arXiv subjects

Xiong Jiang

Publications and source records attributed to Xiong Jiang.

12 recordsLinked to original sources

arXiv2026

Transition of Photonic Dissipative Dynamics through the Exceptional Point

The decay of light in an optical structure depends not only on the intrinsic properties of the material but also on the surrounding electromagnetic environment. This principle has laid the foundation for the engineering of dissipation in photonic emitters. In the conventional wisdom, dissipation is governed by a fixed set of decay channels, each defined by the eigenstates of the structure, and energy leaks through and interacts with these channels. Here we provide experimental evidence that this paradigm fails in non-Hermitian systems. Specifically, we observe an accelerated transient decay in a pair of coupled microcavities tuned near the exceptional point, revealing that photonic dissipation can be governed not by reconfiguring existing loss channels, but rather by restructuring the underlying state space. The universality of this phenomenon is corroborated through two independent control parameters.The finding provides a new perspective on dissipative dynamics in open optical systems and offers a distinct mechanism for controlling transient decay in ultrafast photonic systems.

physics.optics↗

arXiv2026

Fermi-LAT Detection of a Gamma-ray Excess toward the Radio-quiet Narrow-line Seyfert 1 Galaxy 1H 1934-063

We report a $γ$-ray excess toward the radio-quiet narrow-line Seyfert 1 galaxy 1H 1934-063 using data collected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope and taking into account the LAT 16-year Source List (FL16Y). During the flare interval, the excess is detected in the 1--500 GeV band at a significance of $\sim 5.2σ$ (TS = 27.12), with a photon flux of $(4.94\pm2.33)\times10^{-10}$ ph cm$^{-2}$ s$^{-1}$ and a hard photon index of $Γ=1.50\pm0.25$. The best-fit $γ$-ray position is consistent with the radio position of 1H 1934-063, while the nearby source FL16Y J1936.9-0552 is not significantly detected during the same interval. In the absence of contemporaneous multiwavelength data, the broadband interpretation cannot be tightly constrained. A compact nonthermal component can produce the hard GeV emission, but the present data do not allow a unique physical interpretation. The excess therefore provides an interesting case for probing high-energy activity in radio-quiet NLS1 galaxies, although the underlying physical mechanism remains uncertain.

astro-ph.HE↗

arXiv2026

Bound state in the continuum induced room-temperature superfluorescence

Superfluorescence is a collective emission from several quantum emitters that initially have random phases and are then synchronized through vacuum field interactions. Despite its fascinating prospects in quantum information processing, optical computing and advanced photonic devices, a key challenge in harnessing superfluorescence is alleviating its reliance on cryogenic conditions. Recently, room-temperature superfluorescence has been successfully achieved using upconverted nanoparticles and quasi two-dimensional lead halide perovskites. These approaches, however, are restricted to a few specific material designs and unsuitable for wide promotion. Here, we report a universal strategy to elevate the operating temperature of superfluorescence. We reveal that the symmetry-protected optical bound state in the continuum (BIC) can break the size limitation of superfluorescence (λ^3) and correlate distant but similar emitters without violating the selection rules, significantly accelerating synchronization process and promoting the possibility of room-temperature superfluorescence. This effect has been experimentally verified using a series of BIC metasurfaces made of different lead halide perovskites. Key features such as the quadratic increase in transient peak intensity and the reduction in pulse width and build-up time at the BIC wavelength confirm the realization of room-temperature superfluorescence that is absent in the pristine material. A theoretical model is also built to explain the experimental observations. This research demonstrates that the operating temperatures of coherent macroscopic states can be effectively improved by artificial field, paving a critical step towards constructing building blocks for optical and quantum applications.

physics.optics↗

arXiv2026

The $γ$-ray-emitting blazar B3 1239+376 at $z$ = 3.82 identified in a multi-wavelength context

Among thousands of extragalactic $γ$-ray emitters, only a handful of distant ($z >$ 3) sources are detected. Yet, they are crucial probes shedding light on the cosmic evolution of jets of active galactic nuclei and the initial phase of mass growth of supermassive black holes. Here, we report on a multi-band study of the radio quasar B3 1239+376 with $z$ = 3.82. By analyzing the Fermi-LAT data, a significant (globally 7.7$σ$) $γ$-ray source in its direction, with an estimated association probability of 0.91, is observed in a half-year period of 2025. The analysis also reveals the emergence of co-spatial $γ$-ray residues in prior epochs. Moreover, the $γ$-ray and infrared light curves obtained from WISE and SPHEREx observations are likely correlated, as we observe that the emissions in both bands peak at the same time. The temporal coincidence establishes a firm association relationship between the $γ$-ray source and the quasar. Therefore, B3 1239+376 is proposed as the third most distant $γ$-ray detected blazar to date. Benefiting from the multi-wavelength observations, broadband spectral energy distributions in different flux states are compiled and reproduced by the classic one-zone leptonic radiation model to investigate the jet properties. Considering the recent brightening in $γ$ rays, prompt follow-up observations are encouraged, especially radio interferometry observations which may catch the potential ejection of a new jet blob.

astro-ph.HE↗

arXiv2026

The First GeV Gamma-Ray Flares from the CSO-like Source 4C 76.03

We report the first detection of GeV gamma-ray flaring activity from the compact symmetric object (CSO)-like source 4C 76.03, based on 17 years of Fermi-LAT observations. Its long-term, time-averaged gamma-ray properties are consistent with the 4FGL-DR4 catalog. However, a time-resolved analysis with 100-day binning reveals two prominent flares occurring on timescales of approximately 30 days and 20 days, separated by about 2.5 years, with nearly identical fluxes, test statistic (TS) values, and photon indices. The short-timescale variability indicates localized and transient energy dissipation in the nuclear region, likely associated with newly injected jet components. Although the gamma-ray emission does not directly trace the long-term jet power responsible for building the observed radio structure, it demonstrates that the central engine remains active. In the context of CSO evolution, 4C 76.03 may represent a rare transitional case, where repeated energy injections allow the source to exceed the canonical 500 pc scale of most CSOs, providing key insight into the early stages of radio jet evolution.

astro-ph.HE↗

arXiv2026

Photonic Neuromorphic Computing enabled by a BIC Metasurface

Photonic neuromorphic computing promises revolutionary advances in parallel and high-speed processing, yet a key challenge persists: co-integrating nonlinearity, dense connectivity, and intrinsic memory monolithically to enable brain-inspired, spatiotemporal information processing. Here, we overcome this challenge by introducing a monolithic photonic recurrent network based on an active metasurface operating at bound state in the continuum (BIC). The BIC mode mediates strong,long-range coupling across the lattice, creating a reconfigurable recurrent network topology in hardware. Concurrently, the gain medium provides both optical nonlinearity for neuronal activation and a finite carrier lifetime that serves as a built in, analog temporal memory. This synergy enables computation to emerge directly from the collective spatiotemporal dynamics of the driven-dissipative photonic system, effectively realizing a physical reservoir computer on a chip. We experimentally validate a minimal yet physically complete system on benchmark tasks: brain MRI image classification and human action recognition, achieving 92.16% and 85.36% accuracies, respectively. This work establishes a scalable pathway toward ultrafast, energy-efficient neuromorphic intelligence where processing is an inherent property of tailored light matter interaction.

physics.optics↗

arXiv2026

First Detection of $γ$-Ray Emission from the Compact Symmetric Object JVAS J1311+1658

We report the first detection of $γ$-ray emission from the young radio galaxy JVAS~J1311+1658, classified as a compact symmetric object (CSO). This detection is characterized by a recent GeV $γ$-ray flare identified in Fermi-LAT data during MJD~60032.6--60132.6, with a $γ$-ray source detected at a significance level of $\sim6.2σ$. The average 0.1--300~GeV flux is measured to be $(1.6 \pm 0.6)\times10^{-8}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$, with a photon spectral index of $Γ= 2.15 \pm 0.185$. We find that a radiative model of the radio lobes significantly underestimates the observed $γ$-ray emission. The strong flux and short-term variability over $\sim$100 days suggest that the emission likely originates from newly launched sub-kiloparsec-scale jets at the core. This detection provides a unique window into the extreme environments and early-stage jet activity of young radio galaxies, offering insights into their initial evolution and the formation of relativistic jets in the earliest phases of galaxy growth.

astro-ph.HE↗

arXiv2025

A nearby FR I type radio galaxy 3C 120 as a possible PeV neutrino emitter

Although connections between flaring blazars and some IceCube neutrinos have been established, the dominant sources for the bulk extragalactic neutrino emissions are still unclear and one widely suggested candidate is a population of radio galaxies. Because of their relatively low $γ$-ray radiation luminosities ($L_γ$), it is rather challenging to confirm such a hypothesis with the neutrino/GeV $γ$-ray flare association. Here we report on the search for the GeV $γ$-ray counterpart of the neutrino IC-180213A and show that the nearby ($z$ = 0.03) broad line radio galaxy 3C 120 is the only known co-spatial GeV $γ$-ray source in a half-year epoch around the neutrino detection. An intense $γ$-ray flare, the second strongest one among the entire 16-year period, is temporally coincident with the detection of IC-180213A. Moreover, accompanying optical brightenings in $g$-band and $V$-band are observed. We also find that the IC-180213A / 3C 120 association follows the $L_γ$-$D_{L}^{2}$ correlation for the neutrino sources (candidates), including NGC 1068 and some blazars. These facts suggest that 3C 120 is a candidate for emitting high-energy neutrinos and may offer an initial evidence for the radio galaxy origin of some PeV neutrinos.

astro-ph.HE↗

arXiv2025

Leptohadronic Multimessenger Modeling of Two High-redshift (z $>$ 1) Neutrino Emission Blazar Candidates

The blazars are one of the leading candidate sources of high-energy neutrinos. Recently, two blazars have been found to be temporally and spatially correlated with some IceCube high-energy neutrino events. The two blazars, GB6 J2113+1121 and NVSS J171822+423948, are Flat Spectrum Radio Quasars (FSRQs) with redshifts greater than unity. In particular, NVSS J171822+423948 has a redshift of 2.7, which provides an important probe for studying the radiation processes of jets from active galactic nuclei in the early universe. To better understand the physical origin of the IceCube neutrinos, we adopt the one-zone leptohadronic model to fit the multimessenger emission of GB6 J2113+1121 and NVSS J171822+423948 during their $γ$-ray flaring periods and then calculate the high-energy neutrino detection probability. The chance of detecting a single muon neutrino from these two sources is found to be $\sim 2\%$ and $0.8\%$, respectively. Although such detection rates are not high mainly because of their high redshifts, our investigation strongly suggests that these sources are efficient PeV neutrino emitters. Our results also indicate that electromagnetic cascades produced by hadronic processes contribute significantly to X-ray and $γ$-ray emissions. However, high-energy $γ$-rays can be severely absorbed by the soft photon field from the broad-line region (BLR), which weakens the correlation between $γ$-rays and neutrinos, while suggesting a stronger connection between X-rays and neutrinos. We predict that IceCube will continue to detect neutrinos from FSRQs with redshifts greater than 1 in the future.

astro-ph.HE↗

arXiv2024

A $γ$-Ray Emitting Blazar at Redshift 3.64: Fermi-LAT and OVRO Observations of PKS 0201+113

High-redshift ($z >3$) $γ$-ray blazars are rare, but they are crucial for our understanding of jet evolution, $γ$-ray production and propagation, and the growth of supermassive black holes in the early universe. A new analysis of Fermi-LAT data reveals a significant (5$σ$), spectrally soft ($Γ\simeq$ 3.0) $γ$-ray source in a specific 4-month epoch, cospatial with PKS 0201+113 ($z$ = 3.64). Monitoring of PKS 0201+113 at 15 GHz by the Owens Valley Radio Observatory 40 m Telescope from 2008 to 2023 shows a prominent flare that dominates the radio light curve. The maximum of the radio flare coincides with the $γ$-ray flare, strongly suggesting an association ($\textrm{p-value}=0.023$) between the $γ$-ray and the radio sources. PKS 0201+113 is only the third $γ$-ray blazar to be identified with $z> 3.5$, and it is the first such object to be identified by the detection of quasi-simultaneous $γ$-ray and radio flares. The jet properties of this peculiar blazar have been investigated. A detailed study of a two-zone leptonic model is presented that fits the broadband spectral energy distribution. An alternative scenario is also briefly discussed.

astro-ph.HE↗

arXiv2024

Awakening of A Blazar at Redshift 2.7 Temporally Coincident with Arrival of Cospatial Neutrino Event IceCube-201221A

We report on multiwavelength studies of a blazar NVSS J171822+423948, which is identified as the low-energy counterpart of 4FGL J1718.5+4237, the unique $γ$-ray source known to be cospatial with the IceCube neutrino event IC-201221A. After a 12-year long quiescent period undetected by Fermi-LAT, $γ$-ray activities with a tenfold flux increase emerge soon (a few tens of days) after arrival of the neutrino. Associated optical flares in the ZTF $g$, $r$, and $i$ bands are observed together with elevated WISE infrared fluxes. Synchronized variations suggest that both the $γ$-ray emission and the neutrino event are connected to the blazar. Furthermore, the optical spectrum reveals emission lines at a redshift $z$ = 2.68 $\pm$ 0.01. Thus, it is the first candidate for a neutrino-emitting blazar at the redshift above 2. Discussions of theoretical constraints of neutrino production and comparisons with other candidates are presented.

astro-ph.HE↗

arXiv2024

Controllable distant interactions at bound state in the continuum

Distant interactions at arbitrary locations and their dynamic control are fundamentally important for realizing large-scale photonic and quantum circuits. Conventional approaches suffer from short coupling distance, poor controllability, fixed locations and low wavelength uniformity, significantly restricting the scalability of photonic and quantum networks. Here, we exploit the intrinsic advantages of optical bound state in the continuum (BIC) and demonstrate an all-in-one solution for dynamically controllable long-range interactions. BIC metasurface can support a series of finite-sized quasi-BIC microlasers at arbitrary locations. The quasi-BICs microlasers have the same wavelength and are inherently connected through BIC waveguide. Consequently, the coupling distances in experiment increase significantly from subwavelength to tens of micrometers. Such long-range interaction in BIC metasurface enables scaling to two-dimensional architectures and ultrafast control of internal laser actions, e.g., non-Hermitian zero-mode lasing and enhanced optical gain. This research shall facilitate the advancement of scalable and reconfigurable photonic networks.

physics.optics↗