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Tm$^{3+}$:Y$_3$Ga$_5$O$_{12}$ materials for spectrally multiplexed quantum memoriesAug 08 2014Oct 22 2014We investigate the relevant spectroscopic properties of the 795 nm $^3$H$_6$$\leftrightarrow$$^3$H$_4$ transition in 1% Tm$^{3+}$:Y$_3$Ga$_5$O$_{12}$ at temperatures as low as 1.2 K for optical quantum memories based on persistent spectral tailoring of ... More

Optical decoherence studies of Tm$^{3+}$:Y$_3$Ga$_5$O$_{12}$Oct 22 2014Decoherence of the 795 nm $^3$H$_6$ to $^3$H$_4$ transition in 1%Tm$^{3+}$:Y$_3$Ga$_5$O$_{12}$ (Tm:YGG) is studied at temperatures as low as 1.2 K. The temperature, magnetic field, frequency, and time-scale (spectral diffusion) dependence of the optical ... More

A rare-earth-ion-doped waveguide based on a standard photonics technology for quantum signal processingMay 09 2016We measure properties of the 795 nm $^3$H$_6$ to $^3$H$_4$ transition of a rare-earth-ion-doped waveguide, Tm$^{3+}$:Ti$^{4+}$:LiNbO$_{3}$, at temperatures as low as 800 mK. Coherence and hyperfine population lifetimes up to 117 $\mu$s and 2.5 hours, ... More

Modification of phonon processes in nanostructured rare-earth-ion-doped crystalsApr 09 2015Jun 27 2016Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals ... More

Optical decoherence and spectral diffusion in an erbium-doped silica glass fiber featuring long-lived spin sublevelsSep 23 2016Nov 21 2016Understanding decoherence in cryogenically-cooled rare-earth-ion doped glass fibers is of fundamental interest and a prerequisite for applications of these material in quantum information applications. Here we study the coherence properties in a weakly ... More

Optical decoherence and spectral diffusion in an erbium-doped silica glass fiber featuring long-lived spin sublevelsSep 23 2016Understanding decoherence in cryogenically-cooled rare-earth-ion doped glass fibers is of fundamental interest and a prerequisite for applications of these material in quantum information applications. Here we study the coherence properties in a weakly ... More

Quadratic Zeeman effect and spin-lattice relaxation of Tm$^{3+}$:YAG at high magnetic fieldsAug 22 2016Anisotropy of the quadratic Zeeman effect for the $^3{\rm H}_6 \rightarrow \, ^3{\rm H}_4$ transition at 793 nm wavelength in $^{169}$Tm$^{3+}$-doped Y$_3$Al$_5$O$_{12}$ is studied, revealing shifts ranging from near zero up to + 4.69 GHz/T$^2$ for ions ... More

A non-amenable groupoid whose maximal and reduced $C^*$-algebras are the sameApr 21 2015May 22 2015We construct a locally compact groupoid with the properties in the title. Our example is based closely on constructions used by Higson, Lafforgue, and Skandalis in their work on counterexamples to the Baum-Connes conjecture. It is a bundle of countable ... More

Higher index theory for certain expanders and Gromov monster groups IIDec 19 2010In this paper, the second of a series of two, we continue the study of higher index theory for expanders. We prove that if a sequence of graphs has girth tending to infinity, then the maximal coarse Baum-Connes assembly map is an isomorphism for the associated ... More

Effects of mechanical processing and annealing on optical coherence properties of Er$^{3+}$:LiNbO$_3$ powdersJan 20 2017Optical coherence lifetimes and decoherence processes in erbium-doped lithium niobate (Er$^{3+}$:LiNbO$_3$) crystalline powders are investigated for materials that underwent different mechanical and thermal treatments. Several complimentary methods are ... More

Electron Spin Coherences in Rare-Earth Optically Excited States for Microwave to Optical Quantum TransducersFeb 09 2018Feb 16 2018Efficient and reversible optical to microwave coherent transducers are required to enable entanglement transfer between superconducting qubits and light for quantum networks. Rare-earth-doped crystals that possess narrow optical and spin transitions are ... More

Effects of fabrication methods on spin relaxation and crystallite quality in Tm-doped Y$_2$Al$_5$O$_{12}$ powders studied using spectral hole burningSep 25 2015Apr 27 2016High-quality rare-earth-ion (REI) doped materials are a prerequisite for many applications such as quantum memories, ultra-high-resolution optical spectrum analyzers and information processing. Compared to bulk materials, REI doped powders offer low-cost ... More

Electron Spin Coherences in Rare-Earth Optically Excited States for Microwave to Optical Quantum TransducersFeb 09 2018Efficient and reversible optical to microwave coherent transducers are required to enable entanglement transfer between superconducting qubits and light for quantum networks. Rare-earth-doped crystals that possess narrow optical and spin transitions are ... More

Efficient and long-lived Zeeman-sublevel atomic population storage in an erbium-doped glass fiberJul 10 2015Jan 08 2016Long-lived population storage in optically pumped levels of rare-earth ions doped into solids, referred to as persistent spectral hole burning, is of significant fundamental and technological interest. However, the demonstration of deep and persistent ... More

Modification of relaxation dynamics in Tb$^{3+}$:Y$_3$Al$_5$O$_{12}$ nanopowdersNov 07 2017Mar 01 2018Nanostructured rare-earth-ion doped materials are increasingly being investigated for on-chip implementations of quantum information processing protocols as well as commercial applications such as fluorescent lighting. However, achieving high-quality ... More

Ghostbusting and property AMar 26 2013Apr 04 2013We show that a bounded geometry metric space X has property A if and only if all ghost operators on X are compact.

Characterization of ${}^{171}Yb^{3+}\!:\! YVO_4$ for photonic quantum technologiesMay 03 2018Rare-earth ions in crystals are a proven solid-state platform for quantum technologies in the ensemble regime and attractive for new opportunities at the single ion level. Among the trivalent rare earths, ${}^{171}\mathrm{Yb}^{3+}$ is unique in that it ... More

Roe C*-algebra for groupoids and generalized Lichnerowicz Vanishing theorem for foliated manifoldsMay 25 2016We introduce the concept of Roe C*-algebra for a locally compact groupoid whose unit space is in general not compact, and that is equipped with an appropriate coarse structure and Haar system. Using Connes' tangent groupoid method, we introduce an analytic ... More

Localization C*-algebras and K-theoretic dualitySep 21 2016Feb 27 2018Based on the localization algebras of Yu, and their subsequent analysis by Qiao and Roe, we give a new picture of KK-theory in terms of time-parametrized families of (locally) compact operators that asymptotically commute with appropriate representations. ... More

Continuous Self-Similarity and $S$-DualityNov 06 1995Nov 07 1995We study the spherically symmetric collapse of the axion/dilaton system coupled to gravity. We show numerically that the critical solution at the threshold of black hole formation is continuously self-similar. Numerical and analytical arguments both demonstrate ... More

Photon-Echo Quantum MemoryOct 01 2008The future of long-distance quantum communication relies on the availability of quantum memory, i.e. devices that allow temporal storage of quantum information. We review research related to quantum state storage based on a photon-echo approach in rare ... More

Critical properties of the Néel-to-algebraic spin liquid transitionMay 09 2019The algebraic spin liquid is a long-sought-after phase of matter characterized by the absence of quasiparticle excitations, a low-energy description in terms of emergent Dirac fermions and gauge fields interacting according to (2+1)D quantum electrodynamics ... More

Random graphs, weak coarse embeddings, and higher index theoryApr 25 2014This paper studies higher index theory for a random sequence of bounded degree, finite graphs with diameter tending to infinity. We show that in a natural model for such random sequences the following hold almost surely: the coarse Baum-Connes assembly ... More

Some notes on property ADec 17 2006May 09 2008We provide an expository account of Guoliang Yu's property A. The piece starts from the basic definitions, and goes on to discuss closure properties of the class of property A spaces (and groups) and the relationship of property A to coarse embeddability ... More

Band-Dominated Fredholm Operators and a Question of Rabinovich, Roch and SilbermannJun 28 2008Jul 05 2008Withdrawn due to a likely error with the homeomorphism at line (4). Old abstract: In the monograph 'Limit Operators and their Applications in Operator Theory', the authors define the operator spectrum of a band-dominated operator T and prove that T is ... More

Bott periodicity and almost commuting matricesJan 12 2019We give a proof of the Bott periodicity theorem for topological K-theory of C*-algebras based on Loring's treatment of Voiculescu's almost commuting matrices and Atiyah's rotation trick. We also explain how this relates to the Dirac operator on the circle; ... More

A metric approach to limit operatorsAug 04 2014Jan 13 2015We extend the limit operator machinery of Rabinovich, Roch, and Silbermann from $\mathbb{Z}^N$ to (bounded geometry, strongly) discrete metric spaces. We do not assume the presence of any group structure or action on our metric spaces. Using this machinery ... More

Cartan subalgebras in uniform Roe algebrasAug 13 2018May 16 2019In this paper we study structural and uniqueness questions for Cartan subalgebras of uniform Roe algebras. We characterise when an inclusion $B\subseteq A$ of $\mathrm{C}^*$-algebras is isomorphic to the canonical inclusion of $\ell^\infty(X)$ inside ... More

Impact Dynamics of Moons Within a Planetary PotentialApr 03 2019Current lunar origin scenarios suggest that Earth's Moon may have resulted from the merger of two (or more) smaller moonlets. Dynamical studies of multiple moons find that these satellite systems are not stable, resulting in moonlet collision or loss ... More

Geometric Property (T)Nov 25 2013Apr 25 2014This paper discusses `geometric property (T)'. This is a property of metric spaces introduced in earlier work of the authors for its applications to K-theory. Geometric property (T) is a strong form of `expansion property': in particular for a sequence ... More

On Rigidity of Roe algebrasOct 07 2011Sep 23 2013Roe algebras are C*-algebras built using large-scale (or 'coarse') aspects of a metric space (X,d). In the special case that X=G is a finitely generated group and d is a word metric, the simplest Roe algebra associated to (G,d) is isomorphic to the reduced ... More

Low dimensional properties of uniform Roe algebrasMay 03 2017Jan 04 2018The goal of this paper is to study when uniform Roe algebras have certain $C^*$-algebraic properties in terms of the underlying space: in particular, we study properties like having stable rank one or real rank zero that are thought of as low dimensional, ... More

Cartan subalgebras in uniform Roe algebrasAug 13 2018In this paper we study structural and uniqueness questions for Cartan subalgebras of uniform Roe algebras. We characterise when an inclusion $B\subseteq A$ of $\mathrm{C}^*$-algebras is isomorphic to the canonical inclusion of $\ell^\infty(X)$ inside ... More

Maximal and reduced Roe algebras of coarsely embeddable spacesOct 07 2011Gong, Wang and Yu introduced a maximal, or universal, version of the Roe C*-algebra associated to a metric space. We study the relationship between this maximal Roe algebra and the usual version, in both the uniform and non-uniform cases. The main result ... More

Higher index theory for certain expanders and Gromov monster groups IDec 19 2010In this paper, the first of a series of two, we continue the study of higher index theory for expanders. We prove that if a sequence of graphs is an expander and the girth of the graphs tends to infinity, then the coarse Baum-Connes assembly map is injective, ... More

Impact Dynamics of Moons Within a Planetary PotentialApr 03 2019Apr 04 2019Current lunar origin scenarios suggest that Earth's Moon may have resulted from the merger of two (or more) smaller moonlets. Dynamical studies of multiple moons find that these satellite systems are not stable, resulting in moonlet collision or loss ... More

Dynamic asymptotic dimension and controlled operator K-theorySep 07 2016In earlier work the authors introduced dynamic asymptotic dimension, a notion of dimension for topological dynamical systems that is finite for many interesting examples. In this paper, we use finiteness of dynamic asymptotic dimension of an action to ... More

Expanders, exact crossed products, and the Baum-Connes conjectureNov 11 2013Apr 21 2015We reformulate the Baum-Connes conjecture with coefficients by introducing a new crossed product functor for C*-algebras. All confirming examples for the original Baum-Connes conjecture remain confirming examples for the reformulated conjecture, and at ... More

Triton's Evolution with a Primordial Neptunian Satellite SystemNov 05 2017The Neptunian satellite system is unusual. The major satellites of Jupiter, Saturn, and Uranus are all in prograde, low-inclination orbits. Neptune on the other hand, has the fewest satellites, and most of the system's mass is within one irregular satellite, ... More

Topological property (T) for groupoidsNov 17 2018We introduce a notion of topological property (T) for \'etale groupoids. This simultaneously generalizes Kazhdan's property (T) for groups and geometric property (T) for coarse spaces. One main goal is to use this property (T) to prove the existence of ... More

Localization C*-algebras and K-theoretic dualitySep 21 2016Based on the localization algebras of Yu, and their subsequent analysis by Qiao and Roe, we give a new picture of KK-theory in terms of time-parametrized families of (locally) compact operators that asymptotically commute with appropriate representations. ... More

The minimal exact crossed productApr 08 2018Apr 11 2018Given a locally compact group $G$, we study the smallest exact crossed-product functor $(A,G,\alpha)\mapsto A\rtimes_{\mathcal E} G$ on the category of $G$-$C^*$-dynamical systems. As an outcome, we show that the smallest exact crossed-product functor ... More

Dynamic Asymptotic Dimension: relation to dynamics, topology, coarse geometry, and $C^*$-algebrasOct 27 2015We introduce dynamic asymptotic dimension, a notion of dimension for actions of discrete groups on locally compact spaces, and more generally for locally compact \'etale groupoids. We study our notion for minimal actions of the integer group, its relation ... More

Shear viscosity and imperfect fluidity in bosonic and fermionic superfluidsJul 28 2014Dec 07 2014In this paper we address the ratio of the shear viscosity to entropy density $\eta/s$ in bosonic and fermionic superfluids. A small $\eta/s$ is associated with nearly perfect fluidity, and more general measures of the fluidity perfection/imperfection ... More

Injectivity, crossed products, and amenable group actionsApr 14 2019This paper is motivated primarily by the question of when the maximal and reduced crossed products of a $G$-$C^*$-algebra agree (particularly inspired by results of Matsumura and Suzuki), and the relationships with various notions of amenability and injectivity. ... More

Isentropic Curves at Magnetic Phase TransitionsSep 04 2010Experiments on cold atom systems in which a lattice potential is ramped up on a confined cloud have raised intriguing questions about how the temperature varies along isentropic curves, and how these curves intersect features in the phase diagram. In ... More

Flexible recovery of uniqueness and immutability (Extended Version)Jun 30 2018Jul 18 2018We present an imperative object calculus where types are annotated with qualifiers for aliasing and mutation control. There are two key novelties with respect to similar proposals. First, the type system is very expressive. Notably, it adopts the "recovery" ... More

The spherically symmetric collapse of a massless scalar fieldJun 22 1995We report on a numerical study of the spherically symmetric collapse of a self-gravitating massless scalar field. Earlier results of Choptuik(1992, 1994) are confirmed. The field either disperses to infinity or collapses to a black hole, depending on ... More

A finite dimensional approach to the strong Novikov conjectureMar 28 2012Mar 21 2013The aim of this paper is to introduce an approach to the (strong) Novikov conjecture based on continuous families of finite dimensional representations: this is partly inspired by ideas of Lusztig using the Atiyah-Singer families index theorem, and partly ... More

Exotic crossed products and the Baum-Connes conjectureSep 15 2014Jul 04 2015We study general properties of exotic crossed-product functors and characterise those which extend to functors on equivariant C*-algebra categories based on correspondences. We show that every such functor allows the construction of a descent in KK-theory ... More

Deconfined criticality in the $\text{QED}_{3}$-Gross-Neveu-Yukawa model: the $1/N$ expansion revisitedDec 06 2018The critical properties of the $\text{QED}_{3}$-Gross-Neveu-Yukawa (GNY) model in 2+1 dimensions with $N$ flavors of two-component Dirac fermions are computed to first order in the $1/N$ expansion. For the specific case of $N=2$, the critical point is ... More

Multiple Impact Origin for the MoonMar 06 2019The hypothesis of lunar origin by a single giant impact can explain some aspects of the Earth-Moon system. However, it is difficult to reconcile giant impact models with the compositional similarity of the Earth and Moon without violating angular momentum ... More

Injectivity, crossed products, and amenable group actionsApr 14 2019Apr 28 2019This paper is motivated primarily by the question of when the maximal and reduced crossed products of a $G$-$C^*$-algebra agree (particularly inspired by results of Matsumura and Suzuki), and the relationships with various notions of amenability and injectivity. ... More

Dynamical complexity and controlled operator K-theorySep 07 2016Feb 02 2018In this paper, we introduce a property of topological dynamical systems that we call finite dynamical complexity. For systems with this property, one can in principle compute the $K$-theory of the associated crossed product $C^*$-algebra by splitting ... More

The maximal injective crossed productAug 21 2018A crossed product functor is said to be injective if it takes injective morphisms to injective morphisms. In this paper we show that every locally compact group $G$ admits a maximal injective crossed product $A\mapsto A\rtimes_{\inj}G$. Moreover, we give ... More

Exotic Crossed ProductsOct 09 2015An exotic crossed product is a way of associating a C*-algebra to each C*-dynamical system that generalizes the well-known universal and reduced crossed products. Exotic crossed products provide natural generalizations of, and tools to study, exotic group ... More

Exact correlation functions in the cuprate pseudogap phase: combined effects of charge order and pairingNov 10 2014There is a multiplicity of charge ordered, pairing-based or pair density wave theories of the cuprate pseudogap, albeit arising from different microscopic mechanisms. For mean field schemes (of which there are many) we demonstrate here that they have ... More

Two-dimensional spin-imbalanced Fermi gases at non-zero temperature: Phase separation of a non-condensateMay 05 2016We study a trapped two-dimensional spin-imbalanced Fermi gas over a range of temperatures. In the moderate temperature regime, associated with current experiments, we find reasonable semi-quantitative agreement with the measured density profiles as functions ... More

Combined effects of pairing fluctuations and a pseudogap in the Cuprate Hall effectDec 12 2018The normal-state behavior of the temperature-dependent Hall coefficient in cuprate superconductors is investigated using linear response theory. The Hall conductivity is of paramount importance in that its sign and magnitude directly reflect the sign ... More

Cuprate diamagnetism in the presence of a pseudogap: Beyond the standard fluctuation formalismOct 09 2017It is often claimed that among the strongest evidence for preformed-pair physics in the cuprates are the experimentally observed large values for the diamagnetic susceptibility and Nernst coefficient. These findings are most apparent in the underdoped ... More

Correcting inconsistencies in the conventional superfluid path integral schemeFeb 10 2016In this paper we show how to redress a shortcoming of the path integral scheme for fermionic superfluids and superconductors. This approach is built around a simultaneous calculation of electrodynamics and thermodynamics. An important sum rule, the compressibility ... More

Optimized Confinement of Fermions in Two DimensionsFeb 04 2012One of the challenging features of studying model Hamiltonians with cold atoms in optical lattices is the presence of spatial inhomogeneities induced by the confining potential, which results in the coexistence of different phases. This paper presents ... More

Gauge invariant theories of linear response for strongly correlated superconductorsFeb 05 2016Apr 19 2016We present a general diagrammatic theory for determining consistent electromagnetic response functions in strongly correlated fermionic superfluids. The general treatment of correlations beyond BCS theory requires a new theoretical formalism not contained ... More

Collective mode contributions to the Meissner effect: Fulde-Ferrell and pair-density wave superfluidsFeb 16 2017In this paper we demonstrate the necessity of including the generally omitted collective mode contributions in calculations of the Meissner effect for non-uniform superconductors. We consider superconducting pairing with non-zero center of mass momentum, ... More

Quasi-condensation in two-dimensional Fermi gasesSep 02 2015In this paper we follow the analysis and protocols of recent experiments, combined with simple theory, to arrive at a physical understanding of quasi-condensation in two dimensional Fermi gases. We find that quasi-condensation mirrors Berezinskii-Kosterlitz-Thouless ... More

Exact correlation functions in the cuprate pseudogap phase: combined effects of charge order and pairingNov 10 2014Mar 10 2017There is a multiplicity of charge ordered, pairing-based or pair density wave theories of the cuprate pseudogap, albeit arising from different microscopic mechanisms. For mean field schemes (of which there are many) we demonstrate here that they have ... More

Topological effects on transition temperatures and response functions in three-dimensional Fermi superfluidsJul 09 2015We investigate the effects of topological order on the transition temperature, $T_c$, and response functions in fermionic superfluids with Rashba spin-orbit coupling and a transverse Zeeman field in three dimensions. Our calculations, relevant to the ... More

Signatures of pairing and spin-orbit coupling in correlation functions of Fermi gasesMar 18 2015We derive expressions for spin and density correlation functions in the (greatly enhanced) pseudogap phase of spin-orbit coupled Fermi superfluids. Density-density correlation functions are found to be relatively insensitive to the presence of these Rashba ... More

Critical behavior of the QED$_3$-Gross-Neveu-Yukawa model at four loopsAug 01 2018Oct 16 2018We study the universal critical properties of the QED$_3$-Gross-Neveu-Yukawa model with $N$ flavors of four-component Dirac fermions coupled to a real scalar order parameter at four-loop order in the $\epsilon$ expansion below four dimensions. For $N=1$, ... More

Extremely fast focal-plane wavefront sensing for extreme adaptive opticsJul 13 2012We present a promising approach to the extremely fast sensing and correction of small wavefront errors in adaptive optics systems. As our algorithm's computational complexity is roughly proportional to the number of actuators, it is particularly suitable ... More

Transition between algebraic and $\mathbb{Z}_2$ quantum spin liquids at large $N$Mar 30 2018Jul 24 2018We present a field theory description of a quantum phase transition in two spatial dimensions between a $U(1)$ algebraic spin liquid with $N$ flavors of gapless two-component Dirac fermionic spinons and a gapped $\mathbb{Z}_2$ spin liquid. This transition ... More

Constraints on star formation theories from the Serpens molecular cloud and protoclusterJul 10 2002We have mapped the large-scale structure of the Serpens cloud core using moderately optically thick (13CO(1--0) and CS(2--1)) and optically thin tracers (C18O(1--0), C34S(2--1), and N2H+(1--0)), using the 16-element focal plane array operating at a wavelength ... More

Classification of Poisson-Lie T-dual models with two-dimensional targetsOct 16 2001Dec 20 2001Four-dimensional Manin triples and Drinfeld doubles are classified and corresponding two-dimensional Poisson-Lie T-dual sigma models on them are constructed. The simplest example of a Drinfeld double allowing decomposition into two nontrivially different ... More

Statistical Mechanics of Developable RibbonsFeb 24 2010Jun 11 2010We investigate the statistical mechanics of long developable ribbons of finite width and very small thickness. The constraint of isometric deformations in these ribbon-like structures that follows from the geometric separation of scales introduces a coupling ... More

A bracket polynomial for graphsAug 25 2008Jan 14 2009A knot diagram has an associated looped interlacement graph, obtained from the intersection graph of the Gauss diagram by attaching loops to the vertices that correspond to negative crossings. This construction suggests an extension of the Kauffman bracket ... More

Chapman-Enskog method and synchronization of globally coupled oscillatorsJun 12 2000Jul 10 2000The Chapman-Enskog method of kinetic theory is applied to two problems of synchronization of globally coupled phase oscillators. First, a modified Kuramoto model is obtained in the limit of small inertia from a more general model which includes ``inertial'' ... More

A Dynamical Cross-over Regime in the Transmission and Reflection Spectra of Evanescent Waves with 2D Arrays of Josephson JunctionsFeb 18 2013A dynamical cross-over regime is revealed when exposing a classical two-dimensional ordered Josephson junction (JJ) array to evanescent waves and tuning the incident microwave power. At the lowest possible temperature for these experiments, 1.1 K, and ... More

The invariant factor of the chiral determinantJul 10 2008The coupling of spin 0 and spin 1 external fields to Dirac fermions defines a theory which displays gauge chiral symmetry. Quantum mechanically, functional integration of the fermions yields the determinant of the Dirac operator, known as the chiral determinant. ... More

Derivative expansion for the effective action of chiral gauge fermions. The abnormal parity componentDec 19 2000Mar 01 2001Explicit exact formulas are presented, for the leading order term in a strict chiral covariant derivative expansion, for the abnormal parity component of the effective action of two- and four-dimensional Dirac fermions in presence of scalar, pseudo-scalar, ... More

Representation of Complex ProbabilitiesJul 19 1996Let a ``complex probability'' be a normalizable complex distribution $P(x)$ defined on $\R^D$. A real and positive probability distribution $p(z)$, defined on the complex plane $\C^D$, is said to be a positive representation of $P(x)$ if $\langle Q(x)\rangle_P ... More

Gibbs sampling of complex valued distributionsOct 30 2015Sep 26 2016A new technique is explored for the Monte Carlo sampling of complex-valued distributions. The method is based on a heat bath approach where the conditional probability is replaced by a positive representation of it on the complex plane. Efficient ways ... More

Existence of positive representations for complex weightsJun 29 2007The necessity of computing integrals with complex weights over manifolds with a large number of dimensions, e.g., in some field theoretical settings, poses a problem for the use of Monte Carlo techniques. Here it is shown that very general complex weight ... More

Derivative expansion for the effective action of chiral gauge fermions. The normal parity componentDec 19 2000Mar 01 2001Explicit exact formulas are presented, up to fourth order in a strict chiral covariant derivative expansion, for the normal parity component of the Euclidean effective action of even-dimensional Dirac fermions. The bosonic background fields considered ... More

Parity breaking in 2+1 dimensions and finite temperatureFeb 11 1998Mar 17 1999An expansion in the number of spatial covariant derivatives is carried out to compute the $\zeta$-function regularized effective action of 2+1-dimensional fermions at finite temperature in an arbitrary non-Abelian background. The real and imaginary parts ... More

Absence of classical and quantum mixingSep 15 1995It is shown, under mild assumptions, that classical degrees of freedom dynamically coupled to quantum ones do not inherit their quantum fluctuations. It is further shown that, if the assumptions are strengthen by imposing the existence of a canonical ... More

Population Models With Delay in Dynamic EnvironmentJan 05 2006Mar 15 2006We study the combined effects of periodically varying carrying capacity and survival rates on the fish population in the ocean (sea). We introduce the Getz type delay differential equation model with a control parameter which describes how fish are harvested. ... More

Optical Calibration For Jefferson Lab HKS SpectrometerNov 04 2005In order to accept very forward angle scattering particles, Jefferson Lab HKS experiment uses an on-target zero degree dipole magnet. The usual spectrometer optics calibration procedure has to be modified due to this on-target field. This paper describes ... More

On compositions of d.c. functions and mappingsJun 05 2007A d.c. (delta-convex) function on a normed linear space is a function representable as a difference of two continuous convex functions. We show that an infinite dimensional analogue of Hartman's theorem on stability of d.c. functions under compositions ... More

An alternative approach to the static spherically symmetric vacuum global solution to the Einstein's equationsJun 19 2018Sep 12 2018We propose an alternative description of the Schwarzschild black hole based on the requirement that the solution be static not only outside the horizon but also inside it. As a consequence of this assumption, we are led to a change of signature implying ... More

Skew braces and the Yang-Baxter equationNov 10 2015Mar 16 2016Braces were introduced by Rump to study non-degenerate involutive set-theoretic solutions of the Yang-Baxter equation. We generalize Rump's braces to the non-commutative setting and use this new structure to study not necessarily involutive non-degenerate ... More

Bounds on the Quenched Pressure and Main Eigenvalue of the Ruelle Operator for Brownian Type PotentialsMar 02 2016Jun 23 2016In this paper we consider a random potential derived from the Brownian motion. We obtain upper and lower bounds for the expected value of the main eigenvalue of the associated Ruelle operator and for its quenched topological pressure. We also exhibit ... More

Theory of charge fluctuations and domain relocation times in semiconductor superlatticesDec 07 2004Shot noise affects differently the nonlinear electron transport in semiconductor superlattices depending on the strength of the coupling among the superlattice quantum wells. Strongly coupled superlattices can be described by a miniband Boltzmann-Langevin ... More

New AdS(3) x G/H compactifications of chiral IIB supergravityMar 13 2000May 30 2000We present a new class of solutions of D=10, N=2 chiral supergravity. A nonvanishing background for the field strength G_{MNR} of the complex two-form triggers AdS_3 x M_7 compactifications, where M_7 is a 7-dimensional compact manifold. When M_7 is a ... More

Detailed analysis of quantum phase transitions within the $u(2)$ algebraOct 13 2009We analyze in detail the quantum phase transitions that arise in models based on the $u(2)$ algebraic description for bosonic systems with two types of scalar bosons. First we discuss the quantum phase transition that occurs in hamiltonians that admix ... More

Recent Results on $\psip$ Decays at BesMay 16 2005Recent results on $\psip$ decays, including 10 Vector + Pseudoscalar (VP) modes and $p\bar{p}\pi^0(\eta)$, are reported with $14\times10^6$ $\psip$ events collected with the BESII detector. Cross sections and form factors for $e^+e^- \to \wpi$, $\rho\eta$, ... More

The Effect of Weak Gravitational Lensing on the Angular Distribution of Gamma-Ray BurstsJun 10 1996If Gamma-Ray Bursts (GRBs) are cosmologically distributed standard candles and are associated with the luminous galaxies, then the observed angular distribution of all GRBs is altered due to weak gravitational lensing of bursts by density inhomogeneities. ... More

Expansion of a Bose-Einstein Condensate in an atomic waveguideNov 15 2001The expansion of a Bose-Einstein condensate in an atomic waveguide is analyzed. We study different regimes of expansion, and identify a transient regime between one-dimensional and three-dimensional dynamics, in which the properties of the condensate ... More

Supersymmetric domain wall x G/H solutions of IIB supergravityApr 23 20011-brane nonmaximally supersymmetric solutions of D=10 chiral supergravity are discussed. In the dual frame, their near brane geometry is the product of a 3-dimensional domain wall spacetime and a 7-dimensional homogeneous Einstein space G/H.

Hawking Radiation and Back-ReactionMar 20 1992The puzzles of black hole evaporation can be studied in the simplified context of 1+1 dimensional gravity. The semi-classical equations of Callan, Giddings, Harvey and Strominger provide a consistent description of the evaporation process which we describe ... More

Minimal surfaces bounded by elastic linesAug 02 2011May 30 2012In mathematics, the classical Plateau problem consists of finding the surface of least area that spans a given rigid boundary curve. A physical realization of the problem is obtained by dipping a stiff wire frame of some given shape in soapy water and ... More