Results for "David P. Reichert"

total 126156took 0.25s
Learning and Querying Fast Generative Models for Reinforcement LearningFeb 08 2018A key challenge in model-based reinforcement learning (RL) is to synthesize computationally efficient and accurate environment models. We show that carefully designed generative models that learn and operate on compact state representations, so-called ... More
Characteristic classes of star products on Marsden-Weinstein reduced symplectic manifoldsMay 13 2016Jun 08 2016In this note we consider a quantum reduction scheme in deformation quantization on symplectic manifolds proposed by Bordemann, Herbig and Waldmann based on BRST cohomology. We explicitly construct the induced map on equivalence classes of star products ... More
Future prospects for exploring present day anomalies in flavour physics measurements with Belle II and LHCbSep 29 2017Jan 19 2018A range of flavour physics observables show tensions with their corresponding Standard Model expectations: measurements of leptonic flavour-changing neutral current processes and ratios of semi-leptonic branching fractions involving different generations ... More
Time-dependent amplitude analysis of semileptonically-tagged D0 -> KS0 pi+ pi- decays at LHCbNov 11 2013Nov 12 2013The hadronic decay D0 -> KS0 pi+ pi- provides access to the measurement of the mixing parameters of the neutral D-meson system and allows to test for CP violation. A measurement of the mixing parameters x_D and y_D as well as of the parameters |q/p| and ... More
On The Complexity of Counter Reachability GamesJul 18 2013Jul 19 2013Counter reachability games are played by two players on a graph with labelled edges. Each move consists in picking an edge from the current location and adding its label to a counter vector. The objective is to reach a given counter value in a given location. ... More
Enhancement of Two-photon Absorption in Quantum Wells for Extremely Nondegenerate Photon PairsOct 27 2015Nov 03 2015We recently demonstrated orders of magnitude enhancement of two-photon absorption (2PA) in direct gap semiconductors due to intermediate state resonance enhancement for photons of very different energies. It can be expected that further enhancement of ... More
3-D IR imaging with uncooled GaN photodiodes using nondegenerate two-photon absorptionOct 30 2015Nov 02 2015We utilize the recently demonstrated orders of magnitude enhancement of extremely nondegenerate two-photon absorption in direct-gap semiconductor photodiodes to perform scanned imaging of 3D structures using IR femtosecond illumination pulses (1.6 um ... More
Observation of Nondegenerate Two-Photon Gain in GaAsFeb 18 2016Two-photon lasers require materials with large two-photon gain (2PG) coefficients and low linear and nonlinear losses. Our previous demonstration of large enhancement of two-photon absorption in semiconductors for very different photon energies translates ... More
Measurements of mixing and indirect CP violationAug 20 2015LHCb has collected the world's largest sample of charmed hadrons. This sample is used to measure the mixing parameters in the $D^0$-$\bar{D}^0$ system and to search for indirect $CP$ violation. This contribution focuses on measurements of $A_{\Gamma}$ ... More
Cluster Model of Decagonal TilingsFeb 04 2003Oct 22 2003A relaxed version of Gummelt's covering rules for the aperiodic decagon is considered, which produces certain random-tiling-type structures. These structures are precisely characterized, along with their relationships to various other random tiling ensembles. ... More
Classification of Equivariant Star Products on Symplectic ManifoldsJul 01 2015In this note we classify invariant star products with quantum momentum maps on symplectic manifolds by means of an equivariant characteristic class taking values in the equivariant cohomology. We establish a bijection between the equivalence classes and ... More
Circling particles and drafting in optical vorticesMay 04 2004Particles suspended in a viscous fluid circle in optical vortices generated by holographic optical-tweezer techniques [Curtis J E and Grier D G 2003 Phys. Rev. Lett. 90 133901]. We model this system and show that hydrodynamic interactions between the ... More
Finite-Temperature Order-Disorder Phase Transition in a Cluster Model of Decagonal TilingsFeb 04 2003Oct 22 2003In a recent paper ["Cluster Model of Decagonal Tilings" (to be published in Phys. Rev. B)], we have introduced a cluster model for decagonal tilings in two dimensions. This model is now extended to three dimensions. Two-dimensional tilings are stacked ... More
Hydrodynamic coupling of two rotating spheres trapped in harmonic potentialsJul 11 2003Mar 15 2004We theoretically study in detail the hydrodynamic coupling of two equal-sized colloidal spheres at low Reynolds numbers assuming the particles to be harmonically trapped with respect to both their positions and orientations. By taking into account the ... More
The Complexity of Robot Games on the Integer LineJan 31 2013Aug 02 2013In robot games on Z, two players add integers to a counter. Each player has a finite set from which he picks the integer to add, and the objective of the first player is to let the counter reach 0. We present an exponential-time algorithm for deciding ... More
Synchronization of rotating helices by hydrodynamic interactionsOct 29 2004Aug 02 2005Some types of bacteria use rotating helical flagella to swim. The motion of such organisms takes place in the regime of low Reynolds numbers where viscous effects dominate and where the dynamics is governed by hydrodynamic interactions. Typically, rotating ... More
Multi-Frequency Monitoring of the Seyfert 1 Galaxy NGC~4593 II: a Small, Compact Nucleus ?Mar 06 1995We discuss the results of a campaign to monitor spectral variations in the low-luminosity Seyfert~1 galaxy NGC~4593, at X-rays, ultraviolet, optical and near IR frequencies. The observations and data analysis have been described in a companion paper (Santos-Lle\'o ... More
One-sided ideals and approximate identities in operator algebrasNov 16 2001A left ideal of any $C^*$-algebra is an example of an operator algebra with a right contractive approximate identity (r.c.a.i.). Indeed left ideals in $C^*$-algebras may be characterized as the class of such operator algebras, which happen also to be ... More
An Application of Okada's Minor Summation FormulaMay 23 1998Noam Elkies and Everett Howe independently noticed a certain elegant product formula for the multiple integral \int_R \prod_{1 \le i < j \le k} (x_j-x_i) dx_1 \cdots dx_k, where the region $R$ is the set of $k$-tuples satisfying $0 < x_1 < \cdots < x_k ... More
Exact encounter times for many random walkers on regular and complex networksJun 04 2009The exact mean time between encounters of a given particle in a system consisting of many particles undergoing random walks in discrete time is calculated, on both regular and complex networks. Analytical results are obtained both for independent walkers, ... More
Fine structure of distributions and central limit theorem in diffusive billiardsNov 04 2004We investigate deterministic diffusion in periodic billiard models, in terms of the convergence of rescaled distributions to the limiting normal distribution required by the central limit theorem; this is stronger than the usual requirement that the mean ... More
Fault tolerant architectures for superconducting qubitsMay 29 2009Sep 30 2009In this short review, I draw attention to new developments in the theory of fault tolerance in quantum computation that may give concrete direction to future work in the development of superconducting qubit systems. The basics of quantum error correction ... More
Topics in Quantum ComputersDec 12 1996Dec 16 1996I provide an introduction to quantum computers, describing how they might be realized using language accessible to a solid state physicist. A listing of the minimal requirements for creating a quantum computer is given. I also discuss several recent developments ... More
Hurwitz-Belyi MapsAug 30 2016The study of the moduli of covers of the projective line leads to the theory of Hurwitz varieties covering configuration varieties. Certain one-dimensional slices of these coverings are particularly interesting Belyi maps. We present systematic examples ... More
Hurwitz Number FieldsAug 30 2016The canonical covering maps from Hurwitz varieties to configuration varieties are important in algebraic geometry. The scheme-theoretic fiber above a rational point is commonly connected, in which case it is the spectrum of a Hurwitz number field. We ... More
Red Clump Stars as a Tracer of Microlensing Optical DepthOct 13 1997Zaritsky and Lin have recently suggested that the color magnitude diagram of the Large Magellanic Cloud (LMC) contains evidence of foreground red clump stars. They interpret this as evidence of tidal debris or a dwarf galaxy at a distance of $\sim 35$ ... More
Sketching as a Tool for Numerical Linear AlgebraNov 17 2014Feb 10 2015This survey highlights the recent advances in algorithms for numerical linear algebra that have come from the technique of linear sketching, whereby given a matrix, one first compresses it to a much smaller matrix by multiplying it by a (usually) random ... More
Chandra X-ray Observatory High-resolution X-ray Spectroscopy of Stars: Modeling and InterpretationMar 03 2004The Chandra X-ray Observatory grating spectrometers allow study of stellar spectra at resolutions on the order of 1000. Prior x-ray observatories' low resolution data have shown that nearly all classes of stars emit x-rays. Chandra reveals details of ... More
The Quantum Logic of Direct-Sum DecompositionsApr 04 2016Apr 14 2016Since the pioneering work of Birkhoff and von Neumann, quantum logic has been interpreted as the logic of (closed) subspaces of a Hilbert space. There is a progression from the usual Boolean logic of subsets to the "quantum logic" of subspaces of a general ... More
Shadow boundary effects in hybrid numerical-asymptotic methods for high frequency scatteringSep 12 2014Jun 03 2015The hybrid numerical-asymptotic (HNA) approach aims to reduce the computational cost of conventional numerical methods for high frequency wave scattering problems by enriching the numerical approximation space with oscillatory basis functions, chosen ... More
O carater de Chern-Connes para C$^*$-sistemas dinamicos calculado em algumas algebras de operadores pseudodiferenciaisAug 04 2008Given a C$^*$-dynamical system $(A, G, \alpha)$ one defines a homomorphism, called the Chern-Connes character, that take an element in $K_0(A) \oplus K_1(A)$, the K-theory groups of the C$^*$-algebra $A$, and maps it into $H_{\mathbb{R}}^*(G)$, the real ... More
Coherent population transfer in a chain of tunnel coupled quantum dotsJun 11 2007We consider the dynamics of a single electron in a chain of tunnel coupled quantum dots, exploring the formal analogies of this system with some of the laser-driven multilevel atomic or molecular systems studied by Bruce W. Shore and collaborators over ... More
Symmetry Classes of Alternating Sign MatricesAug 05 2000An alternating sign matrix is a square matrix satisfying (i) all entries are equal to 1, -1 or 0; (ii) every row and column has sum 1; (iii) in every row and column the non-zero entries alternate in sign. The 8-element group of symmetries of the square ... More
Normal diffusion in crystal structures and higher-dimensional billiard models with gapsAug 16 2008Jan 26 2009We show, both heuristically and numerically, that three-dimensional periodic Lorentz gases -- clouds of particles scattering off crystalline arrays of hard spheres -- often exhibit normal diffusion, even when there are gaps through which particles can ... More
Density of cubic field discriminantsApr 26 1999In this paper we give a conjectural refinement of the Davenport-Heilbronn theorem on the density of cubic field discriminants. We explain how this refinement is plausible theoretically and agrees very well with computational data.
The Physical Implementation of Quantum ComputationFeb 25 2000Apr 13 2000After a brief introduction to the principles and promise of quantum information processing, the requirements for the physical implementation of quantum computation are discussed. These five requirements, plus two relating to the communication of quantum ... More
Quantum computing and single-qubit measurements using the spin filter effectOct 22 1998Many things will have to go right for quantum computation to become a reality in the lab. For any of the presently-proposed approaches involving spin states in solids, an essential requirement is that these spins should be measured at the single-Bohr-magneton ... More
The Detection of Terrestrial Planets via Gravitational Microlensing: Space vs. Ground-based SurveysApr 05 2004I compare an aggressive ground-based gravitational microlensing survey for terrestrial planets to a space-based survey. The Ground-based survey assumes a global network of very wide field-of-view ~2m telescopes that monitor fields in the central Galactic ... More
Newforms with rational coefficientsNov 21 2016We consider the set of classical newforms with rational coefficients and no complex multiplication. We study the distribution of quadratic-twist classes of these forms with respect to weight $k$ and minimal level $N$. We conjecture that for each weight ... More
Asymptotic safety of gravity-matter systemsOct 23 2015May 20 2016We study the ultraviolet stability of gravity-matter systems for general numbers of minimally coupled scalars and fermions. This is done within the functional renormalisation group setup put forward in \cite{Christiansen:2015rva} for pure gravity. It ... More
Quasiparticle decay in a one-dimensional Bose-Fermi mixtureNov 03 2016In a one-dimensional weakly interacting Bose-Fermi mixture one branch of elementary excitations is well described by the Bogoliubov spectrum. Here we use the microscopic theory to study the decay of such quasiparticle excitations. The main scattering ... More
Quality of Spatial Entanglement PropagationNov 23 2016We explore, both experimentally and theoretically, the propagation dynamics of spatially entangled photon pairs (biphotons). Characterization of entanglement is done via the Schmidt number, which is a universal measurement of the degree of entanglement ... More
Polynomials with prescribed bad primesJan 30 2014We tabulate polynomials in Z[t] with a given factorization partition, bad reduction entirely within a given set of primes, and satisfying auxiliary conditions associated to 0, 1, and infinity. We explain how these sets of polynomials are of particular ... More
Number fields with discriminant +-2^a 3^b: Examples from three point coversOct 27 1998In this paper we construct number fields ramified at 2 and 3 only, with various moderate-sized non-solvable Galois groups. We construct these fields by specializing three point covers, some from the literature and some new here. The specialization points ... More
$PGL_2(\mathbb{F}_\ell)$ number fields with rational companion formsNov 21 2016We give a list of $PGL_2(\mathbb{F}_\ell)$ number fields for $\ell \geq 11$ which have rational companion forms. Our list has fifty-three fields and seems likely to be complete. Some of the fields on our list are very lightly ramified for their Galois ... More
A Pareto scale-inflated outlier model and its Bayesian analysisNov 02 2016This paper develops a Pareto scale-inflated outlier model. This model is intended for use when data from some standard Pareto distribution of interest is suspected to have been contaminated with a relatively small number of outliers from a Pareto distribution ... More
New Algorithms for Heavy Hitters in Data StreamsMar 05 2016An old and fundamental problem in databases and data streams is that of finding the heavy hitters, also known as the top-$k$, most popular items, frequent items, elephants, or iceberg queries. There are several variants of this problem, which quantify ... More
Rigged modules II: multipliers and dualityJul 31 2016In a previous paper with Kashyap we generalized the theory of $W^*$-modules to the setting of modules over nonselfadjoint dual operator algebras, obtaining the class of weak*-rigged modules. The present paper and its contemporaneous predecessor comprise ... More
Cubic Laurent Series in Characteristic 2 with Bounded Partial QuotientsMar 16 1999There is a theory of continued fractions for Laurent series in x^{-1} with coefficients in a field F. This theory bears a close analogy with classical continued fractions for real numbers with Laurent series playing the role of real numbers and the sum ... More
Division polynomials with Galois group SU3(3).2 = G2(2)Nov 25 2014We use a rigidity argument to prove the existence of two related degree twenty-eight covers of the projective plane with Galois group SU3(3).2 = G2(2). Constructing corresponding two-parameter polynomials directly from the defining group-theoretic data ... More
Lightly ramified number fields with Galois group $S.M_{12}.A$Apr 02 2014We specialize various three-point covers to find number fields with Galois group $M_{12}$, $M_{12}.2$, $2.M_{12}$, or $2.M_{12}.2$ and light ramification in various senses. One of our $2.M_{12}.2$ fields has the unusual property that it is ramified only ... More
The Shilov boundary of an operator space - and the characterization theoremsJun 12 1999Dec 05 2000We study operator spaces, operator algebras, and operator modules, from the point of view of the `noncommutative Shilov boundary'. In this attempt to utilize some `noncommutative Choquet theory', we find that Hilbert C$^*-$modules and their properties, ... More
Two-Bit Gates are Universal for Quantum ComputationJul 05 1994A proof is given, which relies on the commutator algebra of the unitary Lie groups, that quantum gates operating on just two bits at a time are sufficient to construct a general quantum circuit. The best previous result had shown the universality of three-bit ... More
Quantum Gates and CircuitsMay 07 1997A historical review is given of the emergence of the idea of the quantum logic gate from the theory of reversible Boolean gates. I highlight the quantum XOR or controlled NOT as the fundamental two-bit gate for quantum computation. This gate plays a central ... More
Large Magellanic Cloud Microlensing Optical Depth with Imperfect Event SelectionFeb 17 2005Jun 27 2005I present a new analysis of the MACHO Project 5.7 year Large Magellanic Cloud (LMC) microlensing data set that incorporates the effects of contamination of the microlensing event sample by variable stars. Photometric monitoring of MACHO LMC microlensing ... More
An Efficient Method for Modeling High Magnification Planetary Microlensing EventsNov 15 2009Jun 02 2010I present a previously unpublished method for modeling multiple lens microlensing events that is based on the image centered ray shooting approach of Bennett and Rhie. It has been used to model all a wide variety of binary and triple lens systems, but ... More
Noncommutative peak interpolation revisitedNov 21 2012Jun 24 2013Peak interpolation is concerned with a foundational kind of mathematical task: building functions in a fixed algebra $A$ which have prescribed values or behaviour on a fixed closed subset (or on several disjoint subsets). In this paper we do the same ... More
Supersymmetric mass spectra and the seesaw scaleJan 11 2011Apr 21 2011Supersymmetric mass spectra within two variants of the seesaw mechanism, commonly known as type-II and type-III seesaw, are calculated using full 2-loop RGEs and minimal Supergravity boundary conditions. The type-II seesaw is realized using one pair of ... More
Supersymmetric mass spectra and the seesaw type-I scaleDec 20 2011We calculate supersymmetric mass spectra with cMSSM boundary conditions and a type-I seesaw mechanism added to explain current neutrino data. Using published, estimated errors on SUSY mass observables for a combined LHC+ILC analysis, we perform a theoretical ... More
Undecidability of Two-dimensional Robot GamesApr 29 2016Robot game is a two-player vector addition game played on the integer lattice $\mathbb{Z}^n$. Both players have sets of vectors and in each turn the vector chosen by a player is added to the current configuration vector of the game. One of the players, ... More
Towards apparent convergence in asymptotically safe quantum gravityDec 21 2016The asymptotic safety scenario in gravity is accessed within the systematic vertex expansion scheme for functional renormalisation group flows put forward in \cite{Christiansen:2012rx,Christiansen:2014raa}, and implemented in \cite{Christiansen:2015rva} ... More
On Morita's Fundamental Theorem for C*-algebrasJun 12 1999We give a solution, via operator spaces, of an old problem in the Morita equivalence of C*-algebras. Namely, we show that C*-algebras are strongly Morita equivalent in the sense of Rieffel if and only if their categories of left operator modules are isomorphic ... More
Phase-Control of Photoabsorption in Optically Dense MediaJul 03 2000We present a self-consistent theory, as well as an illustrative application to a realistic system, of phase control of photoabsorption in an optically dense medium. We demonstrate that, when propagation effects are taken into consideration, the impact ... More
The Unified Segment Tree and its Application to the Rectangle Intersection ProblemFeb 27 2013In this paper we introduce a variation on the multidimensional segment tree, formed by unifying different interpretations of the dimensionalities of the data structure. We give some new definitions to previously well-defined concepts that arise naturally ... More
Generalization of C*-algebra methods via real positivity for operator and Banach algebrasAug 12 2015With Charles Read we have introduced and studied a new notion of (real) positivity in operator algebras, with an eye to extending certain C*-algebraic results and theories to more general algebras. As motivation note that the `completely' real positive ... More
Deterministic Diffusion in Periodic Billiard ModelsAug 16 2008We investigate statistical properties of several classes of periodic billiard models which are diffusive. An introductory chapter gives motivation, and then a review of statistical properties of dynamical systems is given in chapter 2. In chapter 3, we ... More
Detection of Extrasolar Planets by Gravitational MicrolensingFeb 10 2009Gravitational microlensing provides a unique window on the properties and prevalence of extrasolar planetary systems because of its ability to find low-mass planets at separations of a few AU. The early evidence from microlensing indicates that the most ... More
Quantum Computation and Spin PhysicsDec 12 1996A brief review is given of the physical implementation of quantum computation within spin systems or other two-state quantum systems. The importance of the controlled-NOT or quantum XOR gate as the fundamental primitive operation of quantum logic is emphasized. ... More
Rotational Diffusion in a Chain of ParticlesOct 24 2005We study the coupled rotational diffusion in a two-particle chain on the basis of a Smoluchowski equation and calculate time-correlation functions that are measurable in an experiment. This might be used to explore hydrodynamic interactions in the limit ... More
Dynamics of a quantum two-state system in a linearly driven quantum bathJun 27 2016Sep 29 2016When an open quantum system is driven by an external time-dependent force, the coupling of the driving to the central system is usually included whereas the impact of the driving field on the bath is neglected. We investigate the effect of a quantum bath ... More
Variation in Emission and Absorption Lines and Continuum Flux by Orbital Phase in Vela X-1Mar 20 2004High resolution spectral studies were undertaken at orbital phases 0, 0.25 and 0.5 on the high-mass X-ray binary (HMXB) Vela X-1 using archival Chandra data. We present (a) the first detailed analysis of the multiple strong narrow emission lines present ... More
Absolute frequency measurement of the In$^{+}$ clock transition with a mode-locked laserOct 05 2000The absolute frequency of the In$^{+}$ $5s^{2 1}S_{0}$ - $5s5p^{3}P_{0}$ clock transition at 237 nm was measured with an accuracy of 1.8 parts in $10^{13}$. Using a phase-coherent frequency chain, we compared the $^{1}S_{0}$ - $^{3}P_{0}$ transition with ... More
Lower Bounds for Adaptive Sparse RecoveryMay 15 2012Oct 21 2012We give lower bounds for the problem of stable sparse recovery from /adaptive/ linear measurements. In this problem, one would like to estimate a vector $x \in \R^n$ from $m$ linear measurements $A_1x,..., A_mx$. One may choose each vector $A_i$ based ... More
Optimal CUR Matrix DecompositionsMay 30 2014Jul 16 2014The CUR decomposition of an $m \times n$ matrix $A$ finds an $m \times c$ matrix $C$ with a subset of $c < n$ columns of $A,$ together with an $r \times n$ matrix $R$ with a subset of $r < m$ rows of $A,$ as well as a $c \times r$ low-rank matrix $U$ ... More
The molecular structure of the interface between water and a hydrophobic substrate is liquid-vapor likeJul 16 2014With molecular simulation for water and a tunable hydrophobic substrate, we apply the instantaneous interface construction [A. P. Willard and D. Chandler, J. Phys. Chem. B, 114, 1954 (2010)] to examine the similarity between a water-vapor interface and ... More
Insects, Trees, and Climate: The Bioacoustic Ecology of Deforestation and Entomogenic Climate ChangeDec 11 2006Accumulating observational evidence suggests an intimate connection between rapidly expanding insect populations, deforestation, and global climate change. We review the evidence, emphasizing the vulnerability of key planetary carbon pools, especially ... More
Chandra and XMM-Newton Observations of the Double Cluster Abell 1758Apr 30 2004Abell 1758 was classified as a single rich cluster of galaxies by Abell, but a ROSAT observation showed that this system consists of two distinct clusters (A1758N and A1758S) separated by approximately $8\arcmin$ (a projected separation of 2 Mpc in the ... More
Ueda's peak set theorem for general von Neumann algebrasMay 28 2016We extend Ueda's peak set theorem for subdiagonal subalgebras of tracial finite von Neumann algebras, to sigma-finite von Neumann algebras (that is, von Neumann algebras with a faithful state; which includes those on a separable Hilbert space, or with ... More
Higgs bundles and (A,B,A)-branesMay 20 2013Through the action of anti-holomorphic involutions on a compact Riemann surface, we construct families of (A,B,A)-branes in the moduli spaces of G_c-Higgs bundles on the Riemann surface. We study the geometry of these (A,B,A)-branes in terms of spectral ... More
Completely contractive projections on operator algebrasAug 06 2015Jan 11 2016The main goal of this paper is to find operator algebra variants of certain deep results of Stormer, Friedman and Russo, Choi and Effros, Effros and Stormer, Robertson and Youngson, Youngson, and others, concerning projections on C*-algebras and their ... More
Metric characterizations IIFeb 25 2012The present paper is a sequel to our paper "Metric characterization of isometries and of unital operator spaces and systems". We characterize certain common objects in the theory of operator spaces (unitaries, unital operator spaces, operator systems, ... More
A Theory of the Longitudinal and Hall Conductivities of the Cuprate SuperconductorsSep 16 1996We establish the applicability to transport phenomena in the cuprate superconductors of a nearly antiferromagnetic Fermi liquid (NAFL) description of the magnetic interaction between planar quasiparticles by using it to obtain the temperature dependent ... More
Rank Aggregation: New Bounds for MCxOct 02 2015The rank aggregation problem has received significant recent attention within the computer science community. Its applications today range far beyond the original aim of building metasearch engines to problems in machine learning, recommendation systems ... More
Long-range correlations in a simple stochastic model of coupled transportMar 18 2009Aug 11 2009We study coupled transport in the nonequilibrium stationary state of a model consisting of independent random walkers, moving along a one-dimensional channel, which carry a conserved energy-like quantity, with density and temperature gradients imposed ... More
Subspace Embeddings and $\ell_p$-Regression Using Exponential Random VariablesMay 23 2013Mar 17 2014Oblivious low-distortion subspace embeddings are a crucial building block for numerical linear algebra problems. We show for any real $p, 1 \leq p < \infty$, given a matrix $M \in \mathbb{R}^{n \times d}$ with $n \gg d$, with constant probability we can ... More
Effective fault-tolerant quantum computation with slow measurementsJul 06 2006Aug 03 2006How important is fast measurement for fault-tolerant quantum computation? Using a combination of existing and new ideas, we argue that measurement times as long as even 1,000 gate times or more have a very minimal effect on the quantum accuracy threshold. ... More
Multi-Qubit Joint Measurements in Circuit QED: Stochastic Master Equation AnalysisOct 12 2015We derive a family of stochastic master equations describing homodyne measurement of multi-qubit diagonal observables in circuit quantum electrodynamics. Our approach replaces the polaron-like transformation of previous work, which required a lengthy ... More
Quantum Computation with Quantum DotsJan 08 1997Jul 20 1997We propose a new implementation of a universal set of one- and two-qubit gates for quantum computation using the spin states of coupled single-electron quantum dots. Desired operations are effected by the gating of the tunneling barrier between neighboring ... More
Anisotropic Scalar-Tensor CosmologiesJan 27 1995We examine homogeneous but anisotropic cosmologies in scalar-tensor gravity theories, including Brans-Dicke gravity. We present a method for deriving solutions for any isotropic perfect fluid with a barotropic equation of state ($p\propto\rho$) in a spatially ... More
Massless Fileds in Scalar-Tensor CosmologiesMay 10 1994We derive exact Friedmann--Robertson--Walker cosmological solutions in general scalar--tensor gravity theories, including Brans--Dicke gravity, for stiff matter or radiation. These correspond to the long or short wavelength modes respectively of massless ... More
Exploiting Kerr Cross Non-linearity in Circuit Quantum Electrodynamics for Non-demolition MeasurementsJun 16 2009Feb 14 2010We propose a scheme for dispersive readout of stored energy in one mode of a nonlinear superconducting microwave ring resonator by detection of the frequency shift of a second mode coupled to the first via a Kerr nonlinearity. Symmetry is used to enhance ... More
Roots in operator and Banach algebrasOct 01 2015Dec 26 2015We show that several known facts concerning roots of matrices generalize to operator algebras and Banach algebras. We show for example that the so-called Newton, binomial, Visser, and Halley iterative methods converge to the root in Banach and operator ... More
The Round Complexity of Small Set IntersectionApr 05 2013Apr 09 2013The set disjointness problem is one of the most fundamental and well-studied problems in communication complexity. In this problem Alice and Bob hold sets $S, T \subseteq [n]$, respectively, and the goal is to decide if $S \cap T = \emptyset$. Reductions ... More
(1+eps)-approximate Sparse RecoveryOct 19 2011Dec 26 2011The problem central to sparse recovery and compressive sensing is that of stable sparse recovery: we want a distribution of matrices A in R^{m\times n} such that, for any x \in R^n and with probability at least 2/3 over A, there is an algorithm to recover ... More
HETGS Spectroscopy of a Coronally Active Contact Binary, VW CepSep 10 2004Short-period binaries represent extreme cases in the generation of stellar coronae via a rotational dynamo. Such stars are important for probing the origin and nature of coronae in the regimes of rapid rotation and activity saturation. VW Cep (P=0.28 ... More
Coarse Grained Modeling of The Interface Between Water and Heterogeneous SurfacesApr 07 2008Jun 23 2008Using coarse grained models we investigate the behavior of water adjacent to an extended hydrophobic surface peppered with various fractions of hydrophilic patches of different sizes. We study the spatial dependence of the mean interface height, the solvent ... More
Kinematic dynamo action in a sphere: Effects of periodic time-dependent flows on solutions with axial dipole symmetrySep 28 2004Choosing a simple class of flows, with characteristics that may be present in the Earth's core, we study the ability to generate a magnetic field when the flow is permitted to oscillate periodically in time. The flow characteristics are parameterised ... More
Duality and Operator Algebras II: Operator Algebras as Banach AlgebrasAug 20 2004Dec 06 2004We answer, by counterexample, several open questions concerning algebras of operators on a Hilbert space. The answers add further weight to the thesis that, for many purposes, such algebras ought to be studied in the framework of operator spaces, as opposed ... More
Duality and operator algebrasJul 13 2004Jul 16 2004We investigate some subtle and interesting phenomena in the duality theory of operator spaces and operator algebras. In particular, we give several applications of operator space theory, based on the surprising fact that certain maps are always $w^*$-continuous ... More
Magneto-optical rotation and cross-phase modulation via coherently driven tripod atomsFeb 10 2004Aug 31 2004We study the interaction of a weak probe field, having two orthogonally polarized components, with an optically dense medium of four-level atoms in a tripod configuration. In the presence of a coherent driving laser, electromagnetically induced transparency ... More