Results for "Y. Feng"

total 45582took 0.12s
Group divisible (K_4-e)-packings with any minimum leaveMay 24 2017A decomposition of $K_{n(g)}\setminus L$, the complete n-partite equipartite graph with a subgraph L (called the leave) removed, into edge disjoint copies of a graph G is called a maximum group divisible packing of $K_{n(g)}$ with G if L contains as few ... More
Entanglement preservation for multilevel systems under non-ideal pulse controlMay 18 2010We investigate how to effectively preserve the entanglement between two noninteracting multilevel oscillators coupled to a common reservoir under non-ideal pulse control. A universal characterization using fidelity is developed for the behavior of the ... More
Next-To-Leading Order Differential Cross-Sections for $J/ψ$, $ψ(2S)$ and $Υ$ Production in Proton-Proton Collisions at a Fixed-Target Experiment using the LHC Beams (AFTER@LHC)Oct 18 2015Using nonrelativistic QCD (NRQCD) factorization, we calculate the yields for $J/\psi$, $\psi(2S)$ and $\Upsilon(1S)$ hadroproduction at $\sqrt{s}=$ 72 GeV and 115 GeV including the next-to-leading order QCD corrections. Both these center-of-mass energies ... More
Sudden death and birth of entanglement beyond the Markovian approximationMar 25 2009Apr 19 2009We investigate the entanglement dynamics of two initially entangled qubits interacting independently with two uncorrelated reservoirs beyond the Markovian approximation. Quite different from the Markovian reservoirs [C. E. Lopez et al., Phys. Rev. Lett. ... More
Discovery of Two Types of X-ray Dips in Cyg X-1Dec 06 2001We observed Cyg X-1 with {\em RXTE} contiguously over its 5.6-day binary orbit. The source was found to be in the hard state throughout the observation. Many intensity dips were detected in the X-ray light curves. We found that the dips fell into two ... More
String Organization of Field Theories: Duality and Gauge InvarianceSep 14 1994String theories should reduce to ordinary four-dimensional field theories at low energies. Yet the formulation of the two are so different that such a connection, if it exists, is not immediately obvious. With the Schwinger proper-time representation, ... More
Evaluation of Multiloop Diagrams via Lightcone IntegrationJul 18 1997May 03 1998We present a systematic method to determine the dominant regions of internal momenta contributing to any two-body high-energy near-forward scattering diagram. Such a knowledge is used to evaluate leading high-energy dependences of loop diagrams. It also ... More
Gauge Cancellation for Electroweak Processes and the Gervais-Neveu GaugeAug 02 1996A graphical method is developed to study the total or partial cancellation of gauge-dependent (divergence) terms in electroweak theory. The method is used to work out rules in the Gervais-Neveu gauge, whose triple-gauge vertex contains three terms rather ... More
Multiband Fitting to Three Long GRBs with Fermi/LAT Data: Structured Ejecta Sweeping up a Density-Jump MediumNov 13 2010Jun 04 2011We present broadband (radio, optical, X-ray and GeV) fits to the afterglow light curves and spectra of three long-duration gamma-ray bursts (GRBs 080916C, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor (GBM) and Large Area Telescope (LAT) ... More
On the Nevanlinna characteristic of f(z+η) and difference equations in the complex planeSep 12 2006May 09 2008We investigate the growth of the Nevanlinna Characteristic of f(z+\eta) for a fixed \eta in this paper. In particular, we obtain a precise asymptotic relation between T(r,f(z+\eta) and T(r,f), which is only true for finite order meromorphic functions. ... More
Poincaré Inequality for Dirichlet Distributions and Infinite-Dimensional GeneralizationsApr 11 2015Sep 04 2015For any $N\ge 2$ and $\aa:=(\aa_1,\cdots, \aa_{N+1})\in (0,\infty)^{N+1}$, let $\mu^{(N)}_{\aa}$ be the corresponding Dirichlet distribution on $\DD:= \big\{ x=(x_i)_{1\le i\le N}\in [0,1]^N:\ \sum_{1\le i\le N} x_i\le 1\big\}.$ We prove the Poincar\'e ... More
The analysis of VERITAS muon images using convolutional neural networksNov 29 2016Imaging atmospheric Cherenkov telescopes (IACTs) are sensitive to rare gamma-ray photons, buried in the background of charged cosmic-ray (CR) particles, the flux of which is several orders of magnitude greater. The ability to separate gamma rays from ... More
An isoperimetric inequality for eigenvalues of the bi-harmonic operatorJan 27 2011} In this article, we put forward a Neumann eigenvalue problem for the bi-harmonic operator $\Delta^2$ on a bounded smooth domain $\Om$ in the Euclidean $n$-space ${\bf R}^n$ ($n\ge2$) and then prove that the corresponding first non-zero eigenvalue $\Upsilon_1(\Om)$ ... More
Magnetic phase diagram of the strongly frustrated quantum spin chain system PbCuSO$_4$(OH)$_2$ in tilted magnetic fieldsApr 06 2018Aug 17 2018We report the $\mathbf{H}-T$ phase diagram of $S=1/2$ strongly frustrated anisotropic spin chain material linarite PbCuSO$_4$(OH)$_2$ in tilted magnetic fields up to 10 T and temperatures down to 0.2 K. By means of torque magnetometry we investigate the ... More
Activating Mg acceptors in AlN by oxygen: first principles calculationsSep 17 2007First principles calculations based on density functional theory (DFT) are performed to study the electronic properties of Mg acceptors in AlN at the presence of oxygen. It is found that Mg and O tend to form complexes like Mg-O, Mg$_2$-O, Mg$_3$-O and ... More
Graphitic-BN Based Metal-free Molecular Magnets From A First Principle StudyMar 02 2005We perform a first principle calculation on the electronic properties of carbon doped graphitic boron nitride graphitic BN. It was found that carbon substitution for either boron or nitrogen atom in graphitic BN can induce spontaneous magnetization. Calculations ... More
Generalized Background-Field MethodJun 04 1997The graphical method discussed previously can be used to create new gauges not reachable by the path-integral formalism. By this means a new gauge is designed for more efficient two-loop QCD calculations. It is related to but simpler than the ordinary ... More
A Resolution of the Paradox of EnrichmentApr 21 2011Mar 11 2013The paradox of enrichment was observed by M. Rosenzweig in a class of predator-prey models. Two of the parameters in the models are crucial for the paradox. These two parameters are the prey's carrying capacity and prey's half-saturation for predation. ... More
On the Chaotic Flux Dynamics in a Long Josephson JunctionJul 16 2009Flux dynamics in an annular long Josephson junction is studied. Three main topics are covered. The first is chaotic flux dynamics and its prediction via Melnikov integrals. It turns out that DC current bias cannot induce chaotic flux dynamics, while AC ... More
Multiferroic phases of the frustrated quantum spin-chain compound linariteSep 20 2016Dec 09 2016The dielectric properties of the prototypical frustrated ferromagnetic spin-chain compound PbCuSO$_4$(OH)$_2$ known as linarite, are studied across its strongly anisotropic magnetic phase diagram in single crystal samples. The ferroelectric character ... More
Impact of Baryonic Physics on Intrinsic AlignmentsJul 25 2016We explore the effects of specific assumptions in the subgrid models of star formation and stellar and AGN feedback on intrinsic alignments of galaxies in cosmological simulations of "MassiveBlack-II" family. Using smaller volume simulations, we explored ... More
Multiple Reggeon Exchange from Summing QCD Feynman DiagramsJun 17 1996Multiple reggeon exchange supplies subleading logs that may be used to restore unitarity to the Low-Nussinov Pomeron, provided it can be proven that the sum of Feynman diagrams to all orders gives rise to such multiple regge exchanges. This question cannot ... More
On the Structure of the Bose-Einstein Condensate Ground StateMay 07 1999We construct a macroscopic wave function that describes the Bose-Einstein condensate and weakly excited states, using the su(1,1) structure of the mean-field hamiltonian, and compare this state with the experimental values of second and third order correlation ... More
DIAGRAMMATIC ANALYSIS OF QCD GAUGE TRANSFORMATIONS AND GAUGE CANCELLATIONSMar 13 1995Diagrammatic techniques are invented to implement QCD gauge transformations. These techniques can be used to discover how gauge-dependent terms are cancelled among diagrams to yield gauge-invariant results in the sum. In this way a multiloop pinching ... More
Nuclear spin qubits in a trapped-ion quantum computerApr 26 2009Physical systems must fulfill a number of conditions to qualify as useful quantum bits (qubits) for quantum information processing, including ease of manipulation, long decoherence times, and high fidelity readout operations. Since these conditions are ... More
Graphene on metal surface: gap opening and n-dopingDec 25 2007Graphene grown on metal surface, Cu(111), with a boron nitride(BN) buffer layer is studied for the first time. Our first-principles calculations reveal that charge is transferred from the copper substrate to graphene through the BN buffer layer which ... More
Dissipative dynamics of quantum discord under quantum chaotic environmentOct 19 2010We investigate the dissipative dynamics of quantum discord in a decoherence model with two initially entangled qubits in addition to a quantum kicked top. The two qubits are uncoupled during the period of our study and one of them interacts with the quantum ... More
Quantum anomalous Hall effect with field-tunable Chern number near Z2 topological critical pointJan 05 2016We study the practicability of achieving quantum anomalous Hall (QAH) effect with field-tunable Chern number in a magnetically doped, topologically trivial insulating thin film. Specifically in a candidate material, TlBi(S$_{1-\delta}$Se$_{\delta}$)$_2$, ... More
Multi-waveband polarimetric observations of NRAO 530 on parsec-scaleJun 16 2010We report on multi-bands VLBA polarimetric observations of NRAO 530 in February 1997. Total intensity, EVPA distributions at all these frequencies are presented. Model fitting has been performed, from which the fitted southmost component A is confirmed ... More
Dimerized Decomposition of Quantum Evolution on an Arbitrary GraphJan 12 2017May 26 2017The study of quantum evolution on graphs for diversified topologies is beneficial to modeling various realistic systems. A systematic method, the dimerized decomposition, is proposed to analyze the dynamics on an arbitrary network. By introducing global ... More
Universal quantum computation with quantum-dot cellular automata in dephasing-free subspaceJan 30 2008Aug 22 2008We investigate the possibility to have electron-pairs in dephasing-free subspace (DFS), by means of the quantum-dot cellular automata (QCA) and single-spin rotations, to carry out a high-fidelity and deterministic universal quantum computation. We show ... More
Implementation of three-qubit Grover search in cavity QEDJul 03 2007Using resonant interaction of three Rydberg atoms with a single-mode microwave cavity, we consider a realization of three-qubit Grover search algorithm in the presence of weak cavity decay, based on a previous idea for three-qubit quantum gate [Phys. ... More
Proposed method for direct measurement of non-Markovian character of the qubits coupled to bosonic reservoirsDec 15 2009Mar 24 2010The non-Markovianity is a recently proposed characterization of the non-Markovian behavior in an open quantum system, based on which we first present a practical idea for directly measuring the non-Markovian character of a single qubit coupled to a zero-temperature ... More
X-ray Shots of Cyg X-1Oct 08 1998X-ray shots of Cyg X-1 in different energy bands and spectral states have been studied with PCA/RXTE observations. The detailed shot structure is obtained by superposing many shots with one millisecond time bin through aligning their peaks with an improved ... More
Pressure-induced Spin-Peierls to Incommensurate Charge-Density-Wave Transition in the Ground State of TiOClAug 04 2009The ground state of the spin-Peierls system TiOCl was probed using synchrotron x-ray diffraction on a single-crystal sample at T = 6 K. We tracked the evolution of the structural superlattice peaks associated with the dimerized ground state as a function ... More
Fuzzy Logic-based Implicit Authentication for Mobile Access ControlSep 12 2016In order to address the increasing compromise of user privacy on mobile devices, a Fuzzy Logic based implicit authentication scheme is proposed in this paper. The proposed scheme computes an aggregate score based on selected features and a threshold in ... More
Upgrade of the SDL Control SystemNov 28 2001Feb 06 2002The Source Development Lab (SDL) at BNL consists of a 230 MeV electron linac and a 10 m long wiggler for short wavelength Free Electronic Laser (FEL) development. The original control system [1] was based on the one in use at the National Synchrotron ... More
Nodal Manifolds Bounded by Exceptional Points on Non-Hermitian Honeycomb Lattices and Electrical-Circuit RealizationsOct 22 2018Topological semimetals feature a diversity of nodal manifolds including nodal points, various nodal lines and surfaces, and recently novel quantum states in non-Hermitian systems have been arousing widespread research interests. In contrast to Hermitian ... More
Q-Factor Measurement of Nonlinear Superconducting ResonatorsJan 21 2000A novel method, which combined a multi-bandwidth measurement and an extrapolation procedure, is proposed for extracting the loaded Q-factor (Q_{L}) with improved accuracy from non-Lorentzian resonances of nonlinear superconducting resonators.
Bilinear R-parity Violation and $τ^{\mp} \tildeκ^{\pm}$ mixing production in e^+ e^- collidersJun 27 1998Nov 23 1998A R-parity breaking SUSY model characterized by an effective bilinear violation with only $\tau$-lepton number breaking in the superpotential is outlined. The CP-odd Higgs boson masses and those of charged Higgs bosons are discussed. In the model, several ... More
Probing the Inflow/Out-flow and Accretion Disk of Cyg X-1 in the High State with HETG/ChandraAug 14 2003Cyg X-1 was observed in the high state at the conjunction orbital phase (0) with HETG/Chandra. Strong and asymmetric absorption lines of highly ionized species were detected, such as Fe XXV, Fe XXIV, Fe XXIII, Si XIV, S XVI, Ne X, and etc. In the high ... More
Temporal and Spectral Correlations of Cyg X-1Mar 15 1999Mar 16 1999Temporal and spectral properties of X-ray rapid variability of Cyg X-1 are studied by an approach of correlation analysis in the time domain on different time scales. The correlation coefficients between the total intensity in 2-60 keV and the hardness ... More
Metal Insulator transition at B=0 in p-SiGeAug 15 1997Aug 16 1997Observations are reported of a metal-insulator transition in a 2D hole gas in asymmetrically doped strained SiGe quantum wells. The metallic phase, which appears at low temperatures in these high mobility samples, is characterised by a resistivity that ... More
Event-Driven Implicit Authentication for Mobile Access ControlJul 27 2016In order to protect user privacy on mobile devices, an event-driven implicit authentication scheme is proposed in this paper. Several methods of utilizing the scheme for recognizing legitimate user behavior are investigated. The investigated methods compute ... More
Lepton flavor violation two-body decays of quarkoniumsDec 15 2002In this paper we firstly study various model-independent bounds on lepton flavor violation (LFV) in processes of $J/\Psi$, $\Psi'$ and $\Upsilon$ two-body decays, then calculate their branch ratios % By using the constraints from other ways, we obtain ... More
Continuous Implicit Authentication for Mobile Devices based on Adaptive Neuro-Fuzzy Inference SystemMay 18 2017As mobile devices have become indispensable in modern life, mobile security is becoming much more important. Traditional password or PIN-like point-of-entry security measures score low on usability and are vulnerable to brute force and other types of ... More
Quantum-memory-assisted entropic uncertainty principle under noiseMar 15 2012The measurement outcomes of two incompatible observables on a particle can be precisely predicted when it is maximally entangled with a quantum memory, as quantified recently [Nature Phys. 6, 659 (2010)]. We explore the behavior of the uncertainty relation ... More
Applicability of coupling strength estimation for linear chains of restricted accessMar 10 2019The characterization of an unknown quantum system requires the Hamiltonian identification. The full access to the system, however, is usually restricted, hindering the direct retrieval of relevant parameters, and a reliable indirect estimation is usually ... More
Magnetism in BN nanotubes induced by Carbon SubstitutionJan 06 2005We performed ab initio calculation on the pristine and carbon-doped (5,5) and (9,0) BN nanotubes. It was found that Carbon substitution for either boron or nitrogen in BN nanotubes can induce spontaneous magnetization. Calculations based on density functional ... More
Cut Diagrams for High Energy ScatteringsApr 29 1996A new approach is introduced to study QCD amplitudes at high energy and comparatively small momentum transfer. Novel cut diagrams, representing resummation of Feynman diagrams, are used to simplify calculation and to avoid delicate cancellations encountered ... More
Preparation of 18-filament Cu/NbZr/MgB2 tape with high transport critical current densityJun 05 2001Cu-stabilized 18-filament MgB2 tapes with NbZr buffer have been fabricated by using powder-in-tube technique. The phase composition and microstructure were examined by X-ray diffraction and optical microscopy. Transport critical current measurements were ... More
Morphological evolution of a 3D CME cloud reconstructed from three viewpointsMar 15 2012The propagation properties of coronal mass ejections (CMEs) are crucial to predict its geomagnetic effect. A newly developed three dimensional (3D) mask fitting reconstruction method using coronagraph images from three viewpoints has been described and ... More
Deterministically entangling distant nitrogen-vacancy centers by a nanomechanical cantileverJul 31 2009Aug 27 2009We present a practical scheme by global addressing to deterministically entangle negatively charged nitrogen-vacancy (N-V) centers in distant diamonds using a nano-mechanical cantilever with the magnetic tips strongly coupled to the N-V electron spins. ... More
3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging of quantum materialsMar 27 2019We designed and fabricated a new type of superconducting quantum interference device (SQUID) susceptometers for magnetic imaging of quantum materials. The 2-junction SQUID sensors employ 3D Nb nano-bridges fabricated using electron beam lithography. The ... More
Perfect spin-fillter and spin-valve in carbon atomic chainsNov 01 2009We report ab initio calculations of spin-dependent transport in single atomic carbon chains bridging two zigzag graphene nanoribbon electrodes. Our calculations show that carbon atomic chains coupled to graphene electrodes are perfect spin-filters with ... More
A New Method to Use Chandra Data to Resolve the X-Ray Halos Around Point Sources and Its Application to Cygnus X-1Mar 06 2003Jul 22 2003With excellent angular resolution, good energy resolution and broad energy band, the Chandra ACIS is the best instrument for studying the X-ray halos around some galactic X-ray point sources caused by the dust scattering of X-rays in the interstellar ... More
New prototype scintillator detector for the Tibet AS$γ$ ExperimentDec 18 2017The hybrid Tibet AS array was successfully constructed in 2014. It has 4500 m$^{2}$ underground water Cherenkov pools used as the muon detector (MD) and 789 scintillator detectors covering 36900 m$^{2}$ as the surface array. At 100 TeV, cosmic-ray background ... More
Sealing off a carbon nanotube with a self-assembled aqueous valve for the storage of hydrogen in GPa pressureJun 29 2012The end section of a carbon nanotube, cut by acid treatment, contains hydrophillic oxygen groups. Water molecules can self-assemble around these groups to seal off a carbon nanotube and form an "aqueous valve". Molecular dynamics simulations on single-wall ... More
Franck-Condon Physics in A Single Trapped IonSep 08 2010Mar 23 2011We propose how to explore the Franck-Condon (FC) physics via a single ion confined in a spin-dependent potential, formed by the combination of a Paul trap and a magnetic field gradient. The correlation between electronic and vibrational degrees of freedom, ... More
Radio signatures of CME-streamer interaction and source diagnostics of type II radio burstApr 25 2012It has been suggested that type II radio bursts are due to energetic electrons accelerated at coronal shocks. Radio observations, however, have poor or no spatial resolutions to pinpoint the exact acceleration locations of these electrons. In this paper, ... More
Diagnostics on the source properties of type II radio burst with spectral bumpsMar 06 2013In recent studies (Feng et al., 2012; Kong et al., 2012), we proposed that source properties of type II radio bursts can be inferred through a causal relationship between the special shape of the type II dynamic spectrum (e.g., bump or break) and simultaneous ... More
A Cold Atomic Beam InterferometerFeb 16 2014Nov 08 2014We demonstrate an atom interferometer that uses a laser-cooled continuous beam of $^{87}$Rb atoms having velocities of 10--20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach--Zehnder interference fringes ... More
$Apart: A Generalized Mathematica Apart FunctionApr 11 2012Aug 20 2012We have generalized the \textsc{Mathematica} function \texttt{Apart} from 1 to $N$ dimension, the generalized function \texttt{\$Apart} can decompose any linear dependent elements in $\mathcal{V}_{x}^*$ to irreducible ones. The elements in $\mathcal{V}_{x}^*$ ... More
A Recursive Method to Calculate UV-divergent Parts at One-Loop Level in Dimensional RegularizationFeb 05 2012Feb 20 2012A method is introduced to calculate the UV-divergent parts at one-loop level in dimensional regularization. The method is based on the recursion, and the basic integrals are just the scaleless integrals after the recursive reduction, which involve no ... More
Purification of Single Photons from Room-Temperature Quantum DotsOct 04 2017Single photon emitters are indispensable to photonic quantum technologies. Here we demonstrate waveform-controlled high-purity single photons from room-temperature colloidal quantum dots. The purity of the single photons does not vary with the excitation ... More
Discovery of Weyl nodal lines in a single-layer ferromagnetJan 05 2019Two-dimensional (2D) materials have attracted great attention and spurred rapid development in both fundamental research and device applications. The search for exotic physical properties, such as magnetic and topological order, in 2D materials could ... More
Tunable Fe-vacancy disorder-order transition in FeSe thin filmsNov 17 2015Various Fe-vacancy orders have been reported in tetragonal Fe1-xSe single crystals and nanowires/nanosheets, which are similar to those found in alkali metal intercalated A1-xFe2-ySe2 superconductors. Here we report the in-situ angle-resolved photoemission ... More
Carbon-doped ZnO: A New Class of Room Temperature Dilute Magnetic SemiconductorOct 31 2006We report magnetism in carbon doped ZnO. Our first-principles calculations based on density functional theory predicted that carbon substitution for oxygen in ZnO results in a magnetic moment of 1.78 $\mu_B$ per carbon. The theoretical prediction was ... More
Insulator-metal transition shift related to magnetic polarons in La0.67-xYxCa0.33MnO3Jan 16 2003The magnetic transport properties have been measured for La0.67-xYxCa0.33MnO3 (0 <= x <= 0.14) system. It was found that the transition temperature Tp almost linearly moves to higher temperature as H increases. Electron spin resonance confirms that above ... More
Study on a prototype of the large dimensional refractive lens for the future large field-of-view IACTSep 06 2015In gamma ray astronomy, the energy range from sub-100GeV to TeV is crucial due to where there is a gap between space experiments and ground-based ones. In addition, observations in this energy range are expected to provide more details about the high ... More
Decoupling of magnetism and electric transport in single-crystal (Sr1-xAx)2IrO4 (A = Ca or Ba)Dec 15 2017May 03 2018We report a systematical structural, transport and magnetic study of Ca or Ba doped Sr2IrO4single crystals. Isoelectronically substituting Ca2+ (up to 15%) or Ba2+ (up to 4%) ion for the Sr2+ ion provides no additional charge carriers but effectively ... More
$Pb_{0.4}Bi_{1.6}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$ and Oxygen Stoichiometry: Structure, Resistivity, Fermi Surface Topology and Normal State PropertiesOct 19 1994$Pb_{0.4}Bi_{1.6}Sr_2CaCu_2O_{8+x}$ ($Bi(Pb)-$2212) single crystal samples were studied using transmission electron microscopy (TEM), $ab-$plane ($\rho_{ab}$) and $c-$axis ($\rho_c$) resistivity, and high resolution angle-resolved ultraviolet photoemission ... More
X-ray flares: late internal and late external shocksDec 22 2005We analyze several recently detected gamma-ray bursts (GRBs) with late X-ray flares in the context of late internal shock and late external shock models. We find that the X-ray flares in GRB 050421 and GRB 050502B originate from late internal shocks, ... More
Direct Experimental Observation of the Gas Filamentation Effect using a Two-bunch X-ray FEL BeamMay 28 2017We report the experimental observation of the filamentation effect in gas devices designed for X-ray Free-electron Lasers. The measurements were carried out at the Linac Coherent Light Source on the X-ray Correlation Spectroscopy (XCS) instrument using ... More
Intense source of cold cesium atoms based on a two-dimensional magneto-optical trap with independent axial cooling and pushingSep 24 2015We report our studies on an intense source of cold cesium atoms based on a two-dimensional magneto-optical trap with independent axial cooling and pushing. The new-designed source, proposed as 2D-HP MOT, uses hollow laser beams for axial cooling and a ... More
Possible Nodeless Superconducting Gaps in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ and YBa$_2$Cu$_3$O$_{7-x}$ Revealed by Cross-Sectional Scanning Tunneling SpectroscopyNov 14 2016Pairing in the cuprate high-temperature superconductors and its origin remain among the most enduring mysteries in condensed matter physics. With cross-sectional scanning tunneling microscopy/ spectroscopy, we clearly reveal the spatial-dependence or ... More
An imaging study of a complex solar coronal radio eruptionJul 30 2016Solar coronal radio bursts are enhanced radio emission excited by energetic electrons accelerated during solar eruptions, studies on which are important for investigating the origin and physical mechanism of energetic particles and further diagnosing ... More
Angle-resolved photoemission spectroscopy study on iron-based superconductorsJul 22 2013Aug 13 2013Angle-resolved photoemission spectroscopy (ARPES) has played an important role in determining the band structure and the superconducting gap structure of iron-based superconductors. Here from the ARPES perspective, we briefly review the main results from ... More
Strongly-coupled quantum critical point in an all-in-all-out antiferromagnetMay 04 2018Dimensionality and symmetry play deterministic roles in the laws of Nature. They are important tools to characterize and understand quantum phase transitions, especially in the limit of strong correlations between spin, orbit, charge, and structural degrees ... More
Evolution of Iron K$_α$ Line Emission in the Black Hole Candidate GX 339-4Jan 25 2001GX 339-4 was regularly monitored with RXTE during a period (in 1999) when its X-ray flux decreased significantly (from 4.2$\times 10^{-10}$ erg cm$^{-2} s^{-1}$ to 7.6$\times 10^{-12}$ erg cm$^{-2}$s$^{-1}$ in the 3--20 keV band), as the source settled ... More
Adaptation in multivariate log-concave density estimationDec 30 2018We study the adaptation properties of the multivariate log-concave maximum likelihood estimator over two subclasses of log-concave densities. The first consists of densities with polyhedral support whose logarithms are piecewise affine. The complexity ... More
Design of an electron gun for terahertz radiation sourceJun 03 2013With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an EC-ITC (External-Cathode Independently Tunable Cells) RF gun was employed. As the external injecting electron source of the ITC RF gun, a gridded DC ... More
Spin torque switching with the giant spin Hall effect of tantalumMar 13 2012We report a giant spin Hall effect (SHE) in {\beta}-Ta that generates spin currents intense enough to induce efficient spin-transfer-torque switching of ferromagnets, thereby providing a new approach for controlling magnetic devices that can be superior ... More
High-fidelity quantum memory using nitrogen-vacancy center ensemble for hybrid quantum computationJun 15 2011We study a hybrid quantum computing system using nitrogen-vacancy center ensemble (NVE) as quantum memory, current-biased Josephson junction (CBJJ) superconducting qubit fabricated in a transmission line resonator (TLR) as quantum computing processor ... More
Swift observations of the ultraluminous X-ray source Holmberg IX X-1Sep 01 2010Holmberg IX X-1 is a well-known ultraluminous X-ray source with an X-ray luminosity of ~1e40 erg/s. The source has been monitored by the X-ray Telescope of Swift regularly. Since 2009 April, the source has been in an extended low luminosity state. We ... More
Spin transfer torque devices utilizing the giant spin Hall effect of tungstenAug 08 2012We report a giant spin Hall effect (SHE) in {\beta}-W thin films. Using spin torque induced ferromagnetic resonance with a {\beta}-W/CoFeB bilayer microstrip we determine the spin Hall angle to be |\theta|=0.30\pm0.02, large enough for an in-plane current ... More
Entanglement of separate nitrogen-vacancy centers coupled to a whispering-gallery mode cavityOct 19 2010We present a quantum electrodynamical model involving nitrogen-vacancy centers coupled to a whispering-gallery mode cavity. Two schemes are considered to create W state and Bell state, respectively. One of the schemes makes use of the Raman transition ... More
Intrinsic Instability of Coronal StreamersJun 01 2009Plasma blobs are observed to be weak density enhancements as radially stretched structures emerging from the cusps of quiescent coronal streamers. In this paper, it is suggested that the formation of blobs is a consequence of an intrinsic instability ... More
KK258, a new transition dwarf galaxy neighbouring the Local GroupJun 17 2014Here we present observations with the Advanced Camera for Surveys on the Hubble Space Telescope of the nearby, transition-type dwarf galaxy KK258 = ESO468-020. We measure a distance of 2.23$\pm$0.05 Mpc using the Tip of Red Giant Branch method. We also ... More
Start-to-end simulation of the injector for a compact THz sourceOct 29 2013Terahertz radiation has broad application prospect due to its ability to penetrate deep into many organic materials without damage caused by ionizing radiations. A FEL-based THz source is the best choice to produce high-power radiation. In this paper, ... More
Multi-ion Mach-Zehnder interferometer with artificial nonlinear interactionsMay 03 2012We show how to implement a Mach-Zehnder interferometry based upon a string of trapped ions with artificial nonlinear interactions. By adiabatically sweeping down/up the coupling strength between two involved internal states of the ions, we could achieve ... More
Correlation between local structure and dynamic heterogeneity in a metallic glass-forming liquidOct 15 2015Dynamic heterogeneity as one of the most important properties in supercooled liquids has been found for several decades. However, its structural origin remains open for many systems. Here, we propose a new structural parameter to characterize local atomic ... More
Hysteresis measurement of anomalous microwave surface resistance in superconducting thin filmsJan 03 2000Jan 21 2000The anomalous decrease in microwave surface resistance, R_{s}, of superconducting YBa_{2}Cu_{3}O_{7-d} (YBCO) thin films in the presence of a low dc magnetic field is studied using a microstrip resonator technique. We have done a dc field hysteresis measurement ... More
Quantum Phase Transitions in the p-SiGe systemSep 20 1999The rich variety of phase transitions observed in the strained p-SiGe system are considered and compared. It is shown that the integer quantum Hall effect transitions, the Hall insulating transition and the re-entrant transition into an insulating phase ... More
Phonon drag thermopower and weak localizationJul 09 1998Previous experimental work on a two-dimensional (2D) electron gas in a Si-on-sapphire device led to the conclusion that both conductivity and phonon drag thermopower $S^g$ are affected to the same relative extent by weak localization. The present paper ... More
Transition between strong and weak topological insulator in ZrTe$_5$ and HfTe$_5$Nov 14 2016Mar 04 2017ZrTe$_5$ and HfTe$_5$ have attracted increasingly attention recently since the theoretical prediction of being topological insulators (TIs). However, subsequent works show many contradictions about their topological nature.Three possible phases, i.e. ... More
ARPES/STM study of the surface terminations and 5$f$-electron character in URu$_2$Si$_2$Sep 19 2018Hidden order in URu$_2$Si$_2$ has remained a mystery now entering its 4th decade. The importance of resolving the nature of the hidden order has stimulated extensive research. Here we present a detailed characterization of different surface terminations ... More
Nanotesla-level, shield-less, field-compensation-free, wave-mixing-enhanced body-temperature atomic magnetometry for biomagnetismApr 22 2018We report an optical inelastic-wave-mixing-enhanced atomic magnetometry technique that results in nT-level magnetic field detection at temperatures compatible with the human body without magnetic shielding, zero-field compensation, or high-frequency modulated ... More
Breaking the energy-symmetry blockade in magneto-optical rotationApr 20 2018The magneto-optical polarization rotation effect has prolific applications in various research areas spanning the scientific spectrum including space and interstellar research, nano-technology and material science, biomedical imaging, and sub-atomic particle ... More