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2007-10-04
Thermodynamics of statistically interacting quantum gas in D dimensions
We present the exact thermodynamics (isochores, isotherms, isobars, response functions) of a statistically interacting quantum gas in D dimensions. The results in D=1 are those of the thermodynamic Bethe ansatz for the nonlinear Schroedinger model, a gas with repulsive two-body contact potential. In all dimensions the ...
0710.1031v1
2007-10-05
Renormalization group flow of quartic perturbations in graphene: Strong coupling and large-N limits
We explore the renormalization group flow of quartic perturbations in the low-energy theory of graphene, in the strong Coulomb coupling and large-N limits, where N is the number of fermion flavors. We compute the anomalous dimensions of the quartic couplings u up to next-to-leading order in 1/N and find both relevant a...
0710.1315v2
2007-10-08
Effective Coupling Constant in Renormalization Group for the Quantum Electrodynamics
Effective coupling constant in quantum electrodynamics is investigated. A pole appears in the effective coupling constant for the space-like momentum if it is calculated by perturbation. The pole can be eliminated by the analytic regularization. For QED the effective coupling constant is written in terms of the scale p...
0710.1457v1
2007-10-15
Intersubband spin-orbit coupling and spin splitting in symmetric quantum wells
In semiconductors with inversion asymmetry, spin-orbit coupling gives rise to the well-known Dresselhaus and Rashba effects. If one considers quantum wells with two or more conduction subbands, an additional, intersubband-induced spin-orbit term appears whose strength is comparable to the Rashba coupling, and which rem...
0710.2866v1
2007-10-18
Entanglement between charge qubits induced by a common dissipative environment
We study entanglement generation between two charge qubits due to the strong coupling with a common bosonic environment (Ohmic bath). The coupling to the boson bath is a source of both quantum noise (leading to decoherence) and an indirect interaction between qubits. As a result, two effects compete as a function of th...
0710.3576v1
2007-10-19
Evolution of coherence between the Jaynes - Cummings Eigenstates in the presence of repeated occupancy measurements: The case of resonant coupling
A two level system resonantly coupled to a single mode cavity field and subject to ground state occupancy measurement like interaction is considered. For this situation, the solution to the Lindblad master equation for the density matrix is obtained with respect to the Jaynes Cummings eigenstate representation. It is s...
0710.3662v1
2007-10-23
Tan(beta) enhanced Yukawa couplings for supersymmetric Higgs singlets at one loop
Extensions of the MSSM generically feature gauge singlet Higgs bosons. These singlet Higgs bosons have tan(beta)-enhanced Yukawa couplings to down-type quarks and leptons at the one-loop level. We present an effective Lagrangian incorporating these Yukawa couplings and use it to study their effect on singlet Higgs boso...
0710.4281v1
2007-10-25
Classical Renormalization of Codimension-two Brane Couplings
The curvature on codimension-two and higher branes is not regular for arbitrary matter sources. Nevertheless, the low-energy theory for an observer on such a brane should be well-defined and independent to any regularization procedure. This is achieved via appropriate classical renormalization of the brane couplings, a...
0710.4598v1
2007-11-21
Josephson Effect between Conventional and Rashba Superconductors
We study the Josephson effect between a conventional s-wave superconductor and a non-centrosymmetric superconductor with Rashba spin-orbit coupling. Rashba spin-orbit coupling affects the Josephson pair tunneling in a characteristic way. The Josephson coupling can be decomposed into two parts, a `spin-singlet-like' and...
0711.3241v2
2007-11-30
Non-local dilaton coupling to dark matter: cosmic acceleration and pressure backreaction
A model of non-local dilaton interactions, motivated by string duality symmetries, is applied to a scenario of "coupled quintessence" in which the dilaton dark energy is non-locally coupled to the dark-matter sources. It is shown that the non-local effects tend to generate a backreaction which -- for strong enough coup...
0711.5022v1
2007-12-11
Valley interference effects on a donor electron close to a Si/SiO2 interface
We analyze the effects of valley interference on the quantum control and manipulation of an electron bound to a donor close to a Si/SiO2 interface as a function of the valley-orbit coupling at the interface. We find that, for finite valley-orbit coupling, the tunneling times involved in shuttling the electron between t...
0712.1823v1
2008-01-11
Generation of d-wave coupling in the two-dimensional Hubbard model from functional renormalization
Within the two-dimensional repulsive t-t'-Hubbard model, an attractive coupling in the d-wave pairing channel is induced by antiferromagnetic fluctuations. We investigate this coupling using functional renormalization group equations. The momentum dependent d-wave coupling can be bosonized by the use of scale dependent...
0801.1773v2
2008-01-29
Microwave-induced coupling of superconducting qubits
We investigate the quantum dynamics of a system of two coupled superconducting qubits under microwave irradiation. We find that, with the qubits operated at the charge co-degeneracy point, the quantum evolution of the system can be described by a new effective Hamiltonian which has the form of two coupled qubits with t...
0801.4541v2
2008-02-03
Anomalous Higgs couplings in egamma collision with initial beam and final state polarizations
We investigate the constraints on the anomalous WWH couplings through the process $e^{-}\gamma \to \nu_{e} W^{-} H$. Considering incoming beam polarizations and the longitudinal and transverse polarization states of the final W boson, we find 95% confidence level limits on the anomalous coupling parameters with an inte...
0802.0293v2
2008-02-08
Noise-dependent stability of the synchronized state in a coupled system of active rotators
We consider a Kuramoto model for the dynamics of an excitable system consisting of two coupled active rotators. Depending on both the coupling strength and the noise, the two rotators can be in a synchronized or desynchronized state. The synchronized state of the system is most stable for intermediate noise intensity i...
0802.1105v1
2008-02-08
Immirzi parameter and fermions with non-minimal coupling
We clarify the role played by the Immirzi parameter in classical gravity coupled to fermions. Considering the general non-minimal coupling, we show that, although the torsion depends explicitly on the Immirzi parameter, in a suitable parametrization the effective action obtained by integrating out the spin-connection i...
0802.1221v2
2008-02-12
Dynamical Coupling Between Ferromagnets Due to Spin Transfer Torque
We use a combination of analytic calculations and numerical simulations to demonstrate that electrical current flowing through a magnetic bilayer induces dynamical coupling between the layers. The coupling originates from the dependence of the spin transfer torque exerted on the layers on the relative orientations of t...
0802.1560v1
2008-02-12
Coupling of Electronic and Motional Dynamics in a Cold Atom Optical Lattice
We study the coupling of internal electronic excitations to vibrational modes of the external motion of ultracold atoms in an optical lattice. For different ground and excited state potentials the on-site coupling of excitations and vibrations term renormalizes the effective electronic transition energy, which appears ...
0802.1618v1
2008-02-12
Strong coupling between a metallic nanoparticle and a single molecule
We theoretically investigate strong coupling between a single molecule and a single metallic nanoparticle. A theory suited for the quantum-mechanical description of surface plasmon polaritons (SPPs) is developed. The coupling between these SPPs and a single molecule, and the modified molecular dynamics in presence of t...
0802.1630v1
2008-02-20
Effect of top quark spin on the unparticle couplings in γγ\to t\bar{t}
We investigate the potential of $\gamma\gamma$ collisions to probe scalar unparticle couplings via top-antitop quark pair production. We find 95% confidence level limits on the unparticle couplings with an integrated luminosity of $500 fb^{-1}$ and $\sqrt{s}=1$ TeV energy. We investigate the effect of top quark spin po...
0802.2818v3
2008-02-20
Bang-Bang control of a qubit coupled to a quantum critical spin bath
We analytically and numerically study the effects of pulsed control on the decoherence of a qubit coupled to a quantum spin bath. When the environment is critical, decoherence is faster and we show that the control is relatively more effective. Two coupling models are investigated, namely a qubit coupled to a bath via ...
0802.2859v2
2008-02-28
Coupling efficiency for phase locking of a spin transfer oscillator to a microwave current
The phase locking behavior of spin transfer nano-oscillators (STNOs) to an external microwave signal is experimentally studied as a function of the STNO intrinsic parameters. We extract the coupling strength from our data using the derived phase dynamics of a forced STNO. The predicted trends on the coupling strength f...
0802.4162v3
2008-03-17
Gluon scattering in N=4 super-Yang-Mills theory from weak to strong coupling
I describe some recent developments in the understanding of gluon scattering amplitudes in N=4 super-Yang-Mills theory in the large-N_c limit. These amplitudes can be computed to high orders in the weak coupling expansion, and also now at strong coupling using the AdS/CFT correspondence. They hold the promise of being ...
0803.2475v1
2008-04-10
Solitary waves for linearly coupled nonlinear Schrodinger equations with inhomogeneous coefficients
Motivated by the study of matter waves in Bose-Einstein condensates and coupled nonlinear optical systems, we study a system of two coupled nonlinear Schrodinger equations with inhomogeneous parameters, including a linear coupling. For that system we prove the existence of two different kinds of homoclinic solutions to...
0804.1785v2
2008-04-15
Entangled photon pairs produced by a quantum dot strongly coupled to a microcavity
We show theoretically that entangled photon pairs can be produced on demand through the biexciton decay of a quantum dot strongly coupled to the modes of a photonic crystal. The strong coupling allows to tune the energy of the mixed exciton-photon (polariton) eigenmodes, and to overcome the natural splitting existing b...
0804.2396v1
2008-04-29
Nonlinear evolution equations for degenerate transverse waves in anisotropic elastic solids
Transverse elastic waves behave differently in nonlinear isotropic and anisotropic media. Quadratically nonlinear coupling in the evolution equations for wave amplitudes is not possible in isotropic solids, but such a coupling may occur for certain directions in anisotropic materials. We identify the expression respons...
0804.4695v1
2008-05-15
Parametrization of the QCD coupling in the Evolution Equations
We examine the parametrization of the QCD coupling in the Evolution Equations, including DGLAP. Our conclusion is that the well-known parametrization, where the argument of the coupling is k^2_{\perp}/\beta or just k^2_{\perp}, stands only if the lowest integration limit in the transverse momentum space (the starting p...
0805.2278v1
2008-05-21
Dynamical Regularization in Scalefree-trees of Coupled 2D Chaotic Maps
The dynamics of coupled 2D chaotic maps with time-delay on a scalefree-tree is studied, with different types of the collective behaviors already been reported for various values of coupling strength [1]. In this work we focus on the dynamics' time-evolution at the coupling strength of the stability threshold and examin...
0805.3311v1
2008-05-29
Driven transverse shear waves in a strongly coupled dusty plasma
The linear dispersion properties of transverse shear waves in a strongly coupled dusty plasma are experimentally studied by exciting them in a controlled manner with a variable frequency external source. The dusty plasma is maintained in the strongly coupled fluid regime with (1 < Gamma << Gamma_c) where Gamma is the C...
0805.4514v2
2008-06-02
Electron and phonon correlations in systems of one-dimensional electrons coupled to phonons
Electron and phonon correlations in systems of one-dimensional electrons coupled to phonons are studied at low temperatures by emphasizing on the effect of electron-phonon backward scattering. It is found that the $2k_F$-wave components of the electron density and phonon displacement field share the same correlations. ...
0806.0310v3
2008-06-03
Spin-Orbit Coupling in an f-electron Tight-Binding Model
We extend a tight-binding method to include the effects of spin-orbit coupling, and apply it to the study of the electronic properties of the actinide elements Th, U, and Pu. These tight-binding parameters are determined for the fcc crystal structure using the equivalent equilibrium volumes. In terms of the single part...
0806.0420v1
2008-06-04
Coupling and Level Repulsion in the Localized Regime: From Isolated to Quasi-Extended Modes
We study the interaction of Anderson localized states in an open 1D random system by varying the internal structure of the sample. As the frequencies of two states come close, they are transformed into multiply-peaked quasi-extended modes. Level repulsion is observed experimentally and explained within a model of coupl...
0806.0704v2
2008-06-20
Identical chaotic synchronization and bidirectional message transmission in incoherently coupled semiconductor laser diodes
A chaos-based communication scheme allowing simultaneous bidirectional message transmission (Opt. Lett. 32, 403, 2007) is investigated numerically. Incoherent feedback and coupling case is analyzed, which is expected in real long-distance optical communication systems. It is shown that identical synchronization of chao...
0806.3375v1
2008-06-24
Decoherence of two qubits coupled with one-mode cavity without rotating-wave approximation
The decoherence of two qubits, coupled with one-mode cavity separately, has been investigated exactly. The results show that, for the resonant case, the decoherence behavior of system is similar to Markovian case when the coupling strength is weak, while the concurrence vanishes in finite time and might recover fractio...
0806.3884v2
2008-08-06
Anomalous WWH couplings in gamma gamma collision with initial beams and final state polarizations
The constraints on anomalous Higgs boson couplings are investigated through the process $\gamma\gamma \to W^{+}W^{-}H$. Considering the longitudinal and transverse polarization states of the final $W^{+}$ and $W^{-}$ bosons and incoming beam polarizations, we find 95% confidence level limits on the anomalous coupling p...
0808.0842v2
2008-09-25
Coherent operation of superconducting flux qubits
We study the quantum operation of coupled superconducting flux qubits under a microwave irradiation. The flux qubits can be described as magnetic dipole moments in the limit of weak microwave field amplitude consistent with usual experimental situations. With the Hamiltonian for coupled qubits under a microwave field, ...
0809.4341v3
2008-09-25
Bias dependence of magnetic exchange interactions: application to interlayer exchange coupling in spin valves
We study how a bias voltage changes magnetic exchange interactions. We derive a general expression for magnetic exchange interactions for systems coupled to reservoirs under a bias potential, and apply it to spin valves. We find that for metallic systems, the interlayer exchange coupling shows a weak, oscillatory depen...
0809.4451v1
2008-09-25
Ground state cooling of nanomechanical resonator via parametric linear coupling
We present a ground state cooling scheme for a nanomechanical resonator linearly coupled with a LC oscillator. The linear coupling, when periodically modulated at red detuning, up-converts the low-frequency nanomechanical mode to the high-frequency LC oscillator mode and generates backaction force that can cool the res...
0809.4459v2
2008-10-01
Higher neutrino mass allowed if Cold Dark Matter and Dark Energy are coupled
Cosmological limits on neutrino masses are softened, by more than a factor 2, if Cold Dark Matter (CDM) and Dark Energy (DE) are coupled. In turn, a neutrino mass yielding $\Omega_\nu$ up to $\sim0.20$ allows coupling levels $\beta \simeq 0.15, $ or more, already easing the coincidence problem. The coupling, in fact, d...
0810.0127v2
2008-10-16
Synchronization of Coupled Anizochronous Auto-Oscillating Systems
The particular properties of synchronization are discussed for coupled auto-oscillating systems, which are characterized by non-quadratic law of potential dependence on the coordinate. In particular, structure of the parameter plane (frequency mismatch - coupling value) is considered for coupled van der Pol - Duffing o...
0810.2863v1
2008-10-30
Berry Phase in a Single Quantum Dot with Spin-Orbit Interaction
Berry phase in a single quantum dot with Rashba spin-orbit coupling is investigated theoretically. Berry phases as functions of magnetic field strength, dot size, spin-orbit coupling and photon-spin coupling constants are evaluated. It is shown that the Berry phase will alter dramatically from 0 to $2\pi$ as the magnet...
0810.5405v1
2008-11-20
Gravitational correction to SU(5) gauge coupling unification
The gravitational corrections to the gauge coupling constants of abelian and non-abelian gauge theories has been shown to diverge quadratically. Since this result will have interesting consequences, this has been analyzed by several authors from different approaches. We propose to discuss this issue from a phenomenolog...
0811.3307v2
2008-11-25
Emergence of zero-lag synchronization in generic mutually coupled chaotic systems
Zero-lag synchronization (ZLS) is achieved in a very restricted mutually coupled chaotic systems, where the delays of the self-coupling and the mutual coupling are identical or fulfil some restricted ratios. Using a set of multiple self-feedbacks we demonstrate both analytically and numerically that ZLS is achieved for...
0811.4066v1
2008-12-01
Gauge Coupling Unification in F-theory GUT Models
We investigate gauge coupling unification for F-theory respectively Type IIB orientifold constructions of SU(5) GUT theories with gauge symmetry breaking via non-trivial hypercharge flux. This flux has the non-trivial effect that it splits the values of the three MSSM gauge couplings at the string scale, thus potential...
0812.0248v3
2008-12-04
Transition to complete synchronization in phase coupled oscillators with nearest neighbours coupling
We investigate synchronization in a Kuramoto-like model with nearest neighbour coupling. Upon analyzing the behaviour of individual oscillators at the onset of complete synchronization, we show that the time interval between bursts in the time dependence of the frequencies of the oscillators exhibits universal scaling ...
0812.0998v1
2009-01-04
Coupling between a dark and a bright eigenmode in a terahertz metamaterial
Terahertz time domain spectroscopy and rigorous simulations are used to probe the coupling between a dark and a bright plasmonic eigenmode in a metamaterial with broken symmetry. The metamaterial consists of two closely spaced split ring resonators that have their gaps in non-identical positions within the ring. For no...
0901.0365v1
2009-01-17
Electronic interferometer capacitively coupled to a quantum dot
We theoretically study electron interference in a ballistic electronic interferometer capacitively coupled to a quantum dot. The visibility of the interference is reduced when the dot has degenerate ground states with different excess charges. The degree of the reduction depends on system parameters such as the strengt...
0901.2626v2
2009-01-27
Weakly coupled discretized gravity
We consider discretized gravity in 4+2 dimensions compactified on a disk of constant negative curvature. The curvature of the disk avoids the presence of dangerous ultra-light scalar modes but comes also along with a high multiplicity of states potentially jeopardizing a good strong-coupling behavior of the discretized...
0901.4304v1
2009-01-31
An improved lattice measurement of the critical coupling in phi^4_2 theory
We use Monte Carlo simulations to obtain an improved lattice measurement of the critical coupling constant [lambda / mu^2]_crit for the continuum (1 + 1)-dimensional (lambda / 4) phi^4 theory. We find that the critical coupling constant depends logarithmically on the lattice coupling, resulting in a continuum value of ...
0902.0045v1
2009-02-03
Asynchronous response of coupled pacemaker neurons
We study a network model of two conductance-based pacemaker neurons of differing natural frequency, coupled with either mutual excitation or inhibition, and receiving shared random inhibitory synaptic input. The networks may phase-lock spike-to-spike for strong mutual coupling. But the shared input can desynchronize th...
0902.0602v1
2009-02-19
Impurity induced spin-orbit coupling in graphene
We study the effect of impurities in inducing spin-orbit coupling in graphene. We show that the sp3 distortion induced by an impurity can lead to a large increase in the spin-orbit coupling with a value comparable to the one found in diamond and other zinc-blende semiconductors. The spin-flip scattering produced by the...
0902.3244v1
2009-03-05
Modification of spin mixing of spinor BEC by cavity QED coupling
Dressed states of spinor Bose-Einstein condensates of spin-1 atoms coupling with optical cavity modes with far off resonance frequency are investigated. The exact solution of time evolution of population of spin component is derived, and the numerical result shows that the evolution is different from spin mixing withou...
0903.0998v1
2009-03-23
Higher Order Couplings in Magnetized Brane Models
We compute three-point and higher order couplings in magnetized brane models. We show that higher order couplings are written as products of three-point couplings. This behavior is the same as higher order amplitudes by conformal field theory calculations e.g. in intersecting D-brane models.
0903.3800v2
2009-03-30
Weakly coupled bound states of Pauli operators
We consider the two-dimensional Pauli operator perturbed by a weakly coupled, attractive potential. We show that besides the eigenvalues arising from the Aharonov-Casher zero modes there are two or one (depending on whether the flux of the magnetic field is integer or not) additional eigenvalues for arbitrarily small c...
0903.5333v1
2009-04-08
On the gauge coupling unification
We consider a quark-lepton symmetry model of unification of the strong and electromagnetic interactions. The model has the gauge group $SU(4)\times U(1)_{Y}$ and the minimal Higgs structure consisting of one complex quartet of scalar particles. The spontaneous breakdown of the gauge group to $SU(3)_{c}\times U(1)_{em}$...
0904.1324v1
2009-04-10
Single bipolaronic Transition in Jahn-Teller Model
We investigate the bipolaronic crossover and the pairing transition for a two-orbital model with Jahn-Teller coupling to a two-fold degenerate phonon mode. The evolution from weak to strong coupling is reminiscent of the behavior of the single-band Holstein model: The polaron crossover in which the electrons and phonon...
0904.1711v1
2009-04-26
Bouncing Universe with a Nonminimally Coupled Scalar Field on a Moving Domain Wall
We study dynamics of a dark energy component nonminimally coupled to gravity on a moving domain wall. We use this setup to explain late-time accelerated expansion and crossing of the phantom divide line by the equation of state parameter of this non-minimally coupled dark energy component. By analyzing parameter space ...
0904.4029v1
2009-04-28
Scalar dark matter-Higgs coupling in the case of electroweak symmetry breaking driven by unparticle
We study the possible annihilation cross section of scalar dark matter and its coupling \lambda_D to the standard model Higgs in the case of the electroweak symmetry breaking driven by unparticle. Here the annihilation process occurs with the help of three intermediate scalars which appear after the mixing. By respecti...
0904.4369v1
2009-05-04
Berry Phase Coupling and the Cuprate Neutron Scattering Resonance
We examine the influence of coupling between particle-hole and particle-particle spin fluctuations on the inelastic neutron scattering resonance (INSR) in cuprate superconductors in both weak and strong interaction limits. For weak-interactions in the particle-hole channel, we find that the interchannel coupling can el...
0905.0464v1
2009-05-05
Transport through a band insulator with Rashba spin-orbit coupling: metal-insulator transition and spin-filtering effects
We calculate the current-voltage characteristic of a one-dimensional band insulator with magnetic field and Rashba spin-orbit coupling which is connected to nonmagnetic leads. Without spin-orbit coupling we find a complete spin-filtering effect, meaning that the electric transport occurs in one spin channel only. For a...
0905.0611v1
2009-05-12
Globally clustered chimera states in delay--coupled populations
We have identified the existence of globally clustered chimera states in delay coupled oscillator populations and find that these states can breathe periodically, aperiodically and become unstable depending upon the value of coupling delay. We also find that the coupling delay induces frequency suppression in the desyn...
0905.1797v1
2009-05-12
Pauli Spin Blockade in the Presence of Strong Spin-Orbit Coupling
We study electron transport in a double quantum dot in the Pauli spin blockade regime, in the presence of strong spin-orbit coupling. The effect of spin-orbit coupling is incorporated into a modified interdot tunnel coupling. We elucidate the role of the external magnetic field, the nuclear fields in the dots, and spin...
0905.1818v1
2009-05-20
Polaronic memristor strongly coupled to electrodes
Attractive electron correlations due to an electron-vibron interaction (EVI) can overcome the direct Coulomb repulsion of polarons in strongly deformable molecular quantum dots (MQDs). If it realizes, a switching appears in the I-V characteristics of the degenerate nonadiabatic molecular bridges weakly coupled to elect...
0905.3230v1
2009-05-20
Strong coupling theory for the Jaynes-Cummings-Hubbard model
We present an analytic strong-coupling approach to the phase diagram and elementary excitations of the Jaynes-Cummings-Hubbard model describing a superfluid-insulator transition of polaritons in an array of coupled QED cavities. In the Mott phase, we find four modes corresponding to particle/hole excitations with lower...
0905.3344v2
2009-05-23
Weak and Strong-Coupling Electrostatic Interactions between Asymmetrically Charged Planar Surfaces
We compare weak and strong coupling theory of counterion-mediated electrostatic interactions between two asymmetrically charged plates with extensive Monte-Carlo simulations. Analytical results in both weak and strong coupling limits compare excellently with simulations in their respective regimes of validity. The syst...
0905.3851v1
2009-06-03
Fast Electrical Control of a Quantum Dot Strongly Coupled to a Nano-resonator
The resonance frequency of an InAs quantum dot strongly coupled to a GaAs photonic crystal cavity was electrically controlled via quantum confined Stark effect. Stark shifts up to 0.3meV were achieved using a lateral Schottky electrode that created a local depletion region at the location of the quantum dot. We report ...
0906.0751v1
2009-06-04
Theory of Optically-Driven Sideband Cooling for Atomic Collective Excitations and Its Generalization
We explore how to cool atomic collective excitations in an optically-driven three-level atomic ensemble, which may be described by a model of coupled two harmonic oscillators (HOs) with a time-dependent coupling. Moreover, the coupled two-HO model is further generalized to address other cooling issues, where the lower-...
0906.0806v1
2009-06-09
Quantum criticality near the Stoner transition in a two-dot with spin-orbit coupling
We study a system of two tunnel-coupled quantum dots, with the first dot containing interacting electrons (described by the Universal Hamiltonian) not subject to spin-orbit coupling, whereas the second contains non-interacting electrons subject to spin-orbit coupling. We focus on describing the behavior of the system n...
0906.1838v1
2009-06-17
Phase transition and correlation decay in Coupled Map Lattices
For a Coupled Map Lattice with a specific strong coupling emulating Stavskaya's probabilistic cellular automata, we prove the existence of a phase transition using a Peierls argument, and exponential convergence to the invariant measures for a wide class of initial states using a technique of decoupling originally deve...
0906.3017v2
2009-06-18
Do data favor neutrino mass and a coupling between Cold Dark Matter and Dark Energy?
We allow simultaneously for a CDM--DE coupling and non--zero neutrino masses and find that significant coupling and neutrino mass are (slightly) statistically favoured in respect to a cosmology with no coupling and negligible neutrino mass (our best fits are: C~1/2m_p, m_\nu~0.12eV each flavor). We assume DE to be a se...
0906.3369v1
2009-06-23
Exact AdS/CFT spectrum: Konishi dimension at any coupling
We compute the full dimension of Konishi operator in planar N=4 SYM theory it for a wide range of couplings, from weak to strong coupling regime, and predict the subleading terms in its strong coupling asymptotics. For this purpose we solve numerically the integral form of the AdS/CFT Y-system equations for the exact e...
0906.4240v2
2009-06-29
Quantum logic with weakly coupled qubits
There are well-known protocols for performing CNOT quantum logic with qubits coupled by particular high-symmetry (Ising or Heisenberg) interactions. However, many architectures being considered for quantum computation involve qubits or qubits and resonators coupled by more complicated and less symmetric interactions. H...
0906.5209v1
2009-07-02
Effect of next-nearest neighbor coupling on the optical spectra in bilayer graphene
We investigate the dependence of the optical conductivity of bilayer graphene (BLG) on the intra- and inter-layer interactions using the most complete model to date. We show that the next nearest-neighbor intralayer coupling introduces new features in the low-energy spectrum that are highly sensitive to sample doping, ...
0907.0504v1
2009-07-09
Higher-dimensional solitons and black holes with a non-minimally coupled scalar field
We study higher-dimensional soliton and hairy black hole solutions of the Einstein equations non-minimally coupled to a scalar field. The scalar field has no self-interaction potential but a cosmological constant is included. Non-trivial solutions exist only when the cosmological constant is negative and the constant g...
0907.1487v2
2009-07-12
Konishi at strong coupling from ABE
In this letter, we derive analytically the scaling dimension of the Konishi operator in planar N=4 gauge theory at strong coupling from the asymptotic Bethe equations. The first two leading terms agree with the recent string computation and numerical analysis of TBA equations. At the third order we find spurious logari...
0907.1919v1
2009-07-16
Entanglement localization after a coupling to incoherent noisy system
We report the experimental realization of entanglement localization which restores polarization entanglement completely redirected after a linear coupling with incoherent and noisy surrounding photon. The method, based only on measurements of the surrounding photon after the coupling and on post-selection, can localize...
0907.2780v1
2009-08-06
Coupled Modulated Bilayers
We propose a model addressing the coupling mechanism between two spatially modulated monolayers. We obtain the mean-field phase diagrams of coupled bilayers when the two monolayers have the same preferred modulation wavelength. Various combinations of the monolayer modulated phases are obtained and their relative stabi...
0908.0871v2
2009-08-13
Relativistic coupled-cluster calculations of $^{20}$Ne, $^{40}$Ar, $^{84}$Kr and $^{129}$Xe: correlation energies and dipole polarizabilities
We have carried out a detailed and systematic study of the correlation energies of inert gas atoms Ne, Ar, Kr and Xe using relativistic many-body perturbation theory and relativistic coupled-cluster theory. In the relativistic coupled-cluster calculations, we implement perturbative triples and include these in the corr...
0908.1899v1
2009-08-20
Anomalous Quartic Gauge Couplings from Six Quark Production
The absence of a light Higgs boson causes vector boson couplings to become strong at 1 TeV. A general framework for a systematic and consistent treatment is provided by effective theories of electroweak symmetry breaking. Already in next-to-leading order there appear quartic gauge couplings that go beyond the standard ...
0908.2951v1
2009-09-07
Fine structure in the tunneling spectra of electron-doped cuprates: No coupling to magnetic resonance mode
We analyze high-resolution scanning tunneling spectra of the electron-doped cuprate Pr0.88LaCe0.12CuO4 (T_c = 24 K). We find that the spectral fine structure below 35 meV is consistent with strong coupling to a bosonic mode at 16 meV, in quantitative agreement with early tunneling spectra of Nd1.85Ce0.15CuO4. Since the...
0909.1136v1
2009-09-15
Critical current density for spin transfer torque switching with composite free layer structure
Critical current density of composite free layer (CFL) in magnetic tunneling junction is investigated. CFL consists of two exchange coupled ferromagnetic layers, where the coupling is parallel or anti-parallel. Instability condition of the CFL under the spin transfer torque, which is related with critical current densi...
0909.2711v1
2009-09-22
The exchange coupling between the valence electrons of the fullerene cage and the electrons of the N atoms in N@C60^{-1,3}
MCSCF calculations are performed in order to determine the exchange coupling between the 2p electrons of the N atom and the LUMOs of the fullerene cage in the case of mono- and tri-anions of N@C60. The exchange coupling resulted by our calculations is large compared to the hyperfine interaction. The strong coupling can...
0909.3939v1
2009-09-22
Probing New Physics in Charm Couplings with Kaon and Other Hadron Processes
It is possible that the low-energy effects of physics beyond the standard model can be parametrized mainly by anomalous couplings of quarks to the W boson. Such couplings can generate potentially significant contributions to various transitions that can be probed by current and future experiments. This work explores co...
0909.3957v1
2009-10-14
Running of the coupling and quark mass in SU(2) with two adjoint fermions
We simulate SU(2) gauge theory with two massless Dirac fermions in the adjoint representation. We calculate the running of the Schroedinger Functional coupling and the renormalised quark mass over a wide range of length scales. The running of the coupling is consistent with the existence of an infrared fixed point (IRF...
0910.2562v1
2009-10-14
Plasmon-phonon Strongly-Coupled Mode in Epitaxial Graphene
We report the dispersion measurements, using angle-resolved reflection electron-energy-loss-spectroscopy (AREELS), on two-dimensional (2D) plasmons in single and multilayer graphene which couple strongly to surface optical phonon (FK phonon) modes of silicon carbide substrate. The coupled modes show discrete dispersion...
0910.2735v1
2009-10-16
Finite-size scaling tests for SU(3) lattice gauge theory with color sextet fermions
The observed slow running of the gauge coupling in SU(3) lattice gauge theory with two flavors of color sextet fermions naturally suggests it is a theory with one relevant coupling, the fermion mass, and that at zero mass correlation functions decay algebraically. I perform a finite-size scaling study on simulation dat...
0910.3072v1
2009-11-19
Non-minimal Kinetic coupling to gravity and accelerated expansion
We study a scalar field with kinetic term coupled to itself and to the curvature, as a source of dark energy, and analyze the role of this new coupling in the accelerated expansion at large times. In the case of scalar field dominance, the scalar field and potential giving rise to power-law expansion are found in some ...
0911.3702v2
2010-01-04
Nonminimal Inflation on the Randall-Sundrum II Brane with Induced Gravity
We study an inflation model that inflaton field is non-minimally coupled to the induced scalar curvature on the Randall-Sundrum (RS) II brane. We investigate the effects of the non-minimal coupling on the inflationary dynamics of this braneworld model. Our study shows that the number of e-folds decreases by increasing ...
1001.0444v1
2010-01-14
State transfer in static and dynamic spin chains with disorder
We examine the speed and fidelity of several protocols for state or single excitation transfer in finite spin chains subject to diagonal and off-diagonal disorder. We find that, for a given chain length and maximal achievable inter-spin exchange (XY) coupling strength, the optimal static spin-coupling protocol, impleme...
1001.2444v1
2010-01-15
The innocuousness of adiabatic instabilities in coupled scalar field-dark matter models
Non-minimally coupled scalar field models suffer of unstable growing modes at the linear perturbation level. The nature of these instabilities depends on the dynamical state of the scalar field. In particular in systems which admit adiabatic solutions, large scale instabilities are suppressed by the slow-roll dynamics ...
1001.2687v1
2010-01-25
Spontaneous creation of non-zero angular momentum modes in tunnel-coupled two-dimensional degenerate Bose gases
We investigate the dynamics of two tunnel-coupled two-dimensional degenerate Bose gases. The reduced dimensionality of the clouds enables us to excite specific angular momentum modes by tuning the coupling strength, thereby creating striking patterns in the atom density profile. The extreme sensitivity of the system to...
1001.4344v1
2010-02-03
Deformation Potentials and Electron-Phonon Coupling in Silicon Nanowires
The role of reduced dimensionality and of the surface on electron-phonon (e-ph) coupling in silicon nanowires is determined from first principles. Surface termination and chemistry is found to have a relatively small influence, whereas reduced dimensionality fundamentally alters the behavior of deformation potentials. ...
1002.0719v1
2010-02-04
Entanglement of fields in coupled-cavities: effects of pumping and fluctuations
A system of two coupled cavities is studied in the context of bipartite, continuous variable entanglement. One of the cavities is pumped by an external classical source that is coupled quadratically, to the cavity field. Dynamics of entanglement, quantified by covariance measure [Dodonov {\it et al}, Phys. Lett A {\bf ...
1002.0913v1
2010-02-04
The electron-phonon theory of superconductors: Tc map and vertex correction
The strong coupling Eliashberg theory plus vertex correction is used to calculate maps of transition temperature (Tc) in parameter-space characterizing superconductivity. Based on these Tc maps, crossover behaviors are found when electron-phonon interaction increases from weak-coupling region to strong coupling region....
1002.0998v2
2010-03-08
Spin-orbit coupling in a graphene bilayer and in graphite
The intrinsic spin-orbit interactions in bilayer graphene and in graphite are studied, using a tight binding model, and an intraatomic LS coupling. The spin-orbit interactions in bilayer graphene and graphite are larger, by about one order of magnitude, than the interactions in single layer graphene, due to the mixing ...
1003.1618v1
2010-03-09
Ground state properties of the Holstein model near the adiabatic limit
We adapt a variational procedure to calculate ground state properties of the Holstein model in the adiabatic limit. At strong coupling, this adaption leads to rapid convergence of results. The intermediate coupling regime is further handled with an adaptive algorithm. We also use semi-classically derived results for th...
1003.1952v1
2010-03-19
Competition between symmetry breaking and onset of collapse in weakly coupled atomic condensates
We analyze the symmetry breaking of matter-wave solitons in a pair of cigar-shaped traps coupled by tunneling of atoms. The model is based on a system of linearly coupled nonpolynomial Schr\"odinger equations (NPSEs). Unlike the well-known spontaneous-symmetry-breaking (SSB) bifurcation in coupled cubic equations, in t...
1003.3835v1
2010-03-30
The constructive role of diversity on the global response of coupled neuron systems
We study the effect that the heterogeneity present among the elements of an ensemble of coupled excitable neurons have on the collective response of the system to an external signal. We have considered two different interaction scenarios, one in which the neurons are diffusively coupled and another in which the neurons...
1003.5804v1
2010-04-12
Spontaneous Symmetry Breaking in Two Coupled Nanomechanical Electron Shuttles
We present spontaneous symmetry breaking in a nanoscale version of a setup prolific in classical mechanics: two coupled nanomechanical pendulums. The two pendulums are electron shuttles fabricated as nanopillars and placed between two capacitor plates in a homogeneous electric field. Instead of being mechanically coupl...
1004.2028v1
2010-04-23
Spin-orbit coupling and perpendicular Zeeman field for fermionic cold atoms: observation of the intrinsic anomalous Hall effect
We propose a scheme for generating Rashba spin-orbit coupling and perpendicular Zeeman field simultaneously for cold fermionic atoms in a harmonic trap through the coupling between atoms and laser fields. The realization of Rashba spin-orbit coupling and perpendicular Zeeman field provides opportunities for exploring m...
1004.4231v3