Results for "Benjamin C. Pooley"

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On a model for the Navier--Stokes equations using magnetization variablesJan 19 2016Jan 09 2018It is known that in a classical setting, the Navier--Stokes equations can be reformulated in terms of so-called magnetization variables $w$ that satisfy \begin{equation}\label{Abs_magform} \partial_tw + (\mathbb{P} w \cdot\nabla)w + (\nabla \mathbb{P} ... More
Well-posedness for the diffusive 3D Burgers equations with initial data in $H^{1/2}$Jan 19 2016In this note we discuss the diffusive, vector-valued Burgers equations in a three-dimensional domain with periodic boundary conditions. We prove that given initial data in $H^{1/2}$ these equations admit a unique global solution that becomes classical ... More
An Eulerian-Lagrangian Form for the Euler Equations in Sobolev SpacesMar 27 2014Jan 19 2016In 2000 Constantin showed that the incompressible Euler equations can be written in an "Eulerian-Lagrangian" form which involves the back-to-labels map (the inverse of the trajectory map for each fixed time). In the same paper a local existence result ... More
Asymptotics for vortex filaments using a modified Biot-Savart kernelMar 18 2019We consider a family of approximations to the Euler equations obtained by adding $(-\Delta)^{-\alpha/2}$ to the non-locality in the Biot-Savart kernel together with a mollification (with parameter $\varepsilon$). We consider the evolution of a thin vortex ... More
Leray's fundamental work on the Navier-Stokes equations: a modern review of "Sur le mouvement d'un liquide visqueux emplissant l'espace"Aug 31 2017This article offers a modern perspective which exposes the many contributions of Leray in his celebrated work on the Navier--Stokes equations from 1934. Although the importance of his work is widely acknowledged, the precise contents of his paper are ... More
Non-conservation of dimension in divergence-free solutions of passive and active scalar systemsMay 14 2019For any $h\in(1,2]$, we give an explicit construction of a compactly supported, uniformly continuous, and (weakly) divergence-free velocity field in $\mathbb{R}^2$ that weakly advects a measure whose support is initially the origin but for positive times ... More
Interface Width and Bulk Stability: requirements for the simulation of Deeply Quenched Liquid-Gas SystemsJun 11 2007Simulations of liquid-gas systems with extended interfaces are observed to fail to give accurate results for two reasons: the interface can get ``stuck'' on the lattice or a density overshoot develops around the interface. In the first case the bulk densities ... More
On a model for the Navier--Stokes equations using magnetization variablesJan 19 2016Aug 04 2016The Navier--Stokes equations can be reformulated in terms of so-called magnetization variables $w$ that satisfy \begin{equation}\label{Abs_magform} \partial_tw + (\mathbb{P} w \cdot\nabla)w + (\nabla \mathbb{P} w)^\top w - \mathrm{\Delta} w =0, \end{equation} ... More
Swimming with a friend at low Reynolds numberMay 24 2007We investigate the hydrodynamic interactions between microorganisms swimming at low Reynolds number. By considering simple model swimmers, and combining analytic and numerical approaches, we investigate the time-averaged flow field around a swimmer. At ... More
An integral monitoring of GRS1915+105: simultaneous observations with INTEGRAL, RXTE, the Ryle and Nancay radio telescopesNov 07 2006Since the launch of INTEGRAL in late 2002 we have monitored the Galactic microquasar GRS 1915+105 with long exposures (~100 ks) pointings. All the observations have been conducted simultaneously with other instruments, in particular RXTE and the Ryle ... More
The orbital modulation in the radio emission of Cygnus X-1Jun 26 2002We present model lightcurves which have been created in order to explain the orbital modulation observed in the radio emission of Cyg X-1. We invoke variable absorption by the stellar wind as the black hole jet orbits around the OB companion star and ... More
Orbital modulation and longer-term variability in the radio emission from Cygnus X-1Sep 24 199820 months of observations of the radio emission at 15 GHz from Cygnus X-1, starting in 1996 October, show variations at the binary period of 5.6 days, but with a phase offset from those at X-ray wavelengths. There are also longer-term variations on a ... More
The Distortion of the Cosmic Microwave Background by the Milky WayJul 21 2014The Milky Way can act as a large-scale weak gravitational lens of the cosmic microwave background (CMB). We study this effect using a photon ray-tracing code and a Galactic mass distribution with disk, bulge and halo components. For an observer at the ... More
Radio and X-ray observations of an exceptional radio flare in the extreme z=4.72 blazar GB B1428+4217Feb 15 2006We report on the extreme behaviour of the high redshift blazar GB B1428+4217 at z=4.72. A continued programme of radio measurements has revealed an exceptional flare in the lightcurve, with the 15.2 GHz flux density rising by a factor ~3 from ~140 mJy ... More
Posterior-based proposals for speeding up Markov chain Monte CarloMar 25 2019Markov chain Monte Carlo (MCMC) is widely used for Bayesian inference in models of complex systems. Performance, however, is often unsatisfactory in models with many latent variables due to so-called poor mixing, necessitating development of application ... More
Modeling microscopic swimmers at low Reynolds numberJan 22 2007We employ three numerical methods to explore the motion of low Reynolds number swimmers, modeling the hydrodynamic interactions by means of the Oseen tensor approximation, lattice Boltzmann simulations and multiparticle collision dynamics. By applying ... More
GMRT radio observations of microquasar GRS 1915+105Aug 01 2002We have observed microquasar GRS 1915+105 at 1.28 GHz for 8 days from June 18 to July 1, 2001 using Giant Metrewave Radio Telescope (GMRT). We have seen several isolated radio baby flares of varying intensity and duration. We have also observed broad ... More
The Hardness-Intensity Diagram of Cygnus X-3: Revisiting the Radio/X-Ray StatesMar 23 2010Cygnus X-3 is one of the brightest X-ray and radio sources in the Galaxy, and is well known for its erratic behaviour in X-rays as well as in the radio, occasionally producing major radio flares associated with relativistic ejections. However, even after ... More
Discovery of Radio Outbursts in the Active Nucleus of M81May 06 1999The low-luminosity active galactic nucleus of M81 has been monitored at centimeter wavelengths since early 1993 as a by-product of radio programs to study the radio emission from Supernova 1993J. The extensive data sets reveal that the nucleus experienced ... More
Some estimates of the source counts at Planck Surveyor frequencies, using the 9C survey at 15 GHzJun 08 2007We have used multi-frequency follow-up observations of a sample of extragalactic sources from the 9C survey at 15 GHz to make deductions about the expected source population at higher radio frequencies, such as those in the lower frequency bands of the ... More
A bright off-nuclear X-ray source: A bright off-nuclear X-ray source: a type IIn supernova, a bright ULX or a recoiling super-massive black hole in CXO J122518.6+144545Apr 29 2010In this Paper we report the discovery of CXO J122518.6+144545; a peculiar X-ray source with a position 3.6+-0.2",off-nuclear from an SDSS DR7 z=0.0447 galaxy. The 3.6" offset corresponds to 3.2 kpc at the distance of the galaxy. The 0.3-8 keV X-ray flux ... More
X-ray and optical observations of M55 and NGC 6366: evidence for primordial binariesJul 02 2008We present Chandra X-ray Observatory ACIS-S3 X-ray imaging observations and VLT/FORS2 and Hubble Space Telescope optical observations of two low-density Galactic globular clusters; NGC 6366 and M55. We detect 16 X-ray sources with 0.5-6.0 keV luminosities ... More
Avoiding the Global Sort: A Faster Contour Tree AlgorithmNov 11 2014Dec 10 2015We revisit the classical problem of computing the \emph{contour tree} of a scalar field $f:\mathbb{M} \to \mathbb{R}$, where $\mathbb{M}$ is a triangulated simplicial mesh in $\mathbb{R}^d$. The contour tree is a fundamental topological structure that ... More
Quantum Computing with Globally Controlled Exchange-type InteractionsApr 24 2001If the interaction between qubits in a quantum computer has a non-diagonal form (e.g. the Heisenberg interaction), then one must be able to "switch it off" in order to prevent uncontrolled propagation of states. Therefore, such QC schemes typically demand ... More
Efficient Graph State Construction Under the Barrett and Kok SchemeApr 14 2005Sep 25 2005Recently Barrett and Kok (BK) proposed an elegant method for entangling separated matter qubits. They outlined a strategy for using their entangling operation (EO) to build graph states, the resource for one-way quantum computing. However by viewing their ... More
Multi-Qubit Gates in Arrays Coupled by 'Always On' InteractionsMar 09 2004May 12 2004Recently there has been interest in the idea of quantum computing without control of the physical interactions between component qubits. This is highly appealing since the 'switching' of such interactions is a principal difficulty in creating real devices. ... More
Schemes for Parallel Quantum Computation Without Local Control of QubitsSep 02 1999Sep 18 1999Typical quantum computing schemes require transformations (gates) to be targeted at specific elements (qubits). In many physical systems, direct targeting is difficult to achieve; an alternative is to encode local gates into globally applied transformations. ... More
Rapid infrared flares in GRS 1915+105 : evidence for infrared synchrotron emissionJul 29 1997We report imaging photometry of the radio-jet black hole candidate source GRS 1915+105 in the infrared K band. The observations reveal rapid infrared flare events on timescales of less than an hour. These events are strikingly similar to those regularly ... More
Was the Narrow Line Seyfert 1 RGB J0044+193 ever radio loud?Dec 16 2004We show new radio data and a re-analysis of old data for the Narrow Line Seyfert 1 (NLSy1) galaxy RGB J0044+193. This galaxy has previously been suggested to be both radio loud, and highly variable in the radio. As most NLSy 1 galaxies are radio quiet, ... More
The radio source counts at 15 GHz and their implications for cm-wave CMB imagingFeb 28 2001We present the preliminary results of a new survey of radio sources using the Ryle telescope at 15.2 GHz. This is the highest frequency at which a survey has been done that is relevant to the issue of radio source contamination in CMB experiments. The ... More
Computation in Self-assembled Nanometre Scale ArraysMar 14 2005Apr 05 2006Ordered nanoarrays, i.e. regular patterns of quantum structures at the nanometre scale, have recently been synthesized in a wide range of systems. Here I explore a possible route to technological exploitation: assuming a simple form of bistability for ... More
Gravitationally Focused Dark Matter Around Compact StarsDec 11 2011If dark matter self-annihilates then it may produce an observable signal when its density is high. The details depend on the intrinsic properties of dark matter and how it clusters in space. For example, the density profile of some dark matter candidates ... More
Hyper-commutative algebras and cyclic cohomologyJan 26 2016This paper investigates a chain model for the Deligne-Mumford operad formed by homotopically trivializing the circle in a chain model for the framed little disks. The latter acts on the deformation complex of a multiplicative cyclic operad and under degeneration ... More
Massey products for graph homologyMar 28 2019This paper shows that the operad encoding modular operads is Koszul. Using this result we construct higher composition operations on (hairy) graph homology which characterize its rational homotopy type.
Radio, Infrared and X-ray observations of GRS 1915+105Dec 10 1996We present multiwavelength observations of the superluminal jet source GRS 1915+105 in 1996 April-May, over which period a variety of phenomena, including radio QPO, strong infrared emission lines and rapid X-ray flickering and outbursts were observed. ... More
A superburst candidate in EXO 1745--248 as a challenge to thermonuclear ignition modelsJul 23 2012We report on Chandra, RXTE, Swift/BAT and MAXI observations of a ~1 day X-ray flare and subsequent outburst of a transient X-ray source observed in October-November 2011 in the globular cluster Terzan 5. We show that the source is the same as the transient ... More
Low frequency radio monitoring of Cygnus X-1 and Cygnus X-3Sep 19 2005We present results of monitoring observations of the micro-quasars CygnusX-1 and Cygnus X-3 at 0.61 and 1.28 GHz. The observations were performed with Giant Meter-wave Radio Telescope, GMRT, between 2003 June and 2005 January. Variable, unresolved sources ... More
Merger-driven Fueling of Active Galactic Nuclei: Six Dual and Offset Active Galactic Nuclei Discovered with Chandra and Hubble Space Telescope ObservationsApr 06 2015Dual active galactic nuclei (AGNs) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers, where both or one of the black holes are AGNs, respectively. These dual and offset AGNs are valuable probes of the ... More
X-rays from the Globular Cluster G1: Intermediate Mass Black Hole or Low Mass X-ray Binary?May 02 2006The globular cluster G1 (Mayall II) in M31 is the most massive (~10^7 M_sun) stellar cluster in the Local Group, and it has the highest central velocity dispersion (~28 km/s). It has been claimed to host a central ~20,000 M_sun black hole, but these claims ... More
X-ray and Optical Eclipses in ULXs as Possible Indicators of Black Hole MassSep 20 2005Ultraluminous X-ray sources (ULXs) with 10^39 < L_x < 10^41 erg/s have been discovered in great numbers in external galaxies with ROSAT, Chandra, and XMM-Newton. The central question regarding this important class of sources is whether they represent ... More
Synchrotron flaring behaviour of CygnusX-3 during the February-March 1994 and September 2001 outburstsJul 18 2007Aims: In this paper we study whether the shock-in-jet model, widely used to explain the outbursting behaviour of quasars, can be used to explain the radio flaring behaviour of the microquasar Cygnus X-3. Method: We have used a method developed to model ... More
Variability of the extreme z=4.72 blazar, GB 1428+4217Jul 02 1999We report X-ray and radio variability of GB 1428+4217 which confirm its blazar nature. IR observations reveal a powerful optical-UV component, not obscured by dust, which is suggestive of the presence of a billion solar mass black hole, already formed ... More
Faint X-ray Sources in the Globular Cluster Terzan 5Jun 11 2006Jun 13 2006We report our analysis of a Chandra X-ray observation of the rich globular cluster Terzan 5, in which we detect 50 sources to a limiting 1.0-6 keV X-ray luminosity of 3*10^{31} ergs/s within the half-mass radius of the cluster. Thirty-three of these have ... More
Evidence for deceleration in the radio jets of GRS1915+105?Dec 08 2006There is currently a clear discrepancy in the proper motions measured on different angular scales in the approaching radio jets of the black hole X-ray binary GRS1915+105. Lower velocities were measured with the Very Large Array (VLA) prior to 1996 than ... More
X-ray Swift observations of SN 2018cowJul 17 2018Apr 01 2019Supernova (SN) 2018cow (or AT2018cow) is an optical transient detected in the galaxy CGCG 137-068. It has been classified as a SN due to various characteristics in its optical spectra. The transient is also a bright X-ray source. We present results of ... More
Is the cosmic microwave background really non-Gaussian?Apr 20 1999Aug 08 1999Two recent papers have claimed detection of non-Gaussian features in the COBE DMR sky maps of the cosmic microwave background. We confirm these results, but argue that Gaussianity is still not convincingly ruled out. Since a score of non-Gaussianity tests ... More
SU(3) Corrections to B -> D l nu Form Factors at O(1/M)Feb 16 1995We compute the O(1/M,m_s) heavy quark and SU(3) corrections to B_s -> D_s e nu form factors. In the limit of vanishing light quark mass, B_s -> D_s e nu form factors are given in terms of the the B -> D e nu form factors, the leading order chiral parameter ... More
Distance rationalization of social rulesOct 06 2016The concept of distance rationalizability of social choice rules has been explored in recent years by several authors. We deal here with several foundational questions, and unify, correct, and generalize previous work. For example, we study a new question ... More
Distance rationalization of anonymous and homogeneous voting rulesOct 06 2016Jun 07 2018The concept of distance rationalizability of voting rules has been explored in recent years by several authors. Roughly speaking, we first choose a consensus set of elections (defined via preferences of voters over candidates) for which the result is ... More
X-ray Swift observations of SN 2018cowJul 17 2018Aug 03 2018Supernova (SN) 2018cow is an optical transient detected in the galaxy CGCG 137-068. It has been classified as a SN due to various characteristics in its optical spectra. The transient is also a bright X-ray source. We present results of the analysis of ... More
Relativistic Iron Emission and Disk Reflection in Galactic Microquasar XTE J1748-288Aug 08 2000Aug 24 2000We report evidence for an Fe K-alpha fluorescence line feature and disk reflection in the Very High, High, and Low State X-ray spectra of the galactic microquasar XTE J1748-288 during its June~1998 outburst. Spectral analyses are made on data gathered ... More
Limits on thermal variations in a dozen quiescent neutron stars over a decadeJul 14 2015In quiescent low-mass X-ray binaries (qLMXBs) containing neutron stars, the origin of the thermal X-ray component may be either release of heat from the core of the neutron star, or continuing low-level accretion. In general, heat from the core should ... More
Panglossian Prospects for Detecting Neutralino Dark Matter in Light of Natural PriorsJun 11 2008Sep 22 2008In most global fits of the constrained minimal supersymmetric model (CMSSM) to indirect data, the a priori likelihoods of any two points in tan beta are treated as equal, and the more fundamental mu and B Higgs potential parameters are fixed by potential ... More
Hierarchical surface code for network quantum computing with modules of arbitrary sizeSep 25 2015The network paradigm for quantum computing involves interconnecting many modules to form a scalable machine. Typically it is assumed that the links between modules are prone to noise while operations within modules have significantly higher fidelity. ... More
High threshold distributed quantum computing with three-qubit nodesApr 02 2012May 05 2012In the distributed quantum computing paradigm, well-controlled few-qubit `nodes' are networked together by connections which are relatively noisy and failure prone. A practical scheme must offer high tolerance to errors while requiring only simple (i.e. ... More
Quantum Computing in Arrays Coupled by 'Always On' InteractionsJan 12 2004It has recently been shown that one can perform quantum computation in a Heisenberg chain in which the interactions are 'always on', provided that one can abruptly tune the Zeeman energies of the individual (pseudo-)spins. Here we provide a more complete ... More
Quantum Computing with an 'Always On' Heisenberg InteractionOct 23 2002May 22 2003Many promising ideas for quantum computing demand the experimental ability to directly switch 'on' and 'off' a physical coupling between the component qubits. This is typically the key difficulty in implementation, and precludes quantum computation in ... More
Gravity FormalityJul 03 2017We show that Willwacher's cyclic formality theorem can be extended to preserve natural Gravity operations on cyclic multivector fields and cyclic multidifferential operators. We express this in terms of a homotopy Gravity quasi-isomorphism with explicit ... More
Bayesian semiparametric analysis of multivariate continuous responses, with variable selectionMay 21 2019We develop models for multivariate Gaussian responses with nonparametric models for the means, the variances and the correlation matrix, with automatic variable selection based on spike-slab priors. We use the separation strategy to factorize the covariance ... More
Quantum compilation and circuit optimisation via energy dissipationNov 07 2018Dec 19 2018We describe a method for automatically recompiling a quantum circuit A into a target circuit B, with the goal that both circuits have the same action on a specific input i.e. A|in> = B|in>. This is of particular relevance to hybrid, NISQ-era algorithms ... More
The radio source population at high frequency: follow-up of the 15-GHz 9C surveyJul 12 2004We have carried out extensive radio and optical follow-up of 176 sources from the 15 GHz 9th Cambridge survey. Optical identifications have been found for 155 of the radio sources; optical images are given with radio maps overlaid. The continuum radio ... More
On the Role of the Accretion Disk in Black Hole Disk-Jet ConnectionsJul 16 2012Models of jet production in black hole systems suggest that the properties of the accretion disk - such as its mass accretion rate, inner radius, and emergent magnetic field - should drive and modulate the production of relativistic jets. Stellar-mass ... More
Supernova Remnants in High DefinitionMar 22 2019Supernova remnants (SNRs) offer the means to study SN explosions, dynamics, and shocks at sub-parsec scales. X-ray observations probe the hot metals synthesized in the explosion and the TeV electrons accelerated by the shocks, and thus they are key to ... More
Minkowski space-time: a glorious non-entityMar 17 2004Einstein distinguished between ``principle'' and ``constructive'' theories in physics, and although he thought the latter were more explanatory than the former, he regarded his 1905 formulation of special relativity theory as a principle theory. Some ... More
A transient relativistic radio jet from Cygnus X-1Feb 14 2006We report the first observation of a transient relativistic jet from the canonical black hole candidate, Cygnus X-1, obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN). The jet was observed in only one of six epochs of MERLIN ... More
High Frequency Quasi-Periodic Oscillations in the 2000 Outburst of the Galactic Microquasar XTE J1550-564May 21 2001Sep 23 2001We present an analysis of the high frequency timing properties of the April-May 2000 outburst of the black hole candidate and Galactic microquasar XTE J1550-564, measured with the Rossi X-ray Timing Explorer. The rapid X-ray variability we measure is ... More
9C: A Survey of Radio Sources at 15 GHz with the Ryle TelescopeApr 15 2003The fields chosen for the first observations of the cosmic microwave background with the Very Small Array have been surveyed with the Ryle Telescope at 15 GHz. We have covered three regions around RA 00h20m Dec +30deg, RA 09h40m Dec +32deg and RA 15h40m ... More
First e-VLBI observations of Cygnus X-3Nov 02 2006We report the results of the first two 5 GHz e-VLBI observations of the X-ray binary Cygnus X-3 using the European VLBI Network. Two successful observing sessions were held, on 2006 April 20, when the system was in a quasi-quiescent state several weeks ... More
The 2010 May Flaring Episode of Cygnus X-3 in Radio, X-Rays, and γ-RaysApr 27 2011In 2009, Cygnus X-3 (Cyg X-3) became the first microquasar to be detected in the GeV {\gamma}-ray regime, via the satellites Fermi and AGILE. The addition of this new band to the observational toolbox holds promise for building a more detailed understanding ... More
Searching for the expelled hydrogen envelope in Type I supernovae via late-time H-alpha emissionFeb 16 2017We report the first results from our long-term observational survey aimed at discovering late-time interaction between the ejecta of hydrogen-poor Type I supernovae and the hydrogen-rich envelope expelled from the progenitor star several decades/centuries ... More
Continued Neutron Star Crust Cooling of the 11 Hz X-Ray Pulsar in Terzan 5: A Challenge to Heating and Cooling Models?Jun 10 2013Aug 23 2013The transient neutron star low-mass X-ray binary and 11 Hz X-ray pulsar IGR J17480-2446 in the globular cluster Terzan 5 exhibited an 11-week accretion outburst in 2010. Chandra observations performed within five months after the end of the outburst revealed ... More
Chandra and Hubble Space Telescope Study of the Globular Cluster NGC 288Mar 14 2006Apr 28 2006We report on the Chandra X-ray Observatory observations of the globular cluster NGC 288. We detect four X-ray sources within the core radius and seven additional sources within the half-mass radius down to a limiting luminosity of Lx=7e30 erg/s (assuming ... More
A Chandra X-ray observation of the globular cluster Terzan 1Dec 06 2005Mar 14 2006We present a 19 ks Chandra ACIS-S observation of the globular cluster Terzan 1. Fourteen sources are detected within 1.4 arcmin of the cluster center with 2 of these sources predicted to be not associated with the cluster (background AGN or foreground ... More
Simultaneous multi-wavelength observations of microquasars (the MINE collaboration)Dec 15 2003We present the international collaboration MINE (Multi-lambda INTEGRAL NEtwork) aimed at conducting multi-wavelength observations of microquasars simultaneously with the INTEGRAL satellite. The first results on GRS 1915+105 are encouraging and those to ... More
Universal behaviour of four-boson systems from a functional renormalisation groupApr 19 2013Sep 12 2013We apply a functional renormalisation group to systems of four bosonic atoms close to the unitary limit. We work with a local effective action that includes a dynamical trimer field and we use this field to eliminate structures that do not correspond ... More
Exact Performance of Concatenated Quantum CodesJun 11 2002When a logical qubit is protected using a quantum error-correcting code, the net effect of coding, decoherence (a physical channel acting on qubits in the codeword) and recovery can be represented exactly by an effective channel acting directly on the ... More
Sampling using a `bank' of cluesMay 03 2007Nov 26 2007An easy-to-implement form of the Metropolis Algorithm is described which, unlike most standard techniques, is well suited to sampling from multi-modal distributions on spaces with moderate numbers of dimensions (order ten) in environments typical of investigations ... More
On Noncontextual, Non-Kolmogorovian Hidden Variable TheoriesAug 11 2016One implication of Bell's theorem is that there cannot in general be hidden variable models for quantum mechanics that both are noncontextual and retain the structure of a classical probability space. Thus, some hidden variable programs aim to retain ... More
Magnet field sensing beyond the standard quantum limit under the effect of decoherenceJan 13 2011Entangled states can potentially be used to outperform the standard quantum limit which every classical sensor is bounded by. However, entangled states are very susceptible to decoherence, and so it is not clear whether one can really create a superior ... More
Distributed quantum computation with arbitrarily poor photon detectionMar 11 2010In a distributed quantum computer scalability is accomplished by networking together many elementary nodes. Typically the network is optical and inter-node entanglement involves photon detection. In complex networks the entanglement fidelity may be degraded ... More
Direct Numerical Simulations of Reflection-Driven, Reduced MHD Turbulence from the Sun to the Alfven Critical PointAug 19 2013Sep 09 2013We present direct numerical simulations of inhomogeneous reduced magnetohydrodynamic (RMHD) turbulence between the Sun and the Alfv\'en critical point. These are the first such simulations that take into account the solar-wind outflow velocity and the ... More
Quantum error correction in globally controlled arraysAug 21 2003Aug 21 2004An interesting concept in quantum computation is that of global control (GC), where there is no need to manipulate qubits individually. One can implement a universal set of quantum gates on a one-dimensional array purely via signals that target the entire ... More
Effective Lagrangian for strongly coupled domain wall fermionsMay 17 2001Aug 03 2001We derive the effective Lagrangian for mesons in lattice gauge theory with domain-wall fermions in the strong-coupling and large-N_c limits. We use the formalism of supergroups to deal with the Pauli-Villars fields, needed to regulate the contributions ... More
Numerical Simulations of Gaseous Disks Generated from Collisional Cascades at the Roche Limits of White Dwarf StarsOct 31 2017We consider the long-term evolution of gaseous disks fed by the vaporization of small particles produced in a collisional cascade inside the Roche limit of a 0.6 Msun white dwarf. Adding solids with radius \r0\ at a constant rate $\dot{M}_0$ into a narrow ... More
Making Planet Nine: A Scattered Giant in the Outer Solar SystemMar 25 2016Correlations in the orbits of several minor planets in the outer solar system suggest the presence of a remote, massive Planet Nine. With at least ten times the mass of the Earth and a perihelion well beyond 100 AU, Planet Nine poses a challenge to planet ... More
Making Planet Nine: Pebble Accretion at 250--750 AU in a Gravitationally Unstable RingMar 25 2016We investigate the formation of icy super-Earth mass planets within a gravitationally unstable ring of solids orbiting at 250-750 AU around a 1 solar mass star. Coagulation calculations demonstrate that a system of a few large oligarchs and a swarm of ... More
A New Hybrid N-Body-Coagulation Code for the Formation of Gas Giant PlanetsDec 02 2010Feb 18 2011We describe an updated version of our hybrid N-body-coagulation code for planet formation. In addition to the features of our 2006-2008 code, our treatment now includes algorithms for the 1D evolution of the viscous disk, the accretion of small particles ... More
Simple, broadband, optical spatial cloaking of very large objectsJun 04 2013Jun 10 2013We demonstrate three simple cloaking devices that can hide very large spatial objects over the entire visible spectrum using only passive, off-the-shelf optics. The cloaked region for all of the devices exceeds 10^6 mm3 with the largest exceeding 10^8 ... More
Stabilisers as a design tool for new forms of Lechner-Hauke-Zoller AnnealerMar 28 2016May 02 2016In a recent paper Lechner, Hauke and Zoller (LHZ) described a means to translate a Hamiltonian of $N$ spin-$\frac{1}{2}$ particles with 'all-to-all' interactions into a larger physical lattice with only on-site energies and local parity constraints. LHZ ... More
Line emission from an accretion disk around black hole: effects of the disk structureNov 19 1997The observed iron K-alpha fluorescence lines in Seyfert galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. Previous studies of line emission have considered only geometrically thin disks, ... More
Four-boson bound states from a functional renormalisation groupJun 16 2015We use the functional renormalisation group to study the spectrum of three- and four-body states in bosonic systems around the unitary limit. Our effective action includes all energy-independent contact interactions in the four-atom sector and we introduce ... More
Resonance Region Structure Functions and Parity Violating Deep Inelastic ScatteringJan 16 2012May 01 2012The primary motive of parity violating deep inelastic scattering experiments has been to test the standard model, particularly the axial couplings to the quarks, in the scaling region. The measurements can also test for the validity of models for the ... More
Migration of planets embedded in a circumstellar diskJan 20 2011Apr 19 2011Planetary migration poses a serious challenge to theories of planet formation. In gaseous and planetesimal disks, migration can remove planets as quickly as they form. To explore migration in a planetesimal disk, we combine analytic and numerical approaches. ... More
Rapid Formation of Icy Super-Earths and the Cores of Gas Giant PlanetsNov 28 2008We describe a coagulation model that leads to the rapid formation of super-Earths and the cores of gas giant planets. Interaction of collision fragments with the gaseous disk is the crucial element of this model. The gas entrains small collision fragments, ... More
Collisional Cascade Caclulations for Irregular Satellite Swarms in Fomalhaut bAug 13 2015We describe an extensive suite of numerical calculations for the collisional evolution of irregular satellite swarms around 1--300 M-earth planets orbiting at 120 AU in the Fomalhaut system. For 10--100 M-earth planets, swarms with initial masses of roughly ... More
Coagulation Calculations of Icy Planet Formation at 15--150 AU: A Correlation Between the Maximum Radius and the Slope of the Size Distribution for Transneptunian ObjectsJan 20 2012We investigate whether coagulation models of planet formation can explain the observed size distributions of transneptunian objects (TNOs). Analyzing published and new calculations, we demonstrate robust relations between the size of the largest object ... More
Prospects for Detection of Catastrophic Collisions in Debris DisksMar 24 2005We investigate the prospects for detecting dust from two body collisions during the late stages of planet formation at 1-150 AU. We develop an analytic model to describe the formation of a dusty cloud of debris and use numerical coagulation and n-body ... More
Gamma-Z box contributions to parity violating elastic e-p scatteringNov 10 2010Nov 15 2010Parity-violating (PV) elastic electron-proton scattering measures Q-weak for the proton, $Q_W^p$. To extract $Q_W^p$ from data, all radiative corrections must be well-known. Recently, disagreement on the gamma-Z box contribution to $Q_W^p$ has prompted ... More
Convergence of the Min-Sum Algorithm for Convex OptimizationMay 29 2007We establish that the min-sum message-passing algorithm and its asynchronous variants converge for a large class of unconstrained convex optimization problems.
On the origin of the various types of radio emission in GRS 1915+105Aug 06 2003Aug 07 2003We investigate the association between the radio ``plateau'' states and the large superluminal flares in GRS 1915+105 and propose a qualitative scenario to explain this association. We identify several candidate superluminal flare events from available ... More