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Strong Anderson localization in cold atom quantum quenchesNov 10 2013Mar 31 2014Signatures of strong Anderson localization in the momentum distribution of a cold atom cloud after a quantum quench are studied. We consider a quasi one-dimensional cloud initially prepared in a well defined momentum state, and expanding for some time ... More

Spin effects in strong-field laser-electron interactionsAug 01 2013Aug 02 2013The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field ... More

GEM Module Design for the ILD TPCSep 05 2013Oct 02 2013A Time Projection Chamber (TPC) using micro-pattern gas detectors is planned as the main tracking device for a detector at the next Linear Collider. A novel support structure for Gas Electron Multipliers (GEMs), which minimizes the material and improves ... More

High-resolution ac-calorimetry studies of the quasi-2D organic superconductor $κ$-(BEDT-TTF)$_2$Cu(NCS)$_2$Sep 03 2001We report high-resolution specific heat measurements on the quasi-2D organic superconductor $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$, performed by using a most sensitive ac-modulation technique. The main observations are (i) a discontinuity at \tc\ much in ... More

Laser-induced nonresonant nuclear excitation in muonic atomsDec 13 2008Coherent nuclear excitation in strongly laser-driven muonic atoms is calculated. The nuclear transition is caused by the time-dependent Coulomb field of the oscillating charge density of the bound muon. A closed-form analytical expression for electric ... More

Quantum-chemical insights from interpretable atomistic neural networksJun 27 2018With the rise of deep neural networks for quantum chemistry applications, there is a pressing need for architectures that, beyond delivering accurate predictions of chemical properties, are readily interpretable by researchers. Here, we describe interpretation ... More

Electron-magnon scattering in elementary ferromagnets from first principles: lifetime broadening and kinksSep 07 2018We study the electron-magnon scattering in bulk Fe, Co, and Ni within the framework of many-body perturbation theory implemented in the full-potential linearized augmented-plane-wave method. To this end, a k-dependent self-energy describing the scattering ... More

Learning representations of molecules and materials with atomistic neural networksDec 11 2018Deep Learning has been shown to learn efficient representations for structured data such as image, text or audio. In this chapter, we present neural network architectures that are able to learn efficient representations of molecules and materials. In ... More

A two-frequency acousto-optic modulator driver to improve the beam pointing stability during intensity rampsJan 16 2007We report on a scheme to improve the pointing stability of the first order beam diffracted by an acousto-optic modulator (AOM). Due to thermal effects inside the crystal, the angular position of the beam can change by as much as 1 mrad when the radio-frequency ... More

Room temperature Rydberg Single Photon SourceDec 12 2012We present an optimal protocol to implement a room temperature Rydberg single photon source within an experimental setup based on micro cells filled with thermal vapor. The optimization of a pulsed four wave mixing scheme allows to double the effective ... More

Correlations between resonances in a statistical scattering modelFeb 28 1997The distortion of the regular motion in a quantum system by its coupling to the continuum of decay channels is investigated. The regular motion is described by means of a Poissonian ensemble. We focus on the case of only few channels K<10. The coupling ... More

Ray-tracing in pseudo-complex General RelativityDec 04 2013Apr 29 2014Motivated by possible observations of the black hole candidate in the center of our galaxy and the galaxy M87, ray-tracing methods are applied to both standard General Relativity (GR) and a recently proposed extension, the pseudo-complex General Relativity ... More

SchNetPack: A Deep Learning Toolbox For Atomistic SystemsSep 04 2018SchNetPack is a toolbox for the development and application of deep neural networks to the prediction of potential energy surfaces and other quantum-chemical properties of molecules and materials. It contains basic building blocks of atomistic neural ... More

Learning from Label Proportions in Brain-Computer Interfaces: Online Unsupervised Learning with GuaranteesJan 25 2017Objective: Using traditional approaches, a Brain-Computer Interface (BCI) requires the collection of calibration data for new subjects prior to online use. Calibration time can be reduced or eliminated e.g.~by transfer of a pre-trained classifier or unsupervised ... More

SchNet - a deep learning architecture for molecules and materialsDec 17 2017Mar 22 2018Deep learning has led to a paradigm shift in artificial intelligence, including web, text and image search, speech recognition, as well as bioinformatics, with growing impact in chemical physics. Machine learning in general and deep learning in particular ... More

Coherent Forward Scattering Peak Induced by Anderson LocalizationApr 16 2012Nov 18 2012Numerical simulations show that, at the onset of Anderson localization, the momentum distribution of a coherent wave packet launched inside a random potential exhibits, in the forward direction, a novel interference peak that complements the coherent ... More

Comet C/2013 A1 (Siding Spring) as seen with the Herschel Space ObservatoryOct 08 2014Dec 25 2014The thermal emission of comet C/2013 A1 (Siding Spring) was observed on March 31, 2013, at a heliocentric distance of 6.48 au using the PACS photometer camera of the Herschel Space Observatory. The comet was clearly active, showing a coma that could be ... More

PACS photometer calibration block analysisOct 10 2013The absolute stability of the PACS bolometer response over the entire mission lifetime without applying any corrections is about 0.5% (standard deviation) or about 8% peak-to-peak. This fantastic stability allows us to calibrate all scientific measurements ... More

PrBa_2Cu_3O_{7-y}: Superconducting or Anomalously Magnetic?Sep 07 1999In PrBa_2Cu_3O_{7-y} (Pr123) single crystals grown by the flux method the kink in the magnetic susceptibility chi_{ab}(T), connected with AFM ordering of Pr, disappears after field cooling (FC) in a field H||ab-plane whereas the kink in chi_c(T) remains ... More

Versatile sputtering technology for Al2O3 gate insulators on grapheneOct 07 2011We report a novel fabrication method of graphene Al2O3 gate insulators based on sputtering. Electrical performance of dual-gated mono- and bilayer exfoliated graphene devices is presented. Sputtered Al2O3 layers possess comparable quality to oxides obtained ... More

How to represent crystal structures for machine learning: towards fast prediction of electronic propertiesJul 04 2013May 22 2014High-throughput density-functional calculations of solids are extremely time consuming. As an alternative, we here propose a machine learning approach for the fast prediction of solid-state properties. To achieve this, LSDA calculations are used as training ... More

Quantum-Chemical Insights from Deep Tensor Neural NetworksSep 27 2016Nov 07 2016Learning from data has led to paradigm shifts in a multitude of disciplines, including web, text, and image search, speech recognition, as well as bioinformatics. Can machine learning enable similar breakthroughs in understanding quantum many-body systems? ... More

Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanideOct 09 2014The largest non-cyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times ... More

Global stability properties of renewal epidemic modelsJul 11 2017Oct 03 2018We investigate the global dynamics of a general Kermack-McKendrick-type epidemic model formulated in terms of a system of renewal equations. Specifically, we consider a renewal model for which both the force of infection and the infected removal rates ... More

Nuclear signatures in high-harmonic generation from laser-driven muonic atomsMar 14 2007Jun 02 2007High-harmonic generation from muonic atoms exposed to intense laser fields is considered. Our particular interest lies in effects arising from the finite nuclear mass and size. We numerically perform a fully quantum mechanical treatment of the muon-nucleus ... More

SchNet: A continuous-filter convolutional neural network for modeling quantum interactionsJun 26 2017Dec 19 2017Deep learning has the potential to revolutionize quantum chemistry as it is ideally suited to learn representations for structured data and speed up the exploration of chemical space. While convolutional neural networks have proven to be the first choice ... More

The Flavours of the Quark-Gluon PlasmaDec 26 2008Quarks of other flavours than up and down, i.e. $s$, $c$, and $b$ quarks, have been long recognized as effective probes of the structure of hot QCD matter. In this talk, I review some of the motivations for their investigation and discuss the salient ... More

Phenomenology of Jet Quenching in Heavy Ion CollisionsAug 20 2002Mar 23 2003We derive an analytical expression for the quenching factor in the strong quenching limit where the $p_T$ spectrum of hard partons is dominated by surface emission. We explore the phenomenological consequences of different scaling laws for the energy ... More

Quark Matter 2005 -- Theoretical SummaryAug 29 2005Nov 14 2005This is a review of the latest developments in the theory of superdense nuclear matter, formed in relativistic heavy ion collisions or in the core of collapsed stars, as they were reported and discussed at the Quark Matter 2005 conference in Budapest ... More

Erdmessung mit Quanten und RelativitätAug 30 2016Recent developments in fundamental physics (in theory as well as in technology) provide novel capabilities for geodetic applications such as refined observations of the Earth`s gravity field. We will focus on two new concepts: one applies atomic interferometry ... More

A metric approach to Fréchet geometryDec 14 2006Jun 16 2007The aim of this article is to present the category of bounded Frechet manifolds in respect to which we will review the geometry of Frechet manifolds with a stronger accent on its metric aspect. An inverse function theorem in the sense of Nash and Moser ... More

Intensional Constructed Numbers: Towards Formalizing the Notion of AlgorithmSep 25 2017This work is meant to be a step towards the formal definition of the notion of algorithm, in the sense of an equivalence class of programs working "in a similar way". But instead of defining equivalence transformations directly on programs, we look at ... More

On the von Neumann rule in quantizationMar 25 2019Apr 15 2019We show that any linear quantization map into the space of self-adjoint operators in a Hilbert space violates the von Neumann rule on post-composition with real functions.

Epsilon-non-squeezing and $C^0$-rigidity of epsilon-symplectic embeddingsMay 03 2018An embedding $\varphi \colon (M_1, \omega_1) \to (M_2, \omega_2)$ (of symplectic manifolds of the same dimension) is called $\epsilon$-symplectic if the difference $\varphi^* \omega_2 - \omega_1$ is $\epsilon$-small with respect to a fixed Riemannian ... More

Recurrence and Transience for Branching Random Walks in an iid Random EnvironmentJun 02 2006We give three different criteria for transience of a Branching Markov Chain. These conditions enable us to give a classification of Branching Random Walks in Random Environment (BRWRE) on Cayley Graphs in recurrence and transience. This classification ... More

Another Proof of Segre's Theorem about OvalsNov 13 2013In 1955 B. Segre showed that any oval in a projective plane over a finite field of odd order is a conic. His proof constructs a conic which matches the oval in some points, and then shows that it actually coincides with the oval. Here we give another ... More

MPPhys - A many-particle simulation package for computational physics educationMar 07 2014In a first course to classical mechanics elementary physical processes like elastic two-body collisions, the mass-spring model, or the gravitational two-body problem are discussed in detail. The continuation to many-body systems, however, is defered to ... More

Heavy Ions -- Prospects at the LHCOct 07 2004Oct 13 2004This is a review of the physics prospects for relativistic heavy ion collisions in the CERN Large Hadron Collider. The motivation for the study of superdense matter created in relativistic heavy ion collision is the prospect of observing a novel state ... More

Quark Matter '99 --- Theoretical Summary: What Next?Jun 09 1999Jul 15 1999I review the three broad areas where major progress has been reported: The phase structure of strongly interacting matter, the properties of matter at the instant when it freezes out into individual hadrons in the final stage of the expansion of the hot ... More

Parton Energy Loss in Strongly Coupled AdS/CFTOct 20 2010Nov 30 2010This is a brief review of the theory and phenomenology of parton energy loss in strongly coupled field theories with a gravity dual and its comparison with parton energy loss in QCD at weak coupling.

Symmetries of Surface SingularitiesApr 24 1996The automorphism group ${\rm Aut}\: X$ of a weighted homogeneous normal surface singularity $X$ has a maximal reductive algebraic subgroup $G$ which contains every reductive algebraic subgroup of ${\rm Aut}\: X$ up to conjugation. In all cases except ... More

$J$-holomorphic disks with pre-Lagrangian boundary conditionsApr 09 2017Apr 28 2017The purpose of this paper is to carry out a classical construction of a non-constant holomorphic disk with boundary on (the suspension of) a Lagrangian submanifold in $\mathbb{R}^{2 n}$ in the case the Lagrangian is the lift of a coisotropic (a.k.a. pre-Lagrangian) ... More

A note on invariant temporal functionsFeb 09 2015Jul 18 2016The purpose of this article is to present a result on the existence of Cauchy temporal functions invariant by the action of a compact group of conformal transformations in arbitrary globally hyperbolic manifolds. Moreover, the previous results about the ... More

Special temporal functions on globally hyperbolic manifoldsApr 09 2009Oct 22 2012In this article, existence results concerning temporal functions with additional properties on a globally hyperbolic manifold are obtained. These properties are certain bounds on geometric quantities as lapse and shift. The results are linked to completeness ... More

A note on closed isometric embeddingsMay 30 2008May 20 2016This note is about a little extension of Nash's embedding theorem in the case of complete manifolds.

Central limit theorem analogues for multicolour urn modelsApr 11 2016Mar 12 2019The asymptotic behaviour of a generalised P\'olya--Eggenberger urn is well--known to depend on the spectrum of its replacement matrix: If its dominant eigenvalue $r$ is simple and no other eigenvalue is `large' in the sense that its real part is greater ... More

(Science) Teacher Education in a Knowledge Society. Good Practice at the University of GenevaJul 03 2018The present text summarizes several factors considered as essential for teacher education according to the state of current research and best practice, with a focus on science teacher education, and as realized at the University of Geneva.

On low-degree representations of the symmetric groupNov 22 2015Jul 07 2016The aim of the present paper is to obtain a classification of all the irreducible modular representations of the symmetric group on $n$ letters of dimension at most $n^3$, including dimension formulae. This is achieved by improving an idea, originally ... More

Applying the index theorem to non-smooth operatorsJun 15 2015Oct 10 2016We give a simple way to extend index-theoretical statements from partial differential operators with smooth coefficients to operators with coefficients of finite Sobolev order.

A note on the volume flux of smooth and continuous strictly contact isotopiesJul 25 2011This note on the flux homomorphism for strictly contact isotopies complements the recent paper [MS11a] by P. Spaeth and the author. We determine the volume flux restricted to symplectic and volume-preserving contact isotopies and their C^0-limits for ... More

Simulations of the Glasma in 3+1DApr 08 2019Apr 10 2019The Glasma is a gluonic state of matter which can be created in collisions of relativistic heavy ions and is a precursor to the quark-gluon plasma. The existence of this state is a prediction of the color glass condensate (CGC) effective theory. In many ... More

Fraïssé Structures with Universal Automorphism GroupsJan 19 2015We prove that the automorphism group of a Fra\"iss\'e structure M equipped with a notion of stationary independence is universal for the class of automorphism groups of substructures of M. Furthermore, we show that this applies to certain homogeneous ... More

Restricted conformal invariance in QCD and its predictive power for virtual two-photon processesApr 26 1997Dec 23 1998The conformal algebra provides powerful constraints, which guarantee that renormalized conformally covariant operators exist in the hypothetical conformal limit of the theory, where the $\beta$-function vanishes. Thus, in this limit also the conformally ... More

On Berry's conjectures about the stable order in PCFAug 02 2011Oct 11 2012PCF is a sequential simply typed lambda calculus language. There is a unique order-extensional fully abstract cpo model of PCF, built up from equivalence classes of terms. In 1979, G\'erard Berry defined the stable order in this model and proved that ... More

Quasi-ordered RingsJun 14 2017Jul 27 2017A quasi-order is a binary, reflexive and transitive relation. In the Journal of Pure and Applied Algebra 45 (1987), S.M. Fakhruddin introduced the notion of (totally) quasi-ordered fields and showed that each such field is either an ordered field or else ... More

On the von Neumann rule in quantizationMar 25 2019We show that any linear quantization map into the space of self-adjoint operators in a Hilbert space violates the von Neumann rule about post-composition with real functions.

An Obstacle Problem for Elastic Curves: Existence ResultsDec 07 2018We consider an obstacle problem for elastic curves with fixed ends. We attempt to extend the graph approach provided in [8]. More precisely, we investigate nonexistence of graph solutions for special obstacles and extend the class of admissible curves ... More

The pullback of a theta divisor to M_{g,n}Mar 14 2012Jan 07 2013We compute the class of a divisor on M_{g,n} given as the closure of the locus of smooth pointed curves [C; x_1,..., x_n] for which \sum d_j x_j has an effective representative, where d_j are integers summing up to g-1, not all positive. The techniques ... More

$C^0$-characterization of symplectic and contact embeddings and Lagrangian rigidityJul 11 2016May 11 2017We present a novel $C^0$-characterization of symplectic embeddings and diffeomorphisms in terms of Lagrangian embeddings. Our approach is based on the shape invariant, which was discovered by J.-C. Sikorav and Y. Eliashberg, intersection theory and the ... More

HorizonsNov 19 2011Aug 13 2015We define different notions of black holes, event horizons and Killing horizons for a general time-oriented manifold $(M,g)$ extending previous notions but without the assumption of asymptotical flatness. The notions of 'horizon' are always conformally ... More

On Gradient Flows with Obstacles and Euler's ElasticaMar 01 2019We examine a steepest energy descent flow with obstacle constraint in higher order energy frameworks where the maximum principle is not available. We construct the flow under general assumptions using De Giorgi's minimizing movement scheme. Our main application ... More

Recurrence for branching Markov chainsOct 25 2007Nov 12 2008The question of recurrence and transience of branching Markov chains is more subtle than for ordinary Markov chains; they can be classified in transience, weak recurrence, and strong recurrence. We review criteria for transience and weak recurrence and ... More

Branch dependence in the "consistent histories" approach to quantum mechanicsJun 07 2005Nov 12 2006In the consistent histories formalism one specifies a family of histories as an exhaustive set of pairwise exclusive descriptions of the dynamics of a quantum system. We define branching families of histories, which strike a middle ground between the ... More

Numerical Chladni figuresAug 26 2013Chladni patterns of vibrating membranes or thin plates faszinated the people already in the eighteenth century. As a simple way to visualize acoustic phenomena it is a valuable experiment for beginners' courses. In this paper I present NumChladni, an ... More

Investigation of Hot QCD Matter: Theoretical AspectsSep 29 2013Oct 12 2013This lecture presents an overview of the status of the investigation of the properties of the quark-gluon plasma using relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). It focuses on the ... More

Statistical Fluctuations as Probes of Dense MatterNov 04 2001The use of statistical fluctuations as probes of the microscopic dynamics of hot and dense hadronic matter is reviewed. Critical fluctuations near the critical point of QCD matter are predicted to enhance fluctuations in pionic observables. Chemical fluctuations, ... More

From Sazonov's Non-Dcpo Natural Domains to Closed Directed-Lub Partial OrdersMay 06 2016Normann proved that the domains of the game model of PCF (the domains of sequential functionals) need not be dcpos. Sazonov has defined natural domains for a theory of such incomplete domains. This paper further develops that theory. It defines lub-rules ... More

Full Abstraction for a Recursively Typed Lambda Calculus with Parallel ConditionalJun 11 2008We define the syntax and reduction relation of a recursively typed lambda calculus with a parallel case-function (a parallel conditional). The reduction is shown to be confluent. We interpret the recursive types as information systems in a restricted ... More

Metrizability of spaces of homomorphisms between metric vector spacesMay 22 2009Nov 29 2014This note tries to give an answer to the following question: Is there a sufficiently rich class of metric vector spaces such that sufficiently large spaces of continuous linear maps between them are metrizable?

On the Tree Structure of Orderings and Valuations on arbitrary unital RingsJul 30 2018Dec 20 2018In the present paper, we first introduce the notion of quasi-ordered rings, which axiomatically subsumes the classes of all ordered and valued rings. Then we uniformly define a finer relation $\leq$ on the set of all quasi-orders on a ring $R$, generalizing ... More

Analysis of invariant PDO's on the Heisenberg groupAug 12 2014In these lecture notes, the representation theory of the Heisenberg group as well as Howe's construction of the metaplectic group by means of twisted convolution operators with generalized, complex Gaussians are reviewed, and it is shown how these tools ... More

Uniform approximation of homeomorphisms by diffeomorphismsJan 08 2009May 22 2014We prove that a compactly supported homeomorphism of a smooth manifold of dimension greater or equal to 5 can be approximated uniformly by compactly supported diffeomorphisms if and only if it is isotopic to a diffeomorphism. If the given homeomorphism ... More

Cheeger-Gromov compactness for manifolds with boundaryAug 20 2018We prove Cheeger-Gromov convergence for a subsequence of a given sequence of manifolds (with boundary) of bounded geometry.

A Central Limit Theorem for Lipschitz-Killing Curvatures of Gaussian ExcursionsJul 22 2016Feb 20 2017This paper studies the excursion set of a real stationary isotropic Gaussian random field above a fixed level. We show that the standardized Lipschitz-Killing curvatures of the intersection of the excursion set with a window converges in distribution ... More

Which spacetimes admit conformal compactifications?Sep 29 2014Nov 21 2014We consider the future causal boundary as a tool to find obstructions to conformal extensions, the latter being a slight generalization to conformal compactifications.

Asymptotic flexibility of globally hyperbolic manifoldsOct 05 2011In this short note, a question of patching together globally hyperbolic manifolds is adressed which appeared in the context of the construction of Hadamard states.

The Group of Hamiltonian Homeomorphisms in the L^\infty-normMay 08 2007The group Hameo (M,\omega) of Hamiltonian homeomorphisms of a connected symplectic manifold (M,\omega) was defined and studied in [7] and further in [6]. In these papers, the authors consistently used the L^{(1,\infty)}-Hofer norm (and not the L^\infty-Hofer ... More

Minimax principles, Hardy-Dirac inequalities and operator cores for two and three dimensional Coulomb-Dirac operatorsMar 04 2016For $n\in\{2,3\}$ we prove minimax characterisations of eigenvalues in the gap of the $n$ dimensional Dirac operator with an potential, which may have a Coulomb singularity with a coupling constant up to the critical value $1/(4-n)$. This result implies ... More

A criterion for transience of multidimensional branching random walk in random environmentMay 14 2007We develop a criterion for transience for a general model of branching Markov chains. In the case of multi-dimensional branching random walk in random environment (BRWRE) this criterion becomes explicit. In particular, we show that \emph{Condition L} ... More

Leptoquarks in Flavour PhysicsJan 10 2018Feb 05 2018While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in $b\to s\ell^{+}\ell^{-}$ and $b\to c\ell\nu$. In this context, also the discrepancy ... More

Study of leakage currents in pCVD diamonds as function of the magnetic fieldMay 04 2009Jul 06 2009pCVD diamond sensors are regularly used as beam loss monitors in accelerators by measuring the ionization of the lost particles. In the past these beam loss monitors showed sudden increases in the dark leakage current without beam losses and these erratic ... More

Thermal dilepton rates from quenched lattice QCDJan 30 2013We present new lattice results on the continuum extrapolation of the vector current correlation function. Lattice calculations have been carried out in the deconfined phase at a temperature of 1.1 Tc, extending our previous results at 1.45 Tc, utilizing ... More

A Cu2+ (S = 1/2) Kagomé Antiferromagnet: MgxCu4-x(OH)6Cl2Apr 06 2010Spin-frustrated systems are one avenue for inducing macroscopic quantum states in materials. However, experimental realization of this goal has been difficult because of the lack of simple materials and, if available, the separation of the unusual magnetic ... More

Continuous Lyman-alpha generation by four-wave mixing in mercury for laser-cooling of antihydrogenSep 28 2010Cooling antihydrogen atoms is important for future experiments both to test the fundamental CPT symmetry by high-resolution laser spectroscopy and also to measure the gravitational acceleration of antimatter. Laser-cooling of antihydrogen can be done ... More

Prominent role of multi-electron processes in K-shell double and triple photodetachment of oxygen anionsSep 17 2016The photon-ion merged-beams technique was used at a synchrotron light source for measuring absolute cross sections of double and triple photodetachment of O$^{-}$ ions. The experimental photon energy range of 524-543 eV comprised the threshold for K-shell ... More

Synchronous Phase Shift at LHCJun 24 2013The electron cloud in vacuum pipes of accelerators of positively charged particle beams causes a beam energy loss which could be estimated from the synchronous phase. Measurements done with beams of 75 ns, 50 ns, and 25 ns bunch spacing in the LHC for ... More

Magneto-oscillations of the mobility edge in Coulomb frustrated bosons and fermionsJun 24 2016Jul 30 2016We study the crossover from strong to weak localization of hard-core bosons on a two dimensional honeycomb lattice in a magnetic field, as motivated by recent experiments on structured films. Taking into account long range Coulomb interactions among the ... More

Dipolar Stabilization of an Attractive Bose Gas in a One Dimensional LatticeMay 25 2011We experimentally show that dipolar interaction can stabilize otherwise unstable many-body systems like an attractive Bose gas. In a one dimensional lattice the repulsive dipolar on-site interaction balances negative scattering lengths up to -17 Bohr ... More

Thin-film based phase plates for transmission electron microscopy fabricated from metallic glassesOct 13 2015Thin-film based phase plates are meanwhile a widespread tool to enhance the contrast of weak-phase objects in transmission electron microscopy (TEM). The thin film usually consists of amorphous carbon, which suffers from quick degeneration under the intense ... More

Tunable few electron quantum dots in InAs nanowiresSep 19 2006Quantum dots realized in InAs are versatile systems to study the effect of spin-orbit interaction on the spin coherence, as well as the possibility to manipulate single spins using an electric field. We present transport measurements on quantum dots realized ... More

Momentum isotropisation in random potentialsSep 07 2012Apr 10 2013When particles are multiply scattered by a random potential, their momentum distribution becomes isotropic on average. We study this quantum dynamics numerically and with a master equation. We show how to measure the elastic scattering time as well as ... More

Confinement-induced collapse of a dipolar Bose-Einstein condensateMay 23 2012We report on the observation of the confinement-induced collapse dynamics of a dipolar Bose-Einstein condensate (dBEC) in a one-dimensional optical lattice. We show that for a fixed interaction strength the collapse can be initiated in-trap by lowering ... More

An observational study of dust nucleation in Mira ($o$ Ceti): II. Titanium oxides are negligible for nucleation at high temperaturesOct 04 2016The formation of silicate dust in oxygen-rich envelopes of evolved stars is thought to be initiated by formation of seed particles that can withstand the high temperatures close to the stellar photosphere and act as condensation cores farther away from ... More

Investigating source confusion in PMN J1603$-$4904Jan 05 2018PMN J1603$-$4904 is a likely member of the rare class of $\gamma$-ray emitting young radio galaxies. Only one other source, PKS 1718$-$649, has been confirmed so far. These objects, which may transition into larger radio galaxies, are a stepping stone ... More

Charge Fluctuations from the Chiral Magnetic Effect in Nuclear CollisionsSep 06 2010Sep 21 2010We derive a nonlocal effective Lagrangian for the chiral magnetic effect. An electric field is generated by winding number fluctuations of the nonabelian gauge field in the presence of a strong magnetic field. We estimate the magnitude of charge asymmetry ... More

Visual appearance of wireframe objects in special relativityOct 14 2014The visual appearance of a moving object in special relativity can be constructed in a straightforward manner when representing the surface of the object, or at least a wire frame model of it, as a point cloud. The apparent position of each individual ... More

On the chromatic number of random geometric graphsJan 31 2011Aug 27 2011Given independent random points $X_1,...,X_n\in\eR^d$ with common probability distribution $\nu$, and a positive distance $r=r(n)>0$, we construct a random geometric graph $G_n$ with vertex set $\{1,...,n\}$ where distinct $i$ and $j$ are adjacent when ... More

Hadron Mass Spectrum from Lattice QCDAug 10 2010Aug 17 2010Finite temperature lattice simulations of quantum chromodynamics (QCD) are sensitive to the hadronic mass spectrum for temperatures below the "critical" temperature T_c ~ 160 MeV. We show that a recent precision determination of the QCD trace anomaly ... More

Localization for random block operatorsAug 09 2012We continue the investigations of Kirsch, Metzger and the second-named author [J. Stat. Phys. 143, 1035--1054 (2011)] on spectral properties of a certain type of random block operators. In particular, we establish an alternative version of a Wegner estimate ... More

Jean Bourgain's analytic partition of unity via holomorphic martingalesApr 27 1992Using stopping time arguments on holomorphic martingales we present a soft way of constructing J. Bourgain's analytic partitions of unity. Applications to Marcinkiewicz interploation in weighted Hardy spaces are discussed.