0.5} M_\mathrm{P}$, $\log_{10} ω_L = 7.1^{+0.6}_{-0.3}$, and $\log_{10} σ= -8.3^{+0.3}_{-0.6}$ at 90\% confidence level. Our results demonstrate the growing capability of pulsar timing arrays to probe early Universe physics, complementing traditional cosmic microwave background observations by providing unique constraints on inflationary dynamics at small scales.

gr-qc↗

arXiv2025

Repulsive quantum gravitoelectric-gravitomagnetic interaction

We investigate, in the framework of linearized quantum gravity, the quantum gravitational interaction between a gravitoelectrically polarizable object and a gravitomagnetically polarizable object. This interaction originates from the coupling between the instantaneous mass quadrupole moment and the mass-current quadrupole moment of the objects, induced by fluctuating gravitoelectric and gravitomagnetic fields in a vacuum. Using leading-order perturbation theory, we derive the explicit expression of the quantum gravitoelectric-gravitomagnetic interaction energy, which shows a distance dependence of $r^{-8}$ in the near regime and $r^{-11}$ in the far regime, where $r$ is the distance between the two objects. Remarkably, this interaction energy is positive, indicating that the force is repulsive. Since interactions between objects polarizable in the same gravitoelectric or gravitomagnetic manner are inherently attractive, for objects which are both gravitoelectrically and gravitomagnetically polarizable, the overall quantum gravitational interaction potential is reduced when the repulsive quantum gravitoelectric-gravitomagnetic interaction is taken into account. However, for two isotropically polarizable objects with identical gravitoelectric and gravitomagnetic polarizabilities and energy level spacing, the repulsive quantum interaction cannot surpass the attractive interactions.

gr-qc↗

arXiv2025

$\textrm{A}^{\textrm{2}}$RNet: Adversarial Attack Resilient Network for Robust Infrared and Visible Image Fusion

Infrared and visible image fusion (IVIF) is a crucial technique for enhancing visual performance by integrating unique information from different modalities into one fused image. Exiting methods pay more attention to conducting fusion with undisturbed data, while overlooking the impact of deliberate interference on the effectiveness of fusion results. To investigate the robustness of fusion models, in this paper, we propose a novel adversarial attack resilient network, called $\textrm{A}^{\textrm{2}}$RNet. Specifically, we develop an adversarial paradigm with an anti-attack loss function to implement adversarial attacks and training. It is constructed based on the intrinsic nature of IVIF and provide a robust foundation for future research advancements. We adopt a Unet as the pipeline with a transformer-based defensive refinement module (DRM) under this paradigm, which guarantees fused image quality in a robust coarse-to-fine manner. Compared to previous works, our method mitigates the adverse effects of adversarial perturbations, consistently maintaining high-fidelity fusion results. Furthermore, the performance of downstream tasks can also be well maintained under adversarial attacks. Code is available at https://github.com/lok-18/A2RNet.

cs.CV↗

arXiv2025

Infrared Behavior of Induced Gravitational Waves from Isocurvature Perturbations

Induced gravitational waves provide a powerful probe of primordial perturbations in the early universe through their distinctive spectral properties. We analyze the spectral energy density $Ω_{\text{GW}}$ of gravitational waves induced by isocurvature scalar perturbations. In the infrared regime, we find that the spectral slope $n_{\text{GW}} \equiv \text{d} \lnΩ_\mathrm{GW}/\text{d}\ln k$ takes the log-dependent form $3-4/ \ln (\tilde{k}_*^2 / 6k^2)$, where $\tilde{k}_*$ represents the effective peak scale of the primordial scalar power spectrum. This characteristic behavior differs markedly from that of adiabatic-induced gravitational waves, establishing a robust observational discriminant between isocurvature and adiabatic primordial perturbation modes.

gr-qc↗

arXiv2025

High-fidelity Generation of Bell and W States in Giant Atom System via Bound State in the Continuum

In this paper, we propose a high-fidelity scheme for generating entangled states in a system of two and three giant atoms coupled to the coupled resonator waveguide. Our approach leverages the bound state in the continuum, which is robust against waveguide disorder. Specifically, we achieve a fidelity exceeding $98\%$ for Bell state generation, overcoming the limitations of conventional decoherence-free interaction mechanisms. This scheme can be readily extended to a three-giant-atom system for generating W states. In both the two- and three-atom setups, the maximally entangled states are generated in a short time and remain stable even as time approaches infinity. Our proposal is feasible for implementation on state-of-the-art solid-state quantum platforms and significantly broadens the applications of giant atoms and waveguide QED system in quantum information processing.

quant-ph↗

arXiv2024

Neutron stars in Gauss-Bonnet extended Starobinsky gravity

Recently, a class of Gauss-Bonnet extended Starobinsky gravity was proposed, allowing black holes to carry ghost-free massive scalar hair for the first time without requiring additional matter fields. This intriguing feature offers a new perspective for understanding higher-curvature pure gravity and highlights the importance of further studying the potential effects of Gauss-Bonnet extensions in gravitational systems beyond black holes. In this study, we investigate the properties of neutron stars within this model, focusing on how the higher-curvature terms, particularly the coupling between the Gauss-Bonnet term and the curvature-squared term, impact the stellar structure. We present a detailed analysis of these effects and compute the moment of inertia for rotating neutron stars under the slow-rotation approximation. The substantial differences in the moment of inertia between general relativity and Gauss-Bonnet extended Starobinsky gravity are expected to be detectable through future high-precision observations.

gr-qc↗

arXiv2024

Rabi oscillation and fractional population via the bound states in the continuum in a giant atom waveguide QED setup

We study the dynamics of two giant atoms interacting with a coupled resonator waveguide (CRW) beyond the Markovian approximation. The distinct atomic configurations determine the number of bound states in the continuum (BIC), leading to different dynamical behaviors. Our results show that when the system supports two BICs, Rabi oscillations dominate the dynamics, whereas fractional population dynamics emerge in the presence of a single BIC. The connection between these dynamics and the existence of BICs is further verified by analyzing the photonic distribution in the CRW during time evolution. These findings challenge the conventional notion that the environment always induces dissipation and decoherence. Instead, the bound states in the CRW-emitters coupled system can suppress complete dissipation of the emitters. This work offers an effective approach for controlling dissipative dynamics in open quantum systems.

quant-ph↗

arXiv2024

Interaction between Unruh-Dewitt detectors exclusively due to acceleration: A Parallel to the FDU Effect

We have discovered an interaction between two detectors in a vacuum that emerges exclusively due to acceleration, akin to the spontaneous excitation of a single detector as predicted by the Fulling-Davies-Unruh (FDU) effect. However, this interaction contrasts sharply with the FDU effect, which suggests that a uniformly accelerated detector behaves as if it were in a thermal bath, as the discovered interaction does not manifest in a thermal environment. The novel interaction displays unique dependencies on the separation between detectors: it can be either attractive or repulsive, with the potential to transition between these behaviors as the inter-detector separation changes. More intriguingly, it exhibits a surprising large-small duality in its dependence on acceleration, suggesting the existence of an optimal acceleration at which the interaction is strongest, in contrast to the monotonic acceleration-dependence of the FDU effect.

gr-qc↗

arXiv2024

Fed-MUnet: Multi-modal Federated Unet for Brain Tumor Segmentation

Deep learning-based techniques have been widely utilized for brain tumor segmentation using both single and multi-modal Magnetic Resonance Imaging (MRI) images. Most current studies focus on centralized training due to the intrinsic challenge of data sharing across clinics. To mitigate privacy concerns, researchers have introduced Federated Learning (FL) methods to brain tumor segmentation tasks. However, currently such methods are focusing on single modal MRI, with limited study on multi-modal MRI. The challenges include complex structure, large-scale parameters, and overfitting issues of the FL based methods using multi-modal MRI. To address the above challenges, we propose a novel multi-modal FL framework for brain tumor segmentation (Fed-MUnet) that is suitable for FL training. We evaluate our approach with the BraTS2022 datasets, which are publicly available. The experimental results demonstrate that our framework achieves FL nature of distributed learning and privacy preserving. For the enhancing tumor, tumor core and whole tumor, the mean of five major metrics were 87.5%, 90.6% and 92.2%, respectively, which were higher than SOTA methods while preserving privacy. In terms of parameters count, quantity of floating-point operations (FLOPs) and inference, Fed-MUnet is Pareto optimal compared with the state-of-the-art segmentation backbone while achieves higher performance and tackles privacy issue. Our codes are open-sourced at https://github.com/Arnold-Jun/Fed-MUnet.

cs.CV↗

arXiv2024

Entanglement harvesting in cosmic string spacetime

We investigate the entanglement harvesting phenomenon for static detectors that locally interact with massless scalar fields in the cosmic string spacetime, which, though locally flat, features a conical structure defined by a deficit angle. Specifically, we analyze three detector alignments relative to the string: parallel and orthogonal alignments with detectors on the same side of the string, and an orthogonal alignment with detectors on opposite sides of the string. For the alignments on the same side of the string, we observe that the cosmic string's presence can either aid or hinder entanglement harvesting, affecting both the extent of entanglement harvested and the achievable range of interdetector separation. This effect depends on the distance between the detectors and the string and differs markedly from scenarios in a locally flat spacetime with a reflecting boundary, where the boundary invariably extends the harvesting-achievable range. Conversely, for the alignment with detectors on opposite sides of the string, we find that detectors consistently harvest more entanglement than those in a flat spacetime devoid of a cosmic string. This starkly contrasts the behavior observed with detectors on the same side. Interestingly, the presence of a cosmic string expands the harvesting-achievable range for detectors in orthogonal alignment only when near the string, whereas it invariably reduces the achievable range for detectors in parallel alignment.

quant-ph↗

arXiv2024

Probing Cosmic Background Dynamics with a Cosmological-model-independent Method

The Hubble constant $H_0$ tension has emerged as the most serious crisis in modern cosmology, potentially indicating that the $Λ$CDM model may not describe our universe accurately. In this paper, we establish a new, cosmological-model-independent method to study the cosmic background dynamics. Using the latest Pantheon+ Type Ia supernova (SN Ia) sample and the model-independent SN Ia sample (P+1690), we derive values for the luminosity distance, the Hubble parameter, and the deceleration parameter at five different redshift points ranging from 0.12 to 0.52. Our analysis shows that results obtained from the Pantheon+ sample align with the predictions of the $Λ$CDM model within 2$σ$ confidence level (CL), while those obtained from the P+1690 sample exhibit deviations of about $2\sim3σ$ CL. Furthermore, we explore the equation of state (EoS) of dark energy and find that while the EoS values from the Pantheon+ sample remain consistent with $-1$ within 2$σ$ CL, the P+1690 sample does not conform to this standard. These findings remain unchanged after the inclusion of the Hubble parameter measurements in our analysis. Our results indicate that the $Λ$CDM model remains compatible with the Pantheon+ SN Ia and the Hubble parameter measurements at 2$σ$ CL.

astro-ph.CO↗

arXiv2024

Alleviating the Hubble-constant tension and the growth tension via a transition of absolute magnitude favored by the Pantheon+ sample

We establish a cosmological-model-independent method to extract the apparent magnitude and its derivative at different redshifts from the Pantheon+ type Ia supernova sample, and find that the obtained values deviate clearly from the prediction of the $Λ$CDM model at the lowest redshift. This deviation can be explained as a result of a transition of the absolute magnitude $M$ in the low redshift region. The observations seem to favor this transition since the minimum values of $χ^2$ for two ansatzes of a varying $M$ are less than that of a constant $M$. The Hubble constant tension is alleviated from larger than $5σ$ to be about $1$ to $2σ$ for a varying $M$, and the growth tension can be resolved after attributing the variation of $M$ to a modification of the effective Newton's constant.

astro-ph.CO↗

arXiv2024

Entanglement island and Page curve for one-sided charged black hole

In this paper, we extend the method of calculating the entanglement entropy of Hawking radiation of black holes using the "in" vacuum state, which describes one-sided asymptotically flat neutral black hole formed by gravitational collapse, to dynamic charged black holes. We explore the influence of charge on the position of the boundary of island $\partial I$ and the Page time. Due to their distinct geometric structures, we discuss non-extremal and extremal charged black holes separately. In non-extremal cases, the emergence of island saves the bound of entropy at late times, and the entanglement entropy of Hawking radiation satisfies the Page curve. Moreover, we also find that the position of the boundary of island $\partial I$ depends on the position of the cutoff surface (observers), differing from the behavior in eternal charged black holes. In extremal black holes, when the island exists, the entanglement entropy is approximately equal to the Bekenstein-Hawking entropy, while the entanglement entropy becomes ill-defined when island is absent. Our analysis underscores how different geometric configurations significantly influence the behavior of entropy.

gr-qc↗

arXiv2024

Quantum gravitomagnetic interaction

In the framework of linearized quantum gravity, we study the quantum gravitational interaction between two nonpointlike objects induced by fluctuating gravitomagnetic fields in vacuum. We find that, in addition to the quantum gravitational interaction induced by fluctuating gravitoelectric fields previously studied, there exists a quantum gravitomagnetic interaction. This interaction originates from the interaction between the instantaneous localized mass currents in nonpointlike objects induced by the fluctuating gravitomagnetic fields. Using fourth-order perturbation theory, we derive the explicit form of the quantum gravitomagnetic interaction energy, which shows an $r^{-10}$ dependence in the near regime and an $r^{-11}$ dependence in the far regime, where $r$ is the distance between the two objects. This interaction energy is expected to be significant when the gravitomagnetic polarizability of the objects is large.

gr-qc↗

arXiv2024

Constraints on Cosmological Models from Quasars Calibrated with Type Ia Supernova by a Gaussian Process

In this paper, we use quasars calibrated from type Ia supernova (SN Ia) to constrain cosmological models. We consider three different X-ray luminosity ($L_{X}$) - ultraviolet luminosity ($L_{UV}$) relations of quasars, i.e., the standard $L_{X}$-$L_{UV}$ relation and two redshift-evolutionary relations (Type I and Type II) respectively constructed from copula and considering a redshift correction to the luminosity of quasars. Only in the case of the Type I relation, quasars can always provide effective constraints on the $Λ$CDM model. Furthermore, we show that, when the observational Hubble data (OHD) are added, the constraints on the absolute magnitude $M$ of SN Ia and the Hubble constant $H_0$ can be obtained. In the $Λ$CDM model, the OHD measurements plus quasars with the Type I relation yields $M$ =$-19.321^{+0.085}_{-0.076}$, which is in good agreement with the measurement from SH0ES ($M=-19.253\pm{0.027}$), and $H_0$ = $70.80\pm3.6~\mathrm{km~s^{-1}Mpc^{-1}}$, falling between the measurements from SH0ES and the Planck cosmic microwave background radiation data.

astro-ph.CO↗

arXiv2024

BotanicGarden: A High-Quality Dataset for Robot Navigation in Unstructured Natural Environments

The rapid developments of mobile robotics and autonomous navigation over the years are largely empowered by public datasets for testing and upgrading, such as sensor odometry and SLAM tasks. Impressive demos and benchmark scores have arisen, which may suggest the maturity of existing navigation techniques. However, these results are primarily based on moderate structured scenario testing. When transitioning to challenging unstructured environments, especially in GNSS-denied, texture-monotonous, and dense-vegetated natural fields, their performance can hardly sustain at a high level and requires further validation and improvement. To bridge this gap, we build a novel robot navigation dataset in a luxuriant botanic garden of more than 48000m2. Comprehensive sensors are used, including Gray and RGB stereo cameras, spinning and MEMS 3D LiDARs, and low-cost and industrial-grade IMUs, all of which are well calibrated and hardware-synchronized. An all-terrain wheeled robot is employed for data collection, traversing through thick woods, riversides, narrow trails, bridges, and grasslands, which are scarce in previous resources. This yields 33 short and long sequences, forming 17.1km trajectories in total. Excitedly, both highly-accurate ego-motions and 3D map ground truth are provided, along with fine-annotated vision semantics. We firmly believe that our dataset can advance robot navigation and sensor fusion research to a higher level.

cs.RO↗

arXiv2024

Resonant amplification of curvature perturbations in inflation model with periodical derivative coupling

In this paper, we introduce a weak, transient and periodical derivative coupling between the inflaton field and gravity, and find that the square of the sound speed of the curvature perturbations becomes a periodic function, which results in that the equation of the curvature perturbations can be transformed into the form of the Mathieu equation in the sub-horizon limit. Thus, the parametric resonance will amplify the curvature perturbations so as to generate a formation of abundant primordial black holes (PBHs). We show that the generated PBHs can make up most of dark matter. Associated with the generation of PBHs, the large scalar perturbations will give rise to the scalar induced gravitational waves which may be detected by future gravitational wave projects.

gr-qc↗