Results for "Emanuel Tutuc"

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DFT Simulations of Inter-Graphene-Layer Coupling with Rotationally Misaligned hBN Tunnel Barriers in Graphene/hBN/Graphene Tunnel FETsOct 07 2016Van der Waal's heterostrucutures allow for novel devices such as two-dimensional-to-two-dimensional tunnel devices, exemplified by interlayer tunnel FETs. These devices employ channel/tunnel-barrier/channel geometries. However, during layer-by-layer exfoliation ... More
Coulomb Drag and Magnetotransport in Graphene Double LayersJun 13 2012We review the fabrication and key transport properties of graphene double layers, consisting of two graphene monolayers placed in close proximity, independently contacted, and separated by an ultra-thin dielectric. We outline a simple band structure model ... More
Giant Frictional Drag in Double Bilayer Graphene HeterostructuresMar 02 2016We study the frictional drag between carriers in two bilayer graphene flakes separated by a 2 $-$ 5 nm thick hexagonal boron nitride dielectric. At temperatures ($T$) lower than $\sim$ 10 K, we observe a large anomalous negative drag emerging predominantly ... More
Chemical Potential and Quantum Hall Ferromagnetism in Bilayer GrapheneJan 03 2014Jul 07 2014Bilayer graphene has a unique electronic structure influenced by a complex interplay between various degrees of freedom. We probe its chemical potential using double bilayer graphene heterostructures, separated by a hexagonal boron nitride dielectric. ... More
Spin-Polarized to Valley-Polarized Transition in Graphene Bilayers at $ν=0$ in High Magnetic FieldsFeb 01 2011Jul 04 2011We investigate the transverse electric field ($E$) dependence of the $\nu$=0 quantum Hall state (QHS) in dual-gated graphene bilayers in high magnetic fields. The longitudinal resistivity ($\rho_{xx}$) measured at $\nu$=0 shows an insulating behavior ... More
Structural and Electrical Properties of MoTe$_2$ and MoSe$_2$ Grown by Molecular Beam EpitaxyMar 08 2016Mar 09 2016We demonstrate the growth of thin films of molybdenum ditelluride and molybdenum diselenide on sapphire substrates by molecular beam epitaxy. In-situ structural and chemical analyses reveal stoichiometric layered film growth with atomically smooth surface ... More
Dielectric Thickness Dependence of Carrier Mobility in Graphene with HfO2 Top DielectricOct 05 2010We investigate the carrier mobility in mono- and bi-layer graphene with a top HfO2 dielectric, as a function of the HfO2 film thickness and temperature. The results show that the carrier mobility decreases during the deposition of the first 2-4 nm of ... More
Lateral Spin Injection in Germanium NanowiresMar 19 2010Aug 24 2010Electrical injection of spin-polarized electrons into a semiconductor, large spin diffusion length, and an integration friendly platform are desirable ingredients for spin-based devices. Here we demonstrate lateral spin injection and detection in germanium ... More
Hubbard model physics in transition metal dichalcogenide moiré bandsApr 09 2018Jun 27 2018Flexible long period moir\' e superlattices form in two-dimensional van der Waals crystals containing layers that differ slightly in lattice constant or orientation. In this Letter we show theoretically that isolated flat moir\' e bands described by generalized ... More
Photonic-Crystal Exciton-Polaritons in Monolayer SemiconductorsJun 26 2017Sep 27 2017Semiconductor microcavity polaritons, formed via strong exciton-photon coupling, provide a quantum many-body system on a chip, featuring rich physics phenomena for better photonic technology. However, conventional polariton cavities are bulky, difficult ... More
Interaction and disorder in bilayer counterflow transport at filling factor oneApr 05 2005We study high mobility, interacting GaAs bilayer hole systems exhibiting counterflow superfluid transport at total filling factor $\nu=1$. As the density of the two layers is reduced, making the bilayer more interacting, the counterflow Hall resistivity ... More
Atomistic simulation of the electronic states of adatoms in monolayer MoS2May 30 2013Mar 26 2014Using an ab initio density functional theory (DFT) based electronic structure method, we study the effects of adatoms on the electronic properties of monolayer transition metal dichalcogenide (TMD) Molybdenum-disulfide (MoS2). We consider the 1st (Li, ... More
From Exceptional Field Theory to Heterotic Double Field Theory via K3Dec 06 2016In this paper we show how to obtain the heterotic double field theory from exceptional field theory by breaking half of the supersymmetry. We focus on the $\mathrm{SL}(5)$ exceptional field theory and show that when the extended space contains a generalised ... More
The Perception of Time, Risk and Return During Periods of SpeculationJan 18 2002What return should you expect when you take on a given amount of risk? How should that return depend upon other people's behavior? What principles can you use to answer these questions? In this paper, we approach these topics by exploring the consequences ... More
Graph generated union-closed families of setsSep 16 1994Let G be a graph with vertices V and edges E. Let F be the union-closed family of sets generated by E. Then F is the family of subsets of V without isolated points. Theorem: There is an edge e belongs to E such that |{U belongs to F | e belongs to U}| ... More
Minimality and nonergodicity on a family of flat surfaces in genus 3Jan 03 2008We prove that a certain family of flat surfaces in genus 3 does not fulfill Veech's Dichotomy. These flat surfaces provide uncountably many minimal but nonergodic directions. The conditions on this family are a combinatorical one and an irrationality ... More
Invertible families of sets of bounded degreeSep 16 1994Let H = (H,V) be a hypergraph with edge set H and vertex set V. Then hypergraph H is invertible iff there exists a permutation pi of V such that for all E belongs to H(edges) intersection of(pi(E) and E)=0. H is invertibility critical if H is not invertible ... More
A sharp inequality for the Strichartz normSep 23 2008Let $u:\R \times \R^n \to \C$ be the solution of the linear Schr\"odinger equation $iu_t + \Delta u =0$ with initial data $u(0,x) = f(x)$. In the first part of this paper we obtain a sharp inequality for the Strichartz norm $\|u(t,x)\|_{L^{2k}_tL^{2k}_x(\R ... More
An analysis of Bennett's pebble gameAug 08 1995Bennett's pebble game was introduced to obtain better time/space tradeoffs in the simulation of standard Turing machines by reversible ones. So far only upper bounds for the tradeoff based on the pebble game have been published. Here we give a recursion ... More
Sharp approximations to the Bernoulli periodic functions by trigonometric polynomialsSep 23 2008Oct 29 2008We obtain optimal trigonometric polynomials of a given degree $N$ that majorize, minorize and approximate in $L^1(\mathbb{R}/\mathbb{Z})$ the Bernoulli periodic functions. These are the periodic analogues of two works of F. Littmann that generalize a ... More
Interlayer Exciton Laser with Extended Spatial Coherence in an Atomically-Thin HeterostructureJan 03 2019Two-dimensional semiconductors have emerged as a new class of materials for nanophotonics for their strong exciton-photon interaction and flexibility for engineering and integration. Taking advantage of these properties, we engineer an efficient lasing ... More
Scaling Properties of Ge-SixGe1-x Core-Shell Nanowire Field Effect TransistorsDec 09 2009We demonstrate the fabrication of high-performance Ge-SixGe1-x core-shell nanowire field-effect transistors with highly doped source and drain, and systematically investigate their scaling properties. Highly doped source and drain regions are realized ... More
Topological insulators in twisted transition metal dichalcogenide homobilayersJul 09 2018Feb 11 2019We show that moir\'e bands of twisted homobilayers can be topologically nontrivial, and illustrate the tendency by studying valence band states in $\pm K$ valleys of twisted bilayer transition metal dichalcogenides, in particular, bilayer MoTe$_2$. Because ... More
Advances in Artificial Intelligence: Deep Intentions, Shallow AchievementsMay 18 2015Over the past decade, AI has made a remarkable progress due to recently revived Deep Learning technology. Deep Learning enables to process large amounts of data using simplified neuron networks that simulate the way in which the brain works. At the same ... More
You want to survive the data deluge: Be careful, Computational Intelligence will not serve you as a rescue boatJul 20 2016We are at the dawn of a new era, where advances in computer power, broadband communication and digital sensor technologies have led to an unprecedented flood of data inundating our surrounding. It is generally believed that means such as Computational ... More
The physical and circuit-theoretic significance of the Memristor : Full versionFeb 07 2016Feb 10 2016It is observed that the inductive and capacitive features of the memristor reflect (and are a quintessence of) such features of any resistor. The very presence of the voltage and current state variables, associated by their electrodynamics sense with ... More
Dualising consistent truncationsDec 30 2015We use exceptional field theory to establish a duality between certain consistent 7-dimensional truncations with maximal SUSY from IIA to IIB. We use this technique to obtain new consistent truncations of IIB on $S^3$ and $H^{p,q}$ and also give a no-go ... More
Beyond traditional Curvature-Dimension I: new model spaces for isoperimetric and concentration inequalities in negative dimensionSep 14 2014Aug 03 2015We study the isoperimetric, functional and concentration properties of $n$-dimensional weighted Riemannian manifolds satisfying the Curvature-Dimension condition, when the generalized dimension $N$ is negative, and more generally, is in the range $N \in ... More
Cognitive Surveillance: Why does it never appear among the AVSS Conferences topics?Jun 22 2014Video Surveillance is a fast evolving field of research and development (R&D) driven by the urgent need for public security and safety (due to the growing threats of terrorism, vandalism, and anti-social behavior). Traditionally, surveillance systems ... More
Cognitive Robotics: for never was a story of more woe than thisJan 08 2014Jul 19 2014We are now on the verge of the next technical revolution - robots are going to invade our lives. However, to interact with humans or to be incorporated into a human "collective" robots have to be provided with some human-like cognitive abilities. What ... More
A Proof of Bobkov's Spectral Bound For Convex Domains via Gaussian Fitting and Free Energy EstimationFeb 05 2012We obtain a new proof of Bobkov's lower bound on the first positive eigenvalue of the (negative) Neumann Laplacian (or equivalently, the Cheeger constant) on a bounded convex domain $K$ in Euclidean space. Our proof avoids employing the localization method ... More
An approximate analytical (structural) superposition in terms of two, or more, "alfa"-circuits of the same topology: Pt. 2 - the "internal circuit mechanism"Apr 26 2010Apr 27 2010This is the second part, after [1], of the research devoted to analysis of 1-ports composed of similar conductors ("f-circuits") described by the characteristic i = f(v) of a polynomial type. This analysis is performed by means of the power-law "alfa"-circuits" ... More
When you talk about "Information processing" what actually do you have in mind?Dec 19 2012"Information Processing" is a recently launched buzzword whose meaning is vague and obscure even for the majority of its users. The reason for this is the lack of a suitable definition for the term "information". In my attempt to amend this bizarre situation, ... More
Unveiling the mystery of visual information processing in human brainJul 02 2008It is generally accepted that human vision is an extremely powerful information processing system that facilitates our interaction with the surrounding world. However, despite extended and extensive research efforts, which encompass many exploration fields, ... More
Modeling Visual Information Processing in Brain: A Computer Vision Point of View and ApproachAug 07 2007We live in the Information Age, and information has become a critically important component of our life. The success of the Internet made huge amounts of it easily available and accessible to everyone. To keep the flow of this information manageable, ... More
A comment on the low-dimensional Busemann-Petty problemDec 10 2005The generalized Busemann-Petty problem asks whether centrally-symmetric convex bodies having larger volume of all m-dimensional sections necessarily have larger volume. When m>3 this is known to be false, but the cases m=2,3 are still open. In those cases, ... More
Generalized Intersection BodiesDec 02 2005Apr 28 2006We study the structures of two types of generalizations of intersection-bodies and the problem of whether they are in fact equivalent. Intersection-bodies were introduced by Lutwak and played a key role in the solution of the Busemann-Petty problem. A ... More
Searching for image information content, its discovery, extraction, and representationMay 02 2005Image information content is known to be a complicated and controvercial problem. This paper posits a new image information content definition. Following the theory of Solomonoff-Kolmogorov-Chaitin's complexity, we define image information content as ... More
Switched systems and the logical foundation of circuit theoryDec 15 2008Switched (singular) systems become very common, which requires some revision of the conceptual basis of system theory.
On the concept of switching nonlinearity (a comment on "Switching control of linear systems for generating chaos" by X. Liu, K-L. Teo, H. Zhang and G. Chen)Mar 21 2008Mar 22 2008It is explained and stressed that the chaotic states in [1] are obtained by means of nonlinear switching.
On the role of Convexity in Isoperimetry, Spectral-Gap and ConcentrationDec 26 2007Dec 24 2008We show that for convex domains in Euclidean space, Cheeger's isoperimetric inequality, spectral gap of the Neumann Laplacian, exponential concentration of Lipschitz functions, and the a-priori weakest requirement that Lipschitz functions have \emph{arbitrarily ... More
Notes on the connectivity of Cayley coset digraphsNov 10 1994Hamidoune's connectivity results for hierarchical Cayley digraphs are extended to Cayley coset digraphs and thus to arbitrary vertex transitive digraphs. It is shown that if a Cayley coset digraph can be hierarchically decomposed in a certain way, then ... More
Sharp Isoperimetric Inequalities and Model Spaces for Curvature-Dimension-Diameter ConditionAug 23 2011Aug 29 2012We obtain new sharp isoperimetric inequalities on a Riemannian manifold equipped with a probability measure, whose generalized Ricci curvature is bounded from below (possibly negatively), and generalized dimension and diameter of the convex support are ... More
Spectral Estimates, Contractions and HypercontractivityAug 03 2015Jul 14 2016Sharp comparison theorems are derived for all eigenvalues of the (weighted) Laplacian, for various classes of weighted-manifolds (i.e. Riemannian manifolds endowed with a smooth positive density). Examples include Euclidean space endowed with strongly ... More
Advances in Computational Biology: A Real Boost or a Wishful ThinkingMay 18 2015Computational biology is on the verge of a paradigm shift in its research practice - from a data-based (computational) paradigm to an information-based (cognitive) paradigm. As in the other research fields, this transition is impeded by lack of a right ... More
Harmonic Measures on the Sphere via Curvature-DimensionMay 16 2015We show that the family of probability measures on the $n$-dimensional unit sphere, having density proportional to: \[ S^n \ni y \mapsto \frac{1}{|y - x|^{n+\alpha}}, \] satisfies the Curvature-Dimension condition $CD(n-1-\frac{n+\alpha}{4},-\alpha)$, ... More
Advances in Artificial Intelligence: Are you sure, we are on the right track?Feb 17 2015Over the past decade, AI has made a remarkable progress. It is agreed that this is due to the recently revived Deep Learning technology. Deep Learning enables to process large amounts of data using simplified neuron networks that simulate the way in which ... More
The Spatial Structure of Transnational Human ActivityJan 23 2015Recent studies have shown that the spatial structures of animal displacements and local-scale human motion follow L\'{e}vy flights. Whether transnational human activity (THA) also exhibits such a pattern has however not been thoroughly examined as yet. ... More
Not only a lack of right definitions: Arguments for a shift in information-processing paradigmSep 01 2010Machine Consciousness and Machine Intelligence are not simply new buzzwords that occupy our imagination. Over the last decades, we witness an unprecedented rise in attempts to create machines with human-like features and capabilities. However, despite ... More
Higher dimensional conformal metrics from PDEs and Null Surface Formulation of GRNov 14 2011May 31 2012We analyze the relationship between $n$-dimensional conformal metrics and a certain class of partial differential equations (PDEs) that are in duality with the eikonal equation. In particular, we extend the Null Surface Formulation of General Relativity ... More
The nonlinear-by-switching systems (a heuristic discussion of some basic singular systems)Jan 23 2008Jan 24 2008Electronics has changed greatly during recent decades, and some its basic concepts should be revisited. Starting from the sampling procedure, we consider some mathematical, physical and engineering aspects related to singular, mainly switching, systems. ... More
Generating Static Black Holes in Higher Dimensional Space-TimesOct 30 2003Nov 06 2003In this article we extend to higher dimensional space-times a recent theorem proved by Salgado which characterizes a three-parameter family of static and spherically symmetric solutions to the Einstein Field Equations. As it happens in four dimensions, ... More
I'm sorry to say, but your understanding of image processing fundamentals is absolutely wrongAug 01 2008The ongoing discussion whether modern vision systems have to be viewed as visually-enabled cognitive systems or cognitively-enabled vision systems is groundless, because perceptual and cognitive faculties of vision are separate components of human (and ... More
Generalized Intersection Bodies are not EquivalentJan 26 2007Feb 04 2007In 2000, A. Koldobsky asked whether two types of generalizations of the notion of an intersection-body, are in fact equivalent. The structures of these two types of generalized intersection-bodies have been studied by the author in [], ... More
A remark on two duality relationsMar 19 2006Jun 17 2006We remark that an easy combination of two known results yields a positive answer, up to log(n) terms, to a duality conjecture that goes back to Pietsch. In particular, we show that for any two symmetric convex bodies K,T in R^n, denoting by N(K,T) the ... More
Paving the Way for Image Understanding: A New Kind of Image Decomposition is DesiredJul 22 2005In this paper we present an unconventional image segmentation approach which is devised to meet the requirements of image understanding and pattern recognition tasks. Generally image understanding assumes interplay of two sub-processes: image information ... More
D-branes on some one- and two-parameter Calabi-Yau hypersurfacesDec 21 1999Feb 10 2000D-branes on one-parameter Calabi-Yau spaces and two-parameter K3-fibered Calabi-Yau manifolds are analyzed from both the Gepner model point of view and the geometric perspective. We compute part of the spectrum of the boundary states and comment on the ... More
One-dimensional guarded fragmentsApr 09 2019We call a first-order formula one-dimensional if its every maximal block of existential (universal) quantifiers leaves at most one variable free. We consider the one-dimensional restrictions of the guarded fragment, GF, and the tri-guarded fragment, TGF, ... More
Half-maximal supersymmetry from exceptional field theoryJul 03 2017Oct 09 2017We study $D \geq 4$-dimensional half-maximal flux backgrounds using exceptional field theory. We define the relevant generalised structures and also find the integrability conditions which give warped half-maximal $\mathrm{Minkowski}_D$ and $\mathrm{AdS}_D$ ... More
On the role of Convexity in Functional and Isoperimetric InequalitiesApr 03 2008Dec 24 2008This is a continuation of our previous work 0712.4092. It is well known that various isoperimetric inequalities imply their functional ``counterparts'', but in general this is not an equivalence. We show that under certain convexity assumptions (e.g. ... More
Lower bounds for identifying subset members with subset queriesNov 03 1994An instance of a group testing problem is a set of objects $\cO$ and an unknown subset $P$ of $\cO$. The task is to determine $P$ by using queries of the type ``does $P$ intersect $Q$'', where $Q$ is a subset of $\cO$. This problem occurs in areas such ... More
Non-transversal intersection of the free and fixed boundary in the mean-field theory of superconductivityOct 20 2018Non-transversal intersection of the free and fixed boundary is shown to hold and a classification of blow-up solutions is given for obstacle problems generated by fully nonlinear uniformly elliptic operators in two dimensions which appear in the mean-field ... More
Analytic Continuation of Hypergeometric Functions in the Resonant CaseFeb 03 2016We perform the analytic continuation of solutions to the hypergeometric differential equation of order $n$ to the third regular singularity, usually denoted $z=1$, with the help of recurrences of their Mellin--Barnes integral representations. In the resonant ... More
On the confinement of semiflexible chains under torsionDec 27 2012The effect of a finite torque on semiflexible polymers in a confined environment is investigated. It is shown how a new lengthscale appears in the strongly confined limit. The influence of a torque on the extension of biopolymers in nanochannels is also ... More
Let us first agree on what the term "semantics" means: An unorthodox approach to an age-old debateJan 01 2012Traditionally, semantics has been seen as a feature of human language. The advent of the information era has led to its widespread redefinition as an information feature. Contrary to this praxis, I define semantics as a special kind of information. Revitalizing ... More
An approximate analytical (structural) superposition in terms of two, or more, "alfa"-circuits of the same topology: Pt.1 - description of the superpositionApr 23 2010Apr 26 2010One-ports named "f-circuits", composed of similar conductors described by a monotonic polynomial, or quasi-polynomial (i.e. with positive but not necessarily integer, powers) characteristic i = f(v) are studied, focusing on the algebraic map f --> F. ... More
Free boundary regularity in the optimal partial transport problemOct 11 2012Mar 19 2013In the optimal partial transport problem, one is asked to transport a fraction $0<m \leq \min\{||f||_{L^1}, ||g||_{L^1}\}$ of the mass of $f=f \chi_\Omega$ onto $g=g\chi_\Lambda$ while minimizing a transportation cost. If $f$ and $g$ are bounded away ... More
The "psychological map of the brain", as a personal information card (file), - a project for the student of the 21st centuryJan 17 2011Jan 19 2011We suggest a procedure that is relevant both to electronic performance and human psychology, so that the creative logic and the respect for human nature appear in a good agreement. The idea is to create an electronic card containing basic information ... More
On the mathematical representation of nonlinearityJul 07 2008Oct 24 2008The suggestion of writing, for some problems, nonlinear state equations not as dx/dt = F(x,u,t), but as dx/dt = [A(t,x)]x + [B(t,x)]u(t), which is more "constructive", is considered supported by arguments related to: the axiomatization of system theory, ... More
In Quest of Image Semantics: Are We Looking for It Under the Right Lamppost?Sep 02 2006In the last years we witness a dramatic growth of research focused on semantic image understanding. Indeed, without understanding image content successful accomplishment of any image-processing task is simply incredible. Up to the recent times, the ultimate ... More
A converse to Maz'ya's inequality for capacities under curvature lower boundMar 27 2009We survey some classical inequalities due to Maz'ya relating isocapacitary inequalities with their functional and isoperimetric counterparts in a measure-metric space setting, and extend Maz'ya's lower bound for the $q$-capacity ($q>1$) in terms of the ... More
Isoperimetric and Concentration Inequalities - Equivalence under Curvature Lower BoundFeb 09 2009Dec 01 2009It is well known that isoperimetric inequalities imply in a very general measure-metric-space setting appropriate concentration inequalities. The former bound the boundary measure of sets as a function of their measure, whereas the latter bound the measure ... More
Does a Plane Imitate a Bird? Does Computer Vision Have to Follow Biological Paradigms?Nov 04 2005We posit a new paradigm for image information processing. For the last 25 years, this task was usually approached in the frame of Treisman's two-stage paradigm [1]. The latter supposes an unsupervised, bottom-up directed process of preliminary information ... More
7-dimensional ${\cal N}=2$ Consistent Truncations using $\mathrm{SL}(5)$ Exceptional Field TheoryDec 06 2016We show how to construct seven-dimensional half-maximally supersymmetric consistent truncations of 11-/10-dimensional SUGRA using $\mathrm{SL}(5)$ exceptional field theory. Such truncations are defined on generalised $\mathrm{SU}(2)$-structure manifolds ... More
Generalized degrees and densities for families of setsNov 08 1994Let F be a family of subsets of {1,2,...,n}. The width-degree of an element x in at least one member of F is the width of the family {U in F | x in U}. If F has maximum width-degree at most k, then F is locally k-wide. Bounds on the size of locally k-wide ... More
Autoequivalences of twisted K3 surfacesNov 02 2017Jan 31 2019Derived equivalences of twisted K3 surfaces induce twisted Hodge isometries between them; that is, isomorphisms of their cohomologies which respect certain natural lattice structures and Hodge structures. We prove a criterion for when a given Hodge isometry ... More
Field-effect transistors and intrinsic mobility in ultra-thin MoSe2 layersNov 13 2012We report the fabrication of back-gated field-effect transistors (FETs) using ultra-thin, mechanically exfoliated MoSe2 flakes. The MoSe2 FETs are n-type and possess a high gate modulation, with On/Off ratios larger than 106. The devices show asymmetric ... More
Spin polarization and g-factor of a dilute GaAs two-dimensional electron systemJul 06 2001Apr 11 2002The effective g-factor ($g^{*}$) of a dilute interacting two-dimensional electron system is expected to increase with respect to its bare value as the density is lowered, and to eventually diverge as the system makes a transition to a ferromagnetic state. ... More
Shubnikov-de Haas oscillations of high mobility holes in monolayer and bilayer WSe$_2$: Landau level degeneracy, effective mass, and negative compressibilityFeb 02 2016We study the magnetotransport properties of high mobility holes in monolayer and bilayer WSe$_2$, which display well defined Shubnikov-de Haas (SdH) oscillations, and quantum Hall states (QHSs) in high magnetic fields. In both mono and bilayer WSe$_2$, ... More
Strong Aharonov-Bohm oscillations in GaAs two-dimensional holesDec 27 2006Mar 07 2007We measured Aharonov-Bohm resistance oscillations in a shallow two-dimensional GaAs hole ring structure, defined by local anodic surface oxidation. The amplitude of the oscillations is about 10% of the ring resistance, the strongest seen in a hole system. ... More
Zeeman splitting of interacting two-dimensional electrons with two effective massesJun 05 2006Jun 06 2006We have realized an AlAs two-dimensional electron system in which electrons occupy conduction-band valleys with different Fermi contours and effective masses. In the quantum Hall regime, we observe both resistivity spikes and persistent gaps at crossings ... More
Strongly enhanced tunneling at total charge neutrality in double bilayer graphene-WSe$_2$ heterostructuresFeb 20 2018Apr 13 2018We report the experimental observation of strongly enhanced tunneling between graphene bilayers through a WSe$_2$ barrier when the graphene bilayers are populated with carriers of opposite polarity and equal density. The enhanced tunneling increases sharply ... More
Giant frictional drag in strongly interacting bilayers near filling factor oneAug 28 2008We study the frictional drag in high mobility, strongly interacting GaAs bilayer hole systems in the vicinity of the filling factor $\nu=1$ quantum Hall state (QHS), at the same fillings where the bilayer resistivity displays a reentrant insulating phase. ... More
Counterflow measurements in strongly correlated GaAs hole bilayers: evidence for electron-hole pairingFeb 06 2004Jul 09 2004We study interacting GaAs bilayer hole systems, with very small interlayer tunneling, in a counterflow geometry where equal currents are passed in opposite directions in the two, independently contacted layers. At low temperatures, both the longitudinal ... More
Highly Valley-Polarized Singlet and Triplet Interlayer Excitons in van der Waals HeterostructureJan 01 2019Jan 31 2019Two-dimensional semiconductors feature valleytronics phenomena due to locking of the spin and momentum valley of the electrons. However, the valley polarization is intrinsically limited in monolayer crystals by the fast intervalley electron-hole exchange. ... More
Density-Dependent Quantum Hall States and Zeeman Splitting in Monolayer and Bilayer WSe$_2$Feb 16 2017We report a study of the quantum Hall states (QHSs) sequence of holes in mono- and bilayer WSe$_2$. The QHSs sequence transitions between predominantly even and predominantly odd filling factors as the hole density is tuned in the range $1.6 - 12\times10^{12}$ ... More
Realization of a High Mobility Dual-gated Graphene Field Effect Transistor with Al2O3 DielectricJan 19 2009Sep 12 2009We fabricate and characterize dual-gated graphene field-effect transistors (FETs) using Al2O3 as top-gate dielectric. We use a thin Al film as a nucleation layer to enable the atomic layer deposition of Al2O3. Our devices show mobility values of over ... More
Silicon-based Infrared Metamaterials with Ultra-Sharp Fano ResonancesSep 25 2013Metamaterials and meta-surfaces represent a remarkably versatile platform for light manipulation, biological and chemical sensing, nonlinear optics, and even spaser lasing. Many of these applications rely on the resonant nature of metamaterials, which ... More
Bounding $ζ(s)$ in the critical stripAug 29 2010Assuming the Riemann Hypothesis, we make use of the recently discovered \cite{CLV} extremal majorants and minorants of prescribed exponential type for the function $\log\left(\tfrac{4 + x^2}{(\alpha-1/2)^2 + x^2}\right)$ to find upper and lower bounds ... More
Extremal problems in de Branges spaces: the case of truncated and odd functionsDec 02 2014In this paper we find extremal one-sided approximations of exponential type for a class of truncated and odd functions with a certain exponential subordination. These approximations optimize the $L^1(\mathbb{R}, |E(x)|^{-2}dx)$-error, where $E$ is an ... More
Weak lensing in a plasma medium and gravitational deflection of massive particles using the Gauss-Bonnet theorem. A unified treatmentApr 16 2018Jun 09 2018We apply the Gauss-Bonnet theorem to the study of light rays in a plasma medium in a static and spherically symmetric gravitational field and also to the study of timelike geodesics followed for test massive particles in a spacetime with the same symmetries. ... More
Expressions for optical scalars and deflection angle at second order in terms of curvature scalarsDec 11 2017Apr 01 2018We present formal expressions for the optical scalars in terms of the curvature scalars in the weak gravitational lensing regime at second order in perturbations of a flat background without mentioning the extension of the lens or their shape. Also, by ... More
Matrix Factorizations, Massey Products and F-Terms for Two-Parameter Calabi-Yau HypersurfacesDec 12 2008We discuss B-type tensor product branes in mirrors of two-parameter Calabi-Yau hypersurfaces, using the language of matrix factorizations. We determine the open string moduli of the branes at the Gepner point. By turning on both bulk and boundary moduli ... More
Transference Principles for Log-Sobolev and Spectral-Gap with Applications to Conservative Spin SystemsFeb 23 2012We obtain new principles for transferring log-Sobolev and Spectral-Gap inequalities from a source metric-measure space to a target one, when the curvature of the target space is bounded from below. As our main application, we obtain explicit estimates ... More
Graphical NewtonAug 05 2015Apr 25 2016Computing the Newton step for a generic function $f: \mathbb{R}^N \rightarrow \mathbb{R}$ takes $O(N^{3})$ flops. In this paper, we explore avenues for reducing this bound, when the computational structure of $f$ is known beforehand. It is shown that ... More
Nonlinear Time Series Modeling: A Unified Perspective, Algorithm, and ApplicationAug 03 2013Dec 24 2017A new comprehensive approach to nonlinear time series analysis and modeling is developed in the present paper. We introduce novel data-specific mid-distribution based Legendre Polynomial (LP) like nonlinear transformations of the original time series ... More
Graphical NewtonAug 05 2015Oct 08 2017Computing the Newton step for a generic function $f: \mathbb{R}^N \rightarrow \mathbb{R}$ takes $O(N^{3})$ flops. In this paper, we explore avenues for reducing this bound, when the computational structure of $f$ is known beforehand. It is shown that ... More
Towards Open String Mirror Symmetry for One-Parameter Calabi-Yau HypersurfacesMay 07 2008Jun 21 2008This work is concerned with branes and differential equations for one-parameter Calabi-Yau hypersurfaces in weighted projective spaces. For a certain class of B-branes we derive the inhomogeneous Picard--Fuchs equations satisfied by the brane superpotential. ... More
Complemented Brunn-Minkowski Inequalities and Isoperimetry for Homogeneous and Non-Homogeneous MeasuresAug 26 2013Jun 21 2014Elementary proofs of sharp isoperimetric inequalities on a normed space $(\mathbb{R}^n,||\cdot||)$ equipped with a measure $\mu = w(x) dx$ so that $w^p$ is homogeneous are provided, along with a characterization of the corresponding equality cases. When ... More
Entire approximations for a class of truncated and odd functionsSep 06 2013We solve the problem of finding optimal entire approximations of prescribed exponential type (unrestricted, majorant and minorant) for a class of truncated and odd functions with a shifted exponential subordination, minimizing the $L^1(\R)$-error. The ... More