publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
2009-03-03
Voids and overdensities of coupled Dark Energy
We investigate the clustering properties of dynamical Dark Energy even in association of a possible coupling between Dark Energy and Dark Matter. We find that within matter inhomogeneities, Dark Energy migth form voids as well as overdensity depending on how its background energy density evolves. Consequently and contr...
0903.0574v1
2009-03-10
Inelastic scattering in a local polaron model with quadratic coupling to bosons
We calculate the inelastic scattering probabilities in the wide band limit of a local polaron model with quadratic coupling to bosons. The central object is a two-particle Green function which is calculated exactly using a purely algebraic approach. Compared with the usual linear interaction term a quadratic interactio...
0903.1786v1
2009-03-11
Quantum breathing mode of trapped bosons and fermions at arbitrary coupling
An analysis of the quantum breathing behavior of few-particle Coulomb systems in one- and two-dimensional harmonic traps is presented. We report the existence of \emph{two independent breathing modes} and present exact numerical results for two particles at any coupling strength which smoothly connect the two known lim...
0903.1993v2
2009-03-14
Shear viscosity, instability and the upper bound of the Gauss-Bonnet coupling constant
We compute the dimensionality dependence of $\eta/s$ for charged black branes with Gauss-Bonnet correction. We find that both causality and stability constrain the value of Gauss-Bonnet coupling constant to be bounded by 1/4 in the infinite dimensionality limit. We further show that higher dimensionality stabilize the ...
0903.2527v3
2009-03-16
Controlled multiqubit entangled states and quantum transmission in quantum molecule-spin systems
he multiqubit entangled states are coherently controlled in the quantum spin systems composed of $N+1$ interacting antiferromagnetic molecular rings. The tunable intermolecular couplings arise from the local exchange interactions between electron spins of $N$ circumjacent magnets and those of one central molecular ring...
0903.2705v1
2009-03-18
Coherent coupling between surface plasmons and excitons in semiconductor nanocrystals
We present an experimental demonstration of strong coupling between a surface plasmon propagating on a planar silver substrate, and the lowest excited state of CdSe nanocrystals. Variable-angle spectroscopic ellipsometry measurements demonstrated the formation of plasmon-exciton mixed states, characterized by a Rabi sp...
0903.3248v1
2009-03-24
Generalized circulant matrix in Coupled Map Lattices
In this paper it is shown that a generalized circulant matrix underlies every weakly Coupled Map Lattice (CML), independently of the form of the coupling term. Therefore, this matrix will appear always perturbative methods are used to get the analytical solutions. In fact, the inverse of this matrix provides the analyt...
0903.4149v1
2009-03-27
Stability of an [N/2]-dimensional invariant torus in the Kuramoto model at small coupling
When the natural frequencies are allocated symmetrically in the Kuramoto model there exists an invariant torus of dimension [N/2]+1 (N is the population size). A global phase shift invariance allows to reduce the model to $N-1$ dimensions using the phase differences, and doing so the invariant torus becomes [N/2]-dimen...
0903.4840v1
2009-03-30
Numerical and Analytical Approach to the Quantum Dynamics of Two Coupled Spins in Bosonic Baths
The quantum dynamics of a spin chain interacting with multiple bosonic baths is described in a mixed Wigner-Heisenberg representation. The formalism is illustrated by simulating the time evolution of the reduced density matrix of two coupled spins, where each spin is also coupled to its own bath of harmonic oscillators...
0903.5181v1
2009-04-01
Dissociative recombination of BeH^+
The cross section for dissociative recombination of BeH^+ is calculated by solution of the time-dependent Schrodinger equation in the local complex potential approximation. The effects of couplings between resonant states and the Rydberg states converging to the ground state of the ion are studied. The relevant potenti...
0904.0127v1
2009-04-02
Quantum synchronization and entanglement of two qubits coupled to a driven dissipative resonator
Using method of quantum trajectories we study the behavior of two identical or different superconducting qubits coupled to a quantum dissipative driven resonator. Above a critical coupling strength the qubit rotations become synchronized with the driving field phase and their evolution becomes entangled even if two qub...
0904.0289v1
2009-04-06
Evolution of the coupling constant in SU(2) lattice gauge theory with two adjoint fermions
We measure the evolution of the coupling constant using the Schroedinger functional method in the lattice formulation of SU(2) gauge theory with two massless Dirac fermions in the adjoint representation. We observe strong evidence for an infrared fixed point, where the theory becomes conformal. We measure the continuum...
0904.0864v2
2009-04-11
Coupled Superconducting Phase and Ferromagnetic Order Parameter Dynamics
Via a direct coupling between the magnetic order parameter and the singlet Josephson supercurrent, we detect spin-wave resonances, and their dispersion, in ferromagnetic Josephson junctions in which the usual insulating or metallic barrier is replaced with a weak ferromagnet. The coupling arises within the Fraunhofer i...
0904.1780v1
2009-04-15
Yukawa Couplings in Heterotic Compactification
We present a practical, algebraic method for efficiently calculating the Yukawa couplings of a large class of heterotic compactifications on Calabi-Yau three-folds with non-standard embeddings. Our methodology covers all of, though is not restricted to, the recently classified positive monads over favourable complete i...
0904.2186v1
2009-04-17
Spin Relaxation in Isotopically Purified Silicon Quantum Dots
We investigate spin-flip processes of Si quantum dots due to spin-orbit coupling. We utilize the spin-orbit coupling constants related to bulk and structure inversion asymmetry obtained numerically for two dimensional heterostructures. We find that the spin-flip rate is very sensitive to these coupling constants. We in...
0904.2592v1
2009-04-17
Tailoring Effective Exchange Interactions via Domain Walls in Coupled Heisenberg Rings
The nature of the exchange coupling variation in an antiferromagnetic spin-1/2 system can be used to tailor its ground-state properties. In particular, dimerized Heisenberg rings containing domain walls have localized states which can serve as "flying spin qubits" when the domain walls are moved. We show theoretically ...
0904.2783v1
2009-04-23
Quantum Electrodynamics of a Nanocavity Coupled with Exciton Complexes in a Quantum Dot
Here, a comprehensive theory of the couplings between a nanocavity and exciton complexes in a quantum dot is developed, which successfully predicts the spectral triplet in the strong coupling regime that has been observed in several experiments but is unexpected according to conventional cavity quantum electrodynamics....
0904.3697v1
2009-05-01
Coupled photonic crystal nanobeam cavities
We describe the design, fabrication, and spectroscopy of coupled, high Quality (Q) factor silicon nanobeam photonic crystal cavities. We show that the single nanobeam cavity modes are coupled into even and odd superposition modes, and we simulate the frequency and Q factor as a function of nanobeam spacing, demonstrati...
0905.0109v1
2009-05-02
Entanglement and Tunable Spin-Spin Couplings Between Trapped Ions Using Multiple Transverse Modes
We demonstrate tunable spin-spin couplings between trapped atomic ions, mediated by laser forces on multiple transverse collective modes of motion. A $\sigma_x \sigma_x$-type Ising interaction is realized between quantum bits stored in the ground hyperfine clock states of Yb ions. We demonstrate entangling gates and ta...
0905.0225v1
2009-05-05
Electron-phonon superconductivity in non-centrosymmetric LaNiC$_2$: first principles calculations
We report first principles calculations of the electronic structure and electron-phonon coupling in the non-centrosymmetric superconductor LaNiC$_2$. These show that the material is a conventional electron-phonon superconductor with intermediate coupling. There are large contributions to the coupling by two low frequen...
0905.0511v2
2009-05-05
Constraints on the excitations in the Strongly Coupled Standard Model
The Strongly Coupled Standard Model predicts a rich spectrum of excited states at the Fermi scale. We study the first radial excitations of the vector bosons. The inclusion of these new states affects the low energy phenomenology of the model. We put constraints on the effective couplings by performing a global fit wit...
0905.0671v2
2009-05-07
Quantum-information transfer in a coupled resonator waveguide
We propose an efficient scheme for the implementation of quantum information transfer in a onedimensional coupled resonator waveguide. We show that, based on the effective long-range dipole-dipole interactions between the atoms mediated by the cavity modes, Raman transitions between the atoms trapped in different nodes...
0905.0943v1
2009-05-07
CP violating anomalous top-quark couplings at the LHC
We study the T odd correlations induced by CP violating anomalous top-quark couplings at both production and decay level in the process gg --> t t_bar --> (b mu+ nu_mu) (b_bar mu- nu_mu_bar). We consider several counting asymmetries at the parton level and find the ones with the most sensitivity to each of these anomal...
0905.1074v2
2009-05-07
Consequences of lattice imperfections and interchain couplings for the critical properties of spin-1/2 chain compounds
To allow for a comparison of theoretical predictions for spin chains with experimental data, it is often important to take impurity effects as well as interchain couplings into account. Here we present the field theory for finite spin chains at finite temperature and calculate experimentally measurable quantities like ...
0905.1075v1
2009-05-10
Cosmic acceleration and crossing of $ω=-1$ in non-minimal modified Gauss-Bonnet gravity
Modified Gauss-Bonnet, i.e, $f(G)$ gravity is a possible explanation of dark energy. Late time cosmology for the $f(G)$ gravity non-minimally coupled with a free massless scalar field have been investigated in Ref. [32]. In this paper we generalize the work of Ref. [32] by including scalar potential in the matter Lagra...
0905.1468v1
2009-05-11
Statistical Mechanics of finite arrays of coupled bistable elements
We discuss the equilibrium of a single collective variable characterizing a finite set of coupled, noisy, bistable systems as the noise strength, the size and the coupling parameter are varied. We identify distinct regions in parameter space. The results obtained in prior works in the asymptotic infinite size limit are...
0905.1564v1
2009-05-12
Polar phonons and spin excitations coupling in multiferroic BiFeO3 crystals
Raman scattering measurements on BiFeO3 single crystals show an important coupling between the magnetic order and lattice vibrations. The temperature evolution of phonons shows that the lowest energy E and A1 phonon modes are coupled to the spin order up to the Neel temperature. Furthermore, low temperature anomalies a...
0905.1891v1
2009-05-15
Polarized DIS in N=4 SYM: Where is spin at strong coupling?
Using the AdS/CFT correspondence, we calculate the polarized structure functions in strongly coupled N=4 supersymmetric Yang-Mills theory deformed in the infrared. We find that the flavor singlet contribution to the g_1 structure function is vanishingly small, while the flavor non-singlet contribution shows the Regge b...
0905.2493v1
2009-05-15
The four-gluon vertex and the running coupling in Landau gauge Yang-Mills theory
We summarise results for the running coupling from the four-gluon vertex in Landau gauge, SU($N_c$) Yang-Mills theory as given by a combination of dressing functions of the vertex and the gluon propagator. These functions have been determined numerically from the corresponding set of Dyson-Schwinger equations. In the i...
0905.2506v1
2009-05-18
Fiber-coupled semiconductor waveguides as an efficient optical interface to a single quantum dipole
We theoretically investigate the interaction of a single quantum dipole with the modes of a fiber-coupled semiconductor waveguide. Through a combination of tight modal confinement and phase-matched evanescent coupling, we predict that approximately 70 % of the dipole's emission can be collected into a single mode optic...
0905.2994v2
2009-05-22
Interlayer and interfacial exchange coupling in ferromagnetic metal/semiconductor heterostructures
We describe a systematic study of the exchange coupling between a magnetically hard metallic ferromagnet (MnAs) and a magnetically soft ferromagnetic semiconductor (GaMnAs) in bilayer and trilayer heterostructures. An exchange spring model of MnAs/GaMnAs bilayers accounts for the variation of the exchange bias field wi...
0905.3691v2
2009-05-26
Quantum transport through a molecule coupled to a mesoscopic ring: A theoretical study
Transport through a molecule sandwiched between two metallic electrodes and coupled to a mesoscopic ring that threads a magnetic flux $\phi$ is studied. An analytic approach for the electron transport through the molecular bridge system is presented. Electronic transport properties are discussed in two aspects: (a) pre...
0905.4175v2
2009-05-27
Strong Coupling Quantum Einstein Gravity at a z=2 Lifshitz Point
We solve a renormalized Wheeler-DeWitt equation for Einstein gravity in D+1 dimensions with D= odd in the strong coupling limit, which is expected to be suited to probe quantum geometry at short distances, in order to test Horava's idea that quantum gravity at short distances will be described by a nonrelativistic syst...
0905.4326v2
2009-05-27
System size stochastic resonance in driven finite arrays of coupled bistable elements
The global response to weak time periodic forces of an array of noisy, coupled nonlinear systems might show a nonmonotonic dependence on the number of units in the array. This effect has been termed system size stochastic resonance. In this paper, we analyze the nonmonotonic dependence on the system size of the signal-...
0905.4470v1
2009-05-29
Spin-lattice coupling, frustration and magnetic order in multiferroic RMnO3
We have performed high resolution neutron diffraction and inelastic neutron scattering experiments in the frustrated multiferroic hexagonal compounds RMnO3 (R=Ho, Yb, Sc, Y), which provide evidence of a strong magneto-elastic coupling in the the whole family. We can correlate the atomic positions, the type of magnetic ...
0905.4824v1
2009-05-29
Coupling between M2-branes and Form Fields
In the context of low-energy effective theory of multiple M2-branes, we construct the interaction terms between the world-volume fields of M2-branes and the antisymmetric tensor fields of three- and six-forms. By utilizing the compactification procedure, we show coincidence between the dimensionally reduced coupling an...
0905.4840v1
2009-06-02
Coupling of higher-mode-light into a single sliver nanowire
Coupling of higher-order-mode light into a single sliver nanowire and the degree of the coupling can be controlled by adjusting the light polarization, showing that nanowire waveguide has no request on the spatial mode of the input light. Photons with different orbital angular momentums (OAM) are used to excite surface...
0906.0406v1
2009-06-03
Non-minimal Maxwell-Modified Gauss-Bonnet Cosmologies: Inflation and Dark Energy
In this paper we show that power-law inflation can be realized in non-minimal gravitational coupling of electromagnetic field with a general function of Gauss-Bonnet invariant. Such a non-minimal coupling may appear due to quantum corrections. We also consider modified Maxwell-$F(G)$ gravity in which non-minimal coupli...
0906.0713v1
2009-06-05
Strong Coupling QCD in the Continuum
A short overview of studies of strong coupling problems in hadron physics is presented. The Schwinger-Dyson/Bethe-Salpeter approach in the continuum allows the perturbative regime to be connected to the world of strong coupling that controls confinement and chiral dynamics that in turn determines the properties of ligh...
0906.1067v1
2009-06-06
The Vector Meson And Heavy Meson Strong Interaction
We calculate the coupling constants between the light vector mesons and heavy mesons within the framework of the light-cone QCD sum rule in the leading order of heavy quark effective theory. The sum rules are very stable with the variations of the Borel parameter and the continuum threshold. The extracted couplings wil...
0906.1287v1
2009-06-08
On gauge coupling constant in linearization of nonlinear supersymmetry
We study in two space-time dimensions (d = 2) the relation between N = 2 supersymmetric (SUSY) QED theory and N = 2 nonlinear (NL) SUSY model by linearizing N = 2 NLSUSY generally based upon the fundamental notions of the basic theory. We find a remarkable mechanism which determines theoretically the magnitude of the b...
0906.1471v1
2009-06-22
Temporal precision of spike response to fluctuating input in pulse-coupled networks of oscillating neurons
A single neuron is known to generate almost identical spike trains when the same fluctuating input is repeatedly applied. Here, we study the reliability of spike firing in a pulse-coupled network of oscillator neurons receiving fluctuating inputs. We can study the precise responses of the network as synchronization bet...
0906.3940v1
2009-06-23
Logarithmic decay of the energy for an hyperbolic-parabolic coupled system
This paper is devoted to the study of a coupled system consisting in a wave and heat equations coupled through transmission condition along a steady interface. This system is a linearized model for fluid-structure interaction introduced by Rauch, Zhang and Zuazua for a simple transmission condition and by Zhang and Zua...
0906.4178v1
2009-06-23
Global Attractor of a coupled Two-Cell Brusselator Model
In this work the existence of a global attractor for the solution semiflow of the coupled two-cell Brusselator model equations is proved. A grouping estimation method and a new decomposition approach are introduced to deal with the challenge in proving the absorbing property and the asymptotic compactness of this type ...
0906.4345v1
2009-06-25
Quantum impurity models with the Coupled Cluster Method
We investigate the ground-state properties of the Anderson single impurity model (finite Coulomb impurity repulsion) with the Coupled Cluster Method. We consider different CCM reference states and approximation schemes and make comparison with exact Green's function results for the non-interacting model and with Brillo...
0906.4684v1
2009-06-29
In-plane noncollinear exchange coupling mediated by helical edge states in Quantum Spin Hall system
We study the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction mediated by helical edge states in quantum spin hall system. The helical edge states induce an in-plane noncollinear exchange coupling between two local spins, in contrast to the isotropic coupling induced in normal metal. The angle between the two local sp...
0906.5204v1
2009-07-03
Uniform estimates for metastable transition times in a coupled bistable system
We consider a coupled bistable N-particle system driven by a Brownian noise, with a strong coupling corresponding to the synchronised regime. Our aim is to obtain sharp estimates on the metastable transition times between the two stable states, both for fixed N and in the limit when N tends to infinity, with error esti...
0907.0537v2
2009-07-17
Electrically controlled persistent spin currents at the interface of multiferroic oxides
We predict the appearance of a persistent spin current in a two-dimensional electron gas formed at the interface of multiferroic oxides with a transverse helical magnetic order. No charge current is generated. This is the result of an effective spin-orbit coupling generated by the topology of the oxide local magnetic m...
0907.3023v1
2009-07-20
Qubit-oscillator dynamics in the dispersive regime: analytical theory beyond rotating-wave approximation
We generalize the dispersive theory of the Jaynes-Cummings model beyond the frequently employed rotating-wave approximation (RWA) in the coupling between the two-level system and the resonator. For a detuning sufficiently larger than the qubit-oscillator coupling, we diagonalize the non-RWA Hamiltonian and discuss the ...
0907.3516v1
2009-07-21
Supersolidity in a Bose-Holstein model
We derive an effective d-dimensional Hamiltonian for a system of hard-core-bosons coupled to optical phonons in a lattice. At non-half-fillings, a superfluid-supersolid transition occurs at intermediate boson-phonon couplings, while at strong-couplings the system phase separates. We demonstrate explicitly that the pres...
0907.3543v1
2009-07-30
Inter-layer Josephson coupling in stripe-ordered superconducting cuprates
Motivated by experiments on LBCO-1/8 which suggest that stripe order co-exists with two-dimensional pairing without inter-layer phase coherence over an extended range of temperatures, we determine the inter-layer Josephson coupling in the presence of stripe order. We employ a mean-field description of bond-centered str...
0907.5202v1
2009-08-03
Pseudoscalar--meson decuplet--baryon coupling constants in light cone QCD
Taking into account the $SU(3)_f$ breaking effects, the strong coupling constants of the $\pi$, $K$ and $\eta$ mesons with decuplet baryons are calculated within light cone QCD sum rules method. It is shown that all coupling constants, even in the case of $SU(3)_f$ breaking, are described in terms of only one universal...
0908.0259v1
2009-08-19
Modeling Three and Four Coupled Phase Qubits
The Josephson junction phase qubit has been shown to be a viable candidate for quantum computation. In recent years, the two coupled phase system has been extensively studied theoretically and experimentally. We have analyzed the quantum behavior of three and four capacitively-coupled phase qubits with different possib...
0908.2823v1
2009-08-21
Time-resolved Raman Spectroscopy of Optical Phonons in Graphite: Phonon Anharmonic Coupling and Anomalous Stiffening
Time-resolved Raman spectroscopy has been applied to probe the anharmonic coupling and electron-phonon interaction of optical phonons in graphite. From the decay of the transient anti-Stokes scattering of the G-mode following ultrafast excitation, we measured a lifetime of 2.2+/-0.1ps for zone-center optical phonons. W...
0908.3036v1
2009-08-21
Bipolaron in the t-J model coupled to longitudinal and transverse quantum lattice vibrations
We explore the influence of two different polarizations of quantum oxygen vibrations on the spacial symmetry of the bound magnetic bipolaron in the context of the t-J model by using exact diagonalization within a limited functional space. Quadratic electron phonon coupling to transverse polarization stabilizes d-wave s...
0908.3119v2
2009-08-27
SU(2) lattice gauge theory in 2+1 dimensions: critical couplings from twisted boundary conditions and universality
We present a precision determination of the critical coupling beta_c for the deconfinement transition in pure SU(2) gauge theory in 2+1 dimensions. This is possible from universality, by intersecting the center vortex free energy as a function of the lattice coupling beta with the exactly known value of the interface f...
0908.4030v1
2009-08-28
Global existence for coupled systems of nonlinear wave and Klein-Gordon equations in three space dimensions
We consider the Cauchy problem for coupled systems of wave and Klein-Gordon equations with quadratic nonlinearity in three space dimensions. We show global existence of small amplitude solutions under certain condition including the null condition on self-interactions between wave equations. Our condition is much weake...
0908.4137v3
2009-08-29
Spin-Phonon Coupling in Iron Pnictide Superconductors
The magnetic moment in the parent phase of the iron-pnictide superconductors varies with composition even when the nominal charge of iron is unchanged. We propose the spin-lattice coupling due to the magneto-volume effect as the primary origin of this effect, and formulate a Landau theory to describe the dependence of ...
0908.4361v1
2009-09-13
Synchronization in discrete-time networks with general pairwise coupling
We consider complete synchronization of identical maps coupled through a general interaction function and in a general network topology where the edges may be directed and may carry both positive and negative weights. We define mixed transverse exponents and derive sufficient conditions for local complete synchronizati...
0909.2416v1
2009-09-14
Electron transport through a quantum wire coupled with a mesoscopic ring
Electronic transport through a quantum wire sandwiched between two metallic electrodes and coupled to a quantum ring, threaded by a magnetic flux $\phi$, is studied. An analytic approach for the electron transport through the bridge system is presented based on the tight-binding model. The transport properties are disc...
0909.2509v1
2009-09-16
Energies and Entanglement in Multiply-coupled Phase Qubit Systems
The superconducting Josephson junction has been demonstrated to be a strong candidate for building quantum bits or "qubits" which are the components of a future quantum computer. In recent years, considerable theoretical and experimental effort have been focused on studying quantum properties of single qubits and two c...
0909.3082v1
2009-09-24
Unification of Gauge Couplings in the E(6)SSM
We argue that in the two-loop approximation gauge coupling unification in the exceptional supersymmetric standard model can be achieved for any phenomenologically reasonable value of strong gauge coupling at the electroweak scale consistent with the experimentally measured central value.
0909.4530v2
2009-09-28
Synchronization in Networks of Coupled Harmonic Oscillators with Stochastic Perturbation and Time Delays
In this paper, we investigate synchronization of coupled second-order linear harmonic oscillators with random noises and time delays. The interaction topology is modeled by a weighted directed graph and the weights are perturbed by white noise. On the basis of stability theory of stochastic differential delay equations...
0909.4987v1
2009-09-29
Fermions and noncommutative emergent gravity II: Curved branes in extra dimensions
We study fermions coupled to Yang-Mills matrix models from the point of view of emergent gravity. The matrix model Dirac operator provides an appropriate coupling for fermions to the effective gravitational metric for general branes with nontrivial embedding, albeit with a non-standard spin connection. This generalizes...
0909.5298v2
2009-09-29
Singlet scalar dark matter effects on Higgs boson driven inflation
A minimal candidate for dark matter is provided by a stable standard model singlet hermitian scalar field. The quantum mechanical effects of this singlet are explored in a model where the standard model Higgs boson has a large non-minimal coupling to the Ricci scalar and plays the role of the inflaton. Imposition of th...
0909.5353v1
2009-10-01
Cosmological consequences of the NonCommutative Geometry Spectral Action
Cosmological consequences of the noncommutative geometry spectral action are presented. Neglecting the nonminimal coupling of the Higgs field to the curvature, background cosmology remains unchanged, and only the inhomogeneous perturbations will evolve differently from the equivalent classical system. However, consider...
0910.0181v1
2009-10-02
Investigations on the Property of $f_0(600)$ and $f_0(980)$ Resonances in $γγ\to ππ$ Process
Using dispersion relation technique and experimental data, a coupled channel analysis on $\gamma\gamma\to\pi\pi$ process is made. Di-photon coupling of $f_0(600)$ and $f_0(980)$ resonances are extracted and their dynamical properties are discussed. Especially we study the physical meaning of the coupling constant $g^2_...
0910.0341v1
2009-10-13
Study of symmetry in F(R) theory of gravity
An action in which the Ricci scalar is nonminimally coupled with a scalar field and contains higher order curvature invariant terms carries a conserved current under certain conditions that decouples geometric part from the scalar field. The conserved current relates the pair of arbitrary coupling parameters $f(\phi)$ ...
0910.2385v1
2009-10-22
Magnetic dipole moments in single and coupled split-ring resonators
We examine the role of magnetic dipoles in single and coupled pairs of metallic split-ring resonators by numerically computing their magnitude and examining their relative contributions to the scattering cross section. We demonstrate that magnetic dipoles can strongly influence the scattering cross section along partic...
0910.4210v1
2009-10-24
Coupling an epitaxial quantum dot to a fiber-based external-mirror microcavity
We report the coupling of individual InAs quantum dots (QDs) to an external-mirror microcavity. The external mirror is bonded to a fiber and positioned above a semiconductor sample consisting of a QD-containing GaAs layer on top of a distributed Bragg reflector (DBR). This open cavity can be rapidly tuned with a piezoe...
0910.4658v1
2009-10-26
Spin Superfluidity versus Solidity of Ultracold Polar Molecules
We present a technique for engineering quantum magnets via ultracold polar molecules in optical lattices and explore exotic interplay between its spin superfluidity and solidity. The molecular ground and first excited rotational states are resonantly coupled by a linearly polarized microwave field. The spin-up (spin-do...
0910.4922v1
2009-10-26
Running Gauge Coupling in Asymptotically Safe Quantum Gravity
We investigate the non-perturbative renormalization group behavior of the gauge coupling constant using a truncated form of the functional flow equation for the effective average action of the Yang-Mills-gravity system. We find a non-zero quantum gravity correction to the standard Yang-Mills beta function which has the...
0910.4938v2
2009-10-28
Vacuum Ambiguity in de Sitter Space at Strong Coupling
It is well known that in the weak coupling regime, quantum field theories in de Sitter space do not have a unique vacuum, but a class of vacua parametrized by a complex parameter $\alpha$, i.e., the so-called $\alpha$-vacua. In this article, using gauge/gravity duality, we calculate the symmetric two-point function of ...
0910.5509v3
2009-11-06
Kondo impurity on the honeycomb lattice at half-filling
We consider a Kondo-like impurity interacting with fermions on a honeycomb lattice at half-filling, as in the case of graphene. We derive from the lattice model an effective one-dimensional continuum theory which has, in general, four flavors with angular momentum mixing in the presence of internode scattering processe...
0911.1255v1
2009-11-06
Topological Casimir effect in power-law FRW cosmologies
We investigate the vacuum expectation values of the field squared and the energy-momentum tensor for a massless scalar field with general curvature coupling parameter in spatially flat Friedmann-Robertson-Walker universes with an arbitrary number of toroidally compactified dimensions. When the comoving lengths of the c...
0911.1260v1
2009-11-11
CP invariance of chiral gauge theories and Majorana-Yukawa couplings on the lattice
The construction of CP-invariant lattice chiral gauge theories and the construction of lattice Majorana fermions with chiral Yukawa couplings is subject to topological obstructions. In the present work we suggest lattice extensions of charge and parity transformation for Weyl fermions. This enables us to construct latt...
0911.2038v1
2009-11-11
Right on time: Measuring Kuramoto model coupling from a survey of wristwatches
Using a survey of wristwatch synchronization from a randomly selected group of independent volunteers, one can model the system as a Kuramoto-type coupled oscillator network. Based on the phase data, both the order parameter and an estimated value of the coupling is derived and the possibilities for similar research to...
0911.2158v3
2009-11-14
Non-geodesic motion in $f({\mathcal G})$ gravity with non-minimal coupling
The dynamics of test particles in $f(\mathcal G)$ modified Gauss-Bonnet gravity is investigated. It is shown that in $f({\mathcal G})$ gravity models with non-minimal coupling to matter, particles experience an extra force normal to their four-velocities and as a result move along non- geodesic world-lines. The explici...
0911.2754v1
2009-11-16
Calculating the running coupling in strong electroweak models
One possibility for Beyond Standard Model physics is a new strongly-interacting gauge theory. One way to determine if a non-abelian gauge theory is QCD-like or conformal is to measure the running of the renormalized gauge coupling. We define the renormalized coupling from Wilson loop ratios, and measure these ratios vi...
0911.2934v1
2009-11-16
Matter Lagrangians Coupled with Connections
We shall here consider extended theories of gravitation in the metric-affine formalism with matter coupled directly to the connection. A sufficiently general procedure will be exhibited to solve the resulting field equation associated to the connection. As special cases one has the no-coupling case (which is standard i...
0911.2981v2
2009-11-17
Large polaron formation induced by Rashba spin-orbit coupling
Here the electron-phonon Holstein model with Rashba spin-orbit interaction is studied for a two dimensional square lattice in the adiabatic limit. It is demonstrated that a delocalized electron at zero spin-orbit coupling localizes into a large polaron state as soon as the Rashba term is nonzero. This spin-orbit induce...
0911.3206v2
2009-11-22
Synchronization and Collective Dynamics in a Carpet of Microfluidic Rotors
We study synchronization of an array of rotors on a substrate that are coupled by hydrodynamic interaction. The rotors that are modeled by an effective rigid body, are driven by an internal torque and exerts an active force on the surrounding fluid. The long-ranged nature of the hydrodynamic interaction between the rot...
0911.4253v2
2009-11-23
Transport through a Kondo quantum dot: Functional RG approach
We apply the functional renormalization group (FRG) method to calculate the conductance of a quantum dot in the Kondo regime. Starting from the exact FRG equations in Keldysh formulation for the Kondo exchange Hamiltonian in pseudo-fermion (pf) representation, we solve the coupled equations for the pf self energy and t...
0911.4383v1
2009-11-26
Quantum state transfer via temporal kicking of information
We propose a strategy for perfect state transfer in spin chains based on the use of an unmodulated coupling Hamiltonian whose coefficients are explicitly time dependent. We show that, if specific and non-demanding conditions are satisfied by the temporal behavior of the coupling strengths, our model allows perfect stat...
0911.5160v2
2009-11-30
Breakdown of perturbative weak coupling approaches for the biomolecular energy transfer
We show that the biomolecular exciton dynamics under the influence of slow polarization fluctuations in the solvent cannot be described by approaches which are perturbative in the system-bath coupling. For this, we compare results for the decoherence rate of the exciton dynamics of a resumed perturbation theory with nu...
0911.5590v1
2010-01-05
Tuning spin-orbit coupling and superconductivity at the SrTiO3/LaAlO3 interface: a magneto-transport study
The superconducting transition temperature, Tc, of the SrTiO3/LaAlO3 interface was varied by the electric field effect. The anisotropy of the upper critical field and the normal state magneto-transport were studied as a function of gate voltage. The spin-orbit coupling energy is extracted. This tunable energy scale is ...
1001.0781v1
2010-01-07
Energy Dissipation and Regularity for a Coupled Navier-Stokes and Q-Tensor System
We study a complex non-newtonian fluid that models the flow of nematic liquid crystals. The fluid is described by a system that couples a forced Navier-Stokes system with a parabolic-type system. We prove the existence of global weak solutions in dimensions two and three. We show the existence of a Lyapunov functional ...
1001.1032v1
2010-01-12
Pairing and condensation in a resonant Bose-Fermi mixture
We study by diagrammatic methods a mixture of single-component bosons and fermions, with boson-fermion coupling tuned by a Fano-Feshbach resonance. For increasing coupling, the growing boson-fermion pairing correlations progressively reduce the boson condensation temperature and make it eventually vanish at a critical ...
1001.1971v1
2010-01-15
Stochastic Semi-Classical Description of Fusion at Near-Barrier Energies
Fusion reactions of heavy ions are investigated by employing a simple stochastic semi-classical model which includes the coupling between relative motion and low frequency collective surface modes of colliding ions similarly to the quantal coupled-channels description. The quantal effect enters into the calculation thr...
1001.2658v2
2010-01-18
Resonance induced by repulsive interactions in a model of globally-coupled bistable systems
We show the existence of a competition-induced resonance effect for a generic globally coupled bistable system. In particular, we demonstrate that the response of the macroscopic variable to an external signal is optimal for a particular proportion of repulsive links. Furthermore, we show that a resonance also occurs f...
1001.2993v1
2010-01-18
Polyakov Loops in Strongly-Coupled Plasmas with Gravity Duals
We study the properties of the Polyakov loop in strongly-coupled gauge plasmas that are conjectured to be dual to five dimensional theories of gravity coupled to a nontrivial single scalar field. We find a gravity dual that can describe the thermodynamic properties and also the expectation value of the Polyakov loop in...
1001.3155v1
2010-01-19
Isospin breaking effects in the dynamical generation of the X(3872)
We have studied isospin breaking effects in the X(3872) resonance and found a natural explanation for the branching fraction of the X decaying to $J/\psi$ with two and three pions being close to unit. Within our framework the X(3872) is a dynamically generated resonance in coupled channels. We also study the relationsh...
1001.3254v1
2010-01-26
Uniformity Studies of Scintillator Tiles directly coupled to SiPMs for Imaging Calorimetry
We present a novel geometry of scintillator tiles developed for fiberless coupling to silicon photomultipliers (SiPMs) for applications in highly granular calorimeters. A high degree of uniformity of the tile response over the full active area was achieved by a drilled slit at the coupling position of the photon sensor...
1001.4665v2
2010-01-26
Bouncing Universe and Reconstructing Vector Field
Motivated by the recent works of Refs. \cite{R1, R2} where a model of inflation has been suggested with non-minimally coupled massive vector fields, we generalize their work to the study of the bouncing solution. So we consider a massive vector field, which is non-minimally coupled to gravity. Also we consider non-mini...
1001.4682v1
2010-01-26
Observation of excited states in a graphene double quantum dot
We study a graphene double quantum dot in different coupling regimes. Despite the strong capacitive coupling between the dots, the tunnel coupling is below the experimental resolution. We observe additional structures inside the finite-bias triangles, part of which can be attributed to electronic excited dot states, wh...
1001.4700v1
2010-01-30
Thermoelectrically Controlled Spin-Switch
The search for novel spintronic devices brings about new ways to control switching in magnetic thin-films. In this work we experimentally demonstrate a device based on thermoelectrically controlled exchange coupling. The read out signal from a giant magnetoresistance element is controlled by exchange coupling through a...
1002.0089v1
2010-01-30
Exchange coupling and magnetoresistance in CoFe/NiCu/CoFe spin-valves near the Curie point of the spacer
Thermal control of exchange coupling between two strongly ferromagnetic layers through a weakly ferromagnetic Ni-Cu spacer and the associated magnetoresistance is investigated. The spacer, having a Curie point slightly above room temperature, can be cycled between its paramagnetic and ferromagnetic states by varying th...
1002.0090v1
2010-01-31
Perturbation of heliosynchronous orbits in stable Kaluza-Klein theory
Although the methods and techniques have been greatly improved since the late nineteenth century, the precision on the measurement of the gravitational constant G does not exceed 1 part in 1000. Intrinsic variations of G caused by the geomagnetic field may explain the observed dispersion of the laboratory measurements....
1002.0116v1
2010-02-16
Slow-roll Extended Quintessence
We derive the slow-roll conditions for a non-minimally coupled scalar field (extended quintessence) during the radiation/matter dominated era extending our previous results for thawing quintessence. We find that the ratio $\ddot\phi/3H\dot\phi$ becomes constant but negative, in sharp contrast to the ratio for the minim...
1002.2986v2
2010-02-22
Wave-packet analysis of interference patterns in output coupled atoms
We study the output coupling of atoms from a magnetic trap into a linear potential slope of gravity using a weak radio-frequency field. We present a one-dimensional wave-packet model based on a continuous loading of a continuous spectrum of generalised eigenstates to describe the scenario. Analyzing the model, we show ...
1002.4184v1