Results for "Friedemann Reinhard"

total 1412took 0.11s
Nanoscale Sensing and Quantum CoherenceJun 11 2019Small solid state qubits, most prominently single spins in solids, can be remarkable sensors for various physical quantities ranging from magnetic fields to temperature. They package the performance of their bulk semiconductor counterparts into a nanoscale ... More
Holography of Wi-Fi radiationNov 30 2016May 05 2017Wireless data transmission systems such as WiFi or Bluetooth emit coherent light - electromagnetic waves with precisely known amplitude and phase. Propagating in space, this radiation forms a hologram - a two-dimensional wavefront encoding a three-dimensional ... More
Augmenting the spin properties of shallow implanted NV-centers by CVD-overgrowthAug 21 2012The controlled scaling of diamond defect center based quantum registers relies on the ability to position NVs with high spatial resolution. Using ion implantation, shallow (< 10 nm) NVs can be placed with accuracy below 20nm, but generally show reduced ... More
Heuristical and numerical considerations for the carbuncle phenomenonJul 02 2015In this study, we investigate the so called carbuncle phenomenon by means of numerical experiments and heuristic considerations. We identify two main sources for the carbuncle: instability of the 1d shock position and low numerical viscosity on shear ... More
Counterpart of the Weyl tensor for Rarita-Schwinger type fieldsDec 12 2016Apr 02 2017In dimensions larger than 3 a modified field strength for Rarita-Schwinger type fields is constructed whose components are not constrained by the field equations. In supergravity theories the result provides a modified (supercovariant) gravitino field ... More
Supersymmetry algebra cohomology II: Primitive elements in 2 and 3 dimensionsApr 17 2010Dec 01 2010The primitive elements of the supersymmetry algebra cohomology as defined in a companion paper are computed exhaustively for standard supersymmetry algebras in dimensions D=2 and D=3, for all signatures (t,D-t) and all numbers N of sets of supersymmetries. ... More
Extended BRST cohomology, consistent deformations and anomalies of four-dimensional supersymmetric gauge theoriesDec 05 2002Mar 25 2003The local cohomology of an extended BRST differential which includes global N=1 supersymmetry and Poincare transformations is completely and explicitly computed in four-dimensional supersymmetric gauge theories with super-Yang-Mills multiplets, chiral ... More
Gauge covariant algebras and local BRST cohomologyNov 24 1997The formulation of the local BRST cohomology on infinite jet bundles and its relation and reduction to gauge covariant algebras are reviewed. As an illustration, we compute the local BRST cohomology for geodesic motion in (pseudo-) Riemannian manifolds ... More
Aspects of supersymmetric BRST cohomologyJan 17 2012The application and extension of well-known BRST cohomological methods to supersymmetric field theories are discussed. The focus is on the emergence and particular features of supersymmetry algebra cohomology in this context. In particular it is discussed ... More
Supersymmetry algebra cohomology I: Definition and general structureNov 11 2009Dec 01 2010The paper concerns standard supersymmetry algebras in diverse dimensions, involving bosonic translational generators and fermionic supersymmetry generators. A cohomology related to these supersymmetry algebras, termed supersymmetry algebra cohomology, ... More
Seiberg-Witten maps and anomalies in noncommutative Yang-Mills theoriesMar 13 2004A BRST-cohomological analysis of Seiberg-Witten maps and results on gauge anomalies in noncommutative Yang-Mills theories with general gauge groups are reviewed.
Local BRST cohomology and covarianceApr 04 1996Sep 03 1997The paper provides a framework for a systematic analysis of the local BRST cohomology in a large class of gauge theories. The approach is based on the cohomology of s+d in the jet space of fields and antifields, s and d being the BRST operator and exterior ... More
Anomaly candidates and invariants of D=4, N=1 supergravity theoriesJun 11 1993All anomaly candidates and the form of the most general invariant local action are given for old and new minimal supergravity, including the cases where additional Yang--Mills and chiral matter multiplets are present. Furthermore nonminimal supergravity ... More
On the Proper Setup of the Double Mach Reflection as a Test Case for the Resolution of Gas Dynamics CodesApr 25 2014May 02 2014This note discusses the initial and boundary conditions as well as the size of the computational domain for the double Mach reflection problem when set up as a test for the resolution of an Euler scheme for gas dynamics.
Local BRST cohomology in minimal D=4, N=1 supergravitySep 24 1996Oct 13 1997The local BRST cohomology is computed in old and new minimal supergravity, including the coupling to Yang-Mills gauge multiplets. This covers the determination of all gauge invariant local actions for these models, the classification of all the possible ... More
Structure of BRS-Invariant Local FunctionalsOct 19 1993For a large class of gauge theories a nilpotent BRS-operator $s$ is constructed and its cohomology in the space of local functionals of the off-shell fields is shown to be isomorphic to the cohomology of $\4s=s+d$ on functions $f(\4C,\PH)$ of tensor fields ... More
A note on the carbuncle in shallow water simulationsJun 02 2012An important problem in gas dynamics simulation is to prevent the carbuncle, a breakdown of discrete shock profiles. We show that for high Froude number, this also occurs in shallow water simulations and give numerical evidence that all cures developed ... More
Roe-type schemes for shallow water magnetohydrodynamics with hyperbolic divergence cleaningSep 30 2014We discuss Roe-type linearizations for non-conservative shallow water magnetohydrodynamics without and with hyperbolic divergence cleaning.
Scanning probe microscopy with chemical contrast by nanoscale nuclear magnetic resonanceJun 12 2014Scanning probe microscopy is one of the most versatile windows into the nanoworld, providing imaging access to a variety of sample properties, depending on the probe employed. Tunneling probes map electronic properties of samples, magnetic and photonic ... More
Quantum Sensing of Weak Radio-Frequency Signals by Pulsed Mollow Absorption SpectroscopyFeb 22 2017Feb 27 2017Quantum sensors, qubits sensitive to external fields, have become powerful detectors for various small acoustic and electromagnetic fields. A major key to their success have been dynamical decoupling protocols which enhance sensitivity to weak oscillating ... More
Optimized Jastrow-Slater wave functions for ground and excited states: Application to the lowest states of etheneMar 19 2004A quantum Monte Carlo method is presented for determining multi-determinantal Jastrow-Slater wave functions for which the energy is stationary with respect to the simultaneous optimization of orbitals and configuration interaction coefficients. The approach ... More
D=4, N=1 Supersymmetric Henneaux-Knaepen ModelsNov 19 1998We construct N=1 supersymmetric versions of four-dimensional Freedman-Townsend models and generalizations thereof found recently by Henneaux and Knaepen, with couplings between 1-form and 2-form gauge potentials. The models are presented both in a superfield ... More
Atomic Diffusion in the Surface State of Mott Insulator NiS2Aug 20 2015We present resistivity measurements of Mott insulator NiS2 single crystals after heat treatment. We find a strong increase of the low temperature resistivity that relaxes back towards the pristine behaviour over several days with a time constant of 45 ... More
Environmental gravitational decoherence and a tensor noise modelFeb 04 2015We discuss decrease of coherence in a massive system due to the emission of gravitational waves. In particular we investigate environmental gravitational decoherence in the context of an interference experiment. The time-evolution of the reduced density ... More
Efficient electrical spin readout of NV- centers in diamondAug 08 2016Using pulsed photoionization the coherent spin manipulation and echo formation of ensembles of NV- centers in diamond are detected electrically realizing contrasts of up to 17 %. The underlying spin-dependent ionization dynamics are investigated experimentally ... More
Tracking Temperature Dependent Relaxation Times of Individual Ferritin Nanomagnets with a Wide-band Quantum SpectrometerJun 02 2014We demonstrate the tracking of the spin dynamics of ensemble and individual magnetic ferritin proteins from cryogenic up to room temperature using the nitrogen-vacancy color center in diamond as magnetic sensor. We employ different detection protocols ... More
High-Resolution Correlation Spectroscopy of 13C Spins Near a Nitrogen-Vacancy Center in DiamondMay 07 2013Spin complexes comprising the nitrogen-vacancy (NV) center and neighboring spins are being considered as a building block for a new generation of spintronic and quantum information processing devices. Because assembling identical spin clusters is difficult, ... More
A Planar Scanning Probe MicroscopeMay 08 2018Scanning probe microscopy (SPM) is traditionally based on very sharp tips, where the small size of the apex is critical for resolution. This paradigm is about to shift, since a novel generation of planar probes (color centers in diamond, superconducting ... More
Dispersion Relations in Gauge Theories with ConfinementNov 01 1995The analytic structure of {\it physical} amplitudes is considered for gauge theories with confinement of excitations corresponding to the elementary fields. Confinement is defined in terms of the BRST algebra. BRST-invariant, local, composite fields are ... More
A physical derivation of the Kerr-Newman black hole solutionOct 02 2013According to the no-hair theorem, the Kerr-Newman black hole solution represents the most general asymptotically flat, stationary (electro-) vacuum black hole solution in general relativity. The procedure described here shows how this solution can indeed ... More
Ends and TanglesOct 14 2015Dec 09 2015We show that an arbitrary infinite graph can be compactified by its ${\aleph_0}$-tangles in much the same way as the ends of a locally finite graph compactify it in its Freudenthal compactification. In general, the ends then appear as a subset of its ... More
Bringing the LHC and ATLAS to a regional planetariumSep 13 2011An outreach effort has started at Michigan State University to bring particle physics, the Large Hadron Collider, and the ATLAS experiment to a general audience at the Abrams planetarium on the MSU campus. A team of undergraduate students majoring in ... More
Relativistic Nucleus-Nucleus Collisions: A Connection between the Strangeness-Maximum at $\sqrt{s} \approx$ 7 GeV and the QCD Critical Endpoint from Lattice StudiesApr 15 2004A steep maximum occurs in the Wroblewski ratio between strange and non-strange quarks created in central nucleus-nucleus collisions, of about A=200, at the lower SPS energy $\sqrt{s} \approx$ 7 GeV. By analyzing hadronic multiplicities within the grand ... More
Relativistic Nucleus-Nucleus Collisions: from the BEVALAC to RHICMay 12 2004I briefly describe the initial goals of relativistic nuclear collisions research, focusing on the LBL Bevatron/Bevalac facility in the 1970's. An early concept of high hadronic density fireball formation, and subsequent isentropic decay (preserving information ... More
Gravitational fields of rotating disks and black holesDec 14 1999The two known exact solutions of Einstein's field equations describing rotating objects of physical significance - a black hole and a rigidly rotating disk of dust - are discussed using a single mathematical framework related to Jacobi's inversion problem. ... More
The Parton-Hadron Phase Transition in Central Nuclear Collisions at the CERN SPSJan 26 1999Jan 27 1999A selection of recent data referring to Pb+Pb collisions at the SPS CERN energy of 158 GeV per nucleon is presented which might describe the state of highly excited strongly interacting matter both above and below the deconfinement to hadronization (phase) ... More
Tangles in the social sciencesJul 17 2019Traditional clustering identifies groups of objects that share certain qualities. Tangles do the converse: they identify groups of qualities that often occur together. They can thereby identify and discover 'types': of behaviour, views, abilities, dispositions. ... More
Existence of solutions for semilinear elliptic boundary value problems on arbitrary open setsJul 31 2015We show the existence of a weak solution of a semilinear elliptic Dirichlet problem on an arbitrary open set. We make no assumptions about the open set, very mild regularity assumptions on the semilinearity, plus a coerciveness assumption which depends ... More
High-dynamic-range imaging of nanoscale magnetic fields using optimal control of a single qubitJul 24 2013We present a novel spectroscopy protocol based on optimal control of a single quantum system. It enables measurements with quantum-limited sensitivity (\eta_\omega ~ 1/sqrt(T_2^*),T_2^* denoting the system's coherence time) but has an orders of magnitude ... More
Identifying Word Translations in Non-Parallel TextsMay 22 1995Common algorithms for sentence and word-alignment allow the automatic identification of word translations from parallel texts. This study suggests that the identification of word translations should also be possible with non-parallel and even unrelated ... More
A simple existence criterion for normal spanning trees in infinite graphsFeb 20 2012Apr 10 2016Halin proved in 1978 that there exists a normal spanning tree in every connected graph $G$ that satisfies the following two conditions: (i) $G$ contains no subdivision of a `fat' $K_{\aleph_0}$, one in which every edge has been replaced by uncountably ... More
Constructive proof of the Kerr-Newman black hole uniqueness including the extreme caseAug 24 2011Dec 20 2011A new proof of the uniqueness of the Kerr-Newman black hole solutions amongst asymptotically flat, stationary and axisymmetric electro-vacuum spacetimes surrounding a connected Killing horizon is given by means of an explicit construction of the corresponding ... More
Relativistic Nuclear CollisionsJul 29 2009A comprehensive introduction is given to the field of relativistic nuclear collisions, and the phase diagram of strongly interacting matter. The content of this complex of reviews is shown.
CALICE Si/W electromagnetic CalorimeterFeb 18 2009The CALICE prototype for a Si/W electromagnetic calorimeter has been tested in large scale test beams. Several million events with electrons and hadrons of different energies and impact angles have been recorded. The energy resolution has been measured ... More
Reduction of Coupling Parameters in Quantum Field TheoriesDec 18 2000A concise survey is given of the general method of reduction in the number of coupling parameters. Theories with several independent couplings are related to a set of theories with a single coupling. The reduced theories may or may not have particular ... More
Quark Matter 99 Summary: Hadronic SignalsNov 19 1999I review the new data presented at QM99. The main emphasis is placed on the CERN SPS hadron production systematics concluding that the boundary between a partonic and a hadronic phase has now been located at $T=180 \pm10\:MeV$ and $\epsilon \approx 1 ... More
The Birman-Murakami-Wenzl Algebra of Coxeter Type DOct 13 2016The paper defines a generic Birman-Wenzl algebra of Coxeter Type D and investigates its structure as a semi-simple algebra.
The Strangeness Signal in Hadron Production at Relativistic EnergyDec 02 2003Strangeness enhancement is discussed as a feature specific to relativistic nuclear collisions which create a fireball of strongly interacting matter at high energy density. At very high energy this is suggested to be partonic matter, but at lower energy ... More
Hadron Production in Relativistic Nuclear CollisionsDec 19 2002May 14 2003Relativistic nucleus-nucleus collisions create a "fireball" of strongly interacting matter at high energy density. At very high energy this is suggested to be partonic matter, but at lower energy it should consist of yet unknown hadronic, perhaps coherent ... More
Variational description of multi-fluid hydrodynamics: Uncharged fluidsSep 06 2002Jan 09 2007We present a formalism for Newtonian multi-fluid hydrodynamics derived from an unconstrained variational principle. This approach provides a natural way of obtaining the general equations of motion for a wide range of hydrodynamic systems containing an ... More
Covariant Vortex In Superconducting-Superfluid-Normal Fluid Mixtures with Stiff Equation of StateApr 26 2000The integrals of motion for a cylindrically symmetric stationary vortex are obtained in a covariant description of a mixture of interacting superconductors, superfluids and normal fluids. The relevant integrated stress-energy coefficients for the vortex ... More
Relativistic Nucleus-Nucleus Collisions and the QCD Matter Phase DiagramJul 10 2008This review will be concerned with our knowledge of extended matter under the governance of strong interaction, in short: QCD matter. Strictly speaking, the hadrons are representing the first layer of extended QCD architecture. In fact we encounter the ... More
A norm - inequality related to affine regular hexagonsJun 30 2011Let $(E, \lVert . \rVert)$ be a two-dimensional real normed space with unit sphere $S = \{x \in E, \lVert x \rVert = 1\}$. The main result of this paper is the following: Consider an affine regular hexagon with vertex set $H = \{\pm v_1, \pm v_2, \pm ... More
An extension of the Yamada-Watanabe condition for pathwise uniqueness to stochastic differential equations with jumpsJun 09 2009Oct 12 2009We extend the Yamada-Watanabe condition for pathwise uniqueness to stochastic differential equations with jumps, in the special case where small jumps are summable.
Optimal decay rate for the wave equation on a square with constant damping on a stripJul 13 2016Mar 02 2017We consider the damped wave equation with Dirichlet boundary conditions on the unit square. We assume the damping to be a characteristic function of a strip. We prove the exact $t^{-4/3}$-decay rate for the energy of classical solutions. This answers ... More
Reduction of Coupling ParametersNov 01 1995The general theory of the reduction in the number of coupling parameters is discussed. The method involves renormalization group invariant relations between couplings. It is more general than the imposition of symmetries. There are reduced theories with ... More
On the Analytic Structure of Hadronic Amplitudes in QCDDec 21 1992Analytic properties of hadronic amplitudes are discussed within the framework of QCD as formulated on the basis of the BRST algebra. Local, composite fields are introduced for hadrons. Given confinement, it is shown that hadronic amplitudes have no thresholds ... More
Regularizing linear inverse problems with convolutional neural networksJul 06 2019Deep convolutional neural networks trained on large datsets have emerged as an intriguing alternative for compressing images and solving inverse problems such as denoising and compressive sensing. However, it has only recently been realized that even ... More
Isovariant mappings of degree 1 and the Gap HypothesisApr 03 2009Unpublished results of S Straus and W Browder state that two notions of homotopy equivalence for manifolds with smooth group actions - isovariant and equivariant - often coincide under a condition called the Gap Hypothesis; the proofs use deep results ... More
Tree setsDec 11 2015Feb 27 2017We study an abstract notion of tree structure which lies at the common core of various tree-like discrete structures commonly used in combinatorics: trees in graphs, order trees, nested subsets of a set, tree-decompositions of graphs and matroids etc. ... More
Dispersion Relations in Quantum ChromodynamicsMay 26 1992Dispersion relations for the scattering of hadrons are considered within the framework of Quantum Chromodynamics. It is argued that the original methods of proof remain applicable. The setting and the spectral conditions are provided by an appropriate ... More
Estimating the gap of finite metric spaces of strict p-negative typeApr 21 2016Let (X,d) be a finite metric space. This paper first discusses the spectrum of the p-distance matrix of a finite metric space of p-negative type and then gives upper and lower bounds for the so called gap of a finite metric space of strict p-negative ... More
Two-locus clines on the real line with a step environmentAug 11 2017The shape of allele-frequency clines maintained by migration-selection balance depends not only on the properties of migration and selection, but also on the dominance relations among alleles and on linkage to other loci under selection. We investigate ... More
A quantified Tauberian theorem and local decay of $C_0$-semigroupsMay 10 2017We prove a quantified Tauberian theorem for functions under a new kind of Tauberian condition. In this condition we assume in particular that the Laplace transform of the considered function extends to a domain to the left of the imaginary axis, given ... More
On the decay rate for the wave equation with viscoelastic boundary dampingJan 04 2017Sep 05 2017We consider the wave equation with a boundary condition of memory type. Under natural conditions on the acoustic impedance $\hat{k}$ of the boundary one can define a corresponding semigroup of contractions (Desch, Fasangova, Milota, Probst 2010). With ... More
A time inhomogeneous Cox-Ingersoll-Ross diffusion with jumpsJun 10 2009We consider a time inhomogeneous Cox-Ingersoll-Ross diffusion with positive jumps. We exploit a branching property to prove existence of a unique strong solution under a restrictive condition on the jump measure. We give Laplace transforms for the transition ... More
Distance dependence of entanglement generation via a bosonic heat bathDec 19 2008Apr 16 2009Within a generalized Caldeira-Leggett model we analyze the conditions under which a bosonic heat bath can entangle two microscopic quantum systems at a distance $r$. We find that the attainable entanglement is extremely distance-sensitive. Significant ... More
Selected Topics from Top Mass Measurements at the TevatronDec 07 2016The most recent results of the top-quark mass measurements at the Tevatron at Fermilab are presented. Data were collected in proton-antiproton collisions at sqrt{s}=1.96 TeV by the CDF and D0 experiments. Top quark mass measurements in the lepton+jets, ... More
Superconvergence, Confinement and DualityNov 02 1995Arguments for the confinement of transverse gauge field excitations, which are based upon superconvergence relations of the propagator, and upon the BRST algebra, are reviewed and applied to supersymmetric models. They are shown to be in agreement with ... More
Analytic Structure of Amplitudes in Gauge Theories with ConfinementDec 05 1994For gauge theories with confinement, the analytic structure of amplitudes is explored. It is shown that the analytic properties of physical amplitudes are the same as those obtained on the basis of an effective theory involving only the composite, physical ... More
Locally finite graphs with ends: a topological approachDec 21 2009Jul 10 2012This paper is intended as an introductory survey of a newly emerging field: a topological approach to the study of locally finite graphs that crucially incorporates their ends. Topological arcs and circles, which may pass through ends, assume the role ... More
On the gap of finite metric spaces of p-negative typeAug 05 2010Let (X,d) be a metric space of p-negative type. Recently I. Doust and A. Weston introduced a quantification of the p-negative type property, the so called gap {\Gamma} of X. This talk introduces some formulas for the gap {\Gamma} of a finite metric space ... More
Abstract Separation SystemsJun 15 2014Apr 17 2017Abstract separation systems provide a simple general framework in which both tree-shape and high cohesion of many combinatorial structures can be expressed, and their duality proved. Applications range from tangle-type duality and tree structure theorems ... More
Local decay of $C_0$-semigroups with a possible singularity of logarithmic type at zeroOct 29 2017We prove decay rates for a vector-valued function $f$ of a non-negative real variable with bounded weak derivative, under rather general conditions on the Laplace transform $\hat{f}$. This generalizes results of Batty-Duyckaerts (2008) and other authors ... More
To which extent is the membrane potential in a neuron between successive spikes adequately modelled by a (continuous) semimartingale?Aug 25 2010We consider $p$-variations in some membrane potential data --viewed as a function of the step size in case where $p$ is fixed, or viewed as a function of $p$ in case where the step size is fixed-- and compare their shape with results in Ait-Sahalia and ... More
A Survey on Migration-Selection Models in Population GeneticsSep 10 2013This survey focuses on the most important aspects of the mathematical theory of population genetic models of selection and migration between discrete niches. Such models are most appropriate if the dispersal distance is short compared to the scale at ... More
A weighted isoperimetric inequality in a wedgeOct 04 2012Let $c, k_1,..., k_N $ be non-negative numbers, and define a measure $\mu $ in the wedge $W:= \{x\in \mathbb{R} ^N :\, x_i >0, i=1,...,N\} $ by $d\mu = e^{c|x|^2} x_1 ^{k_1}...x_N ^{k_N} \, dx $. It is shown that among all measurable subsets of $W$ with ... More
Excitations in photoactive molecules from quantum Monte CarloApr 21 2004Despite significant advances in electronic structure methods for the treatment of excited states, attaining an accurate description of the photoinduced processes in photoactive biomolecules is proving very difficult. For the prototypical photosensitive ... More
Asymptotically anti-de Sitter space-times: symmetries and conservation laws revisitedJun 25 2003In this short note, we verify explicitly in static coordinates that the non trivial asymptotic Killing vectors at spatial infinity for anti-de Sitter space-times correspond one to one to the conformal Killing vectors of the conformally flat metric induced ... More
Global Symmetries in the Antifield-FormalismJun 26 1996In this paper, two things are done. (i) First, it is shown that any global symmetry of a gauge-invariant theory can be extended to the ghosts and the antifields so as to leave invariant the solution of the master-equation (before gauge fixing). (ii) Second, ... More
BRST-Antibracket Cohomology in 2D Conformal GravityJul 12 1994We present results of a computation of the BRST-antibracket cohomology in the space of local functionals of the fields and antifields for a class of 2d gravitational theories which are conformally invariant at the classical level. In particular all classical ... More
Sauter-Schwinger like tunneling in tilted Bose-Hubbard lattices in the Mott phaseJul 19 2011We study the Mott phase of the Bose-Hubbard model on a tilted lattice. On the (Gutzwiller) mean-field level, the tilt has no effect -- but quantum fluctuations entail particle-hole pair creation via tunneling. For small potential gradients (long-wavelength ... More
Pre-earthquake Magnetic PulsesMay 18 2014A semiconductor model of rocks is shown to describe unipolar magnetic pulses, a phenomenon that has been observed prior to earthquakes. These pulses are observable because their extremely long wavelength allows them to pass through the Earth's crust. ... More
Superstring BRST CohomologyApr 11 2001Jul 12 2001We first derive all world-sheet action functionals for NSR superstring models with (1,1) supersymmetry and any number of abelian gauge fields, for gauge transformations of the standard form. Then we prove for these models that the BRST cohomology groups ... More
A Numerical Study of Newton Interpolation with Extremely High DegreesSep 28 2016In current textbooks the use of Chebyshev nodes with Newton interpolation is advocated as the most efficient numerical interpolation method in terms of approximation accuracy and computational effort. However, we show numerically that the approximation ... More
A Distributed Magnetometer NetworkSep 19 2014Sep 30 2014Various possiblities for a distributed magnetometer network are considered. We discuss strategies such as croudsourcing smartphone magnetometer data, the use of trees as magnetometers, and performing interferometry using magnetometer arrays to synthesize ... More
Surrogate Gradient Learning in Spiking Neural NetworksJan 28 2019A growing number of neuromorphic spiking neural network processors that emulate biological neural networks create an imminent need for methods and tools to enable them to solve real-world signal processing problems. Like conventional neural networks, ... More
Nano-engineered Diamond Waveguide as a Robust Bright Platform for Nanomagnetometry Using Shallow Nitrogen Vacancy CentersAug 29 2014Dec 16 2014Photonic structures in diamond are key to most of its application in quantum technology. Here, we demonstrate tapered nano-waveguides structured directly onto the diamond substrate hosting shallow-implanted nitrogen vacancy (NV) centers. By optimization ... More
Entanglement of remote quantum systems by environmental modesNov 23 2011Nov 25 2011We investigate the generation of quantum mechanical entanglement of two remote oscillators that are locally coupled to a common bosonic bath. Starting with a Lagrangian formulation of a suitable model, we derive two coupled Quantum Langevin Equations ... More
Extended antifield-formalismMay 02 1997Oct 10 1997The antifield formalism is extended so as to incorporate the rigid symmetries of a given theory. To that end, it is necessary to introduce global ghosts not only for the given rigid symmetries, but also for all the higher order conservation laws, associated ... More
Weighted isoperimetric inequalities in cones and applicationsJul 27 2011May 17 2012This paper deals with weighted isoperimetric inequalities relative to cones of $\mathbb{R}^{N}$. We study the structure of measures that admit as isoperimetric sets the intersection of a cone with balls centered at the vertex of the cone. For instance, ... More
Surrogate Gradient Learning in Spiking Neural NetworksJan 28 2019May 03 2019Spiking neural networks are nature's versatile solution to fault-tolerant and energy efficient signal processing. To translate these benefits into hardware, a growing number of neuromorphic spiking neural network processors attempt to emulate biological ... More
Relaxometry and dephasing imaging of superparamagnetic magnetite nanoparticles using a single qubitMay 11 2015Oct 26 2015To study the magnetic dynamics of superparamagnetic nanoparticles we use scanning probe relaxometry and dephasing of the nitrogen-vacancy (NV) center in diamond, characterizing the spin-noise of a single 10-nm magnetite particle. Additionally, we show ... More
Correlations in the Bose & Fermi Hubbard ModelMar 09 2012Aug 01 2012We study the Bose-Hubbard and Fermi-Hubbard model in the limit of large coordination numbers Z (i.e., many tunnelling partners). Via a controlled expansion into powers of 1/Z, we establish a hierarchy of correlations, which facilitates an approximate ... More
Electrical resistivity ofYb(Rh1-xCox)2Si2 single crystals at low temperaturesJun 16 2009We report low-temperature measurements of the electrical resistivity of Yb(Rh1-xCox)2Si2 single crystals with 0 <= x <= 0.12. The isoelectronic substitution of Co on the Rh site leads to a decrease of the unit cell volume which stabilizes the antiferromagnetism. ... More
Deformed supergravity with local R-symmetryApr 07 1997Using deformation theory based on BRST cohomology, a supergravity model is constructed which interpolates through a continuous deformation parameter between new minimal supergravity with an extra U(1) gauge multiplet and standard supergravity with local ... More
Gauge theories of spacetime symmetriesMay 02 2001Sep 13 2001Gauge theories of conformal spacetime symmetries are presented which merge features of Yang-Mills theory and general relativity in a new way. The models are local but nonpolynomial in the gauge fields, with a nonpolynomial structure that can be elegantly ... More
An overview of new supersymmetric gauge theories with 2-form gauge potentialsOct 18 2000Nov 13 2000An overview of new 4d supersymmetric gauge theories with 2-form gauge potentials constructed by various authors during the past five years is given. The key role of three particular types of interaction vertices is emphasized. These vertices are used ... More
Jet coordinates for local BRST cohomologyMar 06 2001May 02 2001The construction of appropriate jet space coordinates for calculating local BRST cohomology groups is discussed. The relation to tensor calculus is briefly reviewed too.
Measurement of the Sigma pi photoproduction line shapes near the Lambda(1405)Jan 21 2013Jan 24 2013The reaction gamma + p -> K+ + Sigma + pi was used to determine the invariant mass distributions or "line shapes" of the Sigma+ pi-, Sigma- pi+ and Sigma0 pi0 final states, from threshold at 1328 MeV/c^2 through the mass range of the Lambda(1405) and ... More