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2006-02-09
Strong coupling between single photons in semiconductor microcavities
We discuss the observability of strong coupling between single photons in semiconductor microcavities coupled by a chi(2) nonlinearity. We present two schemes and analyze the feasibility of their practical implementation in three systems: photonic crystal defects, micropillars and microdisks, fabricated out of GaAs. We...
0602085v1
2006-05-07
Quantum Gate Design Metric
What is the time-optimal way of realizing quantum operations? Here, we show how important instances of this problem can be related to the study of shortest paths on the surface of a sphere under a special metric. Specifically, we provide an efficient synthesis of a controlled NOT (CNOT) gate between qubits coupled indi...
0605071v1
2006-07-02
Geometric quantum computation using fictitious spin- 1/2 subspaces of strongly dipolar coupled nuclear spins
Geometric phases have been used in NMR, to implement controlled phase shift gates for quantum information processing, only in weakly coupled systems in which the individual spins can be identified as qubits. In this work, we implement controlled phase shift gates in strongly coupled systems, by using non-adiabatic geom...
0607007v1
2006-10-22
Generation of maximally entangled mixed states of two atoms via on-resonance asymmetric atom-cavity couplings
A scheme for generating the maximally entangled mixed state of two atoms on-resonance asymmetrically coupled to a single mode optical cavity field is presented. The part frontier of both maximally entangled mixed states and maximal Bell violating mixed states can be approximately reached by the evolving reduced density...
0610188v1
2007-05-04
Applicability of layered sine-Gordon models to layered superconductors: II. The case of magnetic coupling
In this paper, we propose a quantum field theoretical renormalization group approach to the vortex dynamics of magnetically coupled layered superconductors, to supplement our earlier investigations on the Josephson-coupled case. We construct a two-dimensional multi-layer sine-Gordon type model which we map onto a gas o...
0705.0578v3
2007-05-08
Particle-vibration coupling within covariant density functional theory
Covariant density functional theory, which has so far been applied only within the framework of static and time dependent mean field theory is extended to include Particle-Vibration Coupling (PVC) in a consistent way. Starting from a conventional energy functional we calculate the low-lying collective vibrations in Rel...
0705.1044v1
2007-05-25
Quantum computation in a Ising spin chain taking into account second neighbor couplings
We consider the realization of a quantum computer in a chain of nuclear spins coupled by an Ising interaction. Quantum algorithms can be performed with the help of appropriate radio-frequency pulses. In addition to the standard nearest-neighbor Ising coupling, we also allow for a second neighbor coupling. It is shown, ...
0705.3688v1
2007-06-15
Efficient analysis and design of low-loss whispering-gallery-mode coupled resonator optical waveguide bends
Waveguides composed of electromagnetically-coupled optical microcavities (coupled resonator optical waveguides or CROWs) can be used for light guiding, slowing and storage. In this paper, we present a two-dimensional analysis of finite-size straight and curved CROW sections based on a rigorous Muller boundary integral ...
0706.2279v1
2007-06-20
Complexity in linearly coupled dynamical networks: Some unusual phenomena in energy accumulation
This paper addresses the energy accumulation problem, in terms of the $H_2$ norm, of linearly coupled dynamical networks. An interesting outer-coupling relationship is constructed, under which the $H_2$ norm of the newly constructed network with column-input and row-output shaped matrices increases exponentially fast w...
0706.2902v1
2007-07-10
Superexchange induced canted ferromagnetism in dilute magnets
We argue, in contrast to recent studies, that the antiferromagnetic superexchange coupling between nearest neighbour spins does not fully destroy the ferromagnetism in dilute magnets with long-ranged ferromagnetic couplings. Above a critical coupling, we find a \textit{canted} ferromagnetic phase with unsaturated momen...
0707.1522v1
2007-07-16
Strong Electron-Hole Exchange in Coherently Coupled Quantum Dots
We have investigated few-body states in vertically stacked quantum dots. Due to small inter-dot tunneling rate, the coupling in our system is in a previously unexplored regime where electron-hole exchange is the dominant spin interaction. By tuning the gate bias, we are able to turn this coupling off and study a comple...
0707.2111v1
2007-08-02
Anomalous exciton lifetime by an electromagnetic coupling of self-assembled quantum dots
We report on the experimental observation of a hitherto ignored long-range electromagnetic coupling between self-assembled quantum dots. A 12 times enhancement of the quantum dot exciton lifetime is observed by means of time-resolved differential reflection spectroscopy. The enhancement is explained by utilizing and ex...
0708.0418v1
2007-08-19
Quantum Energy Inequalities for the Non-Minimally Coupled Scalar Field
In this paper we discuss local averages of the energy density for the non-minimally coupled scalar quantum field, extending a previous investigation of the classical field. By an explicit example, we show that such averages are unbounded from below on the class of Hadamard states. This contrasts with the minimally coup...
0708.2450v2
2007-08-21
Fixed point scenario in the Two Higgs Doublet Model inspired by degenerate vacua
We consider the renormalisation group flow of Higgs and Yukawa couplings within the simplest non--supersymmetric two Higgs doublet extension of the Standard Model (SM). In this model the couplings are adjusted so that the multiple point principle (MPP) assumption, which implies the existence of a large set of degenerat...
0708.2903v2
2007-08-31
Consequences of a Cosmic Scalar with Kinetic Coupling to Curvature
The classical gravitational theory of a scalar field with a gradient coupling to the Ricci tensor is examined. This is a scalar-vector-tensor gravitational theory, but in the case that the coupling is weak and the scalar evolves like a quintessence field on cosmological time scales, the field equations within the solar...
0709.0009v1
2007-09-02
Towards Low Cost Coupling Structures for Short-Distance Optical Interconnections
The performance of short distance optical interconnections in general relies very strongly on coupling structures, since they will determine the overall efficiency of the system to a large extent. Different configurations can be considered and a variety of manufacturing technologies can be used. We present two differen...
0709.0122v1
2007-09-03
Interqubit coupling mediated by a high-excitation-energy quantum object
We consider a system composed of two qubits and a high-excitation-energy quantum object used to mediate coupling between the qubits. We treat the entire system quantum mechanically and analyze the properties of the eigenvalues and eigenstates of the total Hamiltonian. After reproducing well-known results concerning the...
0709.0237v2
2007-09-10
Spin-gap behaviour in the 2-leg spin-ladder BiCu2PO6
We present magnetic suscceptibility and heat capacity data on a new S=1/2 two-leg spin ladder compound BiCu2PO6. From our susceptibility analysis, we find that the leg coupling J1/k_B is ~ 80 K and the ratio of the rung to leg coupling J2/J1 ~ 0.9. We present the magnetic contribution to the heat capacity of a two-leg ...
0709.1338v1
2007-09-11
Dark Energy, scalar-curvature couplings and a critical acceleration scale
We study the effects of coupling a cosmologically rolling scalar field to higher order curvature terms. We show that when the strong coupling scale of the theory is on the 10^{-3}-10^{-1}eV range, the model passes all experimental bounds on the existence of fifth forces even if the field has a mass of the order of the ...
0709.1622v1
2007-09-17
Decoherence induced by a dynamic spin environment (II): Disentanglement by local system-environment interactions
This article studies the decoherence induced on a system of two qubits by local interactions with a spin chain with nontrivial internal dynamics (governed by an XY Hamiltonian). Special attention is payed to the transition between two limits: one in which both qubits interact with the same site of the chain and another...
0709.2643v1
2007-09-27
Time-optimal synthesis of unitary transformations in coupled fast and slow qubit system
In this paper, we study time-optimal control problems related to system of two coupled qubits where the time scales involved in performing unitary transformations on each qubit are significantly different. In particular, we address the case where unitary transformations produced by evolutions of the coupling take much ...
0709.4484v1
2007-10-01
Strong-to-weak-coupling duality in the nonequilibrium interacting resonant-level model
A strong-to-weak-coupling duality is established for the nonequilibrium interacting resonant-level model, describing tunneling through a single spinless level, capacitively coupled to two leads by a contact interaction. For large capacitive coupling, U, and in the presence of a finite voltage bias, the model maps onto ...
0710.0249v1
2007-10-01
Coupling constant constraints in a nonminimally coupled phantom cosmology
In the paper we investigate observational constraints on coupling to gravity constant parameter $\xi$ using distant supernovae SNIa data, baryon oscillation peak (BOP), the cosmic microwave background radiation (CMBR) shift parameter, and $H(z)$ data set. We estimate the value of this parameter to constrain the extende...
0710.0366v3
2007-10-16
Local Normal Mode Coupling and Energy Band Splitting in Elliptically Birefringent 1D Magnetophotonic Crystals
An analysis is presented of wave-vector dispersion in elliptically birefringent stratified magneto-optic media having one-dimensional periodicity. It is found that local normal-mode polarization-state differences between adjacent layers lead to mode coupling and impact the wave-vector dispersion and the character of th...
0710.3176v1
2007-11-06
Finite temperature SU(2) gauge theory: critical coupling and universality class
We examine SU(2) gauge theory in 3+1 dimensions at finite temperature in the vicinity of critical point. For various lattice sizes in time direction ($N_\tau=1,2,4,8$) we extract high precision values of the inverse critical coupling and critical values of the 4-th order cumulant of Polyakov loops (Binder cumulant). We...
0711.0748v2
2007-11-07
Core polarization in coupled-cluster theory induced by a parity and time-reversal violating interaction
The effects of parity and time reversal violating potential, in particular the tensor-pseudotensor electron nucleus interaction are studied. We establish that selected terms representing the interplay of these effects and the residual Coulomb interaction in the coupled-cluster method are equivalent to the coupled pertu...
0711.1047v1
2007-11-10
Bose Hubbard model in the presence of Ohmic dissipation
We study the zero temperature mean-field phase diagram of the Bose-Hubbard model in the presence of local coupling between the bosons and an external bath. We consider a coupling that conserves the on-site occupation number, preserving the robustness of the Mott and superfluid phases. We show that the coupling to the b...
0711.1563v2
2007-11-17
Periodic energy switching of bright solitons in mixed coupled nonlinear Schr{ö}dinger equations with linear self and cross coupling terms
The bright soliton solutions of the mixed 2-coupled nonlinear Schr{\"o}dinger (CNLS) equations with linear self and cross coupling terms have been obtained by identifying a transformation that transforms the corresponding equation to the integrable mixed 2-CNLS equations. The study on the collision dynamics of bright s...
0711.2717v1
2007-12-10
Quantum well states in Fe/Nb(001) multilayers: First principles study
We present a first-principles study to understand the phenomena of interlayer exchange coupling in Fe/Nb multilayers using the linearized-muffin-tin-orbitals method within the generalized gradient approximation. We find that the exchange coupling oscillates with both short and long periodicities, which have been examin...
0712.1432v1
2007-12-12
Infinite coupling duals of N=2 gauge theories and new rank 1 superconformal field theories
We show that a proposed duality [arXiv:0711.0054] between infinitely coupled gauge theories and superconformal field theories (SCFTs) with weakly gauged flavor groups predicts the existence of new rank 1 SCFTs. These superconformal fixed point theories have the same Coulomb branch singularities as the rank 1 E_6, E_7, ...
0712.2028v1
2007-12-19
Direct evidence of overdamped Peierls-coupled modes in TTF-CA temperature-induced phase transition
In this paper we elucidate the optical response resulting from the interplay of charge distribution (ionicity) and Peierls instability (dimerization) in the neutral-ionic, ferroelectric phase transition of tetrathiafulvalene-chloranil (TTF-CA), a mixed-stack quasi-one-dimensional charge-transfer crystal. We present far...
0712.3267v1
2008-01-10
Dynamics of dark energy with a coupling to dark matter
Dark energy and dark matter are the dominant sources in the evolution of the late universe. They are currently only indirectly detected via their gravitational effects, and there could be a coupling between them without violating observational constraints. We investigate the background dynamics when dark energy is mode...
0801.1565v2
2008-01-11
Inflation by non-minimal coupling
Inflationary scenarios based on simple non-minimal coupling and its generalizations are studied. Generalizing the form of non-minimal coupling to "K(phi)R" with an arbitrary function K(phi), we show that the flat potential still is obtainable when V(phi)/K^2(phi) is asymptotically constant. Very interestingly, if the r...
0801.1722v4
2008-01-17
The running coupling from the four-gluon vertex in Landau gauge Yang-Mills theory
We consider 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. We determine these functions numerically from a coupled set of Dyson-Schwinger equations. We reproduce asymptotic freedom in th...
0801.2697v2
2008-01-23
Photon-assistant Fano resonance in coupled multiple quantum dots
Based on calculations of the electronic structure of coupled multiple quantum dots, we study systemically the transport properties of the system driven by an ac electric field. We find qualitative difference between transport properties of double coupled quantum dots (DQDs) and triple quantum dots. For both symmetrical...
0801.3515v1
2008-01-31
What are the interactions in quantum glasses?
The form of the low-temperature interactions between defects in neutral glasses is reconsidered. We analyse the case where the defects can be modelled either as simple 2-level tunneling systems, or tunneling rotational impurities. The coupling to strain fields is determined up to 2nd order in the displacement field. It...
0801.4944v2
2008-02-04
Spectroscopy of superconducting charge qubits coupled by a Josephson inductance
We have designed and experimentally implemented a circuit of inductively-coupled superconducting charge qubits, where a Josephson junction is used as an inductance, and the coupling between the qubits is controlled by an applied magnetic flux. Spectroscopic measurements on the circuit are in good agreement with theoret...
0802.0353v1
2008-02-08
Constraints on coupling constant between dark energy and dark matter
We have investigated constraints on the coupling between dark matter and the interacting Chaplygin gas. Our results indicate that the coupling constant $c$ between these two entities can take arbitrary values, which can be either positive or negative, thus giving arbitrary freedom to the inter-conversion between Chaply...
0802.1144v4
2008-02-18
Finite- to zero-range relativistic mean-field interactions
We study the relation between the finite-range (meson-exchange) and zero-range (point-coupling) representations of effective nuclear interactions in the relativistic mean-field framework. Starting from the phenomenological interaction DD-ME2 with density-dependent meson-nucleon couplings, we construct a family of point...
0802.2442v2
2008-02-21
Transmission of information and synchronization in a pair of coupled chaotic circuits: an experimental overview
We propose a rationale for experimentally studying the intricate relationship between the rate of information transmission and synchronization level in active networks, applying theoretical results recently proposed. We consider two non-identical coupled Chua's circuit with non-identical coupling strengths in order to ...
0802.3121v2
2008-02-26
Interacting Quantum Dot Coupled to a Kondo Spin: A Universal Hamiltonian Study
We study a mesoscopic interacting quantum dot described by the "universal Hamiltonian" that is coupled to a Kondo spin. The ferromagnetic exchange interaction within the dot leads to a stepwise increase of the ground state spin; this Stoner staircase is modified non-trivially by the Kondo interaction. We find that the ...
0802.3753v1
2008-03-04
Parity-Violating Nuclear Force as derived from QCD Sum Rules
Parity-violating nuclear force, as may be accessed from parity violation studies in nuclear systems, represents an area of nonleptonic weak interactions which has been the subject of experimental investigations for several decades. In the simple meson-exchange picture, parity-violating nuclear force may be parameterize...
0803.0407v1
2008-03-18
Is LaO$_{1-x}$F$_x$FeAs an electron-phonon superconductor ?
In this paper we calculate the electron-phonon coupling of the newly-discovered superconductor LaO$_{1-x}$F$_x$FeAs from first-principles, using Density Functional Perturbation Theory. For pure LaOFeAs, the calculated electron-phonon coupling constant $\lambda=0.21$ and logarithmic-averaged frequency $\omega_{ln}=206 K...
0803.2703v1
2008-03-22
Quasifermion spectrum at finite temperature from coupled Schwinger-Dyson equations for a fermion-boson system
We nonperturbatively investigate a fermion spectrum at finite temperature in a chiral invariant linear sigma model. Coupled Schwinger-Dyson equations for fermion and boson are developed in the real time formalism and solved numerically. From the coupling of a massless fermion with a massive boson, the fermion spectrum ...
0803.3257v2
2008-03-28
Statefinder Diagnostic for Quintessence with or without Thermal Interaction
The cosmological dynamics of minimally coupled scalar field that couples to the background matter with thermal interactions is investigated by using statefinder diagnostics. The time evolution of the statefinder pairs $\{r,s\}$ and $\{r,q\}$ are obtained under the circumstance that different values of model parameters ...
0803.4039v1
2008-03-31
Ratio of viscosity to entropy density in a strongly coupled one-component plasma
String theoretical arguments led to the hypothesis that the ratio of viscosity to entropy of any physical system has a lower bound. Strongly coupled systems usually have a small viscosity compared to weakly coupled plasmas in which the viscosity is proportional to the mean free path. In the case of a one-component plas...
0803.4407v2
2008-04-17
Dynamics in a coupled-cavity array
The dynamics of a system composed of two coupled optical cavities, each containing a single two-level atom, is studied over a wide range of detuning and coupling values. A description of the field in terms of delocalized modes reveals that the detuning between the atoms and these modes is controlled by the coupling bet...
0804.2882v1
2008-04-21
Transition from phase to generalized synchronization in time-delay systems
The notion of phase synchronization in time-delay systems, exhibiting highly non-phase-coherent attractors, has not been realized yet even though it has been well studied in chaotic dynamical systems without delay. We report the identification of phase synchronization in coupled nonidentical piece-wise linear and in co...
0804.3270v1
2008-04-25
$πB_{8}B_{8}$ and $σB_{8}B_{8}$ couplings from a chiral quark potential model
From an SU(2)$\otimes $SU(2) chiral quark potential model incorporating spontaneous chiral symmetry breaking the asymptotic $\pi $ and $\sigma $ exchange pieces of the $NN$ potential are generated. From them the $\pi NN$ and $\sigma NN$ coupling constants can be extracted. The generalization to SU(3)$\otimes $SU(3) all...
0804.4119v1
2008-04-25
Coupled-resonator-induced reflection in photonic-crystal waveguide structures
We study the resonant transmission of light in a coupled-resonator optical waveguide interacting with two nearly identical side cavities. We reveal and describe a novel effect of the coupled-resonator-induced reflection (CRIR) characterized by a very high and easily tunable quality factor of the reflection line, for th...
0804.4140v1
2008-05-11
Gauss-Bonnet Cosmology with Induced Gravity and Non-Minimally Coupled Scalar Field on the Brane
We construct a cosmological model with non-minimally coupled scalar field on the brane, where Gauss-Bonnet and Induced Gravity effects are taken into account. This model has 5D character at both high and low energy limits but reduces to 4D gravity in intermediate scales. While induced gravity is a manifestation of the ...
0805.1537v2
2008-05-20
Constraints on Unparticle Interaction from $b\to s γ$
We study unparticle effects on $b\to s \gamma$. The unparticle contributions can contribute significantly to both left- and right-handed chirality amplitudes. Using available experimental data and SM calculation for $B\to X_s \gamma$, we obtain constraints on various vector and scalar unparticle couplings. We find that...
0805.3020v3
2008-05-31
Growing drift-cyclotron modes in the hot solar atmosphere
Well-known analytical results dealing with ion cyclotron and drift waves and which follow from the kinetic theory are used and the dispersion equation, which describes coupled two modes, is solved numerically. The numerical results obtained by using the values for the plasma density, magnetic field and temperature appl...
0806.0071v1
2008-06-03
Zero-Phonon Line Broadening and Satellite Peaks in Nanowire Quantum Dots: The Role of Piezoelectric Coupling
We investigate the influence of the one-dimensional character of the phonon modes in a catalytically grown GaAs nanowire on the absorption spectrum of an embedded quantum dot, focusing on the contribution from the piezoelectric coupling. In general, the reduced dimensionality of the phonons leads to spectral side peaks...
0806.0474v2
2008-06-06
Magnetic moment of hyperons in nuclear matter by using quark-meson coupling models
We calculate the magnetic moments of hyperons in dense nuclear matter by using relativistic quark models. Hyperons are treated as MIT bags, and the interactions are considered to be mediated by the exchange of scalar and vector mesons which are approximated as mean fields. Model dependence is investigated by using the ...
0806.1099v2
2008-06-17
The development of generalized synchronization on complex networks
In this paper, we investigate the development of generalized synchronization (GS) on typical complex networks, such as scale-free networks, small-world networks, random networks and modular networks. By adopting the auxiliary-system approach to networks, we show that GS can take place in oscillator networks with both h...
0806.2689v1
2008-08-07
On the complete integrability and linearization of nonlinear ordinary differential equations - Part III: Coupled first order equations
Continuing our study on the complete integrability of nonlinear ordinary differential equations, in this paper we consider the integrability of a system of coupled first order nonlinear ordinary differential equations (ODEs) of both autonomous and non-autonomous types. For this purpose, we modify the original Prelle-Si...
0808.0958v2
2008-08-07
On the string coupling in a class of stringy orbifold GUTs
In this short note, we examine the relationship between the string coupling constant, $\gstring{}$, and the grand unified gauge coupling constant, $\alphagut{}$, in a highly successful class of models based on anisotropic orbifold compactifications of the weakly coupled heterotic string. These models represent a string...
0808.0992v2
2008-08-07
F-term SUSY Breaking and Moduli
We discuss the coupling of heavy moduli fields to light fields when the dynamics of the latter, absent such couplings, yields metastable vacua. We show that the survival of the vacuum structure of the local model depends nontrivially on the cross-couplings of the two sectors. In particular we find that for "local" mode...
0808.1126v2
2008-08-12
Slow-Roll Suppression of Adiabatic Instabilities in Coupled Scalar Field-Dark Matter Models
We study the evolution of linear density perturbations in the context of interacting scalar field-dark matter cosmologies, where the presence of the coupling acts as a stabilization mechanism for the runaway behavior of the scalar self-interaction potential as in the case of the Chameleon model. We show that in the "ad...
0808.1646v2
2008-08-29
Effect of Induced Spin-Orbit Coupling for Atoms via Laser Fields
We propose an experimental scheme to study spin-orbit coupling effects in a of two-dimensional (2D) Fermi atomic gas cloud by coupling its internal electronic states (pseudospins) to radiation in a delta configuration. The induced spin-orbit coupling can be of the Dresselhaus and Rashba type with and without a Zeeman t...
0808.4137v2
2008-09-02
Commensurate Quantum Oscillations in Coupled Qubits
We study the coupled-qubit oscillation driven by an oscillating field. When the period of the non-resonant mode is commensurate with that of the resonant mode of the Rabi oscillation, we show that the controlled-NOT (CNOT) gate operation can be demonstrated. For a weak coupling the CNOT gate operation is achievable by ...
0809.0364v3
2008-09-05
Carrier-mediated antiferromagnetic interlayer exchange coupling in diluted magnetic semiconductor multilayers Ga$_{1-x}$Mn$_x$As/GaAs:Be
We use neutron reflectometry to investigate the interlayer exchange coupling between Ga$_{0.97}$Mn$_{0.03}$As ferromagnetic semiconductor layers separated by non-magnetic Be-doped GaAs spacers. Polarized neutron reflectivity measured below the Curie temperature of Ga$_{0.97}$Mn$_{0.03}$As reveals a characteristic split...
0809.0955v1
2008-09-08
Charge effect and finite 't Hooft coupling correction on drag force and Jet Quenching Parameter
The effects of charge and finite 't Hooft coupling correction on drag force and jet quenching parameter are investigated. To study charge effect and finite 't Hooft coupling correction, we consider Maxwell charge and Gauss-Bonnet terms, respectively. The background is Reissner-Nordstr\"{o}m-AdS black brane solution in ...
0809.1336v3
2008-09-13
Constraining non-minimally coupled tachyon fields by Noether symmetry
A model for a spatially flat homogeneous and isotropic Universe whose gravitational sources are a pressureless matter field and a tachyon field non-minimally coupled to the gravitational field is analyzed. Noether symmetry is used to find the expressions for the potential density and for the coupling function, and it i...
0809.2331v2
2008-09-14
Interplay between couplings and common noise in phase synchronization: disagreement between global analysis and local stability characterization
We consider two coupled phase oscillators in the presence of proportional ("common") and independent white noises. The global synchronization properties of the system are analytically studied via the Fokker-Planck equation. When the "effective coupling" is big compared to the common noises, the former favors and the la...
0809.2398v2
2008-09-18
Isospin phases of vertically coupled double quantum rings under the influence of perpendicular magnetic fields
Vertically coupled double quantum rings submitted to a perpendicular magnetic field $B$ are addressed within the local spin-density functional theory. We describe the structure of quantum ring molecules containing up to 40 electrons considering different inter-ring distances and intensities of the applied magnetic fiel...
0809.3103v1
2008-09-22
A Jacobi algorithm for distributed model predictive control of dynamically coupled systems
In this paper we introduce an iterative Jacobi algorithm for solving distributed model predictive control (DMPC) problems, with linear coupled dynamics and convex coupled constraints. The algorithm guarantees stability and persistent feasibility, and we provide a localized procedure for constructing an initial feasible...
0809.3647v1
2008-09-26
Time variation of fundamental couplings and dynamical dark energy
Scalar field dynamics may give rise to a nonzero cosmological variation of fundamental constants. Within different scenarios based on the unification of gauge couplings, the various claimed observations and bounds may be combined in order to trace or restrict the time history of the couplings and masses. If the scalar ...
0809.4628v2
2008-09-26
Brownian couplings, convexity, and shy-ness
Benjamini, Burdzy and Chen (2007) introduced the notion of a shy coupling: a coupling of a Markov process such that, for suitable starting points, there is a positive chance of the two component processes of the coupling staying a positive distance away from each other for all time. Among other results, they showed no ...
0809.4682v3
2008-10-03
One- and two-photon spectroscopy of a flux qubit coupled to a microscopic defect
We observed the dynamics of a superconducting flux qubit coupled to an extrinsic quantum system (EQS). The presence of the EQS is revealed by an anticrossing in the spectroscopy of the qubit. The excitation of a two-photon transition to the third excited state of the qubit-EQS system allows us to extract detailed infor...
0810.0590v2
2008-10-06
Relating $e^+e^-$ annihilation to high energy scattering at weak and strong coupling
We explore the correspondence between the final state in e^+e^- annihilation and the small-x hadronic wavefunction in the transverse plane both in weakly coupled QCD and strongly coupled N=4 SYM. At strong coupling, the virtual and static photon produced in e^+e^- annihilation can be treated as a shock wave propagating...
0810.0889v2
2008-10-14
Piezoelectric exciton-acoustic phonon coupling in single quantum dots
Micro-photoluminescence spectroscopy at variable temperature, excitation intensity and energy was performed on a single InAs/AlAs self-assembled quantum dot. The exciton emission line (zero-phonon line, ZPL) exhibits a broad sideband due to exciton-acoustic phonon coupling by the deformation potential mechanism. Additi...
0810.2415v1
2008-10-15
Magnetic Exchange Couplings from Noncollinear Spin Density Functional Perturbation Theory
We propose a method for the evaluation of magnetic exchange couplings based on noncollinear spin-density functional calculations. The method employs the second derivative of the total Kohn-Sham energy of a single reference state, in contrast to approximations based on Kohn-Sham total energy differences. The advantage o...
0810.2699v1
2008-10-30
Duality cascade of softly broken supersymmetric theories
We study the duality cascade of softly broken supersymmetric theories. We investigate the renormalization group (RG) flow of SUSY breaking terms as well as supersymmetric couplings. It is found that the magnitudes of SUSY breaking terms are suppressed in most regimes of the RG flow through the duality cascade. At one s...
0810.5451v1
2008-10-31
Magnetoresistance in Spin-Polarized Transport through a Carbon Nanotube
We report on our theoretical study of the magnetoresistance in spin polarized transport through a finite carbon nanotube (CNT). Varying the Fermi energy of a CNT and the relative strength of couplings to two ferromagnetic (FM) electrodes, we studied the conductance as well as the magnetoresistance (MR). Due to resonant...
0810.5719v1
2008-11-06
Exchange coupling between two ferromagnetic electrodes separated by a graphene nanoribbon
In this study, based on the self-energy method and the total energy calculation, the indirect exchange coupling between two semi-infinite ferromagnetic strips (FM electrodes) separated by metallic graphene nanoribbons (GNRs) is investigated. In order to form a FM/GNR/FM junction, a graphitic region of finite length is ...
0811.0934v1
2008-11-13
Nonequilibrium mode-coupling theory for uniformly sheared systems
We develop a nonequilibrium mode-coupling theory for uniformly sheared systems starting from microscopic, thermostatted SLLOD equations of motion. Our theory aims at describing stationary-state properties including rheological ones of sheared systems, and this is accomplished via two steps. Firstly, a set of self-consi...
0811.2120v1
2008-11-18
Nambu-Poisson Bracket and M-Theory Branes Coupled to Antisymmetric Fluxes
By using the recently proposed prescription arXiv:0804.3629 for obtaining the $M5$ brane action from multiple $M2$ branes action in BLG theory, we examine such transition when 11 Dimensional background antisymmetric fluxes couple to the $M2$ brane world volume. Such couplings was suggested in arXiv:0805.3427 where it w...
0811.2976v2
2008-11-23
The Relationship between Tsallis Statistics, the Fourier Transform, and Nonlinear Coupling
Tsallis statistics (or q-statistics) in nonextensive statistical mechanics is a one-parameter description of correlated states. In this paper we use a translated entropic index: $1 - q \to q$ . The essence of this translation is to improve the mathematical symmetry of the q-algebra and make q directly proportional to t...
0811.3777v1
2008-12-05
Evidence for strongly coupled charge-density-wave ordering in three-dimensional RE5Ir4Si10 compounds by optical measurements
We report optical spectra of Lu$_5$Ir$_4$Si$_{10}$ and Er$_5$Ir$_4$Si$_{10}$, exhibiting the phenomenon of coexisting superconductivity or antiferromagnetism and charge density wave (CDW) order. We measure the maximum value of the charge density wave gap present on part of the Fermi surface of Lu5Ir4Si10, corresponding...
0812.1214v2
2008-12-15
Negative Group Velocity from Quadrupole Resonance of Plasmonic Spheres
We study the dispersions of plasmonic bands that arise from the coupling of electric quadrupole resonances in three dimensional photonic crystals (PCs) consisting of plasmonic spheres. Through analytical derivation, we show that two branches of quadrupole bands in simple cubic PCs with a small lattice constant possess ...
0812.2717v1
2008-12-21
Stochastically stable globally coupled maps with bistable thermodynamic limit
We study systems of globally coupled interval maps, where the identical individual maps have two expanding, fractional linear, onto branches, and where the coupling is introduced via a parameter - common to all individual maps - that depends in an analytic way on the mean field of the system. We show: 1) For the range ...
0812.4040v1
2009-01-06
Low-loss negative refraction by laser induced magneto-electric cross-coupling
We discuss the feasibility of negative refraction with reduced absorption in coherently driven atomic media. Coherent coupling of an electric and a magnetic dipole transition by laser fields induces magneto-electric cross-coupling and negative refraction at dipole densities which are considerably smaller than necessary...
0901.0664v1
2009-01-07
Within-burst synchrony changes for coupled elliptic bursters
We study the appearance of a novel phenomenon for linearly coupled identical bursters: synchronized bursts where there are changes of spike synchrony within each burst. The examples we study are for normal form elliptic bursters where there is a periodic slow passage through a Bautin (codimension two degenerate Androno...
0901.0874v1
2009-01-15
The strong coupling constant at large distances
In this paper we discuss effective strong coupling constants. Those are well behaved in the low-Q^2 domain, contrarily to alpha_s from pQCD. We present an extraction of an effective strong coupling constant from Jefferson Lab polarized data at intermediate and low Q^2. We also show how these data, together with spin su...
0901.2190v2
2009-01-24
Residual effects of heavy sparticles in the bottom quark Yukawa coupling: a comparative study for the MSSM and NMSSM
If the sparticles are relatively heavy (a few TeV) while the Higgs sector is not so heavy ($m_A$ is not so large), the Higgs boson Yukawa couplings can harbor sizable quantum effects of sparticles and these large residual effects may play a special role in probing supersymmetry at foreseeable colliders. In this work, f...
0901.3818v2
2009-01-26
Higher Derivative Corrections to Shear Viscosity from Graviton's Effective Coupling
The shear viscosity coefficient of strongly coupled boundary gauge theory plasma depends on the horizon value of the effective coupling of transverse graviton moving in black hole background. The proof for the above statement is based on the canonical form of graviton's action. But in presence of generic higher derivat...
0901.3848v1
2009-01-26
Diverse routes to oscillation death in a coupled oscillator system
We study oscillation death (OD) in a well-known coupled-oscillator system that has been used to model cardiovascular phenomena. We derive exact analytic conditions that allow the prediction of OD through the two known bifurcation routes, in the same model, and for different numbers of coupled oscillators. Our exact ana...
0901.4083v1
2009-02-11
Constraints for weakly interacting light bosons from existence of massive neutron stars
Theories beyond the standard model include a number of new particles some of which might be light and weakly coupled to ordinary matter. Such particles affect equation of state of nuclear matter and can shift admissible masses of neutron stars to higher values. The internal structure of neutron stars is modified provid...
0902.1825v2
2009-02-22
A new scheme for the running coupling constant in gauge theories using Wilson loops
We propose a new renormalization scheme of the running coupling constant in general gauge theories using the Wilson loops. The renormalized coupling constant is obtained from the Creutz ratio in lattice simulations and the corresponding perturbative coefficient at the leading order. The latter can be calculated by adop...
0902.3768v3
2009-02-23
Polaron formation in the presence of Rashba spin-orbit coupling: implications for spintronics
We study the effects of the Rashba spin-orbit coupling on the polaron formation, using a suitable generalization of the Momentum Average approximation. Contrary to previous investigations of this problem, we find that the spin-orbit interaction decreases the effective electron-phonon coupling. It is thus possible to lo...
0902.3853v1
2009-03-05
Quantum critical behavior driven by Hund's rule coupling in quantum antiferromagnets
When localized spins on different d orbitals prefer different types of antiferromagnetic ordering, the Hund's rule coupling creates frustration. Using spin-wave theory we study the case of two such orbitals on a square lattice coupled through Hund's rule, such that the first one couples antiferromagnetically (AF) more ...
0903.0983v1
2009-03-19
The Slow-Roll and Rapid-Roll Conditions in the Space-like Vector Field Scenario
In this note we derive the slow-roll and rapid-roll conditions for the minimally and non-minimally coupled space-like vector fields. The function $f(B^{2})$ represents the non-minimal coupling effect between vector fields and gravity, the $f=0$ case is the minimal coupling case. For a clear comparison with scalar field...
0903.3269v2
2009-03-31
Disappearance of quasi-fermions in the strongly coupled plasma from the Schwinger-Dyson equation with in-medium gauge boson propagator
We non-perturbatively study the fermion spectrum in the chiral symmetric phase focusing on the effects of in-medium corrections for gauge boson. The fermion spectrum is derived by solving the Schwinger-Dyson equation (SDE) with ladder approximation on the real time axis. It is shown that the peak of the fermion spectra...
0903.5495v1
2009-04-05
On the reversal of radial SLE, I: Commutation Relations in Annuli
We aim at finding the reversal of radial SLE and proving the reversibility of whole-plane SLE. For this purpose, we define annulus SLE$(\kappa,\Lambda)$ processes in doubly connected domains with one marked boundary point. We derive some partial differential equation for $\Lambda$, which is sufficient for the annulus S...
0904.0808v2
2009-04-08
A Dispersive Analysis on the $f_0(600)$ and $f_0(980)$ Resonances in $γγ\toπ^+π^-, π^0π^0$ Processes
We estimate the di-photon coupling of $f_0(600)$, $f_0(980)$ and $f_2(1270)$ resonances in a coupled channel dispersive approach. The $f_0(600)$ di-photon coupling is also reinvestigated using a single channel $T$ matrix for $\pi\pi$ scattering with better analyticity property, and it is found to be significantly small...
0904.1445v2
2009-04-13
Magnetically tunable dielectric materials
The coupling between localized spins and phonons can lead to shifts in the dielectric constant of insulating materials at magnetic ordering transitions. Studies on isostructural SeCuO3 (ferromagnetic) and TeCuO3 (antiferromagnetic) illustrate how the q-dependent spin-spin correlation function couples to phonon frequenc...
0904.1974v1
2009-04-13
Renormalization of Oscillator Lattices with Disorder
A real-space renormalization transformation is constructed for lattices of non-identical oscillators with dynamics of the general form $d\phi_{k}/dt=\omega_{k}+g\sum_{l}f_{lk}(\phi_{l},\phi_{k})$. The transformation acts on ensembles of such lattices. Critical properties corresponding to a second order phase transition...
0904.2013v1
2009-04-17
Strong coupling of localized plasmons and molecular excitons in nanostructured silver films
We report on the resonant coupling between localized surface plasmon resonances (LSPRs) in nanostructured Ag films, and an adsorbed monolayer of Rhodamine 6G dye. Hybridization of the plasmons and molecular excitons creates new coupled polaritonic modes, which have been tuned by varying the LSPR wavelength. The resulti...
0904.2674v1