Results for "Jonathan Simon"

total 15395took 0.12s
Total Curvature and Packing of KnotsOct 22 2003Jan 16 2004We establish a new fundamental relationship between total curvature of knots and crossing number. If K is a smooth knot in 3-space, R the cross-section radius of a uniform tube neighborhood of K, L the arclength of K, and k the total curvature of K, then ... More
Engineering Photonic Floquet Hamiltonians through Fabry Pérot ResonatorsNov 02 2015In this letter we analyze an optical Fabry-P\'erot resonator as a time-periodic driving of the (2D) optical field repeatedly traversing the resonator, uncovering that resonator twist produces a synthetic magnetic field applied to the light within the ... More
Active Cancellation of Acoustical Resonances with an FPGA FIR FilterApr 16 2016We present a novel approach to enhancing the bandwidth of a feedback-controlled mechanical system by digitally canceling acoustical resonances (poles) and anti-resonances (zeros) in the open-loop response via an FPGA FIR filter. By performing a real-time ... More
Natural Boundaries and Spectral TheoryFeb 03 2010Aug 08 2010We present and exploit an analogy between lack of absolutely continuous spectrum for Schroedinger operators and natural boundaries for power series. Among our new results are generalizations of Hecke's example and natural boundary examples for random ... More
Principal W-algebras for GL(m|n)May 04 2012Dec 05 2012We consider the (finite) $W$-algebra $W_{m|n}$ attached to the principal nilpotent orbit in the general linear Lie superalgebra $\mathfrak{gl}_{m|n}(\mathbb C)$. Our main result gives an explicit description of $W_{m|n}$ as a certain truncation of a shifted ... More
Representation theory of type B and C standard Levi W-algebrasSep 13 2012We classify the finite dimensional irreducible representations with integral central character of finite $W$-algebras $U(\mathfrak g,e)$ associated to standard Levi nilpotent orbits in classical Lie algebras of types B and C. This classification is given ... More
Fully Complex MagnetoencephalographyAug 25 2005Complex numbers appear naturally in biology whenever a system can be analyzed in the frequency domain, such as physiological data from magnetoencephalography (MEG). For example, the MEG steady state response to a modulated auditory stimulus generates ... More
Moebius energy of thick knotsAug 30 2001The Moebius energy of a knot is an energy functional for smooth curves based on an idea of self-repelling. If a knot has a thick tubular neighborhood, we would intuitively expect the energy to be low. In this paper, we give explicit bounds for energy ... More
Good grading polytopesOct 10 2005Let g be a finite dimensional semisimple Lie algebra over C and e be a nilpotent element. Elashvili and Kac have recently classified all good Z-gradings for e. We instead consider good R-gradings, which are naturally parameterized by an open convex polytope ... More
Effective three-body interactions via photon-assisted tunneling in an optical latticeNov 07 2013We present a simple, experimentally realizable method to make coherent three-body interactions dominate the physics of an ultracold lattice gas. Our scheme employs either lattice modulation or laser-induced tunneling to reduce or turn off two-body interactions ... More
Einstein Equation with Quantum Corrections Reduced to Second OrderNov 03 1992We consider the Einstein equation with first order (semiclassical) quantum corrections. Although the quantum corrections contain up to fourth order derivatives of the metric, the solutions which are physically relevant satisfy a reduced equations which ... More
On the variety of 1-dimensional representations of finite $W$-algebras in low rankAug 29 2017Let $\mathfrak g$ be a simple Lie algebra over $\mathbb C$ and let $e \in \mathfrak g$ be nilpotent. We consider the finite $W$-algebra $U(\mathfrak g,e)$ associated to $e$ and the problem of determining the variety $\mathcal E(\mathfrak g,e)$ of 1-dimensional ... More
Values at s=-1 of L-functions for multiquadratic extensions of number fields, and annililation of the tame kernelJun 06 2006Suppose that $EE$ is a totally real number field which is the composite of all of its subfields $E$ that are relative quadratic extensions of a base field $F$. For each such $E$ with ring of integers $\O_E$, assume the truth of the Birch-Tate conjecture ... More
Quantum Crystals and Laughlin Droplets of Cavity Rydberg PolaritonsJun 01 2015Synthetic quantum materials offer an exciting opportunity to explore quantum many-body physics and novel states of matter under controlled conditions. In particular, they provide an avenue to exchange the short length scales and large energy scales of ... More
Eigenvalue inequalities for Schrödinger operators on unbounded Lipschitz domainsNov 24 2015Jan 14 2016Given a Schr\"odinger differential expression on an exterior Lipschitz domain we prove strict inequalities between the eigenvalues of the corresponding selfadjoint operators subject to Dirichlet and Neumann or Dirichlet and mixed boundary conditions, ... More
Stability of Asymptotics of Christoffel-Darboux KernelsFeb 28 2013We study the stability of convergence of the Christoffel-Darboux kernel, associated with a compactly supported measure, to the sine kernel, under perturbations of the Jacobi coefficients of the measure. We prove stability under variations of the boundary ... More
Non-integral representation theory of even multiplicity finite W-algebrasDec 29 2011We complete the classification of the finite dimensional irreducible representations of finite W-algebras associated to even multiplicity nilpotent elements in classical Lie algebras. This extends earlier work where this classification is determined for ... More
Highest weight theory for finite W-algebrasJan 09 2008We define analogues of Verma modules for finite W-algebras. By the usual ideas of highest weight theory, this is a first step towards the classification of finite dimensional irreducible modules. Motivated by known results in type A, we then formulate ... More
Mobius transformations of polygons and partitions of 3-spaceFeb 21 2006The image of a polygonal knot K under a spherical inversion of R^3 (union infinity) is a simple closed curve made of arcs of circles, having the same knot type as the mirror image of K. Suppose we reconnect the vertices of the inverted polygon with straight ... More
Large Deviations and the Lukic ConjectureMar 02 2017Mar 17 2017We use the large deviation approach to sum rules pioneered by Gamboa, Nagel and Rouault to prove higher order sum rules for orthogonal polynomials on the unit circle. In particular, we prove one half of a conjectured sum rule of Lukic in the case of two ... More
Linking systems of difference setsAug 15 2017Apr 20 2018A linking system of difference sets is a collection of mutually related group difference sets, whose advantageous properties have been used to extend classical constructions of systems of linked symmetric designs. The central problems are to determine ... More
Linking systems of difference setsAug 15 2017A linking system of difference sets is a collection of mutually related group difference sets, whose advantageous properties have been used to extend classical constructions of systems of linked symmetric designs. The central problems are to determine ... More
On changing highest weight theories for finite W-algebrasMay 17 2011A highest weight theory for a finite W-algebra U(g,e) was developed in [BGK]. This leads to a strategy for classifying the irreducible finite dimensional U(g,e)-modules. The highest weight theory depends on the choice of a parabolic subalgebra of g leading ... More
Large Deviations and Sum Rules for Spectral Theory - A Pedagogical ApproachAug 04 2016This is a pedagogical exposition of the large deviation approach to sum rules pioneered by Gamboa, Nagel and Rouault. We'll explain how to use their ideas to recover the Szeg}o and Killip{ Simon Theorems. The primary audience is spectral theorists and ... More
Inhomogeneous self-similar sets with overlapsSep 11 2015It is known that if the underlying iterated function system satisfies the open set condition, then the upper box dimension of an inhomogeneous self-similar set is the maximum of the upper box dimensions of the homogeneous counterpart and the condensation ... More
Equality of the Spectral and Dynamical Definitions of ReflectionMay 22 2009For full-line Jacobi matrices, Schr\"odinger operators, and CMV matrices, we show that being reflectionless, in the sense of the well-known property of $m$-functions, is equivalent to a lack of reflection in the dynamics in the sense that any state that ... More
The Nevai ConditionSep 12 2008We study Nevai's condition that for orthogonal polynomials on the real line, $K_n(x,x_0)^2 K_n(x_0,x_0)^{-1} d\rho (x)\to\delta_{x_0}$ where $K_n$ is the CD kernel. We prove that it holds for the Nevai class of a finite gap set uniformly on the spectrum ... More
Large Deviations and Sum Rules for Spectral Theory - A Pedagogical ApproachAug 04 2016Dec 01 2016This is a pedagogical exposition of the large deviation approach to sum rules pioneered by Gamboa, Nagel and Rouault. We'll explain how to use their ideas to recover the Szeg}o and Killip{ Simon Theorems. The primary audience is spectral theorists and ... More
Theory of Interacting Cavity Rydberg PolaritonsMay 18 2018Photonic materials are an emerging platform to explore quantum matter and quantum dynamics. The development of Rydberg electromagnetically induced transparency provided a clear route to strong interactions between individual optical photons. In conjunction ... More
Finite dimensional irreducible representations of finite W-algebras associated to even multiplicity nilpotent orbits in classical Lie algebrasSep 20 2010Oct 11 2010We consider finite W-algebras U(g,e) associated to even multiplicity nilpotent elements in classical Lie algebras. We give a classification of finite dimensional irreducible U(g,e)-modules with integral central character in terms of the highest weight ... More
Short gamma-ray bursts from binary neutron star mergers in globular clustersDec 30 2005The first locations of short gamma-ray bursts (GRBs) in elliptical galaxies suggest they are produced by the mergers of double neutron star (DNS) binaries in old stellar populations. Globular clusters, where the extreme densities of very old stars in ... More
Knots Connected by Wide RibbonsAug 01 2018A ribbon is, intuitively, a smooth mapping of an annulus $S^1 \times I$ in 3-space having constant width $\varepsilon$. This can be formalized as a triple $(x,\varepsilon, \mathbf{u})$ where $x$ is smooth curve in 3-space and $\mathbf{u}$ is a unit vector ... More
An infinite class of unsaturated rooted trees corresponding to designable RNA secondary structuresSep 23 2017Jan 17 2018An RNA secondary structure is designable if there is an RNA sequence which can attain its maximum number of base pairs only by adopting that structure. The combinatorial RNA design problem, introduced by Hale\v{s} et al. in 2016, is to determine whether ... More
Modeling and Analysing Respondent Driven Sampling as a Counting ProcessApr 11 2013Aug 18 2015Respondent-driven sampling (RDS) is an approach to sampling design and analysis which utilizes the networks of social relationships that connect members of the target population, using chain-referral methods to facilitate sampling. RDS typically leads ... More
Hamiltonian thermodynamics of a Lovelock black holeOct 30 1996We consider the Hamiltonian dynamics and thermodynamics of spherically symmetric spacetimes within a one-parameter family of five-dimensional Lovelock theories. We adopt boundary conditions that make every classical solution part of a black hole exterior, ... More
Synthetic Landau levels for photonsNov 23 2015Synthetic photonic materials are an emerging platform for exploring the interface between microscopic quantum dynamics and macroscopic material properties[1-7]. Making photons experience a Lorentz force imbues them with handedness, providing unique opportunities ... More
GMC Collisions as Triggers of Star Formation. I. Parameter Space Exploration with 2D SimulationsMar 06 2015Jul 31 2015We utilize magnetohydrodynamic (MHD) simulations to develop a numerical model for GMC-GMC collisions between nearly magnetically critical clouds. The goal is to determine if, and under what circumstances, cloud collisions can cause pre-existing magnetically ... More
Capturing photoelectron motion with guiding fictitious particlesMar 19 2018Apr 23 2018Photoelectron momentum distributions (PMDs) from atoms and molecules undergo qualitative changes as laser parameters are varied. We present a model to interpret the shape of the PMDs. The electron's motion is guided by a fictitious particle in our model, ... More
Inclusion of Coulomb effects in laser-atom interactionsFeb 05 2019We investigate the role of the Coulomb interaction in strong field processes. We find that the Coulomb field of the ion makes its presence known even in highly intense laser fields, in contrast to the assumptions of the strong field approximation. The ... More
Time Reversal Invariant Topologically Insulating CircuitsSep 04 2013May 18 2015From studies of exotic quantum many-body phenomena to applications in spintronics and quantum information processing, topological materials are poised to revolutionize the condensed matter frontier and the landscape of modern materials science. Accordingly, ... More
Measuring Electromagnetic and Gravitational Responses of Photonic Landau LevelsFeb 13 2018The topology of an object describes global properties that are insensitive to local perturbations. Classic examples include string knots and the genus (number of handles) of a surface: no manipulation of a closed string short of cutting it changes its ... More
Single and double ionization of magnesium by electron impact: A classical studyJan 19 2017We consider electron impact-driven single and double ionization of magnesium in the 10-100 eV energy range. Our classical Hamiltonian model of these (e, 2e) and (e, 3e) processes sheds light on their total cross sections and reveals the underlying ionization ... More
Rings and gaps in protoplanetary disks: planets or snowlines?Oct 12 2018High resolution ALMA observations of protoplanetary disks have revealed that many, if not all primordial disks consist of ring-like dust structures. The origin of these dust rings remains unclear, but a common explanation is the presence of planetary ... More
The Unit-B Method --- Refinement Guided by Progress ConcernsOct 24 2018We present Unit-B, a formal method inspired by Event-B and UNITY. Unit-B aims at the stepwise design of software systems satisfying safety and liveness properties. The method features the novel notion of coarse and fine schedules, a generalisation of ... More
Adiabatic flux insertion and growing of Laughlin states of cavity Rydberg polaritonsMar 12 2018Recently, the creation of photonic Landau levels in a twisted cavity has been demonstrated in Nature \textbf{534}, 671 (2016). Here we propose a scheme to adiabatically transfer flux quanta in multiples of $3\hbar$ simultaneously to all cavity photons ... More
Assessing the quality of a student-generated question repositoryAug 09 2013Aug 16 2013We present results from a study that categorizes and assesses the quality of questions and explanations authored by students, in question repositories produced as part of the summative assessment in introductory physics courses over the past two years. ... More
Quantum Information Processing with Delocalized Qubits under Global ControlJun 22 2006Any technology for quantum information processing (QIP) must embody within it quantum bits (qubits) and maintain control of their key quantum properties of superposition and entanglement. Typical QIP schemes envisage an array of physical systems, such ... More
Towards a More Systematic Approach to Secure Systems Design and AnalysisMay 31 2013The task of designing secure software systems is fraught with uncertainty, as data on uncommon attacks is limited, costs are difficult to estimate, and technology and tools are continually changing. Consequently, experts may interpret the security risks ... More
A Young Ultramassive White Dwarf in the AB Doradus Moving GroupJun 20 2018We use Gaia DR2 kinematic data and white dwarf evolutionary models to determine that the young and ultramassive white dwarf GD 50 is a likely member of the AB Doradus moving group. Comparison with the Montr\'eal white dwarf evolutionary models and the ... More
Which graphs occur as $γ$-graphs?Oct 03 2018The $\gamma$-graph of a graph $G$ is the graph whose vertices are labelled by the minimum dominating sets of $G$, in which two vertices are adjacent when their corresponding minimum dominating sets (each of size $\gamma(G)$) intersect in a set of size ... More
Quadrupolar quantum criticality on a fractalAug 26 2017We study the ground state ordering of quadrupolar ordered $S=1$ magnets as a function of spin dilution probability $p$ on the triangular lattice. In sharp contrast to the ordering of $S=1/2$ dipolar N\'eel magnets on percolating clusters, we find that ... More
Modelling Cyber-Security Experts' Decision Making Processes using Aggregation OperatorsAug 30 2016An important role carried out by cyber-security experts is the assessment of proposed computer systems, during their design stage. This task is fraught with difficulties and uncertainty, making the knowledge provided by human experts essential for successful ... More
Temporal Symmetry in Primary Auditory Cortex: Implications for Cortical ConnectivityAug 15 2006Neurons in primary auditory cortex (AI) in the ferret (Mustela putorius) that are well described by their spectro-temporal response field (STRF), are found also to have a distinctive property that we call temporal symmetry. For temporally symmetric neurons, ... More
Optical study of lithographically defined, subwavelength plasmonic wires and their coupling to embedded quantum emittersJul 26 2013Jan 07 2014We present an optical investigation of surface plasmon polaritons propagating along nanoscale Au-wires, lithographically defined on GaAs substrates. A two-axis confocal microscope was used to perform spatially and polarization resolved measurements in ... More
Montblanc: GPU accelerated Radio Interferometer Measurement Equations in support of Bayesian Inference for Radio ObservationsJan 30 2015Jun 19 2015We present Montblanc, a GPU implementation of the Radio interferometer measurement equation (RIME) in support of the Bayesian inference for radio observations (BIRO) technique. BIRO uses Bayesian inference to select sky models that best match the visibilities ... More
The Monitor project: Data processing and lightcurve productionDec 14 2006We have begun a large-scale photometric survey of nearby open clusters and star-forming regions, the Monitor project, aiming to measure time-series photometry for >10,000 cluster members over >10 sq.deg of sky, to find low-mass eclipsing binary and planet ... More
Quantum gas microscopy with spin, atom-number and multi-layer readoutApr 20 2015Atom- and site-resolved experiments with ultracold atoms in optical lattices provide a powerful platform for the simulation of strongly correlated materials. In this letter, we present a toolbox for the preparation, control and site-resolved detection ... More
Strong rules for discarding predictors in lasso-type problemsNov 09 2010Nov 24 2010We consider rules for discarding predictors in lasso regression and related problems, for computational efficiency. El Ghaoui et al (2010) propose "SAFE" rules that guarantee that a coefficient will be zero in the solution, based on the inner products ... More
A Strongly Interacting Polaritonic Quantum DotMay 21 2017Polaritons are an emerging platform for exploration of synthetic materials [1] and quantum information processing [2] that draw properties from two disparate particles: a photon and an atom. Cavity polaritons are particularly promising, as they are long-lived ... More
Quarter-Flux Hofstadter Lattice in Qubit-Compatible Microwave Cavity ArrayAug 04 2017Nov 14 2017Topological- and strongly-correlated- materials are exciting frontiers in condensed matter physics, married prominently in studies of the fractional quantum hall effect [1]. There is an active effort to develop synthetic materials where the microscopic ... More
An Idealized Pulsar Magnetosphere: the Relativistic Force-Free ApproximationJul 12 2004The non-dissipative relativistic force-free condition should be a good approximation to describe the electromagnetic field in much of the pulsar magnetosphere, but we may plausibly expect it to break down in singular domains. Self-consistent magnetospheric ... More
Hamiltonian Tomography of Photonic LatticesJul 18 2016In this letter we introduce a novel approach to Hamiltonian tomography of non-interacting tight-binding photonic lattices. To begin with, we prove that the matrix element of the low-energy effective Hamiltonian between sites $i$ and $j$ may be obtained ... More
Orbital excitation blockade and algorithmic cooling in quantum gasesMay 29 2011Oct 07 2011Interaction blockade occurs when strong interactions in a confined few-body system prevent a particle from occupying an otherwise accessible quantum state. Blockade phenomena reveal the underlying granular nature of quantum systems and allow the detection ... More
The Monitor project: the search for transits in the open cluster NGC 2362Mar 28 2008We present the results of a systematic search for transiting planets in a ~5 Myr open cluster, NGC 2362. We observed ~1200 candidate cluster members, of which ~475 are believed to be genuine cluster members, for a total of ~100 hours. We identify 15 light ... More
The Monitor project: Rotation of low-mass stars in the open cluster NGC 2547Nov 02 2007We report on the results of an I-band time-series photometric survey of NGC 2547 using the MPG/ESO 2.2m telescope with WFI, achieving better than 1% photometric precision per data point over 14 <~ I <~ 18. Candidate cluster members were selected from ... More
Observation of Cavity Rydberg PolaritonsNov 05 2015Nov 12 2015We demonstrate hybridization of optical cavity photons with atomic Rydberg excitations using electromagnetically induced transparency (EIT). The resulting dark state Rydberg polaritons exhibit a compressed frequency spectrum and enhanced lifetime indicating ... More
Resolving the blazar CGRaBS J0809+5341 in the presence of telescope systematicsOct 12 2016We analyse Very Long Baseline Interferometry (VLBI) observations of the blazar CGRaBS J0809+5341 using Bayesian inference methods. The observation was carried out at 5 GHz using 8 telescopes that form part of the European VLBI Network. Imaging and deconvolution ... More
An Autonomous Stabilizer for Incompressible Photon Fluids and SolidsJan 17 2017We suggest a simple approach to populate photonic quantum materials at non-zero chemical potential and near-zero temperature. Taking inspiration from forced evaporation in cold-atom experiments, the essential ingredients for our low-entropy thermal reservoir ... More
Photons and polaritons in a time-reversal-broken non-planar resonatorAug 31 2017Dec 01 2017From generation of backscatter-free transmission lines, to optical isolators, to chiral Hamiltonian dynamics, breaking time-reversal symmetry is a key tool for development of next-generation photonic devices and materials. Of particular importance is ... More
Probing the Berry Curvature and Fermi Arcs of a Weyl CircuitJul 13 2018The Weyl particle is the massless fermionic cousin of the photon. While no fundamental Weyl particles have been identified, they arise in condensed matter and meta-material systems, where their spinor nature imposes topological constraints on low-energy ... More
Variational formulation of classical and quantum models for intense laser pulse propagationJul 03 2018We consider the theoretical description of intense laser pulses propagating through gases. Starting from a first-principles description of both the electromagnetic field and the electron motion within the gas atoms, we derive a hierarchy of reduced models. ... More
A Dissipatively Stabilized Mott Insulator of PhotonsJul 30 2018Superconducting circuits have emerged as a competitive platform for quantum computation, satisfying the challenges of controllability, long coherence and strong interactions between individual systems. Here we apply this toolbox to the exploration of ... More
Formation and evolution of kinky vortonsAug 13 2009We present field theory simulations of a model with Z_2xU(1) symmetry in (2+1)-dimensions. This model has two discrete vacua, allowing for domain walls, and also a conserved Noether charge. For initial conditions in which the field is placed in one of ... More
Quantum Simulation of Antiferromagnetic Spin Chains in an Optical LatticeMar 07 2011May 15 2011Understanding exotic forms of magnetism in quantum mechanical systems is a central goal of modern condensed matter physics, with implications from high temperature superconductors to spintronic devices. Simulating magnetic materials in the vicinity of ... More
Vacuum-Induced TransparencyJul 20 2011Photons are excellent information carriers but normally pass through each other without consequence. Engineered interactions between photons would enable applications from quantum information processing to simulation of condensed matter systems. Using ... More
The Monitor project: Rotation of low-mass stars in NGC 2362 -- testing the disc regulation paradigm at 5 MyrNov 15 2007We report on the results of a time-series photometric survey of NGC 2362, carried out using the CTIO 4m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 271 candidate cluster members over the mass ... More
Non-Equilibrium Chemistry and Destruction of CO by X-ray FlaresMar 28 2018Sources of X-rays such as active galactic nuclei and X-ray binaries are often variable by orders of magnitude in luminosity over timescales of years. During and after these flares the surrounding gas is out of chemical and thermal equilibrium. We introduce ... More
Overcoming the critical slowing down of flat-histogram Monte Carlo simulations: Cluster updates and optimized broad-histogram ensemblesDec 03 2004We study the performance of Monte Carlo simulations that sample a broad histogram in energy by determining the mean first-passage time to span the entire energy space of d-dimensional ferromagnetic Ising/Potts models. We first show that flat-histogram ... More
Photon-Assisted Tunneling in a Biased Strongly Correlated Bose GasMay 23 2011Aug 21 2011We study the impact of coherently generated lattice photons on an atomic Mott insulator subjected to a uniform force. Analogous to an array of tunnel-coupled and biased quantum dots, we observe sharp, interaction-shifted photon-assisted tunneling resonances ... More
Stimulus-invariant processing and spectrotemporal reverse correlation in primary auditory cortexAug 29 2005The spectrotemporal receptive field (STRF) provides a versatile and integrated, spectral and temporal, functional characterization of single cells in primary auditory cortex (AI). In this paper, we explore the origin of, and relationship between, different ... More
Rotation periods for very low mass stars in PraesepeJan 10 2011We investigate the rotation periods of fully convective very low mass stars (VLM, M<0.3 Msol), with the aim to derive empirical constraints for the spindown due to magnetically driven stellar winds. Our analysis is based on a new sample of rotation periods ... More
The Monitor project: Rotation periods of low-mass stars in M50Oct 28 2008We report on the results of a time-series photometric survey of M50 (NGC 2323), a ~130 Myr open cluster, carried out using the CTIO 4m Blanco telescope and Mosaic-II detector as part of the Monitor project. Rotation periods were derived for 812 candidate ... More
An Empirical Determination of the Dust Mass Absorption Coefficient, $κ_{d}$, Using the Herschel Reference SurveyMar 15 2016We use the published photometry and spectroscopy of 22 galaxies in the Herschel Reference Survey to determine that the value of the dust mass absorption coefficient $\kappa_{d}$ at a wavelength of 500 $\mu m$ is $\kappa_{500} = 0.051^{+0.070}_{-0.026}\,{\rm ... More
The Monitor project: Rotation of low-mass stars in the open cluster M34May 24 2006We report on the results of a V and i-band time-series photometric survey of M34 (NGC 1039) using the Wide Field Camera (WFC) on the Isaac Newton Telescope (INT), achieving better than 1% precision per data point for 13 <~ i <~ 17. Candidate cluster members ... More
Engineering topological materials in microwave cavity arraysMay 10 2016We present a scalable architecture for the exploration of interacting topological phases of photons in arrays of microwave cavities, using established techniques from cavity and circuit quantum electrodynamics. A time-reversal symmetry breaking (non-reciprocal) ... More
High-frequency limit of non-autonomous gradient flowsJan 18 2016We study the high-frequency limit of non-autonomous gradient flows in metric spaces of energy functionals comprising an explicitly time-dependent perturbation term which might oscillate in a rapid way, but fulfills a certain Lipschitz condition. On grounds ... More
Dressed, noise- or disorder- resilient optical latticesMay 28 2012External noise is inherent in any quantum system, and can have especially strong effects for systems exhibiting sensitive many-body phenomena. We show how a dressed lattice scheme can provide control over certain types of noise for atomic quantum gases ... More
The Monitor project: tracking the evolution of low mass and pre-main sequence starsNov 06 2007The Monitor project is a large-scale program of photometric and spectroscopic monitoring of young open clusters using telescopes at ESO and other observatories. Its primary goal is to detect and characterise new low-mass eclipsing binaries, and the first ... More
The Monitor project: Searching for occultations in young open clustersNov 14 2006The Monitor project is a photometric monitoring survey of nine young (1-200Myr) clusters in the solar neighbourhood to search for eclipses by very low mass stars and brown dwarfs and for planetary transits in the light curves of cluster members. It began ... More
The deleterious mutation load is insensitive to recent population historyMay 09 2013Human populations have undergone dramatic changes in population size in the past 100,000 years, including a severe bottleneck of non-African populations and recent explosive population growth. There is currently great interest in how these demographic ... More
Interacting Floquet polaritonsJun 27 2018Ordinarily, photons do not interact with one another. However, atoms can be used to mediate photonic interactions, raising the prospect of forming synthetic materials and quantum information systems from photons. One promising approach uses electromagnetically-induced ... More
Kriging-Based Robotic Exploration for Soil Moisture Mapping Using a Cosmic-Ray SensorNov 13 2018Soil moisture monitoring is a fundamental process to enhance agricultural outcomes and to protect the environment. The traditional methods for measuring moisture content in soil are laborious and expensive, and therefore there is a growing interest in ... More
Direct Observation of Dynamic Symmetry Breaking above Room Temperature in Methylammonium Lead Iodide PerovskiteJun 29 2016Oct 05 2016Lead halide perovskites such as methylammonium lead triiodide (MAPI) have outstanding optical and electronic properties for photovoltaic applications, yet a full understanding of how this solution processable material works so well is currently missing. ... More
Probing the Superfluid to Mott Insulator Transition at the Single Atom LevelJun 03 2010Quantum gases in optical lattices offer an opportunity to experimentally realize and explore condensed matter models in a clean, tunable system. We investigate the Bose-Hubbard model on a microscopic level using single atom-single lattice site imaging; ... More
Broadband Purcell enhanced emission dynamics of quantum dots in linear photonic crystal waveguidesMay 07 2012The authors investigate the spontaneous emission dynamics of self-assembled InGaAs quantum dots embedded in GaAs photonic crystal waveguides. For an ensemble of dots coupled to guided modes in the waveguide we report spatially, spectrally, and time-resolved ... More
Kickstarting Deep Reinforcement LearningMar 10 2018We present a method for using previously-trained 'teacher' agents to kickstart the training of a new 'student' agent. To this end, we leverage ideas from policy distillation and population based training. Our method places no constraints on the architecture ... More
Shared intentions and the advance of cumulative culture in hunter-gatherersMar 23 2015Mar 24 2015It has been hypothesized that the evolution of modern human cognition was catalyzed by the development of jointly intentional modes of behaviour. From an early age (1-2 years), human infants outperform apes at tasks that involve collaborative activity. ... More
Fermi-surface induced modulation in an optimally doped YBCO superconductorMay 27 2008We have observed a Fermi-surface (FS) induced lattice modulation in a YBCO superconductor with a wavevector along CuO chains, {\it i.e.} ${\bf q}_1$=(0,$\delta$,0). The value of $\delta\sim0.21$ is twice the Fermi wavevector ($2{\bf k}_F$) along {\bf ... More
Rapid Acquisition Pair Distribution Function (RA-PDF) AnalysisApr 28 2003An image plate (IP) detector coupled with high energy synchrotron radiation was used for atomic pair distribution function (PDF) analysis, with high probed momentum transfer \Qmax $\leq 28.5$ \RAA from crystalline materials. Materials with different structural ... More
Detection of the secondary eclipse of WASP-10b in the Ks-bandDec 09 2014WASP-10b, a non-inflated hot Jupiter, was discovered around a K-dwarf in a near circular orbit ($\sim $$0.06$). Since its discovery in 2009, different published parameters for this system have led to a discussion about the size, density, and eccentricity ... More