Results for "J. -P. Li"

total 266037took 0.14s
Phonon structure in dispersion curves and density of states of massive Dirac FermionsJul 01 2013Dirac fermions exist in many solid state systems including graphene, silicene and other two dimensional membranes such as are found in group VI dichalcogenides, as well as on the surface of some insulators where such states are protected by topology. ... More
Optical spectral weight: comparison of weak and strong spin-orbit couplingMar 08 2015The Fermi velocity ($v_{F}$) associated with the spin-orbit coupling is two orders of magnitude smaller for spintronic semiconductors than it is for topological insulators. Both families can be treated with the same Hamiltonian which contains a relativistic ... More
A Likely Redback Millisecond Pulsar Counterpart of 3FGL J0838.8-2829Jun 28 2017Aug 02 2017We obtained new optical observations of the X-ray source XMMU J083850.38-282756.8, the previously proposed counterpart of the gamma-ray source 3FGL J0838.8-2829. Time-series photometry in the $r'$ band reveals periodic modulation of $\approx1$ magnitude ... More
X-ray spectroscopy of PSR B1951+32 and its pulsar wind nebulaApr 13 2005We present spatially resolved X-ray spectroscopy of PSR B1951+32 and its pulsar wind nebula (PWN) in supernova remnant (SNR) CTB 80 using a {\sl Chandra} observation. The {\sl Chandra} X-ray map reveals clearly various components of a ram-pressure confined ... More
Vanishing of interband light absorption in a persistent spin helix stateOct 15 2013Spin-orbit coupling plays an important role in various properties of very different materials. Moreover efforts are underway to control the degree and quality of spin-orbit coupling in materials with a concomitant control of transport properties. We calculate ... More
Pinning-depinning mechanism of the contact line during evaporation on chemically patterned surfaces: A lattice Boltzmann studySep 01 2016In this paper, the pinning and depinning mechanism of the contact line during droplet evaporation on chemically stripe-patterned surfaces is numerically investigated using a thermal multiphase lattice Boltzmann (LB) model with liquid-vapor phase change. ... More
Changes in Optical Conductivity due to Readjustments in Electronic Density of StatesJan 25 2002Within the model of elastic impurity scattering, we study how changes in the energy dependence of the electronic density of states (EDOS) $N(\epsilon)$ around the Fermi energy $\epsilon_F$ are reflected in the frequency-dependent optical conductivity ... More
Performance of Equal Phase-Shift Search for One IterationMar 23 2006Dec 16 2009Grover presented the phase-shift search by replacing the selective inversions by selective phase shifts of $\pi /3$. In this paper, we investigate the phase-shift search with general equal phase shifts. We show that for small uncertainties, the failure ... More
Improved thermal lattice Boltzmann model for simulation of liquid-vapor phase changeSep 13 2017Oct 30 2017In this paper, an improved thermal lattice Boltzmann (LB) model is proposed for simulating liquid-vapor phase change, which is aimed at improving an existing thermal LB model for liquid-vapor phase change [S. Gong and P. Cheng, Int. J. Heat Mass Transfer ... More
On the Anomalous Silicate Emission Features of AGNs: A Possible Interpretation Based on Porous DustAug 29 2008The recent Spitzer detections of the 9.7 micron Si--O silicate emission in type 1 AGNs provide support for the AGN unification scheme. The properties of the silicate dust are of key importance to understanding the physical, chemical and evolutionary properties ... More
Vortex in a d-wave superconductor at low temperaturesMar 09 2000Aug 24 2000A systematic perturbation theory is developed to describe the magnetic field-induced subdominant $s$- and $d_{xy}$-wave order parameters in the mixed state of a $d_{x^2-y^2}$-wave superconductor, enabling us to obtain, within weak-coupling BCS theory, ... More
Free Energy and Magnetic Penetration Depth of a $d$-Wave Superconductor in the Meissner StateJul 13 1999Mar 09 2000We investigate the free energy and the penetration depth of a quasi-two-dimensional d-wave superconductor in the presence of a weak magnetic field by taking account of thermal, nonlocal and nonlinear effects. In an approximation in which the superfluid ... More
Is the nonlinear Meissner effect unobservable?Aug 23 1998Dec 09 1998We examine the effects of nonlocal electrodynamics for a d-wave superconductor on the field dependence of the magnetic penetration depth. The linear field dependence predicted in the local limit, commonly known as the nonlinear Meissner effect, is instead ... More
Comment on ``$T$-dependence of the magnetic penetration depth in unconventional superconductors at low temperatures: Can it be linear?"Jun 05 1998Oct 31 1998We comment on a recent letter by Schopohl and Dolgov (SD) which raised the possibility that a d-wave superconductor might be thermodynamically unstable in the limit $T\to 0$. The point of our comment is that this instability can be inevitably prevented ... More
Reply to a Comment on "Is the nonlinear Meissner effect unobservable? (Phys. Rev. Lett. 81, 5640 (1998))" (Cond-mat/9812290)Jul 13 1999We reply to a recent comment by Bhattacharya et. al. (cond-mat/9812290) on our previous Letter (PRL 81, 5640 (1998)).
Ab Initio Approach to the Non-Perturbative Scalar Yukawa ModelApr 20 2015Jul 09 2015We report on the first non-perturbative calculation of the scalar Yukawa model in the single-nucleon sector up to four-body Fock sector truncation (one "scalar nucleon" and three "scalar pions"). The light-front Hamiltonian approach with a systematic ... More
Exploring Galaxy Formation Models and Cosmologies with Galaxy ClusteringFeb 14 2012Using N-body simulations and galaxy formation models, we study the galaxy stellar mass correlation and the two-point auto-correlation. The simulations are run with cosmological parameters from the WMAP first, third and seven year results, which mainly ... More
Polarization Variability Arising from Clumps in the Winds of Wolf-Rayet StarsMar 18 2009The polarimetric and photometric variability of Wolf-Rayet (WR) stars as caused by clumps in the winds, is revisited. In the model which is improved from Li et al. 2000, the radial expansion of the thickness is accounted for, but we retain the dependence ... More
Computational Topology: Isotopic Convergence to a Stick KnotMar 28 2016Computational topology is a vibrant contemporary subfield and this article integrates knot theory and mathematical visualization. Previous work on computer graphics developed a sequence of smooth knots that were shown to converge point wise to a piecewise ... More
Enhanced collectivity in neutron-deficient Sn isotopes in energy functional based collective HamiltonianSep 26 2012The low-lying collective states in Sn isotopes are studied by a five-dimensional collective Hamiltonian with parameters determined from the triaxial relativistic mean-field calculations using the PC-PK1 energy density functional. The systematics for both ... More
Diagnostics of the Heating Processes in Solar Flares Using Chromospheric Spectral LinesSep 25 2006We have calculated the H$\alpha$ and Ca {\sc ii} 8542 {\AA} line profiles based on four different atmospheric models, including the effects of nonthermal electron beams with various energy fluxes. These two lines have different responses to thermal and ... More
On Buckyonions as an Interstellar Grain ComponentAug 29 2008The carrier of the 2175 Angstrom interstellar extinction feature remains unidentified since its first detection over 40 years ago. In recent years carbon buckyonions have been proposed as a carrier of this feature, based on the close similarity between ... More
Covariant description of shape evolution and shape coexistence in neutron-rich nuclei at N\approx60Jul 28 2011The shape evolution and shape coexistence phenomena in neutron-rich nuclei at $N\approx60$, including Kr, Sr, Zr, and Mo isotopes, are studied in the covariant density functional theory (DFT) with the new parameter set PC-PK1. Pairing correlations are ... More
Global study of beyond-mean-field correlation energies in covariant energy density functional theory using a collective Hamiltonian methodFeb 24 2015We report the first global study of dynamic correlation energies (DCEs) associated with rotational motion and quadrupole shape vibrational motion in a covariant energy density functional (CEDF) for 575 even-even nuclei with proton numbers ranging from ... More
Effect of pairing correlations on nuclear low-energy structure: BCS and general Bogoliubov transformationDec 02 2013Low-lying nuclear states of Sm isotopes are studied in the framework of a collective Hamiltonian based on covariant energy density functional theory. Pairing correlation are treated by both BCS and Bogoliubov methods. It is found that the pairing correlations ... More
Reply to CommentFeb 14 2007Our experiments \cite{Wang05,Li05,Wang06} persuade us that the Meissner transition at $T_c$ in hole-doped cuprates is driven by the loss of long-range phase coherence caused by singular phase fluctuations, a scenario at odds with the mean-field (MF), ... More
Microscopic Description of Spherical to Gamma-Soft Shape Transitions in Ba and Xe NucleiMar 22 2010The rapid transition between spherical and $\gamma$-soft shapes in Ba and Xe nuclei in the mass region $A \geq 130$ is analyzed using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole ... More
Anisotropic properties of the layered superconductor Cu0.07TiSe2Nov 13 2006The anisotropic superconducting properties of single crystals of Cu0.07TiSe2 were studied by measurements of magnetization and electrical resistivity. TC is around 3.9 K, and the measured upper critical field (Hc2) values are ~1.25 T and 0.8 T, for applied ... More
On Stochastic Error and Computational Efficiency of the Markov Chain Monte Carlo MethodApr 14 2012Jan 07 2015In Markov Chain Monte Carlo (MCMC) simulations, the thermal equilibria quantities are estimated by ensemble average over a sample set containing a large number of correlated samples. These samples are selected in accordance with the probability distribution ... More
Controlling a Nanowire Spin-Orbit Qubit via Electric-Dipole Spin ResonanceApr 11 2013Sep 04 2013A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC) can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, an effect called electric-dipole spin ... More
The Cross-Spectra of Cir X-1: Evolution of Time LagsMar 22 2001Earlier work showed that the track in the X-ray hardness-intensity diagram of Cir X-1 corresponds to a Z track in its color-color diagram. In this paper, we study the cross spectrum of Cir X-1 in different regions of the hardness-intensity diagram with ... More
Gamma-Ray Bursts are Produced Predominately in the Early UniverseNov 16 2003Apr 20 2004It is known that some observed gamma-ray bursts (GRBs) are produced at cosmological distances and that the GRB production rate may follow the star formation rate. We model the BATSE-detected intensity distribution of long GRBs in order to determine their ... More
Validity of the relativistic impulse approximation for elastic proton-nucleus scattering at energies lower than 200 MeVJun 16 2008We present the first study to examine the validity of the relativistic impulse approximation (RIA) for describing elastic proton-nucleus scattering at incident laboratory kinetic energies lower than 200 MeV. For simplicity we choose a $^{208}$Pb target, ... More
Octupole degree of freedom for the critical-point candidate nucleus $^{152}$Sm in a reflection-asymmetric relativistic mean-field approachMar 11 2010The potential energy surfaces of even-even $^{146-156}$Sm are investigated in the constrained reflection-asymmetric relativistic mean-field approach with parameter set PK1. It is shown that the critical-point candidate nucleus $^{152}$Sm marks the shape/phase ... More
Energy-dependent Lorentz covariant parameterization of the NN interaction between 50 and 200 MeVOct 17 2007Dec 03 2007For laboratory kinetic energies between 50 and 200 MeV, we focus on generating an energy-dependent Lorentz covariant parameterization of the on-shell nucleon-nucleon (NN) scattering amplitudes in terms of a number of Yukawa-type meson exchanges in first-order ... More
Evolution of Hard X-Ray Spectra Along the Branches in Cir X-1Sep 05 2003Using the data from the PCA and HEXTE on board the RXTE satellite, we investigate the evolution of the 3-200 keV spectra of the peculiar low mass X-ray binary (LMXB) Cir X-1 along the branches on its hardness-intensity diagram (HID) from the vertical ... More
Hot NH3 Spectra for Astrophysical ApplicationsMay 17 2011We present line lists for ammonia (NH$_{3}$) at high temperatures obtained by recording Fourier transform infrared emission spectra. Calibrated line lists are presented for twelve temperatures (300 -- 1300$^{\circ}$C in 100$^{\circ}$C intervals and 1370$^{\circ}$C) ... More
50 pico arcsecond astrometry of pulsar emissionJan 31 2013Feb 05 2013We use VLBI imaging of the interstellar scattering speckle pattern associated with the pulsar PSR 0834+06 to measure the astrometric motion of its emission. The ~ 5AU interstellar baselines, provided by interference between speckles spanning the scattering ... More
Impurity effect of $Λ$ hyperon on shape-coexistence nucleus $^{44}$S in the energy functional based collective HamiltonianOct 06 2011The non-relativistic Skyrme energy density functional (EDF) based collective Hamiltonian, that takes into account dynamical correlations related to the restoration of broken symmetries and fluctuations of quadrupole collective variables, is applied to ... More
Could 2S 0114+650 be a magnetar?Jan 08 1999Jan 10 1999We investigate the spin evolution of the binary X-ray pulsar 2S 0114+650, which possesses the slowest known spin period of $\sim 2.7$ hours. We argue that, to interpret such long spin period, the magnetic field strength of this pulsar must be initially ... More
Study of Temporal Evolution of Emission Spectrum in a Steeply Rising Submillimeter BurstJun 17 2015In the paper the spectral temporal evolution of a steeply rising submillimeter (THz) burst occurred on 2003 November 2 was investigated in detail for the first time. Observations show that the flux density of the THz spectrum increased steeply with frequency ... More
The DSUB$m$ Approximation Scheme for the Coupled Cluster Method and Applications to Quantum MagnetsMay 01 2009A new approximate scheme, DSUB$m$, is described for the coupled cluster method. We then apply it to two well-studied (spin-1/2 Heisenberg antiferromagnet) spin-lattice models, namely: the $XXZ$ and the $XY$ models on the square lattice in two dimensions. ... More
Low-energy structure and anti-bubble effect of dynamical correlations in 46ArNov 02 2013Jan 20 2014The low-energy structure of 46Ar is of particular interest due to the possible coexistence of different shapes and the possible existence of proton bubble structure. In this work, we apply a beyond relativistic mean-field approach to study the low-energy ... More
Effect of r-mode instability on the evolution of isolated strange starsApr 06 2006May 11 2006We studied the evolution of isolated strange stars synthetically, considering the influence of {\it r-}mode instability. Our results show that the cooling of strange stars with non-ultra strong magnetic fields is delayed by the heating due to the {\it ... More
Distance Determination of Variable Galactic SourcesDec 04 2002We have developed a timing analysis method to determine the distances of variable galactic X-ray sources based on the method advanced by Tr\"{u}mper and Sch\"{o}nfelder in 1973. The light-curve of the halo produced by the scattering of X-rays off the ... More
Microscopic Analysis of Order Parameters in Nuclear Quantum Phase TransitionsDec 07 2009Microscopic signatures of nuclear ground-state shape phase transitions in Nd isotopes are studied using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational ... More
Parity, Charge Conjugation and SU(3) Constraints on Threshold Enhancement in $J/ψ$ decays into $γp\bar p$ and $K p \barΛ$Jul 07 2004Dec 20 2004We study the threshold enhancement effects of baryon-anti-baryon systems in $J/\psi$ decays at BES using parity $P$, charge conjugation $C$, and flavor SU(3) symmetries. The $P$ and $C$ symmetries restrict the $p\bar p$ in $J/\psi \to \gamma p\bar p$ ... More
Beyond relativistic mean-field approach for nuclear octupole excitationsJul 13 2015Oct 08 2015We report the first beyond-mean-field study of low-lying parity-doublet states in 224Ra by extending the multireference relativistic energy density functional method to include dynamical correlations related to symmetry restoration and quadrupole-octupole ... More
Does a proton "bubble" structure exist in the low-lying states of 34Si?May 21 2013The possible existence of a "bubble" structure in the proton density of $^{34}$Si has recently attracted a lot of research interest. To examine the existence of the "bubble" structure in low-lying states, we establish a relativistic version of configuration ... More
Relativistic description of magnetic moments in nuclei with doubly closed shells plus or minus one nucleonJul 08 2013Using the relativistic point-coupling model with density functional PC-PK1, the magnetic moments of the nuclei $^{207}$Pb, $^{209}$Pb, $^{207}$Tl and $^{209}$Bi with a $jj$ closed-shell core $^{208}$Pb are studied on the basis of relativistic mean field ... More
Spinon and eta-spinon correlation functionsFeb 08 2013We calculate real-space static correlation functions related to basic entities of the one-dimensional Hubbard model, which emerge from the exact Bethe-ansatz solution. These entities involve complex rearrangements of the original electrons. Basic ingredients ... More
Diversity of multiwavelength emission bumps in the GRB 100219A afterglowDec 04 2011Context. Multi-wavelength observations of gamma-ray burst (GRB) afterglows provide important information about the activity of their central engines and their environments. In particular, the short timescale variability, such as bumps and/or rebrightening ... More
Anatomy of molecular structures in $^{20}$NeOct 18 2015Dec 10 2015We present a beyond mean-field study of clusters and molecular structures in low-spin states of $^{20}$Ne with a multireference relativistic energy density functional, where the dynamical correlation effects of symmetry restoration and quadrupole-octupole ... More
An efficient method for computing the Thouless-Valatin inertia parametersSep 26 2012Starting from the adiabatic time-dependent Hartree-Fock approximation (ATDHF), we propose an efficient method to calculate the Thouless-Valatin moments of inertia for the nuclear system. The method is based on the rapid convergence of the expansion of ... More
Quantum fluctuations in the shape of exotic nucleiSep 09 2009Quantum fluctuations concerning the shape of nuclei are treated within the framework of covariant density functional theory. Long range correlations beyond mean field are taken into account by configuration mixing of wave functions with triaxial shapes ... More
A microscopic benchmark-study of triaxiality in low-lying states of 76KrMar 19 2014Apr 22 2014We report on a seven-dimensional generator coordinate calculation in the two deformation parameters $\beta$ and $\gamma$ together with projection on three-dimensional angular momentum and two particle numbers for the low-lying states in $^{76}$Kr. These ... More
New parametrization for the nuclear covariant energy density functional with point-coupling interactionFeb 09 2010Nov 11 2010A new parametrization PC-PK1 for the nuclear covariant energy density functional with nonlinear point-coupling interaction is proposed by fitting to observables for 60 selected spherical nuclei, including the binding energies, charge radii and empirical ... More
Orbital Period and Outburst Luminosity of Transient Low Mass X-ray BinariesJun 01 2010In this paper we investigate the relation between the maximal luminosity of X-ray outburst and the orbital period in transient low mass X-ray binaries (or soft X-ray transients) observed by the Rossi X-ray Timing Explorer (RXTE) in the past decade. We ... More
Magnetic Soliton and Soliton Collisions of Spinor Bose-Einstein Condensates in an Optical LatticeJun 04 2005We study the magnetic soliton dynamics of spinor Bose-Einstein condensates in an optical lattice which results in an effective Hamiltonian of anisotropic pseudospin chain. A modified Landau-Lifshitz equation is derived and exact magnetic soliton solutions ... More
Identification of Superfluid Phases of 3He in Uniformly Isotropic 98.2% AerogelSep 04 2011Oct 23 2011Superfluid 3He confined to high porosity silica aerogel is the paradigm system for understanding impurity effects in unconventional superconductors. However, a crucial first step has been elusive; exact identification of the microscopic states of the ... More
Quantum s = 1/2 Antiferromagnets on Archimedean Lattices: The Route from Semiclassical Magnetic Order to Nonmagnetic Quantum StatesDec 04 2013We investigate ground states of $s$=1/2 Heisenberg antiferromagnets on the eleven two-dimensional (2D) Archimedian lattices by using the coupled cluster method. Magnetic interactions and quantum fluctuations play against each other subtly in 2D quantum ... More
The frustrated Heisenberg antiferromagnet on the honeycomb lattice: A candidate for deconfined quantum criticalityMar 20 2011We study the ground-state (gs) phase diagram of the frustrated spin-1/2 $J_{1}$-$J_{2}$-$J_{3}$ antiferromagnet with $J_{2} = J_{3} =\kappa J_1$ on the honeycomb lattice, using coupled-cluster theory and exact diagonalization methods. We present results ... More
Density dependencies of interaction strengths and their influence on nuclear matter and neutron star in relativistic mean field theoryFeb 13 2004The density dependencies of various effective interaction strengths in the relativistic mean field are studied and carefully compared for nuclear matter and neutron stars. The influences of different density dependencies are presented and discussed on ... More
Beyond relativistic mean-field studies of low-lying states in neutron-deficient krypton isotopesApr 15 2013Neutron-deficient krypton isotopes are of particular interest due to the coexistence of oblate and prolate shapes in low-lying states and the transition of ground-state from one dominate shape to another as a function of neutron number. A detailed interpretation ... More
Nonlinear field-dependence and f-wave interactions in superfluid 3HeAug 13 2012Nov 14 2012We present results of transverse acoustics studies in superfluid ^{3}He-B at fields up to 0.11 T. Using acoustic cavity interferometry, we observe the Acoustic Faraday Effect for a transverse sound wave propagating along the magnetic field, and we measure ... More
Ground-state phases of the frustrated spin-1/2 $J_{1}$--$J_{2}$--$J_{3}$ Heisenberg ferromagnet ($J_{1}<0$) on the honeycomb lattice with $J_{3}=J_{2}>0$Sep 28 2011Feb 08 2012We study the ground-state (gs) properties of the frustrated spin-1/2 $J_{1}$--$J_{2}$--$J_{3}$ Heisenberg model on a honeycomb lattice with ferromagnetic (FM) nearest-neighbor ($J_{1}=-1$) exchange and frustrating antiferromagnetic (AFM) next-nearest-neighbor ... More
The Heisenberg antiferromagnet on the kagome lattice with arbitrary spin: A high-order coupled cluster treatmentOct 14 2011Starting with the sqrt{3} x sqrt{3} and the q=0 states as reference states we use the coupled cluster method to high orders of approximation to investigate the ground state of the Heisenberg antiferromagnet on the kagome lattice for spin quantum numbers ... More
Topological Equivalence and Curvature Convergence: Bezier Surface ApproximationNov 21 2013A set of control points can determine a Bezier surface and a triangulated surface simultaneously. We prove that the triangulated surface becomes homeomorphic and ambient isotopic to the Bezier surface via subdivision. We also show that the total Gaussian ... More
Zeeman splitting and nonlinear field-dependence in superfluid 3HeAug 13 2012We have studied the acoustic Faraday effect in superfluid 3He up to significantly larger magnetic fields than in previous experiments achieving rotations of the polarization of transverse sound as large as 1710^{\circ}. We report nonlinear field effects, ... More
The frustrated Heisenberg antiferromagnet on the checkerboard lattice: the $J_{1}$--$J_{2}$ modelFeb 13 2012We study the ground-state (gs) phases of the spin-half anisotropic planar pyrochlore (or crossed chain) model using the coupled cluster method (CCM). The model is a frustrated antiferromagnetic (AFM) $J_{1}$--$J_{2}$ system on the checkerboard lattice, ... More
Rapid structural change in low-lying states of neutron-rich Sr and Zr isotopesJan 17 2012The rapid structural change in low-lying collective excitation states of neutron-rich Sr and Zr isotopes is tudied by solving a five-dimensional collective Hamiltonian with parameters determined by both relativistic mean-field and non-relativistic Skyrme-Hartree-Fock ... More
Recent progress in Hamiltonian light-front QCDDec 10 2008Hamiltonian light-front quantum field theory constitutes a framework for the non-perturbative solution of invariant masses and correlated parton amplitudes of self-bound systems. By choosing light-front gauge and adopting a basis function representation, ... More
Optical study on doped polyaniline composite filmsApr 27 2004Localization driven by disorder has a strong influence on the conducting property of conducting polymer. A class of authors hold the opinion that disorder in the material is homogeneous and conducting polymer is disordered metal close to Anderson-Mott ... More
Microscopic Analysis of Nuclear Quantum Phase Transitions in the N=90 regionApr 09 2009The analysis of shape transitions in Nd isotopes, based on the framework of relativistic energy density functionals and restricted to axially symmetric shapes in Ref. \cite{PRL99}, is extended to the region $Z = 60$, 62, 64 with $N \approx 90$, and includes ... More
Probing superconducting energy gap from infrared spectroscopy on a Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystal with T$_c$=37 KJul 07 2008We performed optical spectroscopy measurement on a superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystal with T$_c$=37 K. Formation of the superconducting energy gaps in the far-infared reflectance spectra below T$_c$ is clearly observed. The ... More
Origin of the spin density wave instability in AFe$_2$As$_2$ (A=Ba, Sr) as revealed by optical spectroscopyJun 16 2008Nov 21 2008We performed optical spectroscopy measurement on single crystals of BaFe$_2$As$_2$ and SrFe$_2$As$_2$, the parent compounds of FeAs based superconductors. Both are found to be quite metallic with fairly large plasma frequencies at high temperature. Upon ... More
Correlating Quasi-Electron Relaxation with Quantum Femtosecond Magnetism in the Order Parameter Dynamics of Insulating ManganitesSep 03 2014Femtosecond (fs)-resolved simultaneous measurements of charge and spin dynamics reveal the coexistence of two different quasi-particle excitations in colossal magneto-resistive (CMR) manganites, with {\em fs} and {\em ps} relaxation times respectively. ... More
Fiber-Optic Sources of Quantum EntanglementSep 20 2002We present a fiber-based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 1.5$\mu$m band of standard telecommunication fiber. Quantum-correlated signal and idler photon pairs are produced ... More
The giant arc statistics in the three year WMAP cosmological modelAug 09 2006We use high-resolution $N$-body simulations to investigate the optical depth of giant arcs with length-to-width ratio larger than 7.5 and 10 in the `standard' $\LCDM$ model with $\sigma_8=0.9$ and $\Omega_{\rm m,0}=0.3$ and a model based on three-year ... More
Enhanced low field magnetoresistance of Fe3O4 nano-sphere compactJun 22 2006Unusually large low field magetoresistance (LFMR), ~ 10 %, at 300 K has been observed with the sample of mono-dispersed Fe3O4 magnetite nanospheres, ~ 200 nm, compactly cold-pressed and sintered at 800 C. A detailed analysis on the transport and magnetic ... More
Tuning from failed superconductor to failed insulator with magnetic fieldOct 24 2018Do charge modulations compete with electron pairing in high-temperature copper-oxide superconductors? We investigated this question by suppressing superconductivity in a stripe-ordered cuprate compound at low temperature with high magnetic fields. With ... More
Modal decomposition of a propagating matter wave via electron ptychographyNov 29 2016We employ ptychography, a phase-retrieval imaging technique, to show experimentally for the first time that a partially coherent high-energy matter (electron) wave emanating from an extended source can be decomposed into a set of mutually independent ... More
Beyond the relativistic mean-field approximation (III): collective Hamiltonian in five dimensionsNov 03 2008Feb 24 2009The framework of relativistic energy density functionals is extended to include correlations related to restoration of broken symmetries and fluctuations of collective variables. A new implementation is developed for the solution of the eigenvalue problem ... More
H-Alpha and Hard X-Ray Observations of a Two-Ribbon Flare Associated with a Filament EruptionAug 06 2003We perform a multi-wavelength study of a two-ribbon flare on 2002 September 29 and its associated filament eruption, observed simultaneously in the H-alpha line by a ground-based imaging spectrograph and in hard X-rays by RHESSI. The flare ribbons contain ... More
High-Purity Telecom-Band Entangled Photon-Pairs via Four-Wave Mixing in Dispersion-Shifted FiberFeb 03 2006We have studied the purity of entangled photon-pairs generated in a dispersion-shifted fiber at various temperatures. Two-photon interference with visibility > 98% is observed at 77K, without subtraction of the background Raman photons.
Coexistence of superconductivity and charge-density-wave domain in $1T$-Fe$_x$Ta$_{1-x}$SSeJun 20 2014Jun 23 2014A series of $1T$-Fe$_x$Ta$_{1-x}$SSe (0 $\leq x \leq$ 0.1) single crystals was fabricated via the chemical-vapor-transport (CVT) method and investigated by structure, transport, and magnetic measurements along with the density-functional-theory (DFT) ... More
Nonperturbative Corrections to One Gluon Exchange Quark PotentialsJul 22 1998The leading nonperturbative QCD corrections to the one gluon exchange quark-quark, quark-antiquark and $q \bar{q}$ pair-excitation potentials are derived by using a covariant form of nonlocal two-quark and two-gluon vacuum expectation values. Our numerical ... More
Search for D^0-D^0bar mixing in D^0 -> K+pi- decays and measurement of the doubly-Cabibbo-suppressed decay rateAug 24 2004Nov 08 2004We have searched for mixing in the D0-D0bar system by measuring the decay-time distribution of D0->K+pi- decays. The analysis uses 90 fb^{-1} of data collected by the Belle detector at the KEKB e+e- collider. We fit the decay-time distribution for the ... More
Engineering an atom-interferometer with modulated light-induced $3 π$ spin-orbit couplingFeb 16 2015We have developed an experimental method to modify the single-particle dispersion using periodic modulation of Raman beams which couple two spin-states of an ultracold atomic gas. The modulation introduces a new coupling between Raman-induced spin-orbit-coupled ... More
Particle Energization in 3D Magnetic Reconnection of Relativistic Pair PlasmasMay 13 2010Apr 19 2011We present large scale 3D particle-in-cell (PIC) simulations to examine particle energization in magnetic reconnection of relativistic electron-positron (pair) plasmas. The initial configuration is set up as a relativistic Harris equilibrium without a ... More
Dewetting-controlled binding of ligands to hydrophobic pocketsNov 16 2009We report on a combined atomistic molecular dynamics simulation and implicit solvent analysis of a generic hydrophobic pocket-ligand (host-guest) system. The approaching ligand induces complex wetting/dewetting transitions in the weakly solvated pocket. ... More
Magnetic order on a frustrated spin-1/2 Heisenberg antiferromagnet on the Union Jack latticeApr 14 2010Jun 23 2010We use the coupled cluster method (CCM) to study the zero-temperature phase diagram of a 2D frustrated spin-half antiferromagnet, the so-called Union Jack model. It is defined on a square lattice such that all nearest-neighbor bonds are present with a ... More
Effect of anisotropy on the ground-state magnetic ordering of the spin-half quantum $J_1^{XXZ}$--$J_2^{XXZ}$ model on the square latticeMay 20 2008We study the zero-temperature phase diagram of the 2D quantum $J_{1}^{XXZ}$--$J_{2}^{XXZ}$ spin-1/2 anisotropic Heisenberg model on the square lattice. In particular, the effects of the anisotropy $\Delta$ on the $z$-aligned N\'{e}el and (collinear) stripe ... More
The frustrated Heisenberg antiferromagnet on the honeycomb lattice: $J_{1}$--$J_{2}$ modelJan 17 2012We study the ground-state (gs) phase diagram of the frustrated spin-1/2 $J_{1}$--$J_{2}$ antiferromagnet with $J_{2}=\kappa J_1>0$ ($J_{1}>0$) on the honeycomb lattice, using the coupled-cluster method. We present results for the ground-state energy, ... More
The Effect of Rotational Gravity Darkening on Magnetically Torqued Be Star DisksJul 02 2004In the magnetically torqued disk (MTD) model for hot star disks, as proposed and formulated by \citet{cassi02}, stellar wind mass loss was taken to be uniform over the stellar surface. Here account is taken of the fact that as stellar spin rate S_o (=\sqrt ... More
Phase diagram of a frustrated Heisenberg antiferromagnet on the honeycomb lattice: the $J_{1}$--$J_{2}$--$J_{3}$ modelApr 11 2012We use the coupled cluster method in high orders of approximation to make a comprehensive study of the ground-state (GS) phase diagram of the spin-1/2 $J_{1}$--$J_{2}$--$J_{3}$ model on a two-dimensional honeycomb lattice with antiferromagnetic (AFM) ... More
The ground-state magnetic ordering of the spin-1/2 frustrated J1-J2 XXZ model on the square latticeAug 20 2008Sep 15 2008Using the coupled-cluster method for infinite lattices and the exact diagonalization method for finite lattices, we study the influence of an exchange anisotropy Delta on the ground-state phase diagram of the spin-1/2 frustrated J1-J2 XXZ antiferromagnet ... More
Simultaneous quadrupole and octupole shape phase transitions in ThoriumApr 13 2013Sep 11 2013The evolution of quadrupole and octupole shapes in Th isotopes is studied in the framework of nuclear Density Functional Theory. Constrained energy maps and observables calculated with microscopic collective Hamiltonians indicate the occurrence of a simultaneous ... More
X-ray Emission from Magnetically Torqued Disks of Oe/Be StarsOct 14 2007We focus attention on the Oe/Be stars to test the concept that the disks of these stars form by magnetic channeling of wind material toward the equator. Calculations are made of the X-rays expected from the Magnetically Torqued Disk (MTD) model for Be ... More
Anisotropic phases of superfluid 3He in compressed aerogelJan 10 2015It has been shown that the relative stabilities of various superfluid states of 3He can be influenced by anisotropy in a silica aerogel framework. We prepared a suite of aerogel samples compressed up to 30% for which we performed pulsed NMR on 3He imbibed ... More