Results for "Hans Peter Büchler"

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Strictly local one-dimensional topological quantum error correction with symmetry-constrained cellular automataNov 22 2017Jan 12 2018Active quantum error correction on topological codes is one of the most promising routes to long-term qubit storage. In view of future applications, the scalability of the used decoding algorithms in physical implementations is crucial. In this work, ... More
Topological states in a microscopic model of interacting fermionsApr 16 2015We present a microscopic model of interacting fermions where the ground state degeneracy is topologically protected. The model is based on a double-wire setup with local interactions in a particle number conserving setting. A compelling property of this ... More
Full Counting Statistics for Interacting Fermions with Determinantal Quantum Monte Carlo SimulationsJun 27 2017We present a method for computing the full probability distribution function of quadratic observables for the Fermi-Hubbard model within the framework of determinantal quantum Monte Carlo. Especially, in cold atoms experiments with single site resolution, ... More
Quantum theory of Kerr nonlinearity with Rydberg slow light polaritonsApr 18 2016We study the propagation of Rydberg slow light polaritons through an atomic medium for intermediate interactions. Then, the dispersion relation for the polaritons is well described by the slow light velocity alone, which allows for an analytical solution ... More
Topological networks for quantum communication between distant qubitsMay 19 2017Nov 22 2017Efficient communication between qubits relies on robust networks which allow for fast and coherent transfer of quantum information. It seems natural to harvest the remarkable properties of systems characterized by topological invariants to perform this ... More
Exploring quantum phases by driven dissipationAug 20 2014Ever since the insight spreaded that tailored dissipation can be employed to control quantum systems and drive them towards pure states, the field of non-equilibrium quantum mechanics gained remarkable momentum. So far research focussed on emergent phenomena ... More
Two-Stage Melting in Systems of Strongly Interacting Rydberg AtomsJul 13 2010Feb 04 2011We analyze the ground state properties of a one-dimensional cold atomic system in a lattice, where Rydberg excitations are created by an external laser drive. In the classical limit, the ground state is characterized by a complete devil's staircase for ... More
Ferroelectric quantum phase transition with cold polar moleculesDec 01 2014We analyze a system of polar molecules in a one-dimensional optical lattice. By controlling the internal structure of the polar molecules with static electric and microwave fields, we demonstrate the appearance of a quantum phase transition into a ferroelectric ... More
The Role of Quantum Fluctuations in the Hexatic Phase of Cold Polar MoleculesJan 22 2014Two dimensional crystals melt via an intermediate \textit{hexatic} phase which is characterized by an anomalous scaling of spatial and orientational correlation functions and the absence of an attraction between dislocations. We propose a protocol to ... More
Three-body interaction of Rydberg slow light polaritonsApr 13 2016Aug 08 2016We study a system of three photons in an atomic medium coupled to Rydberg states near the conditions of electromagnetically induced transparency. Based on the analytical analysis of the microscopic set of equations in the far-detuned regime, the effective ... More
Ising anyonic topological phase of interacting Fermions in one dimensionMay 04 2017Oct 06 2017We study a microscopic model of interacting fermions in a ladder setup, where the total number of particles is conserved. At a special point, the ground state is known and gives rise to a topological state of matter with edge modes obeying the statistics ... More
Beyond-mean-field corrections for dipolar bosons in an optical latticeJan 09 2019Mar 29 2019Recent experiments with ultracold lanthanide atoms which are characterized by a large magnetic moment have revealed the crucial importance of beyond-mean-field corrections in understanding the dynamics of the gas. We study how the presence of an external ... More
Quantum Crystals and Laughlin Droplets of Cavity Rydberg PolaritonsJun 01 2015Synthetic quantum materials offer an exciting opportunity to explore quantum many-body physics and novel states of matter under controlled conditions. In particular, they provide an avenue to exchange the short length scales and large energy scales of ... More
Emergent universal dynamics for an atomic cloud coupled to an optical wave-guideMar 23 2018Jul 16 2018We study the dynamics of a single collective excitation in a cold ensemble of atoms coupled to a one-dimensional waveguide. The coupling between the atoms and the photonic modes provides a coherent and a dissipative dynamics for this collective excitation. ... More
Anomalous Behavior of Spin Systems with Dipolar InteractionsMar 07 2012Jul 11 2012We study the properties of spin systems realized by cold polar molecules interacting via dipole-dipole interactions in two dimensions. Using a spin wave theory, that allows for the full treatment of the characteristic long-distance tail of the dipolar ... More
Driving Dipolar Fermions into the Quantum Hall Regime by Spin-Flip Induced Insertion of Angular MomentumFeb 06 2013Apr 03 2013A new method to drive a system of neutral dipolar fermions into the lowest Landau level regime is proposed. By employing adiabatic spin-flip processes in combination with a diabatic transfer, the fermions are pumped to higher orbital angular momentum ... More
Quasiparticles in quantum spin chains with long-range interactionsJan 02 2018Aug 28 2018We study quasiparticle excitations for quantum spin chains with long-range interactions using variational matrix product state techniques. It is confirmed that the local quasiparticle ansatz is able to capture those excitations very accurately, even when ... More
Topological bands with Chern number C=2 by dipolar exchange interactionsOct 21 2014May 19 2015We demonstrate the realization of topological band structures by exploiting the intrinsic spin-orbit coupling of dipolar interactions in combination with broken time-reversal symmetry. The system is based on polar molecules trapped in a deep optical lattice, ... More
Dipolar dephasing of Rydberg D-state polaritonsMay 14 2015Jun 23 2016We experimentally study the effects of the anisotropic Rydberg-interaction on $D$-state Rydberg polaritons slowly propagating through a cold atomic sample. In addition to the few-photon nonlinearity known from similar experiments with Rydberg $S$-states, ... More
Dimensional crossover for the beyond-mean-field correction in Bose gasesJun 05 2018Nov 28 2018We present a detailed beyond-mean-field analysis of a weakly interacting Bose gas in the crossover from three to low dimensions. We find an analytical solution for the energy and provide a clear qualitative picture of the crossover in the case of a box ... More
Majorana modes and $p$-wave superfluids for fermionic atoms in optical latticesMar 03 2014We present a simple approach to create a strong $p$-wave interaction for fermions in an optical lattice. The crucial step is that the combination of a lattice setup with different orbital states and $s$-wave interactions can give rise to a strong induced ... More
The Fate of the Higgs Mode in a Trapped Dipolar SupersolidJul 22 2019We theoretically investigate the spectrum of elementary excitations of a trapped dipolar quantum gas across the BEC-supersolid phase transition. Our calculations reveal the existence of distinct Higgs and Nambu-Goldstone modes that emerge from the softening ... More
Accurate mapping of multilevel Rydberg atoms on interacting spin-$1/2$ particles for the quantum simulation of Ising modelsOct 17 2017We study a system of atoms that are laser-driven to $nD_{3/2}$ Rydberg states and assess how accurately they can be mapped onto spin-$1/2$ particles for the quantum simulation of anisotropic Ising magnets. Using non-perturbative calculations of the pair ... More
Artificial atoms can do more than atoms: Deterministic single photon subtraction from arbitrary light fieldsMar 07 2011We study the interplay of photons interacting with an artificial atom in the presence of a controlled dephasing. Such artifical atoms consisting of several independent scatterer can exhibit remarkable properties superior to single atoms with a prominent ... More
Tutorial: Calculation of Rydberg interaction potentialsDec 23 2016Jun 06 2017The strong interaction between individual Rydberg atoms provides a powerful tool exploited in an ever-growing range of applications in quantum information science, quantum simulation, and ultracold chemistry. One hallmark of the Rydberg interaction is ... More
Topologically protected edge states in small Rydberg systemsMar 14 2018We propose a simple setup of Rydberg atoms in a honeycomb lattice which gives rise to topologically protected edge states. The proposal is based on the combination of dipolar exchange interaction, which couples the internal angular momentum and the orbital ... More
Coupling a single electron to a Bose-Einstein condensateJun 21 2013The coupling of electrons to matter is at the heart of our understanding of material properties such as electrical conductivity. One of the most intriguing effects is that electron-phonon coupling can lead to the formation of a Cooper pair out of two ... More
The low-energy Goldstone mode in a trapped dipolar supersolidJun 11 2019A supersolid is a counter-intuitive state of matter that combines the frictionless flow of a superfluid with the crystal-like periodic density modulation of a solid. Since the first prediction in the 1950s, experimental efforts to realize this state have ... More
Experimental realization of a symmetry protected topological phase of interacting bosons with Rydberg atomsOct 31 2018The concept of topological phases is a powerful framework to characterize ground states of quantum many-body systems that goes beyond the paradigm of symmetry breaking. While a few topological phases appear in condensed matter systems, a current challenge ... More
Universal scaling in a strongly interacting Rydberg gasFeb 26 2009Nov 25 2009We study a gas of ultracold atoms resonantly driven into a strongly interacting Rydberg state. The long distance behavior of the spatially frozen effective pseudospin system is determined by a set of dimensionless parameters, and we find that the experimental ... More
Observation of three-body correlations for photons coupled to a Rydberg superatomMay 31 2018We report on the experimental observation of non-trivial three-photon correlations imprinted onto initially uncorrelated photons through interaction with a single Rydberg superatom. Exploiting the Rydberg blockade mechanism, we turn a cold atomic cloud ... More
Learning to Control Highly Accelerated Ballistic Movements on Muscular RobotsApr 07 2019High-speed and high-acceleration movements are inherently hard to control. Applying learning to the control of such motions on anthropomorphic robot arms can improve the accuracy of the control but might damage the system. The inherent exploration of ... More
Preparation and spectroscopy of a metastable Mott insulator state with attractive interactionsJan 04 2012We prepare and study a metastable attractive Mott insulator state formed with bosonic atoms in a three-dimensional optical lattice. Starting from a Mott insulator with Cs atoms at weak repulsive interactions, we use a magnetic Feshbach resonance to tune ... More
Time averages of polynomialsNov 29 2007We define and study when a polynomial mapping has a local or global time average. We conjecture that a polynomial f in the complex plane has a time average near a point z if and only if z is eventually mapped into a Siegel-disc of f. We prove that the ... More
On Bayes' theorem for improper mixturesDec 14 2011Although Bayes's theorem demands a prior that is a probability distribution on the parameter space, the calculus associated with Bayes's theorem sometimes generates sensible procedures from improper priors, Pitman's estimator being a good example. However, ... More
Non-autonomous dynamics of holomorphic mappings in projective spaceJan 16 2004We study the dynamics of compositions of a sequence of holomorphic mappings in projective space. We define ergodicity and mixing for non-autonomous dynamical systems, and we construct totally invariant measures for which our sequence satisfies these properties. ... More
Minimal instances for toric code ground statesJun 29 2012A decade ago Kitaev's toric code model established the new paradigm of topological quantum computation. Due to remarkable theoretical and experimental progress, the quantum simulation of such complex many-body systems is now within the realms of possibility. ... More
In situ measurement of the dynamic structure factor in ultracold quantum gasesJul 13 2011Apr 09 2012We propose an experimental setup to efficiently measure the dynamic structure factor of ultracold quantum gases. Our method uses the interaction of the trapped atomic system with two different cavity modes, which are driven by external laser fields. By ... More
Dipole Interaction Mediated Laser Cooling of Polar Molecules to Ultra-cold TemperaturesDec 02 2011May 13 2012We present a method to design a finite decay rate for excited rotational states in polar molecules. The setup is based on a hybrid system of polar molecules with atoms driven into a Rydberg state. The atoms and molecules are coupled via the strong dipolar ... More
Polyakov loop renormalization with gradient flowNov 14 2015We propose to use the gradient flow for the renormalization of Polyakov loops in various representations. We study Polyakov loops in 2+1 flavor QCD using the HISQ action and lattices with temporal extents $N_\tau$=6, 8, 10 and 12 in various representations, ... More
Beyond-mean-field corrections for dipolar bosons in an optical latticeJan 09 2019Recent experiments with ultracold lanthanide atoms which are characterized by a large magnetic moment have revealed the crucial importance of beyond-mean-field corrections in understanding the dynamics of the gas. We study how the presence of an external ... More
Quantum K-Theory of Calabi-Yau ManifoldsMay 09 2019The disk partition function of certain 3d N=2 supersymmetric gauge theories computes a quantum K-theoretic ring for Kahler manifolds X. We study the 3d gauge theory/quantum K-theory correspondence for global and local Calabi-Yau manifolds with several ... More
Contributions to Four-Position Theory with Relative RotationsNov 27 2009We consider the geometry of four spatial displacements, arranged in cyclic order, such that the relative motion between neighbouring displacements is a pure rotation. We compute the locus of points whose homologous images lie on a circle, the locus of ... More
Discrete Laplace Cycles of Period FourApr 19 2011We study discrete conjugate nets whose Laplace sequence is of period four. Corresponding points of opposite nets in this cyclic sequence have equal osculating planes in different net directions, that is, they correspond in an asymptotic transformation. ... More
Stringy Origin of Discrete R-symmetriesMay 04 2017Discrete symmetries play a crucial role in particle physics. They appear abundantly in string model constructions. We focus here on the case of discrete $R$-symmetries which are intrinsically connected to the Lorentz group in extra dimensions and the ... More
Singular Frégier Conics in Non-Euclidean GeometryMay 24 2016The hypotenuses of all right triangles inscribed into a fixed conic $C$ with fixed right-angle vertex $p$ are incident with the Fr\'egier point $f$ to $p$ and $C$. As $p$ varies on the conic, the locus of the Fr\'egier point is, in general, a conic as ... More
On the intersection of the spectrum of frequently hypercyclic operators with the unit circleDec 28 2013We exclude the existence of frequently hypercyclic operators that have a spectrum contained in the closed unit disc and that intersects the unit circle in only finitely many points under certain additional conditions. This extends a result of S. Shkarin, ... More
SU(3) Yang-Mills Hamiltonian in the flux-tube gauge: Strong coupling expansion and glueball dynamicsNov 20 2016Aug 02 2017It is shown that the formulation of the SU(3) Yang-Mills quantum Hamiltonian in the "flux-tube gauge" $A_{a1}=0$ for all a=1,2,4,5,6,7 and $A_{a2}=0$ for all a=5,7 allows for a systematic and practical strong coupling expansion of the Hamiltonian in $\lambda\equiv ... More
Computing mean logarithmic mass from muon counts in air shower experimentsNov 15 2017Aug 16 2018I discuss the conversion of muon counts in air showers, which are observable by experiments, into mean logarithmic mass, an important variable to express the mass composition of cosmic rays. Stochastic fluctuations in the shower development and statistical ... More
Quantum K-Theory of Calabi-Yau ManifoldsMay 09 2019Jul 25 2019The disk partition function of certain 3d N=2 supersymmetric gauge theories computes a quantum K-theoretic ring for Kahler manifolds X. We study the 3d gauge theory/quantum K-theory correspondence for global and local Calabi-Yau manifolds with several ... More
From A to B: New Methods to Interpolate Two PosesJun 14 2017We present two methods to interpolate between two given rigid body displacements. Both are based on linear interpolation in the ambient space of well-known curved point models for the group of rigid body displacements. The resulting motions are either ... More
Unconstrained Hamiltonian formulation of low energy QCDMay 08 2014Using a generalized polar decomposition of the gauge fields into gauge-rotation and gauge-invariant parts, which Abelianises the Non-Abelian Gauss-law constraints, an unconstrained Hamiltonian formulation of QCD can be achieved. The exact implementation ... More
QCD in terms of gauge-invariant dynamical variablesMar 15 2013For a complete description of the physical properties of low-energy QCD, it might be advantageous to first reformulate QCD in terms of gauge-invariant dynamical variables, before applying any approximation schemes. Using a canonical transformation of ... More
Fatou components of elliptic polynomial skew productsAug 31 2016We investigate the description of Fatou components for polynomial skew-products in two complex variables. The non-existence of wandering domains near a super-attracting invariant fiber was shown in [L], and the geometrically-attracting case was studied ... More
A 3d Gauge Theory/Quantum K-Theory CorrespondenceAug 06 2018Sep 27 2018The 2d gauged linear sigma model (GLSM) gives a UV model for quantum cohomology on a Kahler manifold X, which is reproduced in the IR limit. We propose and explore a 3d lift of this correspondence, where the UV model is the N=2 supersymmetric 3d gauge ... More
The Bäcklund Transform of Principal Contact Element NetsOct 16 2010We investigate geometric aspects of the the B\"acklund transform of principal contact element nets. A B\"acklund transform exists if and only if it the principal contact element net is of constant negative Gaussian curvature (a pseudosphere). We describe ... More
Location of zeros for the partition function of the Ising model on bounded degree graphsOct 03 2018Aug 29 2019The seminal Lee-Yang theorem states that for any graph the zeros of the partition function of the ferromagnetic Ising model lie on the unit circle in $\mathbb C$. In fact the union of the zeros of all graphs is dense on the unit circle. In this paper ... More
SU(3) Yang-Mills Hamiltonian in the flux-tube gauge: Strong coupling expansion and glueball dynamicsNov 20 2016It is shown that the formulation of the SU(3) Yang-Mills quantum Hamiltonian in the "flux-tube gauge" A_{a1}=0 for all a=1,2,4,5,6,7 and A_{a2}=0 for all a=5,7 allows for a systematic and practical strong coupling expansion of the Hamiltonian in \lambda\equiv ... More
Blocks of monodromy groups in Complex DynamicsJan 28 2009May 20 2010Motivated by a problem in complex dynamics, we examine the block structure of the natural action of monodromy groups on the tree of preimages of a generic point. We show that in many cases, including when the polynomial has prime power degree, there are ... More
From geometry to invertibility preserversMar 31 2013We characterize bijections on matrix spaces (operator algebras) preserving full rank (invertibility) of differences of matrix (operator) pairs in both directions.
Polynomials constant on a hyperplane and CR maps of hyperquadricsOct 14 2009Dec 21 2010We prove a sharp degree bound for polynomials constant on a hyperplane with a fixed number of distinct monomials for dimensions 2 and 3. We study the connection with monomial CR maps of hyperquadrics and prove similar bounds in this setup with emphasis ... More
Polynomials constant on a hyperplane and CR maps of spheresMay 12 2011Sep 26 2011We prove a sharp degree bound for polynomials constant on a hyperplane with a fixed number of nonnegative distinct monomials. This bound was conjectured by John P. D'Angelo, proved in two dimensions by D'Angelo, Kos and Riehl and in three dimensions by ... More
Random local complex dynamicsMar 16 2018The study of the dynamics of an holomorphic map near a fixed point is a central topic in complex dynamical systems. In this paper we will consider the corresponding random setting: given a probability measure $\nu$ with compact support on the space of ... More
Julia sets of complex Hénon mapsJun 01 2017Sep 07 2017There are two natural definitions of the Julia set for complex H\'enon maps: the sets $J$ and $J^\star$. Whether these two sets are always equal is one of the main open questions in the field. We prove equality when the map acts hyperbolically on the ... More
Discrete Gliding Along Principal CurvesApr 08 2010We consider $n$-dimensional discrete motions such that any two neighbouring positions correspond in a pure rotation ("rotating motions"). In the Study quadric model of Euclidean displacements these motions correspond to quadrilateral nets with edges contained ... More
The topological susceptibility in finite temperature QCD and axion cosmologyJun 09 2016Nov 23 2016We study the topological susceptibility in 2+1 flavor QCD above the chiral crossover transition temperature using Highly Improved Staggered Quark action and several lattice spacings, corresponding to temporal extent of the lattice, $N_\tau=6,8,10$ and ... More
The topological susceptibility in finite temperature QCD and axion cosmologyJun 09 2016We study the topological susceptibility in 2+1 flavor QCD above the chiral crossover transition temperature using Highly Improved Staggered Quark action and several lattice spacings, corresponding to temporal extent of the lattice, $N_\tau=6,8,10$ and ... More
Nonthermal production of gravitinos and inflatinos in the Inflationary UniverseNov 23 2001The success of primordial nucleosynthesis imposes stringent bounds on the abundance of gravitational relics. This is particularly true for gravitinos, which - for models with gravitationally mediated supersymmetry breaking - are expected to have a mass ... More
On joint sum/max stability and sum/max domains of attractionJun 09 2016Sep 08 2016Let (W_i, J_i) be a sequence of i.i.d. R_+ x R-valued random vectors. Considering the partial sum of the first component and the corresponding maximum of the second component, we are interested in the limit distributions that can be obtained under an ... More
SOFIA Astronomy and Technology in the 21st CenturyAug 31 1999SOFIA, the Stratospheric Observatory For Infrared Astronomy mounted on-board a Boeing 747SP will open a new era in MIR/FIR astronomy. Starting in 2002, SOFIA will offer German and American astronomers a unique platform, providing regular access to the ... More
The spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimalsJul 24 2017A high fraction of carbon bound in solid carbonaceous material is observed to exist in bodies formed in the cold outskirts of the solar nebula, while bodies in the terrestrial planets region contain nearly none. We study the fate of the carbonaceous material ... More
The Gaugino CodeFeb 14 2007Mar 06 2007Gauginos might play a crucial role in the search for supersymmetry at the Large Hadron Collider (LHC). Mass predictions for gauginos are rather robust and often related to the values of the gauge couplings. We analyse the ratios of gaugino masses in the ... More
Generalized quark number susceptibilities from fugacity expansion at finite chemical potential for $N_f$ = 2 Wilson fermionsNov 19 2014Apr 08 2015Generalized susceptibilities of the net quark number have been proposed to be good probes for the transitions in the QCD phase diagram and for the search of a possible critical end point. In this article we explore a new strategy for computing quark number ... More
Generic boundary behaviour of Taylor series in Hardy and Bergman spacesDec 23 2015It is known that, generically, Taylor series of functions holomorphic in the unit disc turn out to be universal series outside of the unit disc and in particular on the unit circle. Due to classical and recent results on the boundary behaviour of Taylor ... More
Fast Abstracts and Student Forum Proceedings - EDCC 2016 - 12th European Dependable Computing ConferenceSep 05 2016Fast Abstracts are short presentations of work in progress or opinion pieces and aim to serve as a rapid and flexible mechanism to (i) Report on current work that may or may not be complete; (ii) Introduce new ideas to the community; (iii) State positions ... More
Complex dynamics with focus on the real partsOct 17 2013Oct 29 2013We consider the dynamics of holomorphic polynomials in $\mathbb C$. We show that the ergodic properties of the map can be seen already from the real parts of the orbits.
Thermal evolution and sintering of chondritic planetesimals IV. Temperature dependence of heat conductivity of asteroids and meteoritesApr 02 2018Understanding the compaction and differentiation of the planetesimals and protoplanets from the Asteroid Belt and the terrestrial planet region of the Solar System requires a reliable modeling of their internal thermal evolution. An important ingredient ... More
Critical intermittency in rational mapsSep 12 2019This paper will provide and study examples of iterated function systems by two rational maps on the Riemann sphere that give rise to critical intermittency. The main ingredient for this is a superattracting fixed point for one map that is mapped onto ... More
Condensation of MgS in outflows from carbon starsMar 20 2008The basic mechanism responsible for the widespread condensation of MgS in the outflows from carbon rich stars on the tip of the AGB is discussed with the aim of developing a condensation model that can be applied in model calculations of dust formation ... More
A polynomial skew-product with a wandering Fatou-diskMay 06 2014Little is known about the existence of wandering Fatou components for rational maps in two complex variables. In 2003 Lilov proved the non-existence of wandering Fatou components for polynomial skew-products in the neighborhood of an invariant super-attracting ... More
Thermal history modeling of the L chondrite parent bodyJul 01 2019The radius of the L chondrite parent body, its formation time, and its evolution history are determined by fitting theoretical models to empirical data of radioisotopic chronometers for L chondrites. A simplified evolution model for the L chondrite parent ... More
Collective many-body interaction in Rydberg dressed atomsApr 14 2010Sep 17 2010We present a method to control the shape and character of the interaction potential between cold atomic gases by weakly dressing the atomic ground state with a Rydberg level. For increasing particle densities, a crossover takes place from a two-particle ... More
Quantum critical behavior in strongly interacting Rydberg gasesJun 24 2008Dec 16 2008We study the appearance of correlated many-body phenomena in an ensemble of atoms driven resonantly into a strongly interacting Rydberg state. The ground state of the Hamiltonian describing the driven system exhibits a second order quantum phase transition. ... More
Mean Field Behaviour in a Local Low-Dimensional ModelSep 16 1994We point out a new mechanism which can lead to mean field type behaviour in nonequilibrium critical phenomena. We demonstrate this mechanism on a two-dimensional model which can be understood as a stochastic and non-conservative version of the abelian ... More
Gravitational divergences as a mediator of supersymmetry breakingJul 04 1997Gravitational divergences associated with singlet fields in supersymmetric theories are reexamined, and their possible contributions to the low-energy effective theory are pointed out. We demonstrate that such divergences are not necessarily harmful and ... More
Supersymmetric Neutrino Masses, R Symmetries, and The Generalized mu ProblemJun 20 1996In supersymmetric models a tree-level neutrino mass could originate from the (weak-scale) superpotential. We propose and examine a realization of that idea, which arises naturally in the framework of a spontaneously broken U(1) R-symmetry. The solution ... More
Quantitative analysis of galaxy-galaxy lensingJan 31 1996In this paper we explore a quantitative and efficient method to constrain the halo properties of distant galaxy populations through ``galaxy--galaxy" lensing and show that the mean masses and sizes of halos can be estimated accurately, without excessive ... More
The Bak-Chen-Tang Forest Fire Model RevisitedJun 23 1997We reconsider a model introduced by Bak, Chen, and Tang (Phys. Rev. A 38, 364 (1988)) as a supposedly self-organized critical model for forest fires. We verify again that the model is not critical in 2 dimensions, as found also by previous authors. But ... More
Bifurcating vortex solutions of the complex Ginzburg-Landau equationJun 25 1999It is shown that the complex Ginzburg-Landau (CGL) equation on the real line admits nontrivial $2\pi$-periodic vortex solutions that have $2n$ simple zeros (``vortices'') per period. The vortex solutions bifurcate from the trivial solution and inherit ... More
Quark number susceptibilities at finite chemical potential from fugacity expansionSep 16 2014Generalized quark number susceptibilities are expected to be good probes for the phase transitions in QCD and the search of a possible critical point. However, their computation in lattice QCD is plagued by the complex action problem which appears at ... More
Generalized string compactifications with spontaneously broken supersymmetryJun 22 1996Aug 04 1996The Narain lattice construction of string compactifications is generalized to include spontaneously broken supersymmetry. Consistency conditions from modular invariance and Lorentz symmetry are solved in full generality. This framework incorporates models ... More
Self-Induced Compactness in Banach SpacesMar 28 1994The question which led to the title of this note is the following: {\it If $X$ is a Banach space and $K$ is a compact subset of $X$, is it possible to find a compact, or even approximable, operator $v:X\to X$ such that $K\subset\ol{v(B_X)}$?} This question ... More
A generalization of the quantum Rabi model: exact solution and spectral structureJun 08 2017Sep 11 2017We consider a generalization of the quantum Rabi model where the two-level system and the single-mode cavity oscillator are coupled by an additional Stark-like term. By adapting a method recently introduced by Braak [Phys. Rev. Lett. {\bf 107}, 100401 ... More
Two photon conditional phase gate based on Rydberg slow light polaritonsSep 11 2019We analyze the fidelity of a deterministic quantum phase gate for two photons counterpropagating as polaritons through a cloud of Rydberg atoms under the condition of electromagnetically induced transparency (EIT). We provide analytical results for the ... More
Lyapunov Conditions for Differentiability of Markov Chain Expectations: the Absolutely Continuous CaseJul 12 2017We consider a family of Markov chains whose transition dynamics are affected by model parameters. Understanding the parametric dependence of (complex) performance measures of such Markov chains is often of significant interest. The derivatives of the ... More
The LPM effect in sequential bremsstrahlung: 4-gluon verticesAug 19 2016The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue study ... More
Exact Estimation for Markov Chain Equilibrium ExpectationsSep 15 2014We introduce a new class of Monte Carlo methods, which we call exact estimation algorithms. Such algorithms provide unbiased estimators for equilibrium expectations associated with real- valued functionals defined on a Markov chain. We provide easily ... More
A Note on Fine-Tuning in Mirage MediationNov 29 2005Recent progress in string theory moduli stabilization has motivated a mixed modulus-anomaly mediated supersymmetry breaking scenario, also dubbed `mirage mediation'. This scenario has a number of phenomenologically attractive features, in particular with ... More
Kempe's Universality Theorem for Rational Space CurvesSep 29 2015Nov 27 2015We prove that every bounded rational space curve of degree d and circularity c can be drawn by a linkage with 9/2 d - 6c + 1 revolute joints. Our proof is based on two ingredients. The first one is the factorization theory of motion polynomials. The second ... More
Excitation spectra of strongly correlated lattice bosons and polaritonsApr 08 2009Sep 09 2009Spectral properties of the Bose-Hubbard model and a recently proposed coupled-cavity model are studied by means of quantum Monte Carlo simulations in one dimension. Both models exhibit a quantum phase transition from a Mott insulator to a superfluid phase. ... More