Hui Li - Los Alamos National Lab

Hui Li
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Hui Li
Los Alamos National Lab
United States

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Physics - Materials Science (7)
Physics - Optics (5)
Astrophysics of Galaxies (4)
High Energy Astrophysical Phenomena (4)
Physics - Space Physics (3)
Nuclear Theory (3)
Mathematics - Operator Algebras (3)
Physics - Instrumentation and Detectors (2)
Solar and Stellar Astrophysics (2)
Physics - Fluid Dynamics (2)
High Energy Physics - Theory (2)
Computer Science - Computer Vision and Pattern Recognition (2)
Physics - Plasma Physics (2)
General Relativity and Quantum Cosmology (2)
Quantum Physics (2)
Physics - Atomic Physics (2)
Mathematics - Symplectic Geometry (2)
High Energy Physics - Experiment (2)
Physics - Mesoscopic Systems and Quantum Hall Effect (2)
High Energy Physics - Phenomenology (2)
Physics - General Physics (1)
Quantitative Biology - Quantitative Methods (1)
Physics - Chemical Physics (1)
Mathematics - Functional Analysis (1)
Physics - Atomic and Molecular Clusters (1)
Statistics - Theory (1)
Mathematics - Statistics (1)
Physics - Superconductivity (1)
Statistics - Methodology (1)
Mathematical Physics (1)
Mathematics - Mathematical Physics (1)
Physics - Data Analysis; Statistics and Probability (1)
Physics - Physics and Society (1)
Physics - Computational Physics (1)
Statistics - Applications (1)
Statistics - Machine Learning (1)
Cosmology and Nongalactic Astrophysics (1)
Nuclear Experiment (1)
Computer Science - Artificial Intelligence (1)
Computer Science - Neural and Evolutionary Computing (1)
Earth and Planetary Astrophysics (1)

Publications Authored By Hui Li

We present the successful synthesis of single-atom-thick borophene nanoribbons (BNRs) by self-assembly of boron on Ag(110) surface. The scanning tunneling microscopy (STM) studies reveal high quality BNRs: all the ribbons are along the [-110] direction of Ag(110), and can run across the steps on the surface. The width of ribbons is distributed in a narrow range around 10. Read More

The efficiency of optical trapping is determined by the atomic dynamic dipole polarizability, whose real and imaginary parts are associated with the potential energy and photon-scattering rate respectively. In this article we develop a formalism to calculate analytically the real and imaginary parts of the scalar, vector and tensor polarizabilities of lanthanide atoms. We assume that the sum-over-state formula only comprises transitions involving electrons in the valence orbitals like $6s$, $5d$, $6p$ or $7s$, while transitions involving $4f$ core electrons are neglected. Read More

The early optical afterglow emission of several gamma-ray bursts (GRBs) shows a high linear polarization degree (PD) of tens of percent, suggesting an ordered magnetic field in the emission region. The lightcurves are consistent with being of a reverse shock (RS) origin. However, the magnetization parameter, $\sigma$, of the outflow is unknown. Read More

We compute the fermion spin distribution in the vortical fluid created in off-central high-energy heavy-ion collisions. We employ the event-by-event (3+1)D viscous hydrodynamic model. The spin polarization density is proportional to the local fluid vorticity in quantum kinetic theory. Read More

A function has been proposed to evaluate the electron density model constructed by inverse Fourier transform using the observed structure amplitudes and trial phase set. The strategy of this function is applying an imaginary electron density modification to the model, and then measuring how well the calculated structure amplitudes of the modified model matches the expected structure amplitudes for the modified correct model. Since the correct model is not available in advance, a method has been developed to estimate the structure amplitudes of the modified correct model. Read More

The polarizations of $\Lambda$ and $\bar{\Lambda}$ hyperons are important quantities in extracting the fluid vorticity of the strongly coupled QGP and the magnitude of the magnetic field created in off-central heavy-ion collisions, through the spin-vorticity and spin-magnetic coupling. We computed the energy dependence of the global $\Lambda$ polarization in off-central Au+Au collisions in the energy range $\sqrt{s_{\text{NN}}}=7.7-200$ GeV using A Multi-Phase Transport (AMPT) model. Read More

As one of the most important semiconductors, silicon (Si) has been used to fabricate electronic devices, waveguides, detectors, and solar cells etc. However, its indirect bandgap hinders the use of Si for making good emitters1. For integrated photonic circuits, Si-based emitters with sizes in the range of 100-300 nm are highly desirable. Read More

Let $(M, \alpha)$ be a connected compact contact toric manifold of Reeb type. In this note, we give a proof that the fundamental group of $M$ is finite cyclic. We also point out the fundamental groups of certain related quotients of $M$. Read More

In curved space-time, Hamilton-Jacobi equation is a semi-classical particle's motion equation, which plays an important role in the research of black hole physics. In this paper, starting from Dirac equation describing the spin 1/2 fermion and Rarita-Schwinger equation describing the spin 3/2 fermion respectively, we derive a Hamilton-Jacobi equation of the non-stationary spherically symmetric gravitational field background. Furthermore, the quantum tunneling behavior of a charged spherically symmetric black hole is investigated by using this Hamilton-Jacobi equation. Read More

We define branching systems for finitely aligned higher-rank graphs. From these we construct concrete representations of higher-rank graph C*-algebras on Hilbert spaces. We prove a generalized Cuntz-Krieger uniqueness theorem for periodic single-vertex 2-graphs. Read More

The distinctive morphology of head-tail radio galaxies reveals strong interactions between the radio jets and their intra-cluster environment, the general consensus on the morphology origin of head-tail sources is that radio jets are bent by violent intra-cluster weather. We demonstrate in this paper that such strong interactions provide a great opportunity to study the jet properties and also the dynamics of intra-cluster medium (ICM). By three-dimensional magnetohydrodynamical simulations, we analyse the detailed bending process of a magnetically dominated jet, based on the magnetic tower jet model. Read More

Supermassive black holes are the central engines of luminous quasars and are found in most massive galaxies today. But the recent discoveries of ULAS J1120+0641, a 2 $\times$ 10$^9$ M$_{\odot}$ black hole at $z \sim$ 7.1, and SDSS J0100+2802, a 1. Read More

In this paper, we study the boundary quotient C*-algebras associated to products of odometers. One of our main results shows that the boundary quotient C*-algebra of the standard product of k odometers over (n_i)-letter alphabets (i=1,.. Read More

In this work, the authors give a new method for phase determination, the Tian pseudo atom method (TPAM) or pseudo atom method (PAM) for short. In this new method, the figure of merit function, Rtian, replaces Rcf in the charge flipping algorithm. The key difference between Rcf and Rtian is the oberved structure factor was replaced by the pseudo structure factor. Read More

Honeycomb structures of group IV elements can host massless Dirac fermions with non-trivial Berry phases. Their potential for electronic applications has attracted great interest and spurred a broad search for new Dirac materials especially in monolayer structures. We present a detailed investigation of the \beta 12 boron sheet, which is a borophene structure that can form spontaneously on a Ag(111) surface. Read More

By using a new method of forced-field extrapolation, we study the emerging flux region AR 11850 observed by the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamical Observatory (SDO). Our results suggest that the bright points (BPs) in this emerging region have responses in lines formed from the upper photosphere to the transition region, with a relatively similar morphology. They have an oscillation of several minutes according to the Atmospheric Imaging Assembly (AIA) data at 1600 and 1700 A . Read More

Community structure is an important structural property that extensively exists in various complex networks. In the past decade, much attention has been paid to the design of community-detection methods, but analyzing the behaviors of the methods is also of interest in the theoretical research and real applications. Here, we focus on an important measure for community structure, significance [Sci. Read More

The linear superposition principle in quantum mechanics is essential for several no-go theorems such as the no-cloning theorem, the no-deleting theorem and the no-superposing theorem. It remains an open problem of finding general forbidden principles to unify these results. In this paper, we investigate general quantum transformations forbidden or permitted by the superposition principle for various goals. Read More

The focus in this paper is Bayesian system identification based on noisy incomplete modal data where we can impose spatially-sparse stiffness changes when updating a structural model. To this end, based on a similar hierarchical sparse Bayesian learning model from our previous work, we propose two Gibbs sampling algorithms. The algorithms differ in their strategies to deal with the posterior uncertainty of the equation-error precision parameter, but both sample from the conditional posterior probability density functions (PDFs) for the structural stiffness parameters and system modal parameters. Read More

In order to better understand the advantages and disadvantages of a constrained multi-objective evolutionary algorithm (CMOEA), it is important to understand the nature of difficulty of a constrained multi-objective optimization problem (CMOP) that the CMOEA is going to deal with. In this paper, we first propose three primary types of difficulty to characterize the constraints in CMOPs, including feasibility-hardness, convergence-hardness and diversity-hardness. We then develop a general toolkit to construct difficulty adjustable CMOPs with three types of parameterized constraint functions according to the proposed three primary types of difficulty. Read More

Affiliations: 1University of New Mexico, 2Los Alamos National Lab, 3Los Alamos National Lab, 4University of New Mexico

Kink instabilities are likely to occur in the current-carrying magnetized plasma jets. Recent observations of the blazar radiation and polarization signatures suggest that the blazar emission region may be considerably magnetized. While the kink instability has been studied with first-principle magnetohydrodynamic (MHD) simulations, the corresponding time-dependent radiation and polarization signatures have not been investigated. Read More

The number of constituent quark (NCQ) scaling behavior of elliptic flow has been systematically studied at the LHC energy within the framework of a multiphase transport model (AMPT) in this work. We find that the parameters used to generate the initial states and the collision centrality are important for the existence of NCQ scaling even when hadronic rescattering contribution is off in Pb-Pb collisions of $\sqrt{s_{NN}}=2.76$ TeV. Read More

In this letter, we show that the dimensionless parameter in the generalized uncertainty principle (GUP) can be constrained by the gravitational wave event GW150914, which was discovered by the LIGO Scientific and Virgo Collaborations. Firstly, according to the Heisenberg uncertainty principle (HUP) and the data of gravitational wave event GW150914, we derive the standard energy-momentum dispersion relation and calculate the difference between the propagation speed of gravitons and the speed of light, i.e. Read More

In this paper, two sufficient and necessary conditions are given. The first one characterizes when the boundary path groupoid of a topological graph without singular vertices has closed interior of its isotropy group bundle, and the second one characterizes when the path groupoid of a row-finite k-graph without sources has closed interior of its isotropy group bundle. It follows that the associated topological graph algebra and the associated k-graph C*-algebra have Cartan subalgebras due to a result of Brown-Nagy-Reznikoff-Sims-Williams. Read More

Affiliations: 1Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, 2University of Surrey, 3University of Zurich, 4Max-Planck-Institut für Astronomie, 5Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, 6University of Texas, Austin, 7University of Zurich, 8McMaster University, 9Sorbonne Universites, UPMC Univ Paris 6 et CNRS, 10University of Washington, Seattle, 11École Polytechnique Fédérale de Lausanne, 12University of Washington, Seattle, 13Fermi National Accelerator Laboratory, 14University of Maryland, 15University of Cambridge, 16University of Edinburgh, 17National Center for Supercomputing Applications, 18University of Illinois, Urbana, 19Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, 20New Mexico State University, 21McMaster University, 22Rochester Institute of Technology, 23University of Cambridge, 24The Hebrew University, 25National Center for Supercomputing Applications, 26California Institute of Technology, 27California Institute of Technology, 28New Mexico State University, 29University of Michigan, Ann Arbor, 30University of California at Santa Cruz, 31Yale University, 32University of Zurich, 33Osaka University, 34University of Zurich, 35National Superconducting Cyclotron Laboratory, Michigan State University, 36Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, 37The Hebrew University, 38University of Chicago, 39Osaka University, 40Heidelberger Institut für Theoretische Studien, 41University of Kansas, 42McMaster University, 43Georgia Institute of Technology

Using an isolated Milky Way-mass galaxy simulation, we compare results from 9 state-of-the-art gravito-hydrodynamics codes widely used in the numerical community. We utilize the infrastructure we have built for the AGORA High-resolution Galaxy Simulations Comparison Project. This includes the common disk initial conditions, common physics models (e. Read More

We have developed a technique to tune the carrier density in graphene using a lithium-ion-based solid electrolyte. We demonstrate that the solid electrolyte can be used as both a substrate to support graphene and a back gate.It can induce a change in the carrier density as large as 1*10^14/cm^2, which is much larger than that induced with oxide-film dielectrics, and it is comparable with that induced by liquid electrolytes. Read More

A number of transition disks exhibit significant azimuthal asymmetries in thermal dust emission. One possible origin for these asymmetries is dust trapping in vortices formed at the edges of dead zones. We carry out high-resolution, two-dimensional hydrodynamic simulations of this scenario, including the effects of dust feedback. Read More

The notion of almost everywhere convergence has been generalized to vector lattices as unbounded order convergence, which proves a very useful tool in the theory of vector and Banach lattices. In this short note, we establish some new results on unbounded order convergence that tie up some loose ends. In particular, we show that every norm bounded positive increasing net in an order continuous Banach lattice is uo-Cauchy and that every uo-Cauchy net in an order continuous Banach lattice has a uo-limit in the universal completion. Read More

Conventional dual-frequency fringe projection algorithm often suffers from phase unwrapping failure when the frequency ratio between the high frequency and the low one is too large. Zhang Read More

In this paper, we present results from an experimental study into turbulent Rayleigh-Benard convection forced externally by periodically modulated unidirectional rotation rates. We find that the azimuthal rotation velocity $\dot{\theta}$(t) and thermal amplitude $\delta$(t) of the large-scale circulation (LSC) are modulated by the forcing, exhibiting a variety of dynamics including increasing phase delays and a resonant peak in the amplitude of $\dot{\theta}$(t). We also focus on the influence of modulated rotation rates on the frequency of occurrence $\eta$ of stochastic cessation/reorientation events, and on the interplay between such events and the periodically modulated response of $\dot{\theta}$(t). Read More

We present measurements of the azimuthal orientation {\theta}(t) and thermal amplitude {\delta}(t) of the large-scale circulation (LSC) of turbulent rotating convection within an unprecedented large Rossby number range 1Read More

We simulate decaying turbulence in electron-positron pair plasmas using a fully- kinetic particle-in-cell (PIC) code. We run two simulations with moderate-to-low plasma beta. The energy decay rate is found to be similar in both the cases. Read More

Motivated by recent works on Hamiltonian circle actions satisfying certain minimal conditions, in this paper, we consider Hamiltonian circle actions satisfying an almost minimal condition. More precisely, we consider a compact symplectic manifold $(M, \omega)$ admitting a Hamiltonian circle action with fixed point set consisting of two connected components $X$ and $Y$ satisfying $\dim(X)+\dim(Y)=\dim(M)$. Under some cohomology condition, we determine the circle action, the integral cohomology rings of $M$, $X$ and $Y$, and the total Chern classes of $M$, $X$, $Y$, and of the normal bundles of $X$ and $Y$. Read More

The Planck length and Planck energy should be taken as invariant scales are in agreement with various theories of quantum gravity. In this scenario, the original general relativity can be changed to the so-called gravity's rainbow which produces significant modifications to the black holes' evolution. In this paper, using two kinds of rainbow functions, we investigate the thermodynamics and the phase transition of Schwarzschild black hole in the context of gravity's rainbow theory. Read More

Interplanetary (IP) shock plays a key role in causing the global dynamic changes of the geospace environment. For the perspective of Solar-Terrestrial relationship, it will be of great importance to estimate the properties of post-shock solar wind simply and accurately. Motivated by this, we performed a statistical analysis of IP shocks during 1998-2008, focusing on the significantly different responses of two well-used geomagnetic indices (SYMH and AL) to the passive of two types of IP shocks. Read More

Nonlinear cascade of low-frequency Alfvenic fluctuations (AFs) is regarded as one candidate of the energy sources to heat plasma during the non-adiabatic expansion of interplanetary coronal mass ejections (ICMEs). However, AFs inside ICMEs were seldom reported in the literature. In this study, we investigate AFs inside ICMEs using observations from Voyager 2 between 1 and 6 au. Read More

We present a new implementation of star formation in cosmological simulations, by considering star clusters as a unit of star formation. Cluster particles grow in mass over several million years at the rate determined by local gas properties, with high time resolution. The particle growth is terminated by its own energy and momentum feedback on the interstellar medium. Read More

Superconducting proximity effect (SPE) in topological insulator (TI) and superconductor (SC) hybrid structure has attracted intense attention in recent years in an effort to search for mysterious Majorana fermions (MFs) in condensed matter systems. Here we report on the SPE in a Bi2Se3/NbSe2 junction fabricated with an all-dry transfer method. Resulting from the highly transparent interface, two sharp resistance drops are observed at 7 K and 2 K, respectively, corresponding to the superconducting transition of NbSe2 flake and the SPE induced superconductivity in Bi2Se3 flake. Read More

The Large High Altitude Air Shower Observatory (LHAASO) is to be built at Daocheng, Sichuan Province, China. As one of the major components of the LHAASO project, a Water Cherenkov Detector Array (WCDA), with an area of 78,000~$\rm m^{2}$, contains 350,000~tons of purified water. The water transparency and its stability are critical for successful long-term operation of this project. Read More

The efficiency of optical trapping of ultracold atoms depend on the atomic dynamic dipole polarizability governing the atom-field interaction. In this article, we have calculated the real and imaginary parts of the dynamic dipole polarizability of dysprosium in the ground and first excited level. Due to the high electronic angular momentum of those two states, the polarizabilities possess scalar, vector and tensor contributions that we have computed, on a wide range of trapping wavelengths, using the sum-over-state formula. Read More

In this paper, we consider the problem of demixing a multivariate stochastic process made up of independent, fractional Brownian motion entries. The observable, mixed signal is then an operator fractional Brownian motion (OFBM). The law of OFBM scales according to a Hurst matrix that affects every component of the process, which makes its estimation by univariate-like methods quite difficult. Read More

In this paper, the modified entropic force law is studied by using a new kind of generalized uncertainty principle which contains a minimal length, a minimal momentum and a maximal momentum. Firstly, the quantum corrections to the thermodynamics of a black hole is investigated. Then, according to Verlinde's theory, the generalized uncertainty principle (GUP) corrected entropic force is obtained. Read More

In molecular dynamics (MD) simulation, force field determines the capability of an individual model in capturing physical and chemistry properties. The method for generating proper parameters of the force field form is the key component for computational research in chemistry, biochemistry, and condensed-phase physics. Our study showed that the feasibility to predict experimental condensed phase properties (i. Read More

Formation of high spatial frequency laser induced periodic surface structures (HSFL) in germanium by femtosecond mid-IR pulses with wavelengths between $\lambda=2.0$ and $3.6 \; \mathrm{\mu m}$ was studied with varying angle of incidence and polarization. Read More

Emergence of ferromagnetism in non-magnetic semiconductors is strongly desirable, especially in topological materials thanks to the possibility to achieve quantum anomalous Hall effect. Based on first-principles calculations, we propose that for Si thin film grown on metal substrate, the pristine Si(111)-root3xroot3 surface with a spontaneous weak reconstruction has a strong tendency of ferromagnetism and nontrivial topological properties, characterized by spin polarized Dirac-fermion surface states. In contrast to conventional routes relying on introduction of alien charge carriers or specially patterned substrates, the spontaneous magnetic order and spin-orbit coupling on the pristine silicon surface together gives rise to quantized anomalous Hall effect with a finite Chern number C=-1. Read More

It is a challenge for Phase Measurement Profilometry (PMP) to measure objects with a large range of reflectivity variation across the surface. Saturated or dark pixels in the deformed fringe patterns captured by the camera will lead to phase fluctuations and errors. Jiang et al. Read More

The discovery of two-dimensional superconductivity in Bi2Te3/FeTe heterostructure provides a new platform for the search of Majorana fermions in condensed matter systems. Since Majorana fermions are expected to reside at the core of the vortices, a close examination of the vortex dynamics in superconducting interface is of paramount importance. Here, we report the robustness of the interfacial superconductivity and 2D vortex dynamics in four as-grown and aged Bi2Te3/FeTe heterostructure with different Bi2Te3 epilayer thickness (3, 5, 7, 14 nm). Read More

This paper reviews two techniques that have been recently published for 3D profilometry and proposes one shot profilometry using iterative two-step temporal phase-unwrapping by combining the composite fringe projection and the iterative two-step temporal phase unwrapping algorithm. In temporal phase unwrapping, many images with different frequency fringe pattern are needed to project which would take much time. In order to solve this problem, Ochoa proposed a phase unwrapping algorithm based on phase partitions using a composite fringe, which only needs projecting one composite fringe pattern with four kinds of frequency information to complete the process of 3D profilometry. Read More

A model of global magnetic reconnection rate in relativistic collisionless plasmas is developed and validated by the fully kinetic simulation. Through considering the force balance at the upstream and downstream of the diffusion region, we show that the global rate is bounded by a value $\sim 0.3$ even when the local rate goes up to $\sim O(1)$ and the local inflow speed approaches the speed of light in strongly magnetized plasmas. Read More