arXiv subjects

Y. Yin

Publications and source records attributed to Y. Yin.

At least 19 recordsLinked to original sources

arXiv2026

Probing a new subclass of llGRB-SN transients: Insights from EP250304a and its associated supernova

With the advent of the Einstein Probe (EP) mission, we are entering a new era in the study of gamma-ray bursts (GRBs), enabling the detection of faint, low-luminosity transients that would previously have gone undetected. EP250304a was an event discovered by EP associated with the broad-lined type Ic supernova (SN) SN 2025fhm located at z = 0.2. Despite no gamma-ray emission being detected at the time of the EP trigger, we identify evidence for a relativistic outflow consistent with a GRB-like jet across multiple wavelengths. We present a detailed spectral and photometric analysis of EP250304a/SN 2025fhm, including multi-band light curve modelling performed with the Redback Python package. We find that this event closely resembles low-luminosity GRB-SNe (llGRB-SNe) such as GRB 060218/SN 2006aj, GRB 100316D/SN 2010bh, and GRB 171205A/SN 2017iuk, all of which exhibit early-time emission consistent with a thermal shocked cocoon. These similarities suggest that EP250304A/SN 2025fhm may belong to an emerging subclass of shocked cocoon-dominated llGRB-SNe, representing the low-luminosity end of a broader continuum of engine-driven GRB-SN explosions.

astro-ph.HE↗

arXiv2026

Drag Crisis in Fractal Trees Revealed by Simulation and Theory

Trees are key roughness elements in urban environments, shaping airflow, microclimates, and pollutant dispersion. Yet the aerodynamic drag of complex tree-like structures at high Reynolds numbers remains poorly characterized compared with the well-studied drag crisis of simple bluff bodies. We combine large-scale lattice Boltzmann simulations with an analytical branch-wise drag model to examine fractal trees over a wide range of height-based Reynolds numbers, $Re_H$. Direct numerical simulations using a cumulant lattice Boltzmann method with adaptive mesh refinement cover $2.5\times10^3 \le Re_H \le 1.2\times10^5$, and the analytical model extends predictions to $Re_H \sim 10^9$. Under uniform inflow, the analysis indicates a drag-crisis transition near $Re_H \approx 3\times10^6$, with increasing structural complexity smoothing this transition because smaller branches remain subcritical. Introducing inflow turbulence with streamwise intensity $I_u \approx 8\%$, representative of atmospheric-boundary-layer winds, shifts the apparent onset to $Re_H \approx 1.5\times10^5$ and further moderates the drag reduction. Interpreted at full scale, this suggests that urban trees of order $10$--$30$ m exposed to winds of $1$--$10~\mathrm{m/s}$ generally operate in the crisis or post-crisis regime. In both uniform and turbulent inflow, the framework predicts a reversal in drag-coefficient ordering across geometries: simplified trees show lower drag in the subcritical regime but may exhibit higher drag in the supercritical regime, whereas more complex trees undergo a smoother, moderated crisis. These results challenge the common assumption that pruning always reduces aerodynamic loading and highlight the need to reassess vegetation-drag parameterizations and pruning strategies in high-$Re_H$ conditions.

physics.flu-dyn↗

arXiv2026

Statistics and systematics of electron EDM searches with BaF

The NL-$e$EDM experiment searches for a non-zero electric dipole moment of the electron $d_e$ ($e$EDM) in the ground state of barium monofluoride (BaF). A beam of BaF from a supersonic expansion source is probed with the spin precession method presented in \cite{Boeschoten2024}. This method permits the extraction of an $e$EDM value as well as values for parameters causing a possible systematic bias leading to a false $e$EDM. The currently achievable sensitivity is limited by statistics collected in a period of 34 hours and yields an $d_e$ of $2(3) \times 10^{-25}$ $e\,$cm. Furthermore, from the same dataset sufficiently strong limits on parameters which can induce a false $e$EDM are extracted. These are mainly the electric field \textbf{E} and the intensity of the lasers fields in the fiducial volume of the experiment. We summarize the steps required to upgrade of the experiment to reach a competitive level on $d_e$, e.g. an intense laser-cooled beam from a cryogenic buffer gas source and the light collection efficiency of fluorescence.

physics.atom-ph↗

arXiv2025

Reentrant localization in fractionally charged electron wave packets

We investigate the localization transition in fractionally charged electron wave packets, which is injected into a quantum conductor by a single voltage pulse with arbitrary flux quantum. We show that the transition is unidirectional for individual electrons or holes. They always undergo a delocalization-to-localization transition as the flux increases. In contrast, the transition of the neutral electron-hole pairs is bidirectional. As the flux increases, the transition can be a localization-to-delocalization transition or vice versa, which is controlled via the long-time tail of the voltage pulse. The localization-to-delocalization transition occurs in the case of short-tailed pulses, which decay faster than Lorentzian. In this case, the directions of the transitions for the neutral eh pairs and individual electrons or holes are opposite. Certain localized neutral electron-hole pairs can first evolve into delocalized ones, then split into individual electrons and holes with localized wave functions, which gives a reentrant localization. The delocalization-to-localization transition occurs in the case of long-tailed pulses, which decay slower than Lorentzian. The reentrant localization vanishes in this case, as the directions of the two transitions are the same. It is also absent in the case of Lorentzian pulses, where the localized neutral electron-hole pairs cannot be excited at all.

cond-mat.mes-hall↗

arXiv2025

Matrix-Valued Orthogonal Polynomials Related to a Class of Random Walk

The foundational work of Karlin and McGregor established a powerful connection between random walks with tridiagonal transition matrices and the theory of orthogonal polynomials. We consider a particular extension of this framework, where the transition matrix is given by a polynomial in a tridiagonal matrix. This generalization leads to transitions beyond the nearest neighbors. We investigate the matrix-valued orthogonal polynomials associated with these extended models, derive the corresponding matrix-valued measure of orthogonality explicitly, and analyze how spectral properties of the transition matrix relate to probabilistic features of the random walk. As an application, we study generalized Ehrenfest models that incorporates longer-range transitions.

math.PR↗

arXiv2025

Low-energy effective theory of localization-delocalization transition in noninteger-charged electron wave packets

We present a low-energy effective theory to describe the localization-delocalization transition, which occurs for wave functions of electrons and holes injected individually by a voltage pulse with noninteger flux quantum. We find that the transition can be described by an effective scattering matrix in a truncated low-energy space, which is composed of two parts. The first part describes the infrared-divergence of the scattering matrix, while the second part represents the high-energy correlation. For short-tailed pulses which decay faster than Lorentzian, the scattering matrix exhibits solely an inverse linear divergence in the infrared limit. The divergence is responsible for the dynamical orthogonality catastrophe, which leads to electron-hole pairs with delocalized wave functions. In contrast, the high-energy correlation can be approximated by a constant term, which leads to electron-hole pairs with localized wave functions. Due to the competition between the two terms, the wave functions can undergo a localization-delocalization transition, which occurs for electrons and holes injected individually by the voltage pulse. As a consequence, the localization-delocalization transitions for all short-tailed pulses can be described by the same effective scattering matrix, suggesting that they belong to the same universality class. For pulses with longer tails, the scattering matrix can exhibit additional infrared-divergences. We show that a Lorentzian pulse gives rise to a logarithmic divergence, while a fractional-powered Lorentzian pulse gives rise to a power-law divergence. The additional divergence can lead to localization-delocalization transitions belonging to different universality classes. These results demonstrate the fine-tuning capabilities of the localization-delocalization transition in time-dependent quantum transport.

cond-mat.mes-hall↗

arXiv2024

Localization-delocalization transition in non-integer-charged electron wave packets

We investigate the wave function of electrons and holes injected by voltage pulses with non-integer flux quantum. We find that the wave function can be delocalized in the time domain, which is measured by using the inverse participation ratio. As the flux approaches an integer multiples of flux quantum, the wave function can either remain delocalized or undergo a localization-delocalization transition. The former case occurs for the neutral electron-hole pairs, while the latter case occurs for electrons and holes which are injected individually. We perform the finite-size scaling analysis of the inverse participation ratio to further clarify the nature of the localization-delocalization transition. The scaling function and correlation length are determined numerically by the data collapse method. We find that the localization-delocalization transition is universal in the sense that the scaling function and correlation length is insensitive to the pulse profile when the pulse is sufficiently sharp. In contrast, they exhibit quantitatively different behavior for the Lorentzian pulse, indicating the corresponding localization-delocalization transition belongs to a different universality class.

cond-mat.mes-hall↗

arXiv2022

Quantum-to-Classical Crossover in Single-electron Emitter

We investigate the temperature-driven quantum-to-classical crossover in a single-electron emitter. The emitter is composed of a quantum conductor and an electrode, which is coupled via an Ohmic contact. At zero temperature, it has been shown that a single electron can be injected coherently by applying an unit-charge Lorentzian pulse on the electrode. As the electrode temperature increases, we show that the electron emission approaches a time-dependence Poisson process at long times. The Poissonian character is demonstrated from the time-resolved full counting statistics. In the meantime, we show that the emission events remain correlated, which is due to the Pauli exclusion principle. The correlation is revealed from the emission rates of individual electrons, from which a characteristic correlation time can be extracted. The correlation time drops rapidly as the electrode temperature increases, indicating that correlation can only play a non-negligible role at short times in the high-temperature limit. By using the same procedure, we further show that the quantum-to-classical crossover exhibits similar features when the emission is driven by a Lorentzian pulse carrying two electron charge. Our results show how the electron emission process is affected by thermal fluctuations in a single-electron emitter.

cond-mat.mes-hall↗

arXiv2022

Instantaneous Emission Rate of Electron Transport through a quantum point contact

We present a theory to describe the instantaneous emission rate of electron transport in quantum-coherent conductors. Due to the Pauli exclusion principle, electron emission events are usually correlated. This makes the emission rate is not a constant, but depends on the history of the emission process. To incorporate such history dependence, in this paper we characterize the emission rate via the conditional intensity function, which has been introduced in the theory of random point process. The conditional intensity function can be treated as the instantaneous emission rate observed by an ideal single-electron detector since a given starting time. We demonstrate the method by studying the instantaneous emission rate of a single-channel quantum point contact driven by a constant voltage. As the quantum point contact is opened up, we show that the emission process evolves from a simple Poisson process close to pinch-off to a non-renewal process at full transmission. These results shows that the conditional intensity function can provide an intuitive and unified description of the emission process in quantum-coherent conductors.

cond-mat.mes-hall↗

arXiv2021

Late-Time Radio and Millimeter Observations of Superluminous Supernovae and Long Gamma Ray Bursts: Implications for Obscured Star Formation, Central Engines, and Fast Radio Bursts

We present the largest and deepest late-time radio and millimeter survey to date of superluminous supernovae (SLSNe) and long duration gamma-ray bursts (LGRBs) to search for associated non-thermal synchrotron emission. Using the Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA), we observed 43 sources at 6 and 100 GHz on a timescale of $\sim 1 - 19$ yr post-explosion. We do not detect radio/mm emission from any of the sources, with the exception of a 6 GHz detection of PTF10hgi (Eftekhari et al. 2019), as well as the detection of 6 GHz emission near the location of the SLSN PTF12dam, which we associate with its host galaxy. We use our data to place constraints on central engine emission due to magnetar wind nebulae and off-axis relativistic jets. We also explore non-relativistic emission from the SN ejecta, and place constraints on obscured star formation in the host galaxies. In addition, we conduct a search for fast radio bursts (FRBs) from some of the sources using VLA Phased-Array observations; no FRBs are detected to a limit of $16$ mJy ($7σ$; 10 ms duration) in about 40 min on source per event. A comparison to theoretical models suggests that continued radio monitoring may lead to detections of persistent radio emission on timescales of $\gtrsim {\rm decade}$.

astro-ph.HE↗

arXiv2021

Failure of refractory masonry material under monotonic and cyclic loading: crack propagation analysis

Refractory masonry (refractories) is exposed to in-service loads of different types. To rationalise the masonry design and failure analysis, differences of failure under cyclic and monotonic loading were studied. For samples of silica refractories tested in wedge splitting set-up global failure parameters and crack trajectories were assessed. Under cyclic loading, higher fracture energy and lower brittleness at failure were seen. Cracks of different modes had similar non-linearity and branching. However, the size and microstructural characteristics of the fracture process zone was different. In addition, higher energy dissipation during cyclic loading is promoted by repetitive friction events along the crack trajectory.

cond-mat.mtrl-sci↗

arXiv2021

Chiral charge density waves induced by Ti-doping in 1T-TaS2

We investigate the Ti-doping effect on the charge density wave (CDW) of 1T-TaS2 by combining scanning tunneling microscopy (STM) measurements and first-principle calculations. Although the Ti-doping induced phase evolution seems regular with increasing of the doping concentration (x), an unexpected chiral CDW phase is observed in the sample with x = 0.08, in which Ti atoms almost fully occupy the central Ta atoms in the CDW clusters. The emergence of the chiral CDW is proposed to be from the doping-enhanced orbital order. Only when x = 0.08, the possible long-range orbital order can trigger the chiral CDW phase. Compared with other 3d-elements doped 1T-TaS2, the Ti-doping retains the electronic flat band and the corresponding CDW phase, which is a prerequisite for the emergence of chirality. We expect that introducing elements with a strong orbital character may induce a chiral charge order in a broad class of CDW systems. The present results open up another avenue for further exploring the chiral CDW materials.

cond-mat.mtrl-sci↗

arXiv2021

Deceleration and trapping of SrF molecules

We report on the electrostatic trapping of neutral SrF molecules. The molecules are captured from a cryogenic buffer-gas beam source into the moving traps of a 4.5 m long traveling-wave Stark decelerator. The SrF molecules in $X^2Σ^+(v=0, N=1)$ state are brought to rest as the velocity of the moving traps is gradually reduced from 190 m/s to zero. The molecules are held for up to 50 ms in multiple electric traps of the decelerator. The trapped packets have a volume (FWHM) of 1 mm$^{3}$ and a velocity spread of 5(1) m/s which corresponds to a temperature of $60(20)$ mK. Our result demonstrates a factor 3 increase in the molecular mass that has been Stark-decelerated and trapped. Heavy molecules (mass$>$100 amu) offer a highly increased sensitivity to probe physics beyond the Standard Model. This work significantly extends the species of neutral molecules of which slow beams can be created for collision studies, precision measurement and trapping experiments.

physics.atom-ph↗

arXiv2021

Quasiparticles states for integer- and fractional-charged electron wave packets

It is well-known that Lorentzian voltage pulses with integer quantum flux can lead to noiseless current in quantum conductors. The current is carried by charged quasiparticles in the Fermi sea of the conductors, which have well-defined wave functions and have been named as "levitons". However, it is not clear how levitons evolve as the flux of the pulses changes continuously toward a fractional value. To answer this question, we introduce a set of Wannier-like single-body wave functions, which can be used to describe the quantum states of the quasiparticles injected by Lorentzian pulses with arbitrary flux. We show that, by tuning the flux of the pulses, levitons can evolve into quasiparticles carrying fractional charges. In the meantime, additional fractional-charged quasiparticles can also be excited, which can form neutral electron-hole pairs. The information of these quasiparticles can be extracted from the shot noise of the current. These knowledge can be helpful for the time-resolved quantum control of propagating electrons in solid-state circuits.

cond-mat.mes-hall↗

arXiv2020

Temperature-Induced Lifshitz Transition and Possible Excitonic Instability in ZrSiSe

The nodal-line semimetals have attracted immense interest due to the unique electronic structures such as the linear dispersion and the vanishing density of states as the Fermi energy approaching the nodes. Here, we report temperature-dependent transport and scanning tunneling microscope (spectroscopy) (STM[S]) measurements on nodal-line semimetal ZrSiSe.Our experimental results and theoretical analyses consistently demonstrate that the temperature induces Lifshitz transitions at 80 and 106 K in ZrSiSe, which results in the transport anomalies at the same temperatures. More strikingly, we observe a V-shaped dip structure around Fermi energy from the STS spectrum at low temperature,which can be attributed to co-effect of the spin-orbit coupling and excitonic instability. Our observations indicate the correlation interaction may play an important role in ZrSiSe, which owns the quasi-two-dimensional electronic structures.

cond-mat.mtrl-sci↗

arXiv2019

Detecting intracranial aneurysm rupture from 3D surfaces using a novel GraphNet approach

Intracranial aneurysm (IA) is a life-threatening blood spot in human's brain if it ruptures and causes cerebral hemorrhage. It is challenging to detect whether an IA has ruptured from medical images. In this paper, we propose a novel graph based neural network named GraphNet to detect IA rupture from 3D surface data. GraphNet is based on graph convolution network (GCN) and is designed for graph-level classification and node-level segmentation. The network uses GCN blocks to extract surface local features and pools to global features. 1250 patient data including 385 ruptured and 865 unruptured IAs were collected from clinic for experiments. The performance on randomly selected 234 test patient data was reported. The experiment with the proposed GraphNet achieved accuracy of 0.82, area-under-curve (AUC) of receiver operating characteristic (ROC) curve 0.82 in the classification task, significantly outperforming the baseline approach without using graph based networks. The segmentation output of the model achieved mean graph-node-based dice coefficient (DSC) score 0.88.

eess.IV↗

arXiv2019

Lifetime Measurements of the $A^2Π_{1/2}$ and $A^2Π_{3/2}$ States in BaF

Time resolved detection of laser induced fluorescence from pulsed excitation of electronic states in barium monofluoride (BaF) molecules has been performed in order to determine the lifetimes of the $A^2Π_{1/2}$ and $A^2Π_{3/2}$ states. The method permits control over experimental parameters such that systematic biases in the interpretation of the data can be controlled to below $10^{-3}$ relative accuracy. The statistically limited values for the lifetimes of the $A^2Π_{1/2}(ν=0)$ and $A^2Π_{3/2}(ν=0)$ states are 57.1(3) ns and 47.9(7)~ns, respectively. The ratio of these values is in good agreement with scaling for the different excitation energies. The investigated molecular states are of relevance for an experimental search for a permanent electric dipole moment (EDM) of the electron in BaF.

physics.atom-ph↗

arXiv2019

Normal and abnormal electron-hole pairs in a voltage-pulse-driven quantum conductor

Electron-hole pairs can be excited coherently in a quantum conductor by applying voltage pulses on its contact. We find that these electron-hole pairs can be classified into two kinds, whose excitation probabilities have different dependence on the Faraday flux of the pulse. Most of the pairs are of the first kind, which can be referred to as "normal" pairs. Their excitation probabilities increase nearly monotonically with the flux and saturate to the maximum value 1 when the flux is large enough. In contrast, there exist "abnormal" pairs, whose excitation probabilities can exhibit oscillations with the flux. These pairs can only be excited by pulses with small width. Due to the oscillation of the probabilities, the abnormal pairs can lead to different features in the full counting statistics of the electron-hole pairs for pulses with integer and noninteger fluxes.

cond-mat.mes-hall↗