Results for "C. J. R. Clark"

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Modelling the Polarisation of Microwave Foreground Emission on Large Angular ScalesNov 27 2012Jan 18 2013Templates for polarised emission from Galactic foregrounds at frequencies relevant to Cosmic Microwave Background (CMB) polarisation experiments are obtained by modelling the Galactic Magnetic Field (GMF) on large scales. This work extends the results ... More
Excitation spectroscopy of vortex states in dilute Bose-condensed gasesOct 10 1996We apply linear-response analysis to the Gross-Pitaevskii equation to obtain the excitation frequencies of a Bose-Einstein condensate in a vortex state, and apply it to a system of Rubidium atoms confined in a time-averaged orbiting potential trap. The ... More
Collective excitations of Bose-Einstein condensed gases at finite temperaturesAug 19 1997We have applied the Popov version of the Hartree-Fock-Bogoliubov (HFB) approximation to calculate the finite-temperature excitation spectrum of a Bose-Einstein condensate (BEC) of $^{87}$Rb atoms. For lower values of the temperature, we find excellent ... More
NGC300 X-1 and IC10 X-1: a new breed of black hole binary?Jul 03 2008[ABRIDGED] IC10 X-1 has recently been confirmed as a black hole (BH) + Wolf-Rayet (WR) X-ray binary, and NGC300 X-1 is thought to be. IC10 X-1 and NGC300 X-1 have similar X-ray properties, with luminosities ~10^38 erg/s, and orbital periods ~30 hr. We ... More
Adaptive Multigrid Algorithm for Lattice QCDJul 26 2007We present a new multigrid solver that is suitable for the Dirac operator in the presence of disordered gauge fields. The key behind the success of the algorithm is an adaptive projection onto the coarse grids that preserves the near null space. The resulting ... More
Adaptive Multigrid Algorithm for the QCD Dirac-Wilson OperatorOct 18 2007Oct 26 2007We present a new multigrid solver that is suitable for the Dirac operator in the presence of disordered gauge fields. The key behind the success of the algorithm is an adaptive projection onto the coarse grids that preserves the near null space. The resulting ... More
Radio and submillimetre observations of wind structure in zeta PupJun 16 2003We present radio and submillimetre observations of the O4I(n)f star zeta Pup, and discuss structure in the outer region of its wind (~ 10-100 R*). The properties of bremsstrahlung, the dominant emission process at these wavelengths, make it sensitive ... More
ALMA observations of the supergiant B[e] star Wd1-9Sep 12 2016Mass-loss in massive stars plays a critical role in their evolution, although the precise mechanism(s) responsible - radiatively driven winds, impulsive ejection and/or binary interaction -remain uncertain. In this paper we present ALMA line and continuum ... More
A Model For Polarised Microwave Foreground Emission From Interstellar DustJul 22 2011Dec 21 2011The upcoming generation of cosmic microwave background (CMB) experiments face a major challenge in detecting the weak cosmic B-mode signature predicted as a product of primordial gravitational waves. To achieve the required sensitivity these experiments ... More
Multigrid Algorithms for Domain-Wall FermionsMay 14 2012We describe an adaptive multigrid algorithm for solving inverses of the domain-wall fermion operator. Our multigrid algorithm uses an adaptive projection of near-null vectors of the domain-wall operator onto coarser four-dimensional lattices. This extension ... More
Electric field induced charge noise in doped silicon: ionization of phosphorus donorsOct 26 2004Nov 10 2005We report low frequency charge noise measurement on silicon substrates with different phosphorus doping densities. The measurements are performed with aluminum single electron transistors (SETs) at millikelvin temperatures where the substrates are in ... More
Kepler K2 observations of the transitional millisecond pulsar PSR J1023+0038Jan 31 2018For 80 days in 2017, the Kepler Space Telescope continuously observed the transitional millisecond pulsar system PSR J1023$+$0038 in its accreting state. We present analyses of the 59-second cadence data, focusing on investigations of the orbital light ... More
Kepler K2 observations of the transitional millisecond pulsar PSR J1023+0038Jan 31 2018Mar 16 2018For 80 days in 2017, the Kepler Space Telescope continuously observed the transitional millisecond pulsar system PSR J1023+0038 in its accreting state. We present analyses of the 59 second cadence data, focusing on investigations of the orbital light ... More
Optimizing performance per watt on GPUs in High Performance Computing: temperature, frequency and voltage effectsJul 30 2014Oct 20 2015The magnitude of the real-time digital signal processing challenge attached to large radio astronomical antenna arrays motivates use of high performance computing (HPC) systems. The need for high power efficiency (performance per watt) at remote observatory ... More
Multigrid solver for clover fermionsNov 11 2010We present an adaptive multigrid Dirac solver developed for Wilson clover fermions which offers order-of-magnitude reductions in solution time compared to conventional Krylov solvers. The solver incorporates even-odd preconditioning and mixed precision ... More
Total correlations of the diagonal ensemble herald the many-body localization transitionApr 26 2015Nov 06 2015The intriguing phenomenon of many-body localization (MBL) has attracted significant interest recently, but a complete characterization is still lacking. In this work, we introduce the total correlations, a concept from quantum information theory capturing ... More
Starspots on WASP-107 and pulsations of WASP-118Feb 16 2017Apr 23 2017By analysing the K2 short-cadence photometry we detect starspot occultation events in the lightcurve of WASP-107, the host star of a warm-Saturn exoplanet. WASP-107 also shows a rotational modulation with a period of 17.5 +/- 1.4 d. Given that the rotational ... More
VdBH 222: a starburst cluster in the inner Milky WayMay 28 2014It has been suggested that the compact open cluster VdBH 222 is a young massive distant object. We set out to characterise VdBH 222 using a comprehensive set of multi-wavelength observations. We obtained multi-band optical (UBVR) and near-infrared (JHK) ... More
Starspots on WASP-85Aug 28 2015Mar 21 2016By analysing K2 short-cadence observations we detect starspots on WASP-85A, the host star of the hot Jupiter WASP-85Ab. The detection of recurring starspot occultation events indicates that the planet's orbit is aligned with the star's rotational axis ... More
The removal of critical slowing downNov 26 2008Apr 01 2010We present promising initial results of our adaptive multigrid solver developed for application directly to the non-Hermitian Wilson-Dirac system in 4 dimensions, as opposed to the solver developed in [1] for the corresponding normal equations. The key ... More
The efficiency of star formation in clustered and distributed regionsSep 06 2010We investigate the formation of both clustered and distributed populations of young stars in a single molecular cloud. We present a numerical simulation of a 10,000 solar mass elongated, turbulent, molecular cloud and the formation of over 2500 stars. ... More
Capturing long range correlations in two-dimensional quantum lattice systems using correlator product statesJul 05 2011Oct 24 2011We study the suitability of correlator product states for describing ground-state properties of two-dimensional spin models. Our ansatz for the many-body wave function takes the form of either plaquette or bond correlator product states and the energy ... More
An Analysis of Transiting Hot Jupiters Observed with K2: WASP-55b and WASP-75bFeb 06 2018We present our analysis of the K2 short-cadence data of two previously known hot Jupiter exoplanets: WASP-55b and WASP-75b. The high precision of the K2 lightcurves enabled us to search for transit timing and duration variations, rotational modulation, ... More
Pion-Nucleus Scattering at Medium Energies with Densities from Chiral Effective Field TheoriesFeb 20 1998Recently developed chiral effective field theory models provide excellent descriptions of the bulk characteristics of finite nuclei, but have not been tested with other observables. In this work, densities from both relativistic point-coupling models ... More
Gate-controlled charge transfer in Si:P double quantum dotsDec 19 2006Mar 25 2008We present low temperature charge sensing measurements of nanoscale phosphorus-implanted double-dots in silicon. The implanted phosphorus forms two 50 nm diameter islands with source and drain leads, which are separated from each other by undoped silicon ... More
Radiation Rates for Low Z Impurities in Edge PlasmasJun 19 1995Jun 20 1995The role of impurity radiation in the reduction of heat loads on divertor plates in present experiments such as DIII-D, JET, JT-60, ASDEX, and Alcator C-Mod, and in planned experiments such as ITER and TPX places a new degree of importance on the accuracy ... More
Energy-dependent evolution in IC10 X-1: hard evidence for an extended corona, and implicationsJul 21 2014We have analyzed a ~130 ks XMM-Newton observation of the dynamically confirmed black hole + Wolf-Rayet (BH+WR) X-ray binary (XB) IC10 X-1, covering ~1 orbital cycle. This system experiences periodic intensity dips every ~35 hours. We find that energy-independent ... More
The effect of low-energy ion-implantation on the electrical transport properties of Si-SiO2 MOSFETsNov 08 2004Using silicon MOSFETs with thin (5nm) thermally grown SiO2 gate dielectrics, we characterize the density of electrically active traps at low-temperature after 16keV phosphorus ion-implantation through the oxide. We find that, after rapid thermal annealing ... More
Electrically-detected magnetic resonance in ion-implanted Si:P nanostructuresMay 22 2006We present the results of electrically-detected magnetic resonance (EDMR) experiments on silicon with ion-implanted phosphorus nanostructures, performed at 5 K. The devices consist of high-dose implanted metallic leads with a square gap, into which Phosphorus ... More
Capturing the re-entrant behaviour of one-dimensional Bose-Hubbard modelAug 20 2012The Bose Hubbard model (BHM) is an archetypal quantum lattice system exhibiting a quantum phase transition between its superfluid (SF) and Mott-insulator (MI) phase. Unlike in higher dimensions the phase diagram of the BHM in one dimension possesses regions ... More
Deep Near-Infrared Imaging and Photometry of the Antennae Galaxies with WIRCSep 06 2005We present deep near-infrared images of the Antennae galaxies, taken with the Palomar Wide-Field Infrared Camera WIRC. The images cover a 4.33' x 4.33' (24.7kpc x 24.7kpc) area around the galaxy interaction zone. We derive J and K_s band photometric fluxes ... More
Signatures of chaotic and non-chaotic-like behaviour in a non-linear quantum oscillator through photon detectionMar 23 2005Dec 21 2005The driven non-linear duffing osillator is a very good, and standard, example of a quantum mechanical system from which classical-like orbits can be recovered from unravellings of the master equation. In order to generated such trajectories in the phase ... More
Persistent Entanglement in the Classical LimitSep 17 2004Nov 12 2004The apparent difficulty in recovering classical nonlinear dynamics and chaos from standard quantum mechanics has been the subject of a great deal of interest over the last twenty years. For open quantum systems - those coupled to a dissipative environment ... More
Open questions in the study of population III star formationAug 05 2008The first stars were key drivers of early cosmic evolution. We review the main physical elements of the current consensus view, positing that the first stars were predominantly very massive. We continue with a discussion of important open questions that ... More
Towards Rechargeable Zinc-Air Batteries with Aqueous Chloride ElectrolytesFeb 12 2019This paper presents a combined theoretical and experimental investigation of aqueous near-neutral electrolytes based on chloride salts for rechargeable zinc-air batteries (ZABs). The resilience of near-neutral chloride electrolytes in air could extend ... More
Modeling Single Electron Transfer in Si:P Double Quantum DotsSep 13 2004Solid-state systems such as P donors in Si have considerable potential for realization of scalable quantum computation. Recent experimental work in this area has focused on implanted Si:P double quantum dots (DQDs) that represent a preliminary step towards ... More
A Dust Twin of Cas A: Cool Dust and 21-micron Silicate Dust Feature in the Supernova Remnant G54.1+0.3Jul 25 2017Jul 07 2018We present infrared (IR) and submillimeter observations of the Crab-like supernova remnant (SNR) G54.1+0.3 including 350 micron (SHARC-II), 870 micron (LABOCA), 70, 100, 160, 250, 350, 500 micron (Herschel) and 3-40 micron (Spitzer). We detect dust features ... More
The Arches cluster revisited: II. A massive eclipsing spectroscopic binary in the Arches clusterApr 16 2018We have carried out a spectroscopic variability survey of some of the most massive stars in the Arches cluster, using K-band observations obtained with SINFONI on the VLT. One target, F2, exhibits substantial changes in radial velocity; in combination ... More
On the Origin of the Absorption Features in SS433Oct 14 2005We present high-resolution optical spectroscopy of the X-ray binary system SS433, obtained over a wide range of orbital phases. The spectra display numerous weak absorption features, and include the clearest example seen to date of those features, resembling ... More
Adaptive multigrid algorithm for the lattice Wilson-Dirac operatorMay 17 2010Jun 22 2010We present an adaptive multigrid solver for application to the non-Hermitian Wilson-Dirac system of QCD. The key components leading to the success of our proposed algorithm are the use of an adaptive projection onto coarse grids that preserves the near ... More
Close-coupling calculations of low-energy inelastic and elastic processes in $^4$He collisions with H$_2$: A comparative study of two potential energy surfacesDec 09 2004The two most recently published potential energy surfaces (PESs) for the HeH$_2$ complex, the so-called MR (Muchnick and Russek) and BMP (Boothroyd, Martin, and Peterson) surfaces, are quantitatively evaluated and compared through the investigation of ... More
Precise Pointing and Stabilization Performance for the Balloon-borne Imaging Testbed (BIT): 2015 Test FlightMar 03 2016Balloon-borne astronomy offers an attractive option for experiments that require precise pointing and attitude stabilization, due to a large reduction in the atmospheric interference observed by ground-based systems as well as the low-cost and short development ... More
A long-period Cepheid variable in the starburst cluster VdBH222Oct 22 2015Galactic starburst clusters play a twin role in astrophysics, serving as laboratories for the study of stellar physics and also delineating the structure and recent star formation history of the Milky Way. In order to exploit these opportunities we have ... More
Nature of the spin liquid ground state in a breathing kagome compound studied by NMR and series expansionMay 11 2017In the vanadium oxyfluoride compound (NH$_4$)$_2$[C$_7$H$_{14}$N][V$_7$O$_6$F$_{18}$] (DQVOF), the V$^{4+}$ (3d$^1$, $S=1/2$) ions realize a unique, highly frustrated breathing kagome lattice composed of alternately-sized, corner-sharing equilateral triangles. ... More
Coulomb blockade in a nanoscale phosphorus-in-silicon islandOct 18 2005Feb 21 2006We study the low temperature electrical transport behaviour of a silicon single electron transistor. The island and leads are defined by patterned phosphorus doped regions achieved by ion implantation through a polymer resist mask. In the device a 50 ... More
Ion implanted Si:P double-dot with gate tuneable interdot couplingFeb 23 2006We report on millikelvin charge sensing measurements of a silicon double-dot system fabricated by phosphorus ion implantation. An aluminum single-electron transistor (SET) is capacitively coupled to each of the implanted dots enabling the charging behavior ... More
Charge-based quantum computing using single donors in semiconductorsJun 10 2003Nov 20 2003Solid-state quantum computer architectures with qubits encoded using single atoms are now feasible given recent advances in atomic doping of semiconductors. Here we present a charge qubit consisting of two dopant atoms in a semiconductor crystal, one ... More
An ion-implanted silicon single-electron transistorOct 14 2005We report on the fabrication and electrical characterization at millikelvin temperatures of a novel silicon single-electron transistor (Si-SET). The island and source-drain leads of the Si-SET are formed by the implantation of phosphorus ions to a density ... More
The SILCC project: III. Regulation of star formation and outflows by stellar winds and supernovaeJun 16 2016We study the impact of stellar winds and supernovae on the multi-phase interstellar medium using three-dimensional hydrodynamical simulations carried out with FLASH. The selected galactic disc region has a size of (500 pc)$^2$ x $\pm$ 5 kpc and a gas ... More
Thermal emission of WASP-48b in the Ks-bandApr 05 2018We report a detection of thermal emission from the hot Jupiter WASP-48b in the $K_{\rm s}$-band. We used the Wide-field Infra-red Camera on the 3.6-m Canada-France Hawaii Telescope to observe an occultation of the planet by its host star. From the resulting ... More
Mesoscopic Effects in Quantum Phases of Ultracold Quantum Gases in Optical LatticesSep 29 2009We present a wide array of quantum measures on numerical solutions of 1D Bose- and Fermi-Hubbard Hamiltonians for finite-size systems with open boundary conditions. Finite size effects are highly relevant to ultracold quantum gases in optical lattices, ... More
Re-analysing the dynamical stability of the HD 47366 planetary systemNov 15 2018Multi-planet systems around evolved stars are of interest to trace the evolution of planetary systems into the post-main sequence phase. HD 47366, an evolved intermediate mass star, hosts two giant planets on moderately eccentric orbits. Previous analysis ... More
High Voltage Test Apparatus for a Neutron EDM Experiment and Lower Limit on the Dielectric Strength of Liquid Helium at Large VolumesMar 27 2006A new search for a permanent electric dipole moment (EDM) of the neutron is underway using ultracold neutrons produced and held in a bath of superfluid helium. Attaining the target sensitivity requires maintaining an electric field of several tens of ... More
Charge sensing in carbon nanotube quantum dots on microsecond timescalesOct 20 2005We report fast, simultaneous charge sensing and transport measurements of gate-defined carbon nanotube quantum dots. Aluminum radio frequency single electron transistors (rf-SETs) capacitively coupled to the nanotube dot provide single-electron charge ... More
Ground state phase diagram of the one-dimensional $t$-$J$ model with pair hopping termsApr 24 2018The $t$-$J$ model is a standard model of strongly correlated electrons, often studied in the context of high-$T_c$ superconductivity. However, most studies of this model neglect three-site terms, which appear at the same order as the superexchange $J$. ... More
Coexistence of energy diffusion and local thermalization in nonequilibrium XXZ spin chains with integrability breakingOct 21 2014May 05 2015In this work we analyze the simultaneous emergence of diffusive energy transport and local thermalization in a nonequilibrium one-dimensional quantum system, as a result of integrability breaking. Specifically, we discuss the local properties of the steady ... More
Neural Representation of Probabilistic InformationAug 27 2001It has been proposed that populations of neurons process information in terms of probability density functions (PDFs) of analog variables. Such analog variables range, for example, from target luminance and depth on the sensory interface to eye position ... More
Neural Networks Processing Mean Values of Random VariablesJul 16 2004We introduce a class of neural networks derived from probabilistic models in the form of Bayesian belief networks. By imposing additional assumptions about the nature of the probabilistic models represented in the belief networks, we derive neural networks ... More
Neural Propagation of BeliefsFeb 23 2001Aug 28 2001We continue to explore the hypothesis that neuronal populations represent and process analog variables in terms of probability density functions (PDFs). A neural assembly encoding the joint probability density over relevant analog variables can in principle ... More
Efficient generation of graph states for quantum computationJun 21 2004Dec 11 2004We present an entanglement generation scheme which allows arbitrary graph states to be efficiently created in a linear quantum register via an auxiliary entangling bus. The dynamics of the entangling bus is described by an effective non-interacting fermionic ... More
Bias spectroscopy and simultaneous SET charge state detection of Si:P double dotsFeb 04 2008We report a detailed study of low-temperature (mK) transport properties of a silicon double-dot system fabricated by phosphorous ion implantation. The device under study consists of two phosphorous nanoscale islands doped to above the metal-insulator ... More
The VLT-FLAMES Tarantula Survey V. The peculiar B[e]-like supergiant, VFTS698, in 30 DoradusJan 30 2012Apr 20 2012We present an analysis of a peculiar supergiant B-type star (VFTS698/Melnick 2/Parker 1797) in the 30 Doradus region of the Large Magellanic Cloud which exhibits characteristics similar to the broad class of B[e] stars. We analyse optical spectra from ... More
Magnetic susceptibility of the normal-superconducting transition in high-purity single-crystal alpha-uraniumAug 26 2002We report complex ac magnetic susceptibility measurements of a superconducting transition in very high-quality single-crystal alpha-uranium using microfabricated coplanar magnetometers. We identify an onset of superconductivity at T~0.7 K in both the ... More
Gravitational fragmentation and the formation of brown dwarfs in stellar clustersJul 02 2008We investigate the formation of brown dwarfs and very low-mass stars through the gravitational fragmentation of infalling gas into stellar clusters. The gravitational potential of a forming stellar cluster provides the focus that attracts gas from the ... More
Testing Algorithms for Finite Temperature Lattice QCDAug 23 2006We discuss recent algorithmic improvements in simulating finite temperature QCD on a lattice. In particular, the Rational Hybrid Monte Carlo(RHMC) algorithm is employed to generate lattice configurations for 2+1 flavor QCD. Unlike the Hybrid R Algorithm, ... More
The stochastic dynamics of micron and nanoscale elastic cantilevers in fluid: fluctuations from dissipationMay 01 2006The stochastic dynamics of micron and nanoscale cantilevers immersed in a viscous fluid are quantified. Analytical results are presented for long slender cantilevers driven by Brownian noise. The spectral density of the noise force is not assumed to be ... More
The Christiansen Effect in Saturn's narrow dusty rings and the spectral identification of clumps in the F ringFeb 24 2011Mar 31 2011Stellar occultations by Saturn's rings observed with the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft reveal that dusty features such as the F ring and the ringlets in the Encke and the Laplace Gaps have distinctive infrared ... More
Muon-spin relaxation study of the double perovskite insulators Sr$_{2}B$OsO$_6$ ($B={\rm Fe, Y, In}$)Dec 14 2015Jan 26 2016We present the results of zero-field muon-spin relaxation measurements made on the double perovskite insulators Sr$_{2}B$OsO$_6$ ($B={\rm Fe, Y, In}$). Spontaneous muon-spin precession indicative of quasistatic long range magnetic ordering is observed ... More
The Architecture of the Cassini DivisionNov 12 2009Dec 01 2009The Cassini Division in Saturn's rings contains a series of eight named gaps, three of which contain dense ringlets. Observations of stellar occultations by the Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft have yielded ~40 accurate ... More
Young Massive Clusters/Associations in the GMC G23.3-0.3Apr 29 2014An overview of a spectroscopic survey for massive stars in the direction of the Galactic giant molecular complex G23.3-0.3 is presented (Messineo et al. 2010, and 2014 A&A submitted). This region is interesting because it is rich in HII regions and supernova ... More
Observing sub-microsecond telegraph noise with the radio frequency single electron transistorSep 22 2004Telegraph noise, which originates from the switching of charge between meta-stable trapping sites, becomes increasingly important as device sizes approach the nano-scale. For charge-based quantum computing, this noise may lead to decoherence and loss ... More
Ionisation-induced star formation II: External irradiation of a turbulent molecular cloudJan 17 2007In this paper, we examine numerically the difference between triggered and revealed star formation. We present Smoothed Particle Hydrodynamics (SPH) simulations of the impact on a turbulent 10^4 solar-mass molecular cloud of irradiation by an external ... More
Thermal History of Solid 4He Under OscillationNov 22 2007Jan 13 2008We have studied the thermal history of the resonant frequency of a torsional oscillator containing solid 4He. We find that the magnitude of the frequency shift that occurs below 100 mK is multivalued in the low temperature limit, with the exact value ... More
Theory of Feshbach molecule formation in a dilute gas during a magnetic field rampNov 01 2005Starting with coupled atom-molecule Boltzmann equations, we develop a simplified model to understand molecule formation observed in recent experiments. Our theory predicts several key features: (1) the effective adiabatic rate constant is proportional ... More
Radio observations of IRAS selected southern hemisphere classical Be starsApr 03 1998We present the first radio observations of a sample of 13 optically and IR bright southern hemisphere classical Be stars made from the Australian Telescope Compact Array at 3.5cm and 6.3cm simultaneously. One star, delta Cen was detected at 3.5cm and ... More
The structure of molecular clouds and the universality of the clump mass functionSep 16 2008Using an SPH simulation of a star-forming region in a molecular cloud, we show that the emergence of a clump mass function (CMF) resembling the stellar initial mass function (IMF) is a ubiquitous feature of molecular cloud structure, but caution against ... More
Neutron Densities from a Global Analysis of Medium Energy Proton Nucleus Elastic ScatteringSep 18 2002Mar 08 2003A new method for extracting neutron densities from intermediate energy elastic proton-nucleus scattering observables uses a global Dirac phenomenological (DP) approach based on the Relativistic Impulse Approximation (RIA). Data sets for Ca40, Ca48 and ... More
Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic moleculesJun 24 2004We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use ... More
Entanglement consumption of instantaneous nonlocal quantum measurementsApr 06 2010Aug 17 2010Relativistic causality has dramatic consequences on the measurability of nonlocal variables and poses the fundamental question of whether it is physically meaningful to speak about the value of nonlocal variables at a particular time. Recent work has ... More
Non-linear quantum-classical scheme to simulate non-equilibrium strongly correlated fermionic many-body dynamicsOct 19 2015Sep 12 2016We propose a non-linear, hybrid quantum-classical scheme for simulating non-equilibrium dynamics of strongly correlated fermions described by the Hubbard model in a Bethe lattice in the thermodynamic limit. Our scheme implements non-equilibrium dynamical ... More
Limitations of Quantum Simulation Examined by Simulating a Pairing Hamiltonian using Nuclear Magnetic ResonanceJan 03 2006Quantum simulation uses a well-known quantum system to predict the behavior of another quantum system. Certain limitations in this technique arise, however, when applied to specific problems, as we demonstrate with a theoretical and experimental study ... More
Fragmentation in Molecular Clouds and its connection to the IMFMar 18 2009We present an analysis of star-forming gas cores in an SPH simulation of a Giant Molecular Cloud. We identify cores using their deep potential wells. This yields a smoother distribution with clearer boundaries than density. Additionally, this gives an ... More
Nonclassical Rotational Inertia in Single Crystal HeliumJun 06 2007Jul 23 2007It has been proposed that the observed nonclassical rotational inertia (NCRI) in solid helium results from the superflow of thin liquid films along interconnected grain boundaries within the sample. We have carried out new torsional oscillator measurements ... More
Atom-molecule equilibration in a degenerate Fermi gas with resonant interactionsMar 19 2004Jul 06 2004We present a nonequilibrium kinetic theory describing atom-molecule population dynamics in a two-component Fermi gas with a Feshbach resonance. Key collision integrals emerge that govern the relaxation of the atom-molecule mixture to chemical and thermal ... More
Numerical Analysis of Coherent Many-Body Currents in a Single Atom TransistorJun 29 2005We study the dynamics of many atoms in the recently proposed Single Atom Transistor setup [A. Micheli, A. J. Daley, D. Jaksch, and P. Zoller, Phys. Rev. Lett. 93, 140408 (2004)] using recently developed numerical methods. In this setup, a localised spin ... More
Calculations of Energy Losses due to Atomic Processes in Tokamaks with Applications to the ITER DivertorJun 19 1995Reduction of the peak heat loads on the plasma facing components is essential for the success of the next generation of high fusion power tokamaks such as the International Thermonuclear Experimental Reactor (ITER) 1 . Many present concepts for accomplishing ... More
Accelerating Radio Astronomy Cross-Correlation with Graphics Processing UnitsJul 21 2011Aug 01 2011We present a highly parallel implementation of the cross-correlation of time-series data using graphics processing units (GPUs), which is scalable to hundreds of independent inputs and suitable for the processing of signals from "Large-N" arrays of many ... More
IRAS 18357-0604 - an analogue of the galactic yellow hypergiant IRC +10420?Nov 15 2013Yellow hypergiants represent a short-lived evolutionary episode experienced by massive stars as they transit to and from a red supergiant phase. As such, their properties provide a critical test of stellar evolutionary theory. The galactic yellow hypergiant ... More
Linear spin waves in a trapped Bose gasMay 21 2002An ultra-cold Bose gas of two-level atoms can be thought of as a spin-1/2 Bose gas. It supports spin-wave collective modes due to the exchange mean field. Such collective spin oscillations have been observed in recent experiments at JILA with ${}^{87}$Rb ... More
On the rotational energy distributions of reactive, non-polar species in the interstellar mediumFeb 03 2013A basic model for the formation of non-equilibrium rotational energy distributions is described for reactive, homo-polar diatomic molecules and ions in the interstellar medium. Kinetic models were constructed to calculate the rotational populations of ... More
Energy gap measurement of nanostructured thin aluminium films for use in single Cooper-pair devicesJun 28 2007Within the context of superconducting gap engineering, Al-\alox-Al tunnel junctions have been used to study the variation in superconducting gap, $\Delta$, with film thickness. Films of thickness 5, 7, 10 and 30 nm were used to form the small area superconductor-insulator-superconductor ... More
Trapped Bose-Einstein condensates at finite temperature: a two-gas modelDec 24 1997A simple picture describes the results of recent treatments of partially-condensed, dilute, trapped Bose gases at temperature T > 0. The condensate wavefunction is nearly identical to that of a T=0 condensate with the same number of condensate atoms, ... More
Discovery of lake-effect clouds on TitanSep 10 2008Images from instruments on Cassini as well as from telescopes on the ground reveal the presence of sporadic small-scale cloud activity in the cold late-winter north polar of Saturn's large moon Titan. These clouds lie underneath the previously discovered ... More
Simulating Radiating and Magnetized Flows in Multi-Dimensions with ZEUS-MPNov 18 2005Apr 11 2006This paper describes ZEUS-MP, a multi-physics, massively parallel, message- passing implementation of the ZEUS code. ZEUS-MP differs significantly from the ZEUS-2D code, the ZEUS-3D code, and an early "version 1" of ZEUS-MP distributed publicly in 1999. ... More
The magneto-structural relationship in the tetrahedral spin chain oxide CsCoO$_2$Oct 14 2014We have investigated the structural and magnetic transitions in CsCoO$_2$ using calorimetric measurements, neutron powder diffraction (NPD), density functional theory (DFT) calculations and muon-spin relaxation ($\mu$SR) measurements. CsCoO$_2$ exhibits ... More
On the Origin of the Two-Dimensional Electron Gas at the CdO (100) SurfaceSep 21 2018Synchrotron-radiation angle-resolved and core-level photoemission spectroscopy are used together to investigate the origin of the two-dimensional electron gas on the surface of single crystal CdO (100) films. A reduction in the two-dimensional electron ... More
Elucidation of the helical spin structure of FeAsFeb 24 2017We present the results of resonant x-ray scattering measurements and electronic structure calculations on the monoarsenide FeAs. We elucidate details of the magnetic structure, showing the ratio of ellipticity of the spin helix is larger than previously ... More
Modelling the supernova-driven ISM in different environmentsOct 31 2014Mar 08 2015We use hydrodynamical simulations in a $(256\;{\rm pc})^3$ periodic box to model the impact of supernova (SN) explosions on the multi-phase interstellar medium (ISM) for initial densities $n = 0.5-30$ cm$^{-3}$ and SN rates $1-720$ Myr$^{-1}$. We include ... More
Experimental evidence of a natural parity state in $^{26}$Mg and its impact to the production of neutrons for the s processSep 12 2007We have studied natural parity states in $^{26}$Mg via the $^{22}$Ne($^{6}$Li,d)$^{26}$Mg reaction. Our method significantly improves the energy resolution of previous experiments and, as a result, we report the observation of a natural parity state in ... More
The Antennae Ultraluminous X-Ray Source, X-37, Is A Background QuasarSep 06 2005In this paper we report that a bright, X-ray source in the Antennae galaxies (NGC 4038/9), previously identified as an ultra-luminous X-ray source, is in fact a background quasar. We identify an isolated infrared and optical counterpart within 0.3+/-0.5 ... More