Results for "M. J. Gullans"

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Optical Control of Donor Spin Qubits in SiliconJul 28 2015Oct 26 2015We show how to achieve optical, spin-selective transitions from the ground state to excited orbital states of group-V donors (P, As, Sb, Bi) in silicon. We consider two approaches based on either resonant, far-infrared (IR) transitions of the neutral ... More
A Quantum Network of Silicon Qubits using Mid-Infrared Graphene PlasmonsJul 25 2014We consider a quantum network of mid-infrared, graphene plasmons coupled to the hydrogen-like excited states of group-V donors in silicon. First, we show how to use plasmon-enhanced light-matter interactions to achieve single-shot spin readout of the ... More
Probing electron-phonon interactions in the charge-photon dynamics of cavity-coupled double quantum dotsNov 03 2017Electron-phonon coupling is known to play an important role in the charge dynamics of semiconductor quantum dots. Here we explore its role in the combined charge-photon dynamics of cavity-coupled double quantum dots. Previous work on these systems has ... More
Photon thermalization via laser cooling of atomsDec 22 2017Sep 20 2018Laser cooling of atomic motion enables a wide variety of technological and scientific explorations using cold atoms. Here we focus on the effect of laser cooling on the photons instead of on the atoms. Specifically, we show that non-interacting photons ... More
Phonon-Assisted Gain in a Semiconductor Double Quantum Dot MaserJan 14 2015Apr 13 2015We develop a microscopic model for the recently demonstrated double quantum dot (DQD) maser. In characterizing the gain of this device we find that, in addition to the direct stimulated emission of photons, there is a large contribution from the simultaneous ... More
Preparation of Non-equilibrium Nuclear Spin States in Double Quantum DotsDec 31 2012Jul 25 2014We theoretically study the dynamic polarization of lattice nuclear spins in GaAs double quantum dots containing two electrons. In our prior work [Phys. Rev. Lett. 104, 226807 (2010)] we identified three regimes of long-term dynamics, including the build ... More
Valley blockade in a silicon double quantum dotJul 20 2016Electrical transport in double quantum dots (DQDs) illuminates many interesting features of the dots' carrier states. Recent advances in silicon quantum information technologies have renewed interest in the valley states of electrons confined in silicon. ... More
Valley blockade in a silicon double quantum dotJul 20 2016Nov 08 2017Electrical transport in double quantum dots (DQDs) illuminates many interesting features of the dots' carrier states. Recent advances in silicon quantum information technologies have renewed interest in the valley states of electrons confined in silicon. ... More
High-Order Multipole Radiation from Quantum Hall States in Dirac MaterialsJan 12 2017Jun 23 2017We investigate the optical response of strongly disordered quantum Hall states in two-dimensional Dirac materials and find qualitatively different effects in the radiation properties of the bulk versus the edge. We show that the far-field radiation from ... More
Injection Locking of a Semiconductor Double Quantum Dot MicromaserAug 17 2015Emission linewidth is an important figure of merit for masers and lasers. We recently demonstrated a semiconductor double quantum dot (DQD) micromaser where photons are generated through single electron tunneling events. Charge noise directly couples ... More
Sisyphus Thermalization of Photons in a Cavity-Coupled Double Quantum DotDec 03 2015Oct 11 2016We investigate the non-classical states of light that emerge in a microwave resonator coupled to a periodically-driven electron in a nanowire double quantum dot (DQD). Under certain drive configurations, we find that the resonator approaches a thermal ... More
Semiconductor double quantum dot micromaserJul 22 2015The coherent generation of light, from masers to lasers, relies upon the specific structure of the individual emitters that lead to gain. Devices operating as lasers in the few-emitter limit provide opportunities for understanding quantum coherent phenomena, ... More
Photon thermalization via laser cooling of atomsDec 22 2017Laser cooling of atomic motion enables a wide variety of technological and scientific explorations using cold atoms. Here we focus on the effect of laser cooling on the photons instead of on the atoms. Specifically, we show that non-interacting photons ... More
Bose Condensation of Photons Thermalized via Laser Cooling of AtomsSep 20 2018A Bose-Einstein condensate (BEC) is a quantum phase of matter achieved at low temperatures. Photons, one of the most prominent species of bosons, do not typically condense due to the lack of a particle number-conservation. We recently described a photon ... More
Localization as an entanglement phase transition in boundary-driven Anderson modelsJan 31 2019The Anderson localization transition is one of the most well studied examples of a zero temperature quantum phase transition. On the other hand, many open questions remain about the phenomenology of disordered systems driven far out of equilibrium. Here ... More
Nanoplasmonic Lattices for Ultracold atomsAug 30 2012Jul 25 2014We propose to use sub-wavelength confinement of light associated with the near field of plasmonic systems to create nanoscale optical lattices for ultracold atoms. Our approach combines the unique coherence properties of isolated atoms with the sub-wavelength ... More
Quantum Nonlinear Optics Near Optomechanical InstabilitiesApr 14 2014Oct 02 2014Optomechanical systems provide a unique platform for observing quantum behavior of macroscopic objects. However, efforts towards realizing nonlinear behavior at the single photon level have been inhibited by the small size of the radiation pressure interaction. ... More
Threshold Dynamics of a Semiconductor Single Atom MaserApr 06 2017We demonstrate a single-atom maser consisting of a semiconductor double quantum dot (DQD) that is embedded in a high quality factor microwave cavity. A finite bias drives the DQD out of equilibrium, resulting in sequential single electron tunneling and ... More
Site-selective quantum control in an isotopically enriched 28Si/SiGe quadruple quantum dotMar 14 2019Silicon spin qubits are a promising quantum computing platform offering long coherence times, small device sizes, and compatibility with industry-backed device fabrication techniques. In recent years, high fidelity single-qubit and two-qubit operations ... More
Effective Field Theory for Rydberg PolaritonsMay 18 2016Aug 15 2016We develop an effective field theory (EFT) to describe the few- and many-body propagation of one dimensional Rydberg polaritons. We show that the photonic transmission through the Rydberg medium can be found by mapping the propagation problem to a non-equilibrium ... More
Single-photon nonlinear optics with graphene plasmonsSep 10 2013Aug 08 2014We show that it is possible to realize significant nonlinear optical interactions at the few photon level in graphene nanostructures. Our approach takes advantage of the electric field enhancement associated with the strong confinement of graphene plasmons ... More
Double Quantum Dot Floquet Gain MediumJul 27 2016Strongly driving a two-level quantum system with light leads to a ladder of Floquet states separated by the photon energy. Nanoscale quantum devices allow the interplay of confined electrons, phonons, and photons to be studied under strong driving conditions. ... More
Dynamic Nuclear Polarization in Double Quantum DotsMar 23 2010Jun 06 2010We theoretically investigate the controlled dynamic polarization of lattice nuclear spins in GaAs double quantum dots containing two electrons. Three regimes of long-term dynamics are identified, including the build up of a large difference in the Overhauser ... More
Efimov States of Strongly Interacting PhotonsSep 06 2017Sep 28 2017We demonstrate the emergence of universal Efimov physics for interacting photons in cold gases of Rydberg atoms. We consider the behavior of three photons injected into the gas in their propagating frame, where a paraxial approximation allows us to consider ... More
Coulomb bound states of strongly interacting photonsMay 14 2015We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound ... More
Thermal radiation as a probe of one-dimensional electron liquidsApr 02 2018Motivated by recent developments in the field of plasmonics, we develop the theory of radiation from one-dimensional electron liquids, showing that the spectrum of thermal radiation emitted from the system exhibits signatures of non-Fermi liquid behavior. ... More
Fractional quantum Hall phases of bosons with tunable interactions: From the Laughlin liquid to a fractional Wigner crystalSep 12 2018Highly tunable platforms for realizing topological phases of matter are emerging from atomic and photonic systems, and offer the prospect of designing interactions between particles. The shape of the potential, besides playing an important role in the ... More
Adiabatic preparation of many-body states in optical latticesJun 14 2009May 11 2010We analyze a technique for the preparation of low entropy many body states of atoms in optical lattices based on adiabatic passage. In particular, we show that this method allows preparation of strongly correlated states as stable highest energy states ... More
Correlated photon dynamics in dissipative Rydberg mediaAug 22 2016Rydberg blockade physics in optically dense atomic media under the conditions of electromagnetically induced transparency (EIT) leads to strong dissipative interactions between single photons. We introduce a new approach to analyzing this challenging ... More
Scattering resonances and bound states for strongly interacting Rydberg polaritonsFeb 28 2014We provide a theoretical framework describing slow-light polaritons interacting via atomic Rydberg states. We use a diagrammatic method to analytically derive the scattering properties of two polaritons. We identify parameter regimes where polariton-polariton ... More
All-Optical Switch and Transistor Gated by One Stored PhotonJan 14 2014The realization of an all-optical transistor where one 'gate' photon controls a 'source' light beam, is a long-standing goal in optics. By stopping a light pulse in an atomic ensemble contained inside an optical resonator, we realize a device in which ... More
Observation of three-photon bound states in a quantum nonlinear mediumSep 05 2017Nov 10 2017Bound states of massive particles, such as nuclei, atoms or molecules, constitute the bulk of the visible world around us. In contrast, photons typically only interact weakly. We report the observation of traveling three-photon bound states in a quantum ... More
Photon propagation through dissipative Rydberg media at large input ratesJul 19 2018Aug 01 2018We study the dissipative propagation of quantized light in interacting Rydberg media under the conditions of electromagnetically induced transparency (EIT). Rydberg blockade physics in optically dense atomic media leads to strong dissipative interactions ... More
Optical control over bulk excitations in fractional quantum Hall systemsAug 08 2018Local excitations in fractional quantum Hall systems are amongst the most intriguing objects in condensed matter, as they behave like particles of fractional charge and fractional statistics. In order to experimentally reveal these exotic properties and ... More
Observation of chiral photocurrent transport in the quantum Hall regime in grapheneMar 04 2019Optical excitation provides a powerful tool to investigate non-equilibrium physics in quantum Hall systems. Moreover, the length scale associated with photo-excited charge carries lies between that of local probes and global transport measurements. Here, ... More
The global properties of all variety of AGNDec 13 2004Active Galactic Nuclei (AGN) have been a challenging field of research for the past six decades. Nevertheless, many questions still remain unanswered today, regardless of the tremendous theoretical and technological advances. In this brief review I propose ... More
Rational streams coalgebraicallyJul 25 2008Sep 19 2008We study rational streams (over a field) from a coalgebraic perspective. Exploiting the finality of the set of streams, we present an elementary and uniform proof of the equivalence of four notions of representability of rational streams: by finite dimensional ... More
Visualising a FuseOct 27 2010Nov 09 2010In this brief article I describe an experiment to illustrate how a fuse works. I have used this as part of lessons for my year 11 classes to demonstrate how an electrical fuse 'blows' when too high a current passes through it.
Trapped surfaces, horizons and exact solutions in higher dimensionsMar 30 2002May 18 2002A very simple criterion to ascertain if (D-2)-surfaces are trapped in arbitrary D-dimensional Lorentzian manifolds is given. The result is purely geometric, independent of the particular gravitational theory, of any field equations or of any other conditions. ... More
Applications of Super-Energy TensorsDec 13 1999In this contribution I intend to give a summary of the new relevant results obtained by using the general superenergy tensors. After a quick review of the definition and properties of these tensors, several of their mathematical and physical applications ... More
Mobile Phone Faraday CageDec 23 2011A Faraday cage is an interesting physics phenomena where an electromagnetic wave can be excluded from a volume of space by enclosure with an electrically conducting material. The practical application of this in the classroom is to block the signal to ... More
The Wonders of LevitationOct 27 2010I discuss some interesting classroom demonstrations of diamagnetism and how this effect can produce levitation. The possibilities for hands-on demonstrations of diamagnetic and superconducting levitation are discussed. To conclude I discuss some practical ... More
Super-energy tensorsJun 21 1999A purely algebraic construction of super-energy tensors for arbitrary fields is presented in any dimensions. These tensors have good mathematical and physical properties, and they can be used in any theory having as basic arena an n-dimensional manifold ... More
(Super)^n-Energy for arbitrary fields and its interchange: Conserved quantitiesMay 17 1999Inspired by classical work of Bel and Robinson, a natural purely algebraic construction of super-energy tensors for arbitrary fields is presented, having good mathematical and physical properties. Remarkably, there appear quantities with mathematical ... More
Remarks on Superenergy TensorsJan 07 1999We define super-energy tensors for arbitrary physical fields, including the gravitational, electromagnetic and massless scalar fields. We also define super-super-energy tensors, and so on. All these tensors satisfy the so-called "Dominant Superenergy ... More
Superenergy tensors and their applicationsFeb 20 2002In Lorentzian manifolds of any dimension the concept of causal tensors is introduced. Causal tensors have positivity properties analogous to the so-called ``dominant energy condition''. Further, it is shown how to build, from ANY given tensor $A$, a new ... More
Effects on Amorphous Silicon Photovoltaic Performance from High-temperature Annealing Pulses in Photovoltaic Thermal Hybrid DevicesMar 06 2012There is a renewed interest in photovoltaic solar thermal (PVT) hybrid systems, which harvest solar energy for heat and electricity. Typically, a main focus of a PVT system is to cool the photovoltaic (PV) cells to improve the electrical performance, ... More
Violation of causality in f(R) gravityJul 08 2010We examine the question as to whether the f(R) gravity theories, in both metric and in Palatini formalisms, permit space-times in which the causality is violated. We show that the field equations of these f(R) gravity theories admit solutions with violation ... More
Gödel-type universes in f(R) gravityJun 29 2009Sep 21 2009The $f(R)$ gravity theories provide an alternative way to explain the current cosmic acceleration without a dark energy matter component. If gravity is governed by a $f(R)$ theory a number of issues should be reexamined in this framework, including the ... More
Massive String States as Extreme Black HolesJun 15 1994Dec 12 1994We consider the Schwarz-Sen spectrum of elementary electrically charged massive $N_R=1/2$ states of the four-dimensional heterotic string and show the maximum spin $1$ supermultiplets to correspond to extreme black hole solutions. The $N_L=1$ states and ... More
Form Factors for Semileptonic B -> pi and D -> pi Decays from the Omnes RepresentationJul 24 2000Feb 27 2001We use the Omnes representation to obtain the q-squared dependence of the form factors f+ and f0 for semileptonic H -> pi decays from the elastic pi H -> pi H scattering amplitudes, where H denotes a B or D meson. The scattering amplitudes used satisfy ... More
Free-volume kinetic models of granular matterJun 08 2000We show that the main dynamical features of granular media can be understood by means of simple models of fragile-glass forming liquid provided that gravity alone is taken into account. In such lattice-gas models of cohesionless and frictionless particles, ... More
Theory of projections with non-orthogonal basis sets: Partitioning techniques and effective HamiltoniansApr 08 2014Jul 31 2014Here we present a detailed account of the fundamental problems one encounters in projection theory when non-orthogonal basis sets are used for representation of the operators. In particular, we re-examine the use of projection operators in connection ... More
Investigating the rotational evolution of very low-mass stars and brown dwarfs in young clusters using Monte Carlo simulationsNov 19 2016Context. Very low-mass (VLM) stars and brown dwarfs (BDs) present a different rotational behaviour from their solar mass counter-parts. Aims. We investigate the rotational evolution of young VLM stars and BDs using Monte Carlo simulations under the hypothesis ... More
Octupole correlations in low-lying states of 150Nd and 150Sm and their impact on neutrinoless double-beta decayApr 21 2016Jul 07 2016We present a generator-coordinate calculation, based on a relativistic energy-density functional, of the low-lying spectra in the isotopes $^{150}$Nd and $^{150}$Sm and of the nuclear matrix element that governs the neutrinoless double-beta decay of the ... More
X-rays from RU Lupi - Accretion and winds in CTTSJun 20 2007Using three XMM-Newton observations we study the X-ray emission of RU Lup, a accreting and wind-driving CTTS. In comparison with other bright CTTS we study possible signatures of accretion and winds in their X-ray emission. Results: We find three levels ... More
Altair - the 'hottest' magnetically active star in X-raysMar 05 2009The A7 star Altair is one of the hottest magnetically active stars. Its proximity to the Sun allows a detailed investigation of a corona in X-rays for a star with a shallow convection zone. We used a deep XMM-Newton observation of Altair and analyzed ... More
Super Curves, their Jacobians, and super KP equationsJan 15 1996We study the geometry and cohomology of algebraic super curves, using a new contour integral for holomorphic differentials. For a class of super curves (``generic SKP curves'') we define a period matrix. We show that the odd part of the period matrix ... More
Critical phenomena from the two-particle irreducible 1/N expansionApr 06 2004The 1/N expansion of the two-particle irreducible (2PI) effective action is employed to compute universal properties at the second-order phase transition of an O(N)-symmetric N-vector model directly in three dimensions. At next-to-leading order the approach ... More
Spatiotemporal Stochastic Resonance in the Swift-Hohenberg EquationFeb 22 1997We show the appearance of spatiotemporal stochastic resonance in the Swift-Hohenberg equation. This phenomenon emerges when a control parameter varies periodically in time around the bifurcation point. By using general scaling arguments and by taking ... More
Composition Dependence of the Structure and Electronic Properties of Liquid Ga-Se Alloys Studied by Ab Initio Molecular Dynamics SimulationOct 02 1995Ab initio molecular dynamics simulation is used to study the structure and electronic properties of the liquid Ga-Se system at the three compositions Ga$_2$Se, GaSe and Ga$_2$Se$_3$, and of the GaSe and Ga$_2$Se$_3$ crystals. The calculated equilibrium ... More
The Ab-Initio Simulation of the Liquid Ga-Se SystemJul 12 1995Ab-initio dynamical simulation is used to study the liquid Ga-Se system at the three concentrations Ga$_2$Se, GaSe and Ga$_2$Se$_3$ at the temperature 1300~K. The simulations are based on the density functional pseudopotential technique, with the system ... More
Bosonic Partition Functions at Nonzero (Imaginary) Chemical PotentialOct 07 2016We consider bosonic random matrix partition functions at nonzero chemical potential and compare the chiral condensate, the baryon number density and the baryon number susceptibility to the result of the corresponding fermionic partition function. We find ... More
A Twisted Custodial Symmetry in the Two-Higgs-Doublet ModelMar 05 2007In the Standard Model for electroweak interactions, the Higgs sector is known to display a "custodial" symmetry protecting the mass relation m_{W^\pm}^2=m_{W_3}^2 from large corrections. When considering extensions of the scalar sector, this symmetry ... More
Breather initial profiles in chains of weakly coupled anharmonic oscillatorsMay 22 2002A systematic correlation between the initial profile of discrete breathers and their frequency is described. The context is that of a very weakly harmonically coupled chain of softly anharmonic oscillators. The results are structurally stable, that is, ... More
The stability of a bouncing universeMay 29 2003Dec 05 2003We investigate the stability of a spatially homogeneous and isotropic non-singular cosmological model. We show that the complete set of independent perturbations (the electric part of the perturbed Weyl tensor and the perturbed shear) are regular and ... More
Dissipation-induced correlations in 1D bosonic systemsDec 21 2010May 17 2011The quantum dynamics of interacting bosons in a one-dimensional system is investigated numerically. We consider dissipative and conservative two-particle interactions, and integrate the master equation describing the system dynamics via a time-evolving ... More
High Energy PhotoproductionSep 15 2005The experimental and phenomenological status of high energy photoproduction is reviewed. Topics covered include the structure of the photon, production of jets, heavy flavours and prompt photons, rapidity gaps, energy flow and underlying events. The results ... More
Stranger Still: Kaon Loops and Strange Quark Matrix Elements of the NucleonJan 11 1993Intrinsic strangeness contributions to low-energy strange quark matrix elements of the nucleon are modelled using kaon loops and meson-nucleon vertex functions taken from nucleon-nucleon and nucleon-hyperon scattering. A comparison with pion loop contributions ... More
The limiting shape of a full mailboxNov 13 2015We study a model for email communication due to Gabrielli and Caldarelli, where someone receives and answers emails at the times of independent Poisson processes with intensities $\lambda_{\rm in}>\lambda_{\rm out}$. The receiver assigns i.i.d. priorities ... More
Frequency Regularities in $δ$ Scuti StarsAug 26 2013Space missions have produced an incredibly large database on pulsating stars. The light curves via the frequency content contain a detailed description of each star. The critical point is the identification of modes, especially in the non-asymptotic regime. ... More
Calculated optical properties of Si, Ge, and GaAs under hydrostatic pressureMay 01 1996The macroscopic dielectric function in the random-phase-approximation without local field effect has been implemented using the local density approximation with an all electron, full-potential linear muffin-tin orbital basis-set. This method is used to ... More
Neutron Star Structure and the Equation of StateFeb 10 2000The structure of neutron stars is considered from theoretical and observational perspectives. We demonstrate an important aspect of neutron star structure: the neutron star radius is primarily determined by the behavior of the pressure of matter in the ... More
Scaling of polymers in aligned rodsSep 17 2004We study the behavior of self avoiding polymers in a background of vertically aligned rods that are either frozen into random positions or free to move horizontally. We find that in both cases the polymer chains are highly elongated, with vertical and ... More
Nonequilibrium quantum fields with large fluctuationsSep 03 2002We consider the nonequilibrium evolution of an O(N)-symmetric scalar quantum field theory using a systematic two-particle irreducible 1/N-expansion to next-to-leading order, which includes scattering and memory effects. The corresponding ``full Kadanoff-Baym ... More
Quantum computingJan 05 2004Mar 17 2006This article gives an elementary introduction to quantum computing. It is a draft for a book chapter of the "Handbook of Nature-Inspired and Innovative Computing", Eds. A. Zomaya, G.J. Milburn, J. Dongarra, D. Bader, R. Brent, M. Eshaghian-Wilner, F. ... More
The limiting shape of a full mailboxNov 13 2015Nov 23 2016We study a model for email communication due to Gabrielli and Caldarelli, where someone receives and answers emails at the times of independent Poisson processes with intensities $\lambda_{\rm in}>\lambda_{\rm out}$. The receiver assigns i.i.d. priorities ... More
LEP1 vs. Future Colliders: Effective Operators And Extended Gauge GroupJul 24 1992In an effective Lagrangian approach to physics beyond the Standard Model, it has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts the discovery potential of future colliders. We exhibit a possible way out in an extended gauge ... More
Nonlinear stability of relativistic sheared planar jetsOct 14 2005The linear and non-linear stability of sheared, relativistic planar jets is studied by means of linear stability analysis and numerical hydrodynamical simulations. Our results extend the previous Kelvin-Hemlholtz stability studies for relativistic, planar ... More
Stability of hydrodynamical relativistic planar jets. II. Long-term nonlinear evolutionJul 28 2004In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes ... More
Exclusive electromagnetic production of strangeness on the nucleon : review of recent data in a Regge approachAug 12 2003Aug 14 2003In view of the numerous experimental results recently released, we provide in this letter an update on the performance of our simple Regge model for strangeness electroproduction on the nucleon. Without refitting any parameters, a decent description of ... More
Effective Operators and Extended SymmetryJul 30 1993In this note we expand on our previous study of the implications of LEP1 results for future colliders. We extend the effective operator-based analysis of De R\'ujula et al. to a larger symmetry group, and show at which cost their expectations can be relaxed. ... More
Theory of Electric Field-Induced Photoluminescence Quenching in Disordered Molecular SolidsFeb 12 1998The dynamics of excitons in disordered molecular solids is studied theoretically, taking into account migration between different sites, recombination, and dissociation into free charge carriers in the presence of an electric field. The theory is applied ... More
CO adsorption on Cu(111) and Cu(001) surfaces: improving site preference in DFT calculationsAug 18 2004CO adsorption on Cu(111) and Cu(001) surfaces has been studied within ab-initio density functional theory (DFT). The structural, vibrational and thermodynamic properties of the adsorbate-substrate complex have been calculated. Calculations within the ... More
A window to the Galactic X-ray halo: The ISM towards the Lockman holeNov 11 2002We present a combined X-ray/HI-analysis of the ISM towards the Lockman hole. This sky region is considered as the "window to the distant universe" because of its absolute lowest HI column density on the whole sky. The Lockman hole appears to be not as ... More
Limits of abstract elementary classesApr 18 2015Aug 19 2015We show that the category of abstract elementary classes (AECs) and concrete functors is closed under constructions of "limit type," which generalizes the approach of Mariano, Zambrano and Villaveces away from the syntactically oriented framework of institutions. ... More
Origin of half-semimetallicity induced at interfaces of C-BN heterostructuresFeb 04 2010First-principles density functional calculations are performed in C-BN heterojunctions. It is shown that the magnetism of the edge states in zigzag shaped graphene strips and polarity effects in BN strips team up to give a spin asymmetric screening that ... More
Frenkel and charge transfer excitons in C60Mar 11 1999Jul 19 1999We have studied the low energy electronic excitations of C60 using momentum dependent electron energy-loss spectroscopy in transmission. The momentum dependent intensity of the gap excitation allows the first direct experimental determination of the energy ... More
Investigation of quasi-periodic varaiations in hard X-rays of solar flaresAug 05 2009The aim of the present paper is to use quasi-periodic oscillations in hard X-rays (HXRs) of solar flares as a diagnostic tool for investigation of impulsive electron acceleration. We have selected a number of flares which showed quasi-periodic oscillations ... More
Status of Electroweak Phase Transition and BaryogenesisMar 03 2000Mar 08 2000I review recent progress on the electroweak phase transition and baryogenesis, focusing on the minimal supersymmetric standard model as the source of new physics.
Absence of Matter-Induced Flavor-Changing Contribution to Neutrino Oscillation HamiltonianJul 04 1994Nov 01 1994Paper withdrawn; ask me if you would like to know the details.
On the conformal systoles of four-manifoldsDec 06 2005Nov 16 2006We extend a result of M. Katz on conformal systoles to all four-manifolds with b^+=1 which have odd intersection form. The same result holds for all four-manifolds with b^+=1 with even intersection form and which are symplectic or satisfy the so-called ... More
Can the 125 GeV Higgs be the Little Higgs?Dec 24 2012Jan 30 2013After the discovery of the Higgs-like boson by the LHC 2012 it is the most important task to check whether this new particle is the Standard Model Higgs boson or something else. In this paper, we study whether the 125 GeV boson could be the pseudo-Goldstone ... More
Top Partner Discovery in the $T\to tZ$ channel at the LHCSep 24 2014Jan 27 2015In this paper we study the discovery potential of the LHC run II for heavy vector-like top quarks in the decay channel to a top and a $Z$ boson. Despite the usually smaller branching ratio compared to charged-current decays, this channel is rather clean ... More
X-ray photometryJun 23 2015I describe a method for synthesizing photometric passbands for use with current and future X-ray instruments. The method permits the standardisation of X-ray passbands and thus X-ray photometry between different instruments and missions. The method is ... More
Hotspots, Jets and EnvironmentsJul 12 2007I discuss the nature of `hotspots' and `jet knots' in the kpc-scale structures of powerful radio galaxies and their relationship to jet-environment interactions. I describe evidence for interaction between the jets of FRI sources and their local environments, ... More
Testing the beamed inverse-Compton model for jet X-ray emission: velocity structure and deceleration?Nov 17 2005Dec 01 2005By considering a small sample of core-dominated radio-loud quasars with X-ray jets, I show, as has been argued previously by others, that the observations require bulk jet deceleration if all of the X-ray emission is to be explained using the widely adopted ... More
On the group velocity of oscillating neutrino states and the equal velocity assumptionDec 21 2000In a two flavour world, the usual equal $p$, equal $E$, or equal $v$ assumptions used to derive the neutrino oscillation length can be replaced by a specific definition of the velocity of the oscillating state which, unlike those assumptions, is compatible ... More
A quantum central limit theorem for non-equilibrium systems: Exact local relaxation of correlated statesNov 12 2009May 31 2010We prove that quantum many-body systems on a one-dimensional lattice locally relax to Gaussian states under non-equilibrium dynamics generated by a bosonic quadratic Hamiltonian. This is true for a large class of initial states - pure or mixed - which ... More
Correlations, spectral gap, and entanglement in harmonic quantum systems on generic latticesSep 22 2005May 23 2006We investigate the relationship between the gap between the energy of the ground state and the first excited state and the decay of correlation functions in harmonic lattice systems. We prove that in gapped systems, the exponential decay of correlations ... More