Results for "J. Seidel"

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The historical Moran modelNov 18 2015We consider a multi-type Moran model (in continuous time) with selection and type-dependent mutation. This paper is concerned with the evolution of genealogical information forward in time. For this purpose we define and analytically characterize a path-valued ... More
Dwell-time distributions in quantum mechanicsJan 10 2009Some fundamental and formal aspects of the quantum dwell time are reviewed, examples for free motion and scattering off a potential barrier are provided, as well as extensions of the concept. We also examine the connection between the dwell time of a ... More
An open string analogue of Viterbo functorialityDec 19 2007Aug 25 2009Liouville domains are a special type of symplectic manifolds with boundary (they have an everywhere defined Liouville flow, pointing outwards along the boundary). Symplectic cohomology for Liouville domains was introduced by Cieliebak-Floer-Hofer-Wysocki ... More
Adsorption induced pyramidal distortion of the tri-metallic nitride core inside the endohedral fullerene Sc$_3$N@C$_{80}$ on the Ag(111) surfaceMar 13 2019Our ability to understand and tailor metal-organic interfaces is mandatory to functionalize organic complexes for next generation electronic and spintronic devices. For magnetic data storage applications, metal-carrying organic molecules, so called single ... More
Ramsey interferometry with ultracold atomsFeb 02 2006We examine the passage of ultracold two-level atoms through two separated laser fields for the nonresonant case. We show that implications of the atomic quantized motion change dramatically the behavior of the interference fringes compared to the semiclassical ... More
Microlensing Neutron StarsApr 03 2002Apr 25 2002We investigate the chances that neutron stars act as the lense in a gravitational microlensing event towards the galactic bulge or a spiral arm. The observation of neutron stars by means of gravitational microlensing would allow the estimation of neutron ... More
Quivers, Floer cohomology, and braid group actionsJun 07 2000Jun 13 2001We consider the derived categories of modules over a certain family A_m of graded rings, and Floer cohomology of Lagrangian intersections in the symplectic manifolds which are the Milnor fibres of simple singularities of type A_m. We show that each of ... More
Ramsey interferometry with oppositely detuned fieldsJun 08 2006We report a narrowing of the interference pattern obtained in an atomic Ramsey interferometer if the two separated fields have different frequency and their phase difference is controlled. The width of the Ramsey fringes depends inversely on the free ... More
Relation between quantum dwell times and flux-flux correlationsNov 05 2008We examine the connection between the dwell time of a quantum particle in a region of space and flux-flux correlations at the boundaries. It is shown that the first and second moments of a flux-flux correlation function which generalizes a previous proposal ... More
Exact Lagrangian submanifolds in simply-connected cotangent bundlesJan 26 2007Sep 13 2007We consider exact Lagrangian submanifolds in cotangent bundles. Under certain additional restrictions (triviality of the fundamental group of the cotangent bundle, and of the Maslov class and second Stiefel-Whitney class of the Lagrangian submanifold) ... More
Periodic switching strategies for an isoperimetric control problem with application to nonlinear chemical reactionsNov 18 2018This paper deals with an isoperimetric optimal control problem for nonlinear control-affine systems with periodic boundary conditions. As it was shown previously, the candidates for optimal controls for this problem can be obtained within the class of ... More
Clocking the assembly of double-barred galaxies with the MUSE TIMER projectJan 18 2019The formation of two stellar bars within a galaxy has proved challenging for numerical studies. It is yet not clear whether the inner bar is born via a star formation process promoted by gas inflow along the outer bar, or whether it is dynamically assembled ... More
The Jain-2/5 parent Hamiltonian: structure of zero modes, dominance patterns, and zero mode generatorsFeb 02 2017We analyze general zero mode properties of the parent Hamiltonian of the unprojected Jain-2/5 state. We characterize the zero mode condition associated to this Hamiltonian via projection onto a four-dimensional two-particle subspace for given pair angular ... More
Completely automated computation of the heavy-fermion corrections to the three-loop matching coefficient of the vector currentApr 06 2009We evaluate the corrections to the matching coefficient of the vector current between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) to three-loop order containing a closed heavy-fermion loop. The result constitutes a building block both ... More
Scattering of two-level atoms by delta lasers: Exactly solvable models in atom opticsJul 18 2006We study the scattering of two-level atoms at narrow laser fields, modeled by a $\delta$-shape intensity profile. The unique properties of these potentials allow us to give simple analytic solutions for one or two field zones. Several applications are ... More
Quantum motion effects in an ultracold-atom Mach-Zehnder interferometerApr 30 2008We study the effect of quantum motion in a Mach-Zehnder interferometer where ultracold, two-level atoms cross a $\pi/2 $-$\pi $-$\pi/2$ configuration of separated, laser illuminated regions. Explicit and exact expressions are obtained for transmission ... More
Operator normalized quantum arrival times in the presence of interactionsNov 17 2003We model ideal arrival-time measurements for free quantum particles and for particles subject to an external interaction by means of a narrow and weak absorbing potential. This approach is related to the operational approach of measuring the first photon ... More
Quantum kinetic energy densities: An operational approachFeb 14 2005We propose and investigate a procedure to measure, at least in principle, a positive quantum version of the local kinetic energy density. This procedure is based, under certain idealized limits, on the detection rate of photons emitted by moving atoms ... More
Quantum arrival times and operator normalizationAug 15 2003Nov 17 2003A recent approach to arrival times used the fluorescence of an atom entering a laser illuminated region and the resulting arrival-time distribution was close to the axiomatic distribution of Kijowski, but not exactly equal, neither in limiting cases nor ... More
Fermionic Corrections to the Three-Loop Matching Coefficient of the Vector CurrentJul 14 2006In this paper we consider the matching coefficient of the vector current between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) to three-loop order in perturbation theory. We evaluate the fermionic corrections containing a closed massless ... More
Two-phonon coupling to the antiferromagnetic phase transition in multiferroic BiFeO3Dec 03 2007A prominent band centered at around 1000-1300 cm-1 and associated with resonant enhancement of two-phonon Raman scattering is reported in multiferroic BiFeO3 thin films and single crystals. A strong anomaly in this band occurs at the antiferromagnetic ... More
Linear independence of nearest neighbor valence bond states on the kagome lattice and construction of SU(2)-invariant spin-1/2-Hamiltonian with a Sutherland-Rokhsar-Kivelson quantum liquid ground stateJun 02 2009Nov 07 2009A class of local SU(2)-invariant spin-1/2 Hamiltonians is studied that has ground states within the space of nearest neighbor valence bond states on the kagome lattice. Cases include "generalized Klein'' models without obvious non-valence bond ground ... More
Braids and symplectic four-manifolds with abelian fundamental groupFeb 14 2002We explain how a version of Floer homology can be used as an invariant of symplectic manifolds with $b_1>0$. As a concrete example, we look at four-manifolds produced from braids by a surgery construction. The outcome shows that the invariant is nontrivial; ... More
Symplectic Floer homology and the mapping class groupOct 30 2000Mar 04 2001We consider symplectic Floer homology in the lowest nontrivial dimension, that is to say, for area-preserving diffeomorphisms of surfaces. Particular attention is paid to the quantum cap product; we show that it distinguishes the trivial element of the ... More
More about vanishing cycles and mutationOct 03 2000The paper continues the discussion of symplectic aspects of Picard-Lefschetz theory begun in "Vanishing cycles and mutation" (this archive). There we explained how to associate to a suitable fibration over a two-dimensional disc a triangulated category, ... More
Some speculations on pairs-of-pants decompositions and Fukaya categoriesApr 06 2010Dec 07 2011These are notes from a 2010 talk. They concern possible ways in which Fukaya categories might be considered as "local", which means glued together from simpler pieces in a loosely sheaf-theoretic sense. As the title suggests, this is purely speculative. ... More
Vanishing cycles and mutationJul 19 2000Oct 02 2000This is the writeup of a talk given at the European Congress of Mathematics, Barcelona. It considers Picard-Lefschetz theory from the Floer cohomology viewpoint.
$π_1$ of symplectic automorphism groups and invertibles in quantum homology ringsNov 23 1995May 04 1997We define a homomorphism from (a certain extension of) the fundamental group of the Hamiltonian automorphism group of a symplectic manifold to the group of invertibles in its quantum cohomology ring. The manifold must satify a technical condition similar ... More
On Semi-Fredholm Band-Dominated OperatorsJul 30 2014In this paper we study the semi-Fredholm property of band-dominated operators $A$ and prove that it already implies the Fredholmness of $A$ in all cases where this is not disqualified by obvious reasons. Moreover, this observation is applied to show that ... More
Threshold corrections to the gamma t anti-t vertex at O(alpha alpha(s))Feb 18 2009In these proceedings a recent calculation of the last missing piece of the two-loop O(alpha alpha(s)) corrections to gamma t anti-t vertex at the t anti-t threshold due to the exchange of a W boson and a gluon is summarised. The calculation constitutes ... More
S-duality constraints on 1D patterns associated with fractional quantum Hall statesFeb 12 2010Using the modular invariance of the torus, constraints on the 1D patterns are derived that are associated with various fractional quantum Hall ground states, e.g. through the thin torus limit. In the simplest case, these constraints enforce the well known ... More
Exotic iterated Dehn twistsMay 20 2013Apr 14 2014Consider cotangent bundles of exotic spheres, with their canonical symplectic structure. They admit automorphisms which preserve the part at infinity of one fibre, and which are analogous to the square of a Dehn twist. Pursuing that analogy, we show that ... More
Suspending Lefschetz fibrations, with an application to Local Mirror SymmetryJul 12 2009Aug 05 2009We consider the suspension operation on Lefschetz fibrations, which takes p(x) to p(x)-y^2. This leaves the Fukaya category of the fibration invariant, and changes the category of the fibre (or more precisely, the subcategory consisting of a basis of ... More
A long exact sequence for symplectic Floer cohomologyMay 23 2001Jul 20 2002The long exact sequence describes how the Floer cohomology of two Lagrangian submanifolds changes if one of them is modified by applying a Dehn twist. We give a proof in the simplest case (no bubbling). The paper contains a certain amount of material ... More
Fukaya A_\infty structures associated to Lefschetz fibrations. IDec 19 2009Feb 06 2016This (partially expository) paper discusses Lagrangian Floer cohomology in the context of Lefschetz fibrations, with emphasis on the algebraic structures encountered there. In addition to the well-known directed A_infinity algebras which appear in this ... More
A_\infty-subalgebras and natural transformationsJan 26 2007Apr 24 2008The paper explores some algebraic constructions arising in the theory of Lefschetz fibrations. Specifically, it covers in a fair amount of detail the algebraic issues outlined in ``Symplectic homology as Hochschild homology'' (math.SG/0609037). We also ... More
Fukaya A_\infty-structures associated to Lefschetz fibrations. IIIAug 13 2016Floer cohomology groups are usually defined over a field of formal functions (a Novikov field). Under certain assumptions, one can equip them with connections, which means operations of differentiation with respect to the Novikov variable. This allows ... More
The equivariant pair-of-pants product in fixed point Floer cohomologyNov 10 2014May 31 2015The Floer cohomology of a symplectic automorphism and that of its square are related by the pair-of-pants product. For exact symplectic automorphisms, we introduce an equivariant version of that product, and use it to prove a Smith-type inequality of ... More
Lagrangian homology spheres in (A_m) Milnor fibres via C^*-equivariant A_infinity modulesFeb 09 2012Aug 08 2012We establish restrictions on Lagrangian embeddings of rational homology spheres into certain open symplectic manifolds, namely the (A_m) Milnor fibres of odd complex dimension. This relies on general considerations about equivariant objects in module ... More
Exact Lagrangian submanifolds of $T^*S^n$ and the graded Kronecker quiverJan 17 2004This short and fairly informal note is an attempt to explain how methods of homological algebra may be brought to bear on problems in symplectic geometry. We do this by looking at a familiar sample question, which is that of the topology of Lagrangian ... More
Homological mirror symmetry for the quartic surfaceOct 26 2003Aug 06 2013This proves Kontsevich's mirror conjecture for (on the symplectic side) a quartic surface in P^3.
Graded Lagrangian submanifoldsMar 09 1999May 31 2000In the usual setup, the grading on Floer homology is relative: it is unique only up to adding a constant. "Graded Lagrangian submanifolds" are Lagrangian submanifolds with a bit of extra structure, which fixes the ambiguity in the grading. The idea is ... More
Disjoinable Lagrangian spheres and dilationsJul 18 2013Oct 20 2013We consider open symplectic manifolds which admit dilations (in the sense previously introduced by Solomon and the author). We obtain restrictions on collections of Lagrangian submanifolds which are pairwise disjoint (or pairwise disjoinable by Hamiltonian ... More
Analytic two-loop virtual corrections to $b --> d l^+ l^-$Mar 16 2004Jul 16 2004We compute the two-loop virtual corrections to the flavour changing neutral current process $b --> d l^+ l^-$. As calculation techniques integration by parts identities and the method of differential equations are used. The result is presented in closed ... More
Numerical Relativity: Towards Simulations of 3D Black Hole CoalescenceJun 23 1998I review recent developments in numerical relativity, focussing on progress made in 3D black hole evolution. Progress in development of black hole initial data, apparent horizon boundary conditions, adaptive mesh refinement, and characteristic evolution ... More
Fredholm theory for band-dominated and related operators: a surveyJul 05 2013This paper presents the Fredholm theory on l^p-spaces for band-dominated operators and important subclasses, such as operators in the Wiener algebra. It particularly closes several gaps in the previously known results for the case p=\infty and addresses ... More
Beam Dynamics in High Intensity Cyclotrons Including Neighboring Bunch Effects: Model, Implementation and ApplicationMar 01 2010Space charge effects, being one of the most significant collective effects, play an important role in high intensity cyclotrons. However, for cyclotrons with small turn separation, other existing effects are of equal importance. Interactions of radially ... More
Homological mirror symmetry for the genus two curveDec 05 2008Aug 21 2011Katzarkov has proposed a generalization of Kontsevich's mirror symmetry conjecture, covering some varieties of general type. We prove a version of this conjecture in the simplest example, relating the Fukaya category of a genus two curve to the category ... More
Fukaya categories and deformationsJun 15 2002This is an informal (and mostly conjectural) discussion of some aspects of Fukaya categories. We start by looking at exact symplectic manifolds which are obtained from a closed Calabi-Yau by removing a hyperplane section. We look at the possible geometric ... More
On the group of symplectic automorphisms of $\C P^m \times \C P^n$Mar 19 1998Let M be the product of \C P^m and \C P^n, with the standard integral symplectic form. We prove that the inclusion map from the group of symplectic automorphisms of M to its diffeomorphism group is not surjective on homotopy groups. More precisely, it ... More
Picard-Lefschetz theory and dilating C^*-actionsMar 29 2014Sep 10 2015We consider C^*-actions on Fukaya categories of exact symplectic manifolds. Such actions can be constructed by dimensional induction, going from the fibre of a Lefschetz fibration to its total space. We explore applications to the topology of Lagrangian ... More
Abstract analogues of flux as symplectic invariantsAug 01 2011Jan 10 2014We study families of objects in Fukaya categories, specifically ones whose deformation behaviour is prescribed by the choice of an odd degree cohomology class. This leads to invariants of symplectic manifolds, which we apply to blowups along symplectic ... More
Symplectic homology as Hochschild homologySep 01 2006Apr 09 2008These are (heavily revised) notes from lectures given at the AMS Algebraic Geometry meeting in Seattle, 2005. The main topic is symplectic homology seen from the point of view of Lefschetz fibrations. Most of the content is speculative, but some supporting ... More
Symplectic automorphisms of T^*S^2Mar 19 1998Let M be the cotangent bundle of S^2, with the standard symplectic structure. By adapting an argument of Gromov we determine the weak homotopy type of the group S of those symplectic automorphisms of M which are trivial at infinity. It turns out that ... More
Lagrangian two-spheres can be symplectically knottedMar 19 1998May 31 2000This paper shows that there are symplectic four-manifolds M with the following property: a single isotopy class of smooth embedded two-spheres in M contains infinitely many Lagrangian submanifolds, no two of which are isotopic as Lagrangian submanifolds. ... More
Pfaffian statistics through adiabatic transport in the 1D coherent state representationApr 29 2008Dec 20 2008Recent work has shown that the low energy sector of certain quantum Hall states is adiabatically connected to simple charge-density-wave patterns that appear, e.g., when the system is deformed into a thin torus. Here it is shown that the patterns emerging ... More
Composite fermions in Fock space: Operator algebra, recursion relations, and order parametersDec 20 2018Jan 15 2019We develop recursion relations, in particle number, for all (unprojected) Jain composite fermion (CF) wave functions. These recursions generalize a similar recursion originally written down by Read for Laughlin states, in mixed first-second quantized ... More
Numerical evolution of matter in dynamical axisymmetric black hole spacetimes. I. Methods and testsJul 09 1998We have developed a numerical code to study the evolution of self-gravitating matter in dynamic black hole axisymmetric spacetimes in general relativity. The matter fields are evolved with a high-resolution shock-capturing scheme that uses the characteristic ... More
The Synergy between Numerical and Perturbative Approaches to Black HolesJun 23 1998I describe approaches to the study of black hole spacetimes via numerical relativity. After a brief review of the basic formalisms and techniques used in numerical black hole simulations, I discuss a series of calculations from axisymmetry to full 3D ... More
AHCAL Energy ResolutionJun 18 2010The CALICE collaboration has constructed highly granular hadronic and electromagnetic calorimeter prototypes to evaluate technologies for the use in detector systems at a future Linear Collider. The hadron calorimeter uses 7608 small scintillator cells ... More
Fukaya A_\infty-structures associated to Lefschetz fibrations. II 1/2Apr 23 2015Nov 11 2015We consider a version of the relative Fukaya category for anticanonical Lefschetz pencils. There are direct connections between the behaviour of this category and enumerative geometry: some of these are results announced here, others remain conjectural. ... More
Fukaya A_\infty structures associated to Lefschetz fibrations. IIApr 04 2014Jul 21 2015We consider the Fukaya category associated to a basis of vanishing cycles in a Lefschetz fibration. We show that each element of the Floer cohomology of the monodromy around infinity gives rise to a natural transformation from the Serre functor to the ... More
Simple examples of distinct Liouville-type symplectic structuresNov 05 2010Dec 13 2010We discuss some examples of open manifolds which admit non-isomorphic symplectic structures of Liouville type.
A biased view of symplectic cohomologyApr 16 2007Feb 15 2010These are lecture notes from my talks at the "Current Developments in Mathematics" conference (Harvard, 2006). They cover a variety of topics involving symplectic cohomology. In particular, a discussion of (algorithmic) classification issues in symplectic ... More
Lectures on four-dimensional Dehn twistsSep 01 2003Aug 09 2006These are notes from the 2003 C.I.M.E. summer school "symplectic 4-manifolds and algebraic surfaces". They cover the same material as the author's (by now ancient) Ph.D. thesis.
Cyclotrons for high-intensity beamsFeb 05 2013This paper reviews the important physical and technological aspects of cyclotrons for the acceleration of high-intensity beams. Special emphasis is given to the discussion of beam loss mechanisms and extraction schemes.
Orthogonal Matching Pursuit with Tikhonov and Landweber RegularizationFeb 20 2019The Orthogonal Matching Pursuit (OMP) for compressed sensing iterates over a scheme of support augmentation and signal estimation. We present two novel matching pursuit algorithms with intrinsic regularization of the signal estimation step that do not ... More
Can everything be computed? - On the Solvability Complexity Index and Towers of AlgorithmsAug 13 2015This paper establishes some of the fundamental barriers in the theory of computations and finally settles the long standing computational spectral problem. Due to these barriers, there are problems at the heart of computational theory that do not fit ... More
The largest M dwarfs flares from ASAS-SNSep 12 2018The All-Sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light every $\sim$day, reaching a depth of $g\sim18$ mag. Over the course of its first four years of transient alerts (2013-2016), ... More
Towards Quantitative Simulations of High Power Proton CyclotronsDec 03 2010Dec 21 2010PSI operates a cyclotron based high intensity proton accelerator routinely at an average beam power of 1.3MW. With this power the facility is at the worldwide forefront of high intensity proton accelerators. The beam current is practically limited by ... More
Finding Apparent Horizons in Dynamic 3D Numerical SpacetimesSep 25 1996May 20 1998We have developed a general method for finding apparent horizons in 3D numerical relativity. Instead of solving for the partial differential equation describing the location of the apparent horizons, we expand the closed 2D surfaces in terms of symmetric ... More
Test-beds and applications for apparent horizon finders in numerical relativitySep 01 1998We present a series of test beds for numerical codes designed to find apparent horizons. We consider three apparent horizon finders that use different numerical methods: one of them in axisymmetry, and two fully three-dimensional. We concentrate first ... More
Large energy acceptance gantry for proton therapy utilizing superconducting technologyJan 07 2019When using superconducting (SC) magnets in a gantry for proton therapy, the gantry will benefit from some reduction in size and a large reduction in weight. In this contribution we show an important additional advantage of SC magnets in proton therapy ... More
Symmetry without Symmetry: Numerical Simulation of Axisymmetric Systems using Cartesian GridsAug 04 1999We present a new technique for the numerical simulation of axisymmetric systems. This technique avoids the coordinate singularities which often arise when cylindrical or polar-spherical coordinate finite difference grids are used, particularly in simulating ... More
Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) - II. A broadened sodium feature on the ultra-hot giant WASP-76bJan 30 2019High-resolution optical spectroscopy is a powerful tool to characterise exoplanetary atmospheres from the ground. The sodium D lines, with their large cross sections, are especially suited to study the upper layers of atmospheres in this context. We report ... More
Potential for Precision Measurement of Solar Neutrino Luminosity by HERONNov 26 2007Results are presented for a simulation carried out to test the precision with which a detector design (HERON) based on a superfluid helium target material should be able to measure the solar pp and Be7 fluxes. It is found that precisions of +/- 1.68% ... More
Matching QCD and HQET heavy-light currents at three loopsNov 17 2009Mar 07 2010We consider the currents formed by a heavy and a light quark within Quantum Chromodynamics and compute the matching to Heavy Quark Effective Theory to three-loop accuracy. As an application we obtain the third-order perturbative corrections to ratios ... More
Interpretation of Light-Quenching Factor MeasurementsJul 05 2007We observe that the pattern of the quenching factors for scintillation light from various ions, recently studied in $CaWO_4$ in connection with dark matter detectors, can be understood as a saturation phenomenon in which the light output is simply proportional ... More
The timing precision of transit light-curvesJun 06 2012Reliable estimations of ephemeris errors are fundamental for the follow-up of CoRoT candidates. An equation for the precision of minimum times, originally developed for eclipsing binaries, has been optimized for CoRoT photometry and been used to calculate ... More
Nonlinear and Perturbative Evolution of Distorted Black Holes. II. Odd-parity ModesNov 05 1999We compare the fully nonlinear and perturbative evolution of nonrotating black holes with odd-parity distortions utilizing the perturbative results to interpret the nonlinear results. This introduction of the second polarization (odd-parity) mode of the ... More
Three-dimensional relativistic simulations of rotating neutron-star collapse to a Kerr black holeMar 06 2004Jan 30 2005We present a new three-dimensional fully general-relativistic hydrodynamics code using high-resolution shock-capturing techniques and a conformal traceless formulation of the Einstein equations. Besides presenting a thorough set of tests which the code ... More
The BaLROG project - I. Quantifying the influence of bars on the kinematics of nearby galaxiesApr 29 2015We present the BaLROG (Bars in Low Redshift Optical Galaxies) sample of 16 morphologically distinct barred spirals to characterise observationally the influence of bars on nearby galaxies. Each galaxy is a mosaic of several pointings observed with the ... More
A minimal model of quantized conductance in interacting ballistic quantum wiresMay 23 2010Jul 14 2010We review what we consider to be the minimal model of quantized conductance in a finite interacting quantum wire. Our approach utilizes the simplicity of the equation of motion description to both deal with general spatially dependent interactions and ... More
Arcfinder: An algorithm for the automatic detection of gravitational arcsJul 24 2006Jul 25 2006We present an efficient algorithm designed for and capable of detecting elongated, thin features such as lines and curves in astronomical images, and its application to the automatic detection of gravitational arcs. The algorithm is sufficiently robust ... More
A better upper bound on the number of triangulations of a planar point setApr 03 2002Apr 18 2002We show that a point set of cardinality $n$ in the plane cannot be the vertex set of more than $59^n O(n^{-6})$ straight-edge triangulations of its convex hull. This improves the previous upper bound of $276.75^n$.
Entanglement studies of resonating valence bonds on the frustrated square latticeNov 29 2017We study a short-range resonating valence bond (RVB) wave function with diagonal links on the square lattice that permits sign-problem free wave function Monte-Carlo studies. Special attention is given to entanglement properties, in particular, the study ... More
Altering symplectic manifolds by homologous recombinationJul 19 2010Aug 03 2010We use symplectic cohomology to study the non-uniqueness of symplectic structures on the smooth manifolds underlying affine varieties. Starting with a Lefschetz fibration on such a variety and a finite set of primes, the main new tool is a method, which ... More
Thin torus perturbative analysis of elementary excitations in the Gaffnian and Haldane-Rezayi quantum Hall statesJun 25 2014Sep 30 2014We present a systematic perturbative approach to study excitations in the thin cylinder/torus limit of the quantum Hall states. The approach is applied to the Haldane-Rezayi and Gaffnian quantum Hall states, which are both expected to have gapless excitations ... More
Lefschetz fibrations and exotic symplectic structures on cotangent bundles of spheres; includes CorrigendumJun 11 2009Apr 06 2015We construct open symplectic manifolds which are convex at infinity ("Liouville manifolds") and which are diffeomorphic, but not symplectically isomorphic, to cotangent bundles T^*S^{n+1}, for any n+1 \geq 3. These manifolds are constructed as total spaces ... More
Halperin (m, m',n) bilayer quantum Hall states on thin cylindersJan 15 2008Sep 06 2008The Halperin $(m,m',n)$ bilayer quantum Hall states are studied on thin cylinders. In this limit, charge density wave patterns emerge that are characteristic of the underlying quantum Hall state. The general patterns are worked out from a variant of the ... More
Quantum annealing with anneal path control: application to 2-SAT problems with known energy landscapesSep 29 2018Oct 04 2018We study the effect of the anneal path control per qubit, a new user control feature offered on the D-Wave 2000Q quantum annealer, on the performance of quantum annealing for solving optimization problems by numerically solving the time-dependent Schr\"odinger ... More
Entangled Pauli Principles: the DNA of Quantum Hall FluidsMar 02 2018Mar 19 2018A formalism is developed for the rigorous study of solvable fractional quantum Hall parent Hamiltonians with Landau level mixing. The idea of organization through "generalized Pauli principles" is expanded to allow for root level entanglement, giving ... More
An Investigation into the Radiation Damage of the Silicon Detectors of the H1-PLUG Calorimeter within the HERA environmentJul 24 1995Jul 25 1995The silicon detectors used in the H1-PLUG calorimeter have shown increasing aging effects during the '94 run period of the electron proton storage ring HERA. These effects were particularly manifest as degradation of the signal to noise level and the ... More
Improvements for FreeJul 06 2011"Theorems for Free!" (Wadler, FPCA 1989) is a slogan for a technique that allows to derive statements about functions just from their types. So far, the statements considered have always had a purely extensional flavor: statements relating the value semantics ... More
Abelian and non-Abelian statistics in the coherent state representationAug 12 2011Dec 20 2011We further develop an approach to identify the braiding statistics associated to a given fractional quantum Hall state through adiabatic transport of quasiparticles. This approach is based on the notion of adiabatic continuity between quantum Hall states ... More
Correlation functions in SU(2)-invariant RVB spin liquids on nonbipartite latticesMar 29 2012Oct 05 2012We introduce a Monte Carlo scheme based on sampling of Pfaffians to investigate Anderson's resonating-valence-bond (RVB) spin liquid wave function on the kagome and the triangular lattice. This eliminates a sign problem that prevents utilization of the ... More
Momentum resolved tunneling into the Pfaffian and anti-Pfaffian edgesAug 13 2009Sep 14 2010We calculate the electron spectral functions at the edges of the Moore-Read Pfaffian and anti-Pfaffian fractional quantum Hall states, in the clean limit. We show that their qualitative differences can be probed using momentum resolved tunneling, thus ... More
The symplectic topology of Ramanujam's surfaceNov 26 2004Jun 28 2005Ramanujam's surface M is a contractible affine algebraic surface which is not homeomorphic to the affine plane. For any m>1 the product M^m is diffeomorphic to Euclidean space R^{4m}. We show that, for every m>0, M^m cannot be symplectically embedded ... More
Localization for involutions in Floer cohomologyFeb 12 2010Aug 21 2010We consider Lagrangian Floer cohomology for a pair of Lagrangian submanifolds in a symplectic manifold M. Suppose that M carries a symplectic involution, which preserves both submanifolds. Under various topological hypotheses, we prove a localization ... More
Dark Current Measurements on a Superconducting Cavity using a Cryogenic Current ComparatorJul 29 2010This paper presents non-destructive dark current measurements of superconducting TESLA cavities for superconducting LINACs. The measurements were carried out in a highly disturbed accelerator environment using a low temperature superconducting d.c. SQUID ... More