Showing papers in "Physical Review Letters in 1990"
TL;DR: This chapter describes the linking of two chaotic systems with a common signal or signals and highlights that when the signs of the Lyapunov exponents for the subsystems are all negative the systems are synchronized.
Abstract: Certain subsystems of nonlinear, chaotic systems can be made to synchronize by linking them with common signals. The criterion for this is the sign of the sub-Lyapunov exponents. We apply these ideas to a real set of synchronizing chaotic circuits.
9,201 citations
TL;DR: It is shown that it is possible to design special quasirandom structures'' (SQS) that mimic for small {ital N} the first few, physically most relevant radial correlation functions of a perfectly random structure far better than the standard technique does.
Abstract: Structural models used in calculations of properties of substitutionally random ${\mathit{A}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{B}}_{\mathit{x}}$ alloys are usually constructed by randomly occupying each of the N sites of a periodic cell by A or B. We show that it is possible to design ``special quasirandom structures'' (SQS's) that mimic for small N (even N=8) the first few, physically most relevant radial correlation functions of a perfectly random structure far better than the standard technique does. We demonstrate the usefulness of these SQS's by calculating optical and thermodynamic properties of a number of semiconductor alloys in the local-density formalism.
2,545 citations
IBM1
TL;DR: Mise en evidence d'un interaction d'echange intercouche antiferromagnetique et d'une magnetoconductivite en saturation dans les superreseaux Co/Cr et Co/Ru.
Abstract: We report the discovery of antiferromagnetic interlayer exchange coupling and enhanced saturation magnetoresistance in two new metallic superlattice systems, Co/Cr and Co/Ru. In these systems and in Fe/Cr superlattices both the magnitude of the interlayer magnetic exchange coupling and the saturation magnetoresistance are found to oscillate with the Cr or Ru spacer layer thickness with a period ranging from 12 \AA{} in Co/Ru to \ensuremath{\simeq}18--21 \AA{} in the Fe/Cr and Co/Cr systems.
2,202 citations
TL;DR: It is determined that dielectric spheres arranged in the diamond structure do possess a full photonic band gap, and this gap exists for refractive-index contrasts as low as 2.5%.
Abstract: Using a plane-wave expansion method, we have solved Maxwell's equations for the propagation of electromagnetic waves in a periodic lattice of dielectric spheres (dielectric constant ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{a}}$) in a uniform dielectric background (${\mathrm{\ensuremath{\epsilon}}}_{\mathit{b}}$). Contrary to experiment, we find that fcc dielectric structures do not have a ``photonic band gap'' that extends throughout the Brillouin zone. However, we have determined that dielectric spheres arranged in the diamond structure do possess a full photonic band gap. This gap exists for refractive-index contrasts as low as 2.
2,115 citations
TL;DR: It is shown that the islands formed in Stranski-Krastanow (SK) growth of Ge on Si(100) are initially dislocation free, and the limiting critical thickness of coherent SK islands is shown to be higher than that for 2D growth.
Abstract: We show that the islands formed in Stranski-Krastanow (SK) growth of Ge on Si(100) are initially dislocation free. Island formation in true SK growth should be driven by strain relaxation in large, dislocated islands. Coherent SK growth is explained in terms of elastic deformation around the islands, which partially accommodates mismatch. The limiting critical thickness, ${\mathit{h}}_{\mathit{c}}$, of coherent SK islands is shown to be higher than that for 2D growth. We demonstrate growth of dislocation-free Ge islands on Si to a thickness of \ensuremath{\approxeq}500 \AA{}, 50\ifmmode\times\else\texttimes\fi{}higher than ${\mathit{h}}_{\mathit{c}}$ for 2D Ge/Si epitaxy.
1,751 citations
TL;DR: It is shown that an integral {ital S} over the spectral function of spin-1 states of the Higgs sector is constrained by precision weak-interaction measurements.
Abstract: We show that an integral S over the spectral function of spin-1 states of the Higgs sector is constrained by precision weak-interaction measurements. Current data exclude large technicolor models; asymmetry measurements at the CERN ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ collider LEP and the SLAC Linear Collider will soon provide more stringent limits on Higgs-boson strong interactions.
1,541 citations
TL;DR: A force field based on both microscopic and macroscopic data is derived, which combines accuracy with transferability to other polymorphs and the possibility of parametrizing other elements is demonstrated.
Abstract: We address the problem of finding interatomic force fields for silicas from ab initio calculations on small clusters. It is shown that the force field cannot be determined from cluster data alone; incorporation of bulk-system information into the force field remains essential. Bearing this in mind, we derive a force field based on both microscopic (ab initio) and macroscopic (experimental) data. This force field combines accuracy with transferability to other polymorphs. The possibility of parametrizing other elements is also demonstrated.
1,385 citations
TL;DR: It is shown that a pseudo-Nambu-Goldstone boson, with a potential of the form V(d) = A’[1 f cos(+/f)], can naturally give rise to an epoch of infiation in the early universe.
Abstract: It is shown that a pseudo-Nambu-Goldstone boson of given potential can naturally give rise to an epoch of inflation in the early universe. Mass scales which arise in particle physics models with a gauge group that becomes strongly interacting at a certain scales are shown to be conditions for successful inflation. The density fluctuation spectrum is nonscale-invariant, with extra power on large length scales.
1,297 citations
TL;DR: In this paper, a strong coupling field between a metastable state and the upper state of an allowed transition to ground was proposed to obtain a resonantly enhanced third-order susceptibility while at the same time inducing transparency of the media.
Abstract: We show that by applying a strong-coupling field between a metastable state and the upper state of an allowed transition to ground one may obtain a resonantly enhanced third-order susceptibility while at the same time inducing transparency of the media. An improvement in conversion efficiency and parametric gain, as compared to weak-coupling field behavior, of many orders of magnitude is predicted.
1,287 citations
TL;DR: The transition from 2D to 3D growth of Ge on Si(001) has been investigated with scanning tunneling microscope and a metastable 3D cluster phase with well-defined structure and shape is found.
Abstract: The transition from 2D to 3D growth of Ge on Si(001) has been investigated with scanning tunneling microscopy. A metastable 3D cluster phase with well-defined structure and shape is found. The clusters have a {105} facet structure. Results suggest that these clusters define the kinetic path for formation of ``macroscopic'' Ge islands.
1,226 citations
TL;DR: A Bell inequality is derived for a state of n spin-1/2 particles which superposes two macroscopically distinct states and quantum mechanics violates this inequality by an amount that grows exponentially with n.
Abstract: A Bell inequality is derived for a state of n spin-1/2 particles which superposes two macroscopically distinct states. Quantum mechanics violates this inequality by an amount that grows exponentially with n.
TL;DR: The experimental observation of a sustained standing nonequilibrium chemical pattern in a single-phase open reactor is interpreted as the first unambiguous experimental evidence of a Turing structure.
Abstract: We report the experimental observation of a sustained standing nonequilibrium chemical pattern in a single-phase open reactor. Considering the properties of the pattern (symmetry breaking, intrinsic wavelength), it is interpreted as the first unambiguous experimental evidence of a Turing structure.
TL;DR: Sensitive micropipet methods have been used to measure the relation between tension and the projected surface area in fluid membranes of vesicles and confirm the prediction of equilibrium theory that the projected area should increase logarithmically with tension as shape fluctuations become progressively restricted.
Abstract: Sensitive micropipet methods have been used to measure the relation between tension and the projected surface area in fluid membranes of vesicles over a 4-order-of-magnitude range in tension (10 −3 -10 dyn/cm). In the low-tension regime (<0.5 dyn/cm), the data confirm the prediction of equilibrium theory that the projected area should increase logarithmically with tension as shape fluctuations become progressively restricted
TL;DR: Experiments clearly prove that narrow peaks in the fluorescence excitation spectrum of a pentacene-doped p-terphenyl crystal stem from single molecules, and show the feasibility of the optical study of a single molecule and its local environment.
Abstract: Experiments clearly prove that narrow peaks in the fluorescence-excitation spectrum of a pentacene-doped p-terphenyl crystal stem from single molecules. This claim is supported by the distribution, width, and height of the peaks, as well as by the correlation of the emitted light and the sudden drops and surges of the emission of certain peaks. We attribute these to the hole burning of a single molecule. These results show the feasibility of the optical study of a single molecule and its local environment.
TL;DR: A nonperturbative definition of two-dimensional quantum gravity is proposed, based on a double-scaling limit of the random-matrix model, and an exact differential equation for the partition function ofTwo-dimensional gravity coupled to conformal matter is derived.
Abstract: We propose a nonperturbative definition of two-dimensional quantum gravity, based on a double-scaling limit of the random-matrix model. We derive an exact differential equation for the partition function of two-dimensional gravity coupled to conformal matter as a function of the string coupling constant that governs the genus expansion of two-dimensional surfaces, and discuss its properties and consequences. We also construct and discuss the correlation functions of an infinite set of local operators for spherical topology.
TL;DR: The critical state is characterized, and its entropy for an arbitrary finite lattice in any dimension is determined, and the two-point correlation function is shown to satisfy a linear equation.
Abstract: We study a general Bak-Tang-Wiesenfeld--type automaton model of self-organized criticality in which the toppling conditions depend on local height, but not on its gradient. We characterize the critical state, and determine its entropy for an arbitrary finite lattice in any dimension. The two-point correlation function is shown to satisfy a linear equation. The spectrum of relaxation times describing the approach to the critical state is also determined exactly.
TL;DR: Using partial wave unitarity and the observed density of the Universe, it is show that a stable elementary particle which was once in thermal equilibrium cannot have a mass greater than 340 TeV.
Abstract: Using partial wave unitarity and the observed density of the Universe, it is show that a stable elementary particle which was once in thermal equilibrium cannot have a mass greater than 340 TeV. An extended object which was once in thermal equilibrium cannot have a radius less than 7.5 x 10(exp -7) fm. A lower limit to the relic abundance of such particles is also found.
TL;DR: The eigenstates of electrons interacting in quantum dots in a magnetic field are studied and their effects on the magnetic-field dependence of the energy spectrum are illustrated with the calculations of the electronic heat capacity.
Abstract: The eigenstates of electrons interacting in quantum dots in a magnetic field are studied. The interaction has important effects on the magnetic-field dependence of the energy spectrum. However, when the confinement potential is quadratic, the optical excitation energies of the many-body system are exactly the same as those of a single electron. This makes the interaction effects difficult to observe directly but they could be seen by measuring the thermodynamic properties of the electrons. This is illustrated with the calculations of the electronic heat capacity.
TL;DR: Evidence for a flux-periodic persistent current in each ring of average value 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$e${\ensurmath{
u}}_{\mathit{F}}$/L.
Abstract: We have measured the low-temperature magnetization response of ${10}^{7}$ isolated mesoscopic copper rings to a slowly varying magnetic flux. At sufficiently low temperature, the total magnetization response oscillates as a function of the enclosed magnetic flux on the scale of half of a flux quantum. The amplitude of the oscillatory moment is \ensuremath{\approxeq}1.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ ${\mathrm{Am}}^{2}$ and decreases exponentially with increasing temperature on the scale of the correlation energy ${\mathit{E}}_{\mathit{c}}$=hD/(2L${)}^{2}$\ensuremath{\approxeq}80 mK. This is evidence for a flux-periodic persistent current in each ring of average value 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$e${\ensuremath{
u}}_{\mathit{F}}$/L.
TL;DR: It is shown that the integral of the uncertainty of energy with respect to time is independent of the particular Hamiltonian used to transport the quantum system along a given curve in the projective Hilbert space, which gives a new time-energy uncertainty principle.
Abstract: For an arbitrary quantum evolution, it is shown that the integral of the uncertainty of energy with respect to time is independent of the particular Hamiltonian used to transport the quantum system along a given curve in the projective Hilbert space. It is the distance along this curve measured by the Fubini-Study metric. This gives a new time-energy uncertainty principle. New geometric meanings to time as measured by a clock and the transition probability during a quantum measurement are also obtained.
TL;DR: In this paper, two examples are given that substantially simplify the no-hidden-variables theorem of Kochen and Specker, greatly reducing the number of observables considered and requiring no intricate geometric argument.
Abstract: Two examples are given that substantially simplify the no-hidden-variables theorem of Kochen and Specker, greatly reducing the number of observables considered and requiring no intricate geometric argument. While one of the examples also obeys a more powerful version of Bell's theorem, the other does not. The examples provide a new perspective on both of these fundamental theorems and on the relation between them.
TL;DR: Laterally varying surface concentrations associated with the oscillatory oxidation of carbon monoxide on a Pt(110) surface were imaged by photoemission electron microscopy and a large variety of spatiotemporal patterns were observed.
Abstract: Laterally varying surface concentrations associated with the oscillatory oxidation of carbon monoxide on a Pt(110) surface were imaged by photoemission electron microscopy. Depending on the applied conditions, a large variety of spatiotemporal patterns were observed that are characteristic for the nonlinear dynamics of reaction-diffusion systems.
TL;DR: It is shown that in dielectrics exhibiting a complete photonic band gap, quantum electrodynamics predicts the occurrence of bound states of photons to hydrogenic atoms.
Abstract: It is shown that in dielectrics exhibiting a complete photonic band gap, quantum electrodynamics predicts the occurrence of bound states of photons to hydrogenic atoms. When the atomic transition frequency lies near a photonic band edge, the excited atomic level experiences an anomalous Lamb shift and splits into a doublet. One member of this doublet exhibits resonance fluorescence whereas the other level is dressed by the emission and reabsorption of near-resonant photons whose amplitude decays exponentially from the vicinity of the atom.
TL;DR: The first systematic femtosecond pump-probe measurements of the electron-phonon coupling constant {lambda} in thin films of Cu, Au, Cr, Ti, W, Nb, V, Pb, NBN, and V{sub 3}Ga are reported.
Abstract: We report the first systematic femtosecond pump-probe measurements of the electron-phonon coupling constant \ensuremath{\lambda} in thin films of Cu, Au, Cr, Ti, W, Nb, V, Pb, NbN, and ${\mathrm{V}}_{3}$Ga. The agreement between our measured \ensuremath{\lambda} values and those obtained by other techniques is excellent, thus confirming recent theoretical predictions of Allen. By depositing thin Cu overlayers when necessary, we can extend this technique to nearly any metallic thin film.
IBM1
TL;DR: The observation of the photorefractive effect in an amorphous electro-optic material, the nonlinear polymer bisphenol A diglycidyl ether 4-nitro-1,2,phenylenediamine (bisA-NPDA) make photoconductive by doping with the hole transport agent diethylaminobenzaldehyde-diphenyl hydrazone.
Abstract: We report the first observation of the photorefractive effect in a polymeric material, the electro-optic polymer bisphenol-A-diglycidylether 4-nitro-1,2-phenylenediamine made photoconductive by doping with the hole-transport agent diethylamino-benzaldehyde diphenylhydrazone. The gratings formed exhibit dynamic writing and erasure, strong electric-field dependence, polarization anisotropy, and estimated space-charge fields up to 26 kV/cm at an applied field of 126 kV/cm. Application of similar concepts should provide a broad new class of easily fabricated photorefractive materials.
IBM1
TL;DR: Preliminary evidence indicates that shear thickening of suspensions with macroscopic spheres and a negative pore liquid pressure develops at the rigidity threshold, indicating a sphere packing at its rigidity-percolation threshold.
Abstract: The random-loose-packing fraction of uniform spheres at the limit of zero gravitational force is determined to be 0.555\ifmmode\pm\else\textpm\fi{}0.005. This structure corresponds to a sphere packing at its rigidity-percolation threshold. The onset of dilatancy was also measured to be at approximately the same packing fraction. Preliminary evidence also indicates that shear thickening of suspensions with macroscopic spheres and a negative pore liquid pressure develops at the rigidity threshold. These provide further evidence that a hard-sphere glass transition could exist in the packing fraction range of 0.555 to 0.645.
TL;DR: It is shown that for a specific choice of the Higgs potential the vortex satisfies a set of Bogomol'nyi-type, or self-duality, equations in an Abelian Chern-Simons theory with spontaneous symmetry breaking.
Abstract: We study vortex solutions in an Abelian Chern-Simons theory with spontaneous symmetry breaking. We show that for a specific choice of the Higgs potential the vortex satisfies a set of Bogomol'nyi-type, or ``self-duality,'' equations.
TL;DR: A Bloch-wave analysis shows how a signal dependent on the electron intensity at the atom sites can be used to form an incoherent image of a crystal structure that can be predicted and interpreted intuitively.
Abstract: A Bloch-wave analysis shows how a signal dependent on the electron intensity at the atom sites can be used to form an incoherent image of a crystal structure. To a good approximation the image is given by a convolution of a compositionally sensitive object function with an appropriate resolution function, and as such can be predicted and interpreted intuitively. Information on a scale below the resolution limit can be interpreted by deconvolution.
TL;DR: A closed set of fluid moment equations is developed which represents kinetic Landau damping physics and which takes a simple form in wave-number space, useful for nonlinear studies of turbulence driven by the ion-temperature-gradient or other drift-wave microinstabilities.
Abstract: A closed set of fluid moment equations is developed which represents kinetic Landau damping physics and which takes a simple form in wave-number space. The linear-response function corresponds to a three-pole (or four-pole) approximation to the plasma dispersion function Z. Alternatively, the response is exact for a distribution function which is close to Maxwellian, but which decreases asymptotically as 1/${\mathit{v}}^{4}$ (or 1/${\mathit{v}}^{6}$). Among other applications, these equations should be useful for nonlinear studies of turbulence driven by the ion-temperature-gradient or other drift-wave microinstabilities.
TL;DR: The dual of the random-dimer model is also shown to exhibit an absence of localization and is shown to be relevant to transmission resonances in Fibonacci lattices.
Abstract: We consider here a 1D tight-binding model with two uncorrelated random site energies ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{a}}$ and ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{b}}$ and a constant nearest-neighbor matrix element V. We show that if one (or both) of the site energies is assigned at random to pairs of lattice sites (that is, two sites in succession), an initially localized particle can become delocalized. Its mean-square displacement at long times is shown to grow in time as ${\mathit{t}}^{3/2}$ provided that -2V${\mathrm{\ensuremath{\epsilon}}}_{\mathit{a}}$-${\mathrm{\ensuremath{\epsilon}}}_{\mathit{b}}$2V. Diffusion occurs if ${\mathrm{\ensuremath{\epsilon}}}_{\mathit{a}}$-${\mathrm{\ensuremath{\epsilon}}}_{\mathit{b}}$=\ifmmode\pm\else\textpm\fi{}2V and localization otherwise. The dual of the random-dimer model is also shown to exhibit an absence of localization and is shown to be relevant to transmission resonances in Fibonacci lattices.