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2007-09-07
Adiabatic instability in coupled dark energy-dark matter models
We consider theories in which there exists a nontrivial coupling between the dark matter sector and the sector responsible for the acceleration of the universe. Such theories can possess an adiabatic regime in which the quintessence field always sits at the minimum of its effective potential, which is set by the local ...
0709.1128v2
2007-09-12
Spectra, triple and quartic gauge couplings in a Higgsless model
Spectra, triple and quartic gauge couplings of the Higgsless model with gauge group $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ defined in warped space are explored with numerical method. We extend the equation of motions, boundary conditions and formalism of multi-gauge-boson vertices to the Hirn-Sanz scenario. By assumi...
0709.1898v2
2007-09-24
Spin phonon induced colinear order and magnetization plateaus in triangular and kagome antiferromagnets. Applications to CuFeO_2
Coupling between spin and lattice degrees of freedom are important in geometrically frustrated magnets where they can lead to degeneracy lifting and novel orders. We show that moderate spin-lattice couplings in triangular and Kagome antiferromagnets can induce complex colinear magnetic orders. When classical Heisenberg...
0709.3546v1
2007-09-27
Modulation of bilayer quantum Hall states by tilted-field-induced subband-Landau-level coupling
We study effects of tilted magnetic fields on energy levels in a double-quantum-well (DQW) system, focusing on the coupling of subbands and Landau levels (LLs). The subband-LL coupling induces anticrossings between LLs, manifested directly in the magnetoresistance. The anticrossing gap becomes larger than the spin spli...
0709.4306v1
2007-10-03
Corrections to the running of gauge couplings due to quantum gravity
Concerning the gravitational corrections to the running of gauge couplings two different results were reported. Some authors claim that gravitational correction at the one-loop level indicates an interesting effect of universal gravitational decreasing of gauge couplings, that is, gravitational correction works univers...
0710.0713v2
2007-10-24
Exponentially Modified QCD Coupling
We present a specific class of models for an infrared-finite analytic QCD coupling, such that at large space-like energy scales the coupling differs from the perturbative one by less than any inverse power of the energy scale. This condition is motivated by the ITEP Operator Product Expansion philosophy. Allowed by the...
0710.4530v2
2007-11-06
Synchronization of phase oscillators with heterogeneous coupling: A solvable case
We consider an extension of Kuramoto's model of coupled phase oscillators where oscillator pairs interact with different strengths. When the coupling coefficient of each pair can be separated into two different factors, each one associated to an oscillator, Kuramoto's theory for the transition to synchronization can be...
0711.0884v1
2008-01-28
Measuring Z' couplings at the LHC
We study the properties of potential new Z' gauge bosons produced through the Drell-Yan mechanism at the LHC. Our analysis is performed using a fully differential next-to-leading order QCD calculation with spin correlations, interference effects, and experimental acceptances included. We examine the distinguishability ...
0801.4389v2
2008-02-08
Infrared behavior of the running coupling in scalar field theory
We compute the Green function of the massless scalar field theory in the infrared till the next-to-leading order, providing a fully covariant strong coupling expansion. Applying Callan-Symanzik equation we obtain the exact running coupling for this case by computing the beta function. This result is applied using a rec...
0802.1183v4
2008-04-02
Dark Matter - Dark Energy coupling biasing parameter estimates from CMB data
When CMB data are used to derive cosmological parameters, their very choice does matter: some parameter values can be biased if the parameter space does not cover the "true" model. This is a problem, because of the difficulty to parametrize Dark Energy (DE) physics. We test this risk through numerical experiments. We c...
0804.0285v2
2008-04-29
The phase structure of Einstein-Cartan theory
In the Einstein-Cartan theory of torsion-free gravity coupling to massless fermions, the four-fermion interaction is induced and its strength is a function of the gravitational and gauge couplings, as well as the Immirzi parameter. We study the dynamics of the four-fermion interaction to determine whether effective bil...
0804.4619v2
2008-05-13
Janus field theories from multiple M2 branes
Based on the recent proposal of N=8 superconformal gauge theories of the multiple M2 branes, we derive (2+1)-dimensional supersymmetric Janus field theories with a space-time dependent coupling constant. From the original Bagger-Lambert model, we get a supersymmetric field theory with a similar action to the N D2 brane...
0805.1895v3
2008-05-23
New Mechanics of Traumatic Brain Injury
The prediction and prevention of traumatic brain injury is a very important aspect of preventive medical science. This paper proposes a new coupled loading-rate hypothesis for the traumatic brain injury (TBI), which states that the main cause of the TBI is an external Euclidean jolt, or SE(3)-jolt, an impulsive loading...
0805.3583v3
2008-08-05
Unifying cosmological and recent time variations of fundamental couplings
A number of positive and null results on the time variation of fundamental constants have been reported. It is difficult to judge whether or not these claims are mutually consistent, since the observable quantities depend on several parameters, namely the coupling strengths and masses of particles. The evolution of the...
0808.0702v2
2008-08-07
Constraining Interactions in Cosmology's Dark Sector
We consider the cosmological constraints on theories in which there exists a nontrivial coupling between the dark matter sector and the sector responsible for the acceleration of the universe, in light of the most recent supernovae, large scale structure and cosmic microwave background data. For a variety of models, we...
0808.1105v1
2008-08-24
Photon blockade and nonlinear effects for a quantum dot strongly coupled to a semiconductor microcavity
Our model comprehensively simulates modern nanoscale semiconductor microcavities incorporating cavity quantum electrodynamics within both the weak and strong coupling regimes, using on-resonant laser excitation and nonresonant excitation due to a wetting layer. For weak coupling, the most significant effect is photon a...
0808.3280v3
2008-09-17
Cavity-QED based on collective magnetic dipole coupling: spin ensembles as hybrid two-level systems
We analyze the magnetic dipole coupling of an ensemble of spins to a superconducting microwave stripline structure, incorporating a Josephson junction based transmon qubit. We show that this system is described by an embedded Jaynes-Cummings model: in the strong coupling regime, collective spin-wave excitations of the ...
0809.2909v1
2008-09-27
Late-time acceleration and Phantom Divide Line Crossing with Non-minimal Coupling and Lorentz Invariance Violation
We consider two alternative dark energy models: a Lorentz invariance preserving model with a nonminimally coupled scalar field and a Lorentz invariance violating model with a minimally coupled scalar field. We study accelerated expansion and dynamics of equation of state parameter in these scenarios. While a minimally ...
0809.4744v1
2008-09-29
Contact conductance between graphene and quantum wires
The contact conductance between graphene and two quantum wires which serve as the leads to connect graphene and electron reservoirs is theoretically studied. Our investigation indicates that the contact conductance depends sensitively on the graphene-lead coupling configuration. When each quantum wire couples solely to...
0809.4911v1
2008-10-01
Concentration inequalities for Markov processes via coupling
We obtain moment and Gaussian bounds for general Lipschitz functions evaluated along the sample path of a Markov chain. We treat Markov chains on general (possibly unbounded) state spaces via a coupling method. If the first moment of the coupling time exists, then we obtain a variance inequality. If a moment of order 1...
0810.0097v4
2008-10-07
The synchronization transition in correlated oscillator populations
The synchronization transition of correlated ensembles of coupled Kuramoto oscillators on sparse random networks is investigated. Extensive numerical simulations show that correlations between the native frequencies of adjacent oscillators on the network systematically shift the critical point as well as the critical e...
0810.1121v2
2008-10-28
Superfluid Bose-Fermi mixture from weak-coupling to unitarity
We investigate the zero-temperature properties of a superfluid Bose-Fermi mixture by introducing a set of coupled Galilei-invariant nonlinear Schr\"odinger equations valid from weak-coupling to unitarity. The Bose dynamics is described by a Gross-Pitaevskii-type equation including beyond-mean-field corrections possessi...
0810.5046v1
2008-11-23
The quantum optical Josephson interferometer
The interplay between coherent tunnel coupling and on-site interactions in dissipation-free bosonic systems has lead to many spectacular observations, ranging from the demonstration of number-phase uncertainty relation to quantum phase transitions. To explore the effect of dissipation and coherent drive on tunnel coupl...
0811.3762v1
2008-12-03
Z(N) Domain walls in hot N=4 SYM at weak and strong coupling
We study the tensions of domain walls in the deconfined phase of N=4 SUSY Yang-Mills theory on R^3 x S^1, at weak and strong coupling. We calculate the k-wall tension at one-loop order and find that it is proportional to k(N-k) (Casimir scaling). The two-loops analysis suggests that Casimir scaling persists to this ord...
0812.0773v3
2008-12-11
Optical conductivity in the t-J-Holstein Model
Using recently developed numerical method we compute charge stiffness and optical conductivity of the t-J model coupled to optical phonons. Coherent hole motion is most strongly influenced by the electron-phonon coupling within the physically relevant regime of the exchange interaction. We find unusual non-monotonous d...
0812.2131v1
2008-12-17
The strong-coupling limit of lattice Landau gauge
We report on our recent study of the gluon and ghost propagators of pure SU(2) minimal lattice Landau gauge in the strong-coupling limit. In this limit, we find evidence of the conformal infrared behaviour of these propagators as predicted by functional continuum methods. However, in the strong-coupling limit this happ...
0812.3268v1
2008-12-30
Non-minimally coupled scalar field cosmology on the phase plane
In this publication we investigate dynamics of a flat FRW cosmological model with a non-minimally coupled scalar field with the coupling term $\xi R \psi^{2}$ in the scalar field action. The quadratic potential function $V(\psi)\propto \psi^{2}$ is assumed. All the evolutional paths are visualized and classified in the...
0812.5096v2
2009-01-28
Spatial trends of non-collinear exchange coupling mediated by itinerant carriers with different Fermi surfaces
We study the exchange coupling mediated by itinerant carriers with spin-orbit interaction by both analytic and numeric approaches. The mediated exchange coupling is non-collinear and its spatial trends depend on the Fermi surface topology of the itinerant carriers. Taking Rashba interaction as an example, the exchange ...
0901.4577v1
2009-02-16
Coupling between cold dark matter and dark energy from neutrino mass experiments
We consider cosmological models with dynamical dark energy (dDE) coupled to cold dark matter (CDM), while simultaneously allowing neutrinos to be massive. Using a MCMC approach, we compare these models with a wide range of cosmological data sets. We find a strong correlation between this coupling strength and the neutr...
0902.2737v3
2009-03-23
Interplay of noise and coupling in heterogeneous ensembles of phase oscillators
We study the effects of noise on the collective dynamics of an ensemble of coupled phase oscillators whose natural frequencies are all identical, but whose coupling strengths are not the same all over the ensemble. The intensity of noise can also be heterogeneous, representing diversity in the individual responses to e...
0903.3860v1
2009-04-01
Chemical trend of exchange couplings in diluted magnetic II-VI semiconductors
We have calculated the chemical trend of magnetic exchange parameters ($J_{dd}$, $N \alpha$, and $N \beta$) of Zn-based II-VI semiconductors ZnA (A=O, S, Se, and Te) doped with Co or Mn. We show that a proper treatment of electron correlations by the LSDA+$U$ method leads to good agreement between experimental and theo...
0904.0121v1
2009-04-07
Curvature-enhanced spin-orbit coupling in a carbon nanotube
Structure of the spin-orbit coupling varies from material to material and thus finding the correct spin-orbit coupling structure is an important step towards advanced spintronic applications. We show theoretically that the curvature in a carbon nanotube generates two types of the spin-orbit coupling, one of which was n...
0904.1185v2
2009-04-13
Coupling dark energy with Standard Model states
In this contribution one examines the coupling of dark energy to the gauge fields, to neutrinos, and to the Higgs field. In the first case, one shows how a putative evolution of the fundamental couplings of strong and weak interactions via coupling to dark energy through a generalized Bekenstein-type model may cause de...
0904.1933v1
2009-04-15
Asymmetry--induced effects in coupled phase oscillator ensembles: Routes to synchronization
A system of two coupled ensembles of phase oscillators can follow different routes to inter-ensemble synchronization. Following a short report of our preliminary results [Phys. Rev. E. {\bf 78}, 025201(R) (2008)], we present a more detailed study of the effects of coupling, noise and phase asymmetries in coupled phase ...
0904.2239v1
2009-04-15
Inverse synchronizations in coupled time-delay systems with inhibitory coupling
Transitions between inverse anticipatory, inverse complete and inverse lag synchronizations are shown to occur as a function of the coupling delay in unidirectionally coupled time-delay systems with inhibitory coupling. We have also shown that the same general asymptotic stability condition obtained using the Krasovski...
0904.2251v1
2009-05-19
Phase structure of thermal lattice QCD with N_f=2 twisted mass Wilson fermions
We present numerical results for the phase diagram of lattice QCD at finite temperature in the formulation with twisted mass Wilson fermions and a tree-level Symanzik-improved gauge action. Our simulations are performed on lattices with temporal extent N_\tau=8, and lattice coupling \beta ranging from strong coupling t...
0905.3112v2
2009-05-28
The Coupling of Chern-Simons Theory to Topological Gravity
We couple Chern-Simons gauge theory to 3-dimensional topological gravity with the aim of investigating its quantum topological invariance. We derive the relevant BRST rules and Batalin-Vilkovisky action. Standard BRST transformations of the gauge field are modified by terms involving both its anti-field and the super-g...
0905.4631v3
2009-05-31
K-Inflation with a Dark Energy Coupling
It is usually thought that the quintessence as a fundamental scalar field was already present during the inflationary epoch. While there are various models in which the quintessence couples to other species, it is attractive to anticipate a coupling between the quintessence and the inflaton in the very early universe a...
0906.0145v4
2009-07-03
Universality in the one-dimensional chain of phase-coupled oscillators
We apply a recently developed renormalization group (RG) method to study synchronization in a one-dimensional chain of phase-coupled oscillators in the regime of weak randomness. The RG predicts how oscillators with randomly distributed frequencies and couplings form frequency-synchronized clusters. Although the RG was...
0907.0511v3
2009-09-01
SU(5) orientifolds, Yukawa couplings, Stringy Instantons and Proton Decay
We construct a large class of SU(5) orientifold vacua with tadpole cancellation both for the standard and the flipped case. We give a general analysis of superpotential couplings up to quartic order in orientifold vacua and identify the properties of needed Yukawa couplings as well as the baryon number violating coupli...
0909.0271v2
2009-09-18
Vacuum degeneracy of a circuit-QED system in the ultrastrong coupling regime
We investigate theoretically the quantum vacuum properties of a chain of $N$ superconducting Josephson atoms inductively coupled to a transmission line resonator. We derive the quantum field Hamiltonian for such circuit-QED system, showing that, due to the type and strength of the interaction, a quantum phase transitio...
0909.3505v3
2009-09-21
Suppression of radiation loss by hybridization effect in two coupled split-ring resonators
This paper investigates the radiation properties of two coupled split-ring resonators (SRRs). Due to electromagnetic coupling, two hybrid magnetic plasmon modes were induced in the structure. Our calculations show that the radiation loss of the structure was greatly suppressed by the hybridization effect. This led to a...
0909.3751v1
2009-10-16
Current-induced spin polarization for a general two-dimensional electron system
In this paper, current-induced spin polarization for two-dimensional electron gas with a general spin-orbit interaction is investigated. For isotropic energy spectrum, the in-plane current-induced spin polarization is found to be dependent on the electron density for non-linear spin-orbit interaction and increases with...
0910.3050v1
2009-10-29
Cosmological Constraints on Strongly Coupled Moduli from Cosmic Strings
Cosmological constraints on moduli, whose coupling to matter is stronger than Planck mass suppressed coupling, are derived. In particular, moduli are considered to be produced by oscillating loops of cosmic strings and constraints are obtained from their effects on big bang nucleosynthesis and their contribution to dif...
0910.5544v1
2009-10-30
Gap symmetries from the neighbor coupling in square-lattice superconductors
The gap symmetries of superconductivity are studied in this work. It is found that the gap symmetries are simply determined by the 4-fold rotational symmetries of the coupling potential on neighbor sites. A local on-site coupling potential results in the on-site pairing with the conventional s-wave symmetry, but a coup...
0910.5871v2
2010-01-22
RKKY coupling in graphene
We study the carrier-mediated exchange interaction, the so-called RKKY coupling, between two magnetic moments in graphene using exact diagonalization on the honeycomb lattice. By using the tight-binding nearest neighbor band structure of graphene we avoid the use of a momentum cut-off which plagues results in the Dirac...
1001.4024v2
2010-01-25
Spin relaxation due to deflection coupling in nanotube quantum dots
We consider relaxation of an electron spin in a nanotube quantum dot due to its coupling to flexural phonon modes, and identify a new spin-orbit mediated coupling between the nanotube deflection and the electron spin. This mechanism dominates other spin relaxation mechanisms in the limit of small energy transfers. Due ...
1001.4306v2
2010-02-12
Stability and chaos in coupled two-dimensional maps on Gene Regulatory Network of bacterium E.Coli
The collective dynamics of coupled two-dimensional chaotic maps on complex networks is known to exhibit a rich variety of emergent properties which crucially depend on the underlying network topology. We investigate the collective motion of Chirikov standard maps interacting with time delay through directed links of Ge...
1002.2600v2
2010-02-23
Coupling time distribution asymptotics for some couplings of the Levy stochastic area
We exhibit some explicit co-adapted couplings for n-dimensional Brownian motion and all its Levy stochastic areas. In the two-dimensional case we show how to derive exact asymptotics for the coupling time under various mixed coupling strategies, using Dufresne's formula for the distribution of exponential functionals o...
1002.4348v1
2010-03-10
Finite size effects on transport coefficients for models of atomic wires coupled to phonons
We consider models of quasi-1-d, planar atomic wires consisting of several, laterally coupled rows of atoms, with mutually non-interacting electrons. This electronic wire system is coupled to phonons, corresponding, e.g., to some substrate. We aim at computing diffusion coefficients in dependence on the wire widths and...
1003.2156v2
2010-03-25
Complete synchronization in coupled Type-I neurons
For a system of type-I neurons bidirectionally coupled through a nonlinear feedback mechanism, we discuss the issue of noise-induced complete synchronization (CS). For the inputs to the neurons, we point out that the rate of change of instantaneous frequency with the instantaneous phase of the stochastic inputs to each...
1003.4980v1
2010-03-26
Microscopically-constrained Fock energy density functionals from chiral effective field theory. I. Two-nucleon interactions
The density matrix expansion (DME) of Negele and Vautherin is a convenient tool to map finite-range physics associated with vacuum two- and three-nucleon interactions into the form of a Skyme-like energy density functional (EDF) with density-dependent couplings. In this work, we apply the improved formulation of the DM...
1003.5210v1
2010-04-08
Coupling of bonding and antibonding electron orbitals in double quantum dots by spin-orbit interaction
We perform a systematic exact diagonalization study of spin-orbit coupling effects for stationary few-electron states confined in quasi two-dimensional double quantum dots. We describe the spin-orbit-interaction induced coupling between bonding and antibonding orbitals and its consequences for magneto-optical absorptio...
1004.1250v1
2010-04-18
Chiral symmetry breaking and monopole dynamics in non-compact QED3 coupled to a four-fermi interaction
We present results from the first lattice simulations of three dimensional non-compact quantum electrodynamics (QED3) with N_f four-component fermion flavors coupled to a weak Z(2) chirally invariant four-fermi interaction. Results with $N_f \ge 4$ show that the scaling near the strong coupling chiral transition or sha...
1004.3053v3
2010-04-20
Geometric phase as a determinant of a qubit--environment coupling
We investigate the qubit geometric phase and its properties in dependence on the mechanism for decoherence of a qubit weakly coupled to its environment. We consider two sources of decoherence: dephasing coupling (without exchange of energy with environment) and dissipative coupling (with exchange of energy). Reduced dy...
1004.3432v1
2010-07-22
Precision Gauge Unification from Extra Yukawa Couplings
We investigate the impact of extra vector-like GUT multiplets on the predicted value of the strong coupling. We find in particular that Yukawa couplings between such extra multiplets and the MSSM Higgs doublets can resolve the familiar two-loop discrepancy between the SUSY GUT prediction and the measured value of alpha...
1007.3990v6
2010-09-03
Determination of effective microscopic models for the frustrated antiferromagnets Cs$_2$CuCl$_4$ and Cs$_2$CuBr$_4$ by density functional methods
We investigate the electronic and magnetic properties of the frustrated triangular-lattice antiferromagnets Cs$_2$CuCl$_4$ and Cs$_2$CuBr$_4$ in the framework of density functional theory. Analysis of the exchange couplings J and J' using the available X-ray structural data corroborates the values obtained from experim...
1009.0697v2
2010-10-15
Sharp transition for single polarons in the one-dimensional Su-Schrieffer-Heeger model
We study a single polaron in the Su-Schrieffer-Heeger (SSH) model using four different techniques (three numerical and one analytical). Polarons show a smooth crossover from weak to strong coupling, as a function of the electron-phonon coupling strength $\lambda$, in all models where this coupling depends only on phono...
1010.3207v2
2010-10-18
Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering
We show that high resolution Resonant Inelastic X-ray Scattering (RIXS) provides direct, element-specific and momentum-resolved information on the electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates that the e-p coupling can be extracted from RIXS spectra by determining the differential phono...
1010.3565v1
2010-10-29
Effective coupling parameter for 2D Yukawa liquids and non-invasive measurement of plasma parameters
We derive an effective coupling parameter for two-dimensional Yukawa systems based on the height of the first maximum of the pair distribution function. Two variants -- one valid in the high-coupling range, the other for arbitrary couplings of the liquid -- are derived. Comparison to previous approaches to Yukawa coupl...
1010.6193v1
2010-11-19
Electromagnetically induced transparency in hybrid plasmonic-dielectric system
We present theoretical and numerical analysis of a plasmonic-dielectric hybrid system for symmetric and asymmetric coupling between silver cut-wire pairs and silicon grating waveguide with periodic grooves. The results show that both couplings can induce electromagnetically-induced transparency (EIT) analogous to the q...
1011.4360v1
2010-11-29
Synchronous bursts on scale-free neuronal networks with attractive and repulsive coupling
This paper investigates the dependence of synchronization transitions of bursting oscillations on the information transmission delay over scale-free neuronal networks with attractive and repulsive coupling. It is shown that for both types of coupling, the delay always plays a subtle role in either promoting or impairin...
1011.6347v1
2010-11-29
Interedge magnetic coupling in transition-metal terminated graphene nanoribbons
The magnetic structures and interedge magnetic couplings of Fe, Co and Ni transition-metal terminated graphene nanoribbons with zigzag (ZGNR) and armchair (AGNR) edges are studied by first-principles calculations. Fe-ZGNR is found to show antiferromagnetic (AF) coupling between two edges, while the interedge coupling o...
1011.6356v1
2010-12-07
The strong-coupling master equation of quantum open systems
In this paper we demonstrate how to generate the strong-coupling master equations for open quantum systems of continuous variables. These are the dissipative master equations of quantum Brownian particles for which the environmental noise is stronger than other system forces. Our strong-coupling master equations are ve...
1012.1392v1
2010-12-14
Intercellular synchronization of diffusively coupled astrocytes
We examine the synchrony of the dynamics of localized [Ca^{2+}]_i oscillations in internal pool of astrocytes via diffusing coupling of a network of such cells in a certain topology where cytosolic Ca^{2+} and inositol 1,4,5-triphosphate (IP3) are coupling molecules; and possible long range interaction among the cells....
1012.3354v1
2010-12-25
A conservative coupling algorithm between a compressible flow and a rigid body using an Embedded Boundary method
This paper deals with a new solid-fluid coupling algorithm between a rigid body and an unsteady compressible fluid flow, using an Embedded Boundary method. The coupling with a rigid body is a first step towards the coupling with a Discrete Element method. The flow is computed using a Finite Volume approach on a Cartesi...
1012.5479v2
2011-01-16
Ratio of bulk to shear viscosity in a quasigluon plasma: from weak to strong coupling
The ratio of bulk to shear viscosity is expected to exhibit a different behaviour in weakly and in strongly coupled systems. This can be expressed by its dependence on the squared sound velocity. In the high temperature QCD plasma at small running coupling, the viscosity ratio is uniquely determined by a quadratic depe...
1101.3072v2
2011-01-27
Superradiance of cold atoms coupled to a superconducting circuit
We investigate superradiance of an ensemble of atoms coupled to an integrated superconducting LC-circuit. Particular attention is paid to the effect of inhomogeneous coupling constants. Combining perturbation theory in the inhomogeneity and numerical simulations we show that inhomogeneous coupling constants can signifi...
1101.5300v1
2011-01-27
General mechanism for amplitude death in coupled systems
We introduce a general mechanism for amplitude death in coupled synchronizable dynamical systems. It is known that when two systems are coupled directly, they can synchronize under suitable conditions. When an indirect feedback coupling through an environment or an external system is introduced in them, it is found to ...
1101.5340v2
2011-02-11
Monolithic whispering-gallery mode resonators with vertically coupled integrated bus waveguides
We report on the realization and optical characterization of a CMOS-compatible silicon-based microresonator/waveguide coupled system, fully integrated on a silicon chip. The device uses a vertical coupling scheme between the resonator and a buried strip waveguide. We demonstrate that its high optical quality follows fr...
1102.2370v1
2011-02-22
Spin gap of the three-leg S=3/2 Heisenberg tube
The ground-state properties of the three-leg S=3/2 Heisenberg tube are studied using the density-matrix renormalization group method. We find that the spin-excitation gap associated with a spontaneous dimerization opens for the whole coupling regime, as seen in the three-leg S=1/2 Heisenberg tube. However, in contrast ...
1102.4559v1
2011-02-25
Low-temperature tapered-fiber probing of diamond NV ensembles coupled to GaP microcavities
In this work we present a platform for testing the device performance of a cavity-emitter system, using an ensemble of emitters and a tapered optical fiber. This method provides high-contrast spectra of the cavity modes, selective detection of emitters coupled to the cavity, and an estimate of the device performance in...
1102.5372v1
2011-03-05
Three-dimensional quantum phase diagram of the exact ground states of a mixture of two species of spin-1 Bose gases with interspecies spin exchange
We find nearly all the exact ground states of a mixture of two species of spin-1 atoms with both interspecies and intraspecies spin exchanges in absence of a magnetic field. The quantum phase diagram in the three-dimensional parameter space and its two-dimensional cross sections are described. The boundaries where the ...
1103.1023v1
2011-03-09
Coupling ultracold atoms to mechanical oscillators
In this article we discuss and compare different ways to engineer an interface between ultracold atoms and micro- and nanomechanical oscillators. We start by analyzing a direct mechanical coupling of a single atom or ion to a mechanical oscillator and show that the very different masses of the two systems place a limit...
1103.1820v1
2011-03-10
Engineering a p+ip Superconductor: Comparison of Topological Insulator and Rashba Spin-Orbit Coupled Materials
We compare topological insulator materials and Rashba coupled surfaces as candidates for engineering p+ip superconductivity. Specifically, in each type of material we examine 1) the limitations to inducing superconductivity by proximity to an ordinary s-wave superconductor, and 2) the robustness of the resulting superc...
1103.2129v2
2011-03-16
S-duality of D-brane action at order $O(α'^2)$
Using the compatibility of the DBI and the Chern-Simons actions with the T-duality transformations, the curvature corrections to these actions have been recently extended to include the quadratic B-field couplings at order $O(\alpha'^2)$. In this paper, we use the compatibility of the couplings on D$_3$-brane with the ...
1103.3121v5
2011-04-03
Aharonov-Bohm-Coulomb Problem in Graphene Ring
We study the Aharonov-Bohm-Coulomb problem in a graphene ring. We investigate, in particular, the effects of a Coulomb type potential of the form $\xi/r$ on the energy spectrum of Dirac electrons in the graphene ring in two different ways: one for the scalar coupling and the other for the vector coupling. It is found t...
1104.0369v2
2011-05-27
Top quark tensor couplings
We compute the real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the $tbW$ vertex in the Standard Model (SM). For both tensorial couplings we find that the real part of the electroweak SM correction is close to 10$%$ of the leading contribution giv...
1105.5601v1
2011-06-09
Hermitian Flavor Violation
The fundamental constraint on two Higgs doublet models comes from the requirement of sufficiently suppressing flavor-changing neutral currents. There are various standard approaches for dealing with this problem, but they all tend to share a common feature; all of the Higgs doublets couple very weakly to the first gene...
1106.1734v1
2011-06-13
Quantum superposition of a single microwave photon in two different "colour" states
The ability to coherently couple arbitrary harmonic oscillators in a fully-controlled way is an important tool to process quantum information. Coupling between quantum harmonic oscillators has previously been demonstrated in several physical systems by use of a two-level system as a mediating element. Direct interactio...
1106.2523v1
2011-06-23
Dynamics of a magnetic dimer with exchange, dipolar and Dzyalozhinski-Moriya interaction
We investigate the dynamics of a magnetic system consisting of two magnetic moments coupled by either exchange, dipole-dipole, or Dzyalozhinski-Moriya interaction. We compare the switching mechanisms and switching rates as induced by the three couplings. For each coupling and each configuration of the two anisotropy ax...
1106.4713v2
2011-07-13
Probing anomalous tbW couplings in single-top production using top polarization at the Large Hadron Collider
We study the sensitivity of the Large Hadron Collider (LHC) to anomalous tbW couplings in single-top production in association with a W^- boson followed by semileptonic decay of the top. We calculate top polarization and the effects of these anomalous couplings to it at two centre-of-mass (cm) energies of 7 TeV and 14 ...
1107.2597v1
2011-08-08
Coupling Bright and Dark Plasmonic Lattice Resonances
We demonstrate the coupling of bright and dark Surface Lattice Resonances (SLRs), which are collective Fano resonances in 2D plasmonic crystals. As a result of this coupling, a frequency stop-gap in the dispersion relation of SLRs is observed. The different field symmetries of the low and high frequency SLR bands lead ...
1108.1620v1
2011-08-15
Consistent Energy-based Atomistic/Continuum Coupling for Two-body Potentials in Three Dimensions
Very few works exist to date on development of a consistent energy-based coupling of atomistic and continuum models of materials in more than one dimension. The difficulty in constructing such a coupling consists in defining a coupled energy whose minimizers are free from uncontrollable errors on the atomistic/continuu...
1108.2991v2
2011-08-26
Dipole coupling of a double quantum dot to a microwave resonator
Quantum coherence in solid-state systems has been demonstrated in superconducting circuits and in semiconductor quantum dots. This has paved the way to investigate solid-state systems for quantum information processing with the potential benefit of scalability compared to other systems based on atoms, ions and photons....
1108.5378v1
2011-08-30
Quantum Equivalence Principle Violations in Scalar-Tensor Theories
We study the equivalence principle and its violations by quantum effects in scalar-tensor theories that admit a conformal frame in which matter only couples to the spacetime metric. These theories possess Ward identities that guarantee the validity of the weak equivalence principle to all orders in the matter coupling ...
1108.6028v1
2011-09-05
Arrays of waveguide-coupled optical cavities that interact strongly with atoms
We describe a realistic scheme for coupling atoms or other quantum emitters with an array of coupled optical cavities. We consider open Fabry-Perot microcavities coupled to the emitters. Our central innovation is to connect the microcavities to waveguide resonators, which are in turn evanescently coupled to each other ...
1109.0886v1
2011-09-13
Interplay between non equilibrium and equilibrium spin torque using synthetic ferrimagnets
We discuss the current induced magnetization dynamics of spin valves F0|N|SyF where the free layer is a synthetic ferrimagnet SyF made of two ferromagnetic layers F1 and F2 coupled by RKKY exchange coupling. In the interesting situation where the magnetic moment of the outer layer F2 dominates the magnetization of the ...
1109.2705v2
2011-09-22
Ground-state phases of ultracold bosons with Rashba-Dresselhaus spin-orbit coupling
We study ultracold bosons in three dimensions with an anisotropic Rashba-Dresselhaus spin-orbit coupling. We first carry out the exact summation of ladder diagrams for the two-boson t-matrix at zero energy. Then, with the t-matrix as the effective interaction, we find the ground-state phase diagrams of bosons in mean f...
1109.4954v2
2011-09-26
Engineering Dresselhaus spin-orbit coupling for cold atoms in a double tripod configuration
We study laser induced spin-orbit (SO) coupling in cold atom systems where lasers couple three internal states to a pair of excited states, in a double tripod topology. Proper choice of laser amplitudes and phases produces a Hamiltonian with a doubly degenerate ground state separated from the remaining "excited" eigens...
1109.5481v1
2011-10-14
A BCS-BEC crossover in the extended Falicov-Kimball model: Variational cluster approach
We study the spontaneous symmetry breaking of the excitonic insulator state induced by the Coulomb interaction $U$ in the two-dimensional extended Falicov-Kimball model. Using the variational cluster approximation (VCA) and Hartree-Fock approximation (HFA), we evaluate the order parameter, single-particle excitation ga...
1110.3150v1
2011-12-05
Mixed partial-wave scattering with spin-orbit coupling and validity of pseudo-potentials
We present exact solutions of two-body problem for spin-1/2 fermions with isotropic spin-orbit(SO) coupling and interacting with an arbitrary short-range potential. We find that in each partial-wave scattering channel, the parametrization of two-body wavefunction at short inter-particle distance depends on the scatteri...
1112.1122v2
2011-12-19
Counterflow of spontaneous mass currents in trapped spin-orbit coupled Fermi gases
We use the Bogoliubov-de Gennes formalism and study the ground-state phases of trapped spin-orbit coupled Fermi gases in two dimensions. Our main finding is that the presence of a symmetric (Rashba type) spin-orbit coupling spontaneously induces counterflowing mass currents in the vicinity of the trap edge, i.e. $\upar...
1112.4468v2
2011-12-23
Threshold Saturation in Spatially Coupled Constraint Satisfaction Problems
We consider chains of random constraint satisfaction models that are spatially coupled across a finite window along the chain direction. We investigate their phase diagram at zero temperature using the survey propagation formalism and the interpolation method. We prove that the SAT-UNSAT phase transition threshold of a...
1112.6320v2
2012-02-07
BCS-BEC crossover in three-dimensional Fermi gases with spherical spin-orbit coupling
We present a systematic theoretical study of the BCS-BEC crossover problem in three-dimensional atomic Fermi gases at zero temperature with a spherical spin-orbit coupling which can be generated by a synthetic non-Abelian gauge field coupled to neutral fermions. Our investigations are based on the path integral formali...
1202.1492v3
2012-02-12
About possibility of strong coupling between single molecule and surface plasmons
The possibility of strong coupling between a single molecule and surface plasmons is analyzed on the basis of a microscopic classical description. It is predicted that strong single molecule - plasmon coupling can happen for a silver nanoparticle only in the UV range where the real part of the dielectric function of si...
1202.2535v1
2012-03-12
Bose-Einstein Condensates in Spin-Orbit Coupled Optical Lattices: Flat Bands and Superfluidity
Recently spin-orbit (SO) coupled superfluids in free space or harmonic traps have been extensively studied, motivated by the recent experimental realization of SO coupling for Bose-Einstein condensates (BEC). However, the rich physics of SO coupled BEC in optical lattices has been largely unexplored. In this paper, we ...
1203.2389v2
2012-03-13
Impact of Dresselhaus vs. Rashba spin-orbit coupling on the Holstein polaron
We utilize an exact variational numerical procedure to calculate the ground state properties of a polaron in the presence of Rashba and linear Dresselhaus spin-orbit coupling. We find that when the linear Dresselhaus spin-orbit coupling approaches the Rashba spin-orbit coupling, the Van-Hove singularity in the density ...
1203.2795v1
2012-03-20
Doubly and triply coupled nanowire antennas
Nanoantenna is one of the most important optical components for light harvesting. In this study, we show experimental evidence of interactions between coupled nanowires by comparing the fluorescence properties of quantum dots on both non-coupled (single) and coupled (double and triple) nanowire arrays. The fluorescence...
1203.4357v1
2012-03-20
Competing Nematic, Anti-ferromagnetic and Spin-flux orders in the Ground State of Bilayer Graphene
We analyze the phase diagram of the Bilayer graphene (BLG) at zero temperature and doping. Assuming that at the high energies the electronic system of BLG can be described within a weak coupling theory (consistent with the experimental evidence), we systematically study the evolution of the couplings with going from hi...
1203.4608v1