publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
|---|---|---|---|
2023-12-18 | Size dependent optical response in coupled systems of plasmons and electron-hole pairs in metallic nanostructures | In bulk materials, the collective modes and individual modes are orthogonal
each other, and no connection occurs if there is no damping processes. In the
presence of damping, the collective modes, i.e., plasmons decay into the hot
carriers. In finite systems, the collective and individual modes are coupled by
the Coulo... | 2312.10867v2 |
2024-01-30 | Identifying noise transients in gravitational-wave data arising from nonlinear couplings | Noise in various interferometer systems can sometimes couple non-linearly to
create excess noise in the gravitational wave (GW) strain data. Third-order
statistics, such as bicoherence and biphase, can identify these couplings and
help discriminate those occurrences from astrophysical GW signals. However, the
conventio... | 2401.17495v1 |
2024-03-21 | Ab-initio Van der Waals electrodynamics: polaritons and electron scattering from plasmons and phonons in BN-capped graphene | Plasmons and polar phonons are elementary electrodynamic excitations of
matter. In 2d and at long wavelengths, they couple to light and act as the
system polaritons. They also dictate the scattering of charged carriers. Van
der Waals heterostructures offer the opportunity to couple excitations from
different layers via... | 2403.14322v1 |
1997-06-18 | First Order Nonequilibrium Phase Transition in a Spatially Extended System | We investigate a system of harmonically coupled identical nonlinear
constituents subject to noise in different spatial arrangements. For global
coupling we find for infinitely many constituents the coexistence of several
ergodic components and a bifurcation behaviour like in first order phase
transitions. These results... | 9706004v1 |
1997-11-27 | Constraints on the chaotic inflationary scenario with a nonminimally coupled "inflaton" field from the cosmic microwave background radiation anisotropy | We investigate a possibility to restrict the chaotic inflationary scenario
with "large" nonminimally coupled inflaton("phi") field considered by Fakir and
Unruh by means of the observed CMBR anisotropy. We calculate the contributions
of the long wavelength gravitational waves generated in the inflationary period
to CMB... | 9711340v1 |
2000-06-21 | Dark energy and the Boomerang data | The recent high-quality Boomerang data allow to test many competing
cosmological models. Here I present a seven-parameter likelihood analysis of
dark energy models with exponential potential and explicit coupling to dark
matter. Such a model is conformally equivalent to a scalar field with
non-minimal coupling to gravi... | 0006300v2 |
2002-06-07 | Photometric amplitudes and phases of nonradial oscillation in rotating stars | Effects of rotational mode coupling on photometric parameters of stellar
oscillations are studied. At moderate rotation rates, a strong coupling between
modes of spherical harmonic degree, $\ell$, differing by 2 and of the same
azimuthal order, $m$, takes place if the frequencies are close. This is a
common situation a... | 0206109v1 |
2003-03-27 | Probing String Theory with Modulated Cosmological Fluctuations | Superstring theory, models with extra dimensions and other SUSY models
generically predict that the coupling constants are in fact vacuum expectation
values of fields like the dilaton, moduli etc. Assuming some of these fields
are light during inflation, we get generation of small classical
inhomogeneities in these fie... | 0303614v2 |
2003-11-19 | SAX J1808.4-3658 and the origin of X-ray variability in X-ray binaries and active galactic nuclei | The aperiodic X-ray variability in neutron star and black hole X-ray binaries
(XRBs), and active galactic nuclei (AGN) shows a characteristic linear
relationship between rms amplitude and flux, implying a multiplying-together or
`coupling' of variability on different time-scales. Such a coupling may result
from avalanc... | 0311453v1 |
2005-04-23 | Cluster number counts dependence on dark energy inhomogeneities and coupling to dark matter | Cluster number counts can be used to test dark energy models. We investigate
dark energy candidates which are coupled to dark matter. We analyze the cluster
number counts dependence on the amount of dark matter coupled to dark energy.
Further more, we study how dark energy inhomogeneities affect cluster
abundances. It ... | 0504519v4 |
2005-10-28 | Nonlocal radiative coupling in non monotonic stellar winds | There is strong observational evidence of shocks and clumping in
radiation-driven stellar winds from hot, luminous stars. The resulting non
monotonic velocity law allows for radiative coupling between distant locations,
which is so far not accounted for in hydrodynamic wind simulations. In the
present paper, we determi... | 0510806v1 |
2006-04-28 | Coupled Quintessence and CMB | We revise the stability of the tracking solutions and briefly review the
potentials of quintessence models. We discuss the evolution of linear
perturbations for $V(\phi) = V_{0} \exp(\lambda \phi^2/2)$ potential in which
the scalar field is non-minimally coupled to cold dark matter. We consider the
effects of this coup... | 0604602v1 |
2007-02-08 | Dynamics of Quintessence Models of Dark Energy with Exponential Coupling to the Dark Matter | We explore quintessence models of dark energy which exhibit non-minimal
coupling between the dark matter and the dark energy components of the cosmic
fluid. The kind of coupling chosen is inspired in scalar-tensor theories of
gravity. We impose a suitable dynamics of the expansion allowing to derive
exact Friedmann-Rob... | 0702227v1 |
1994-07-06 | Pattern Dynamics of a Coupled Map Lattice for Open Flow | The pattern dynamics of the one-way coupled logistic lattice which can serve
as a phenomenological model for open flow is investigated and shown to be
extremely rich. For medium and large coupling strengths, we find spatially
periodic, quasiperiodic and chaotic patterns with temporal periodicity and
analyze their stabi... | 9407001v1 |
1996-03-05 | Turbulence in Globally Coupled Maps | The phenomenon of turbulence is investigated in the context of globally
coupled maps. The local dynamics is given by the Chat\'e-Manneville minimal map
previously used in studies of spatiotemporal intermittency in locally coupled
map lattices. New features arise in the globally coupled system; for instance,
the transit... | 9603004v1 |
1997-02-28 | Correlations between resonances in a statistical scattering model | The distortion of the regular motion in a quantum system by its coupling to
the continuum of decay channels is investigated. The regular motion is
described by means of a Poissonian ensemble. We focus on the case of only few
channels K<10. The coupling to the continuum induces two main effects, due to
which the distort... | 9703002v1 |
1998-01-09 | Mode-locking in coupled map lattices | We study propagation of pulses along one-way coupled map lattices, which
originate from the transition between two superstable states of the local map.
The velocity of the pulses exhibits a staircase-like behaviour as the coupling
parameter is varied. For a piece-wise linear local map, we prove that the
velocity of the... | 9801010v1 |
1998-10-20 | Time Delay Effects on Coupled Limit Cycle Oscillators at Hopf Bifurcation | We present a detailed study of the effect of time delay on the collective
dynamics of coupled limit cycle oscillators at Hopf bifurcation. For a simple
model consisting of just two oscillators with a time delayed coupling, the
bifurcation diagram obtained by numerical and analytical solutions shows
significant changes ... | 9810023v2 |
1994-06-29 | Cross relaxation and the bilayer coupling in YBCO | There is strong experimental evidence for substantial antiferromagnetic
coupling between the CuO$_2$ planes of the bilayers in YBCO compounds. The
acoustic mode of the spin excitation spectrum has been measured but the optic
mode has not been observed. Theoretical estimates suggest values for the
antiferromagnetic inte... | 9406118v1 |
1994-08-19 | A Plane of Weakly Coupled Heisenberg Chains: Theoretical Arguments and Numerical Calculations | The $S=1/2$, nearest-neighbor, quantum Heisenberg antiferromagnet on the
square lattice with spatially anisotropic couplings is reconsidered, with
particular attention to the following question: at T=0, does N\'eel
orderdevelop at infinitesimal interchain coupling, or is there a nonzero
critical coupling? A heuristic r... | 9408062v1 |
1994-12-23 | Magnetic impurities coupled to quantum antiferromagnets in one dimension | Magnetic impurities coupled antiferromagnetically to a one-dimensional
Heisenberg model are studied by numerical diagonalization of chains of finite
clusters. By calculating the binding energy and the correlation function, it is
shown that a local singlet develops around each impurity. This holds true for
systems with ... | 9412104v1 |
1995-02-10 | Bilayers of Chiral Spin States | We study the behavior of two planes of Quantum Heisenberg Antiferromagnet in
the regime in which a Chiral Spin Liquid is stabilized in each plane. The
planes are coupled by an exchange interaction of strength $J_3$. We show that
in the regime of small $J_3$ (for both ferromagnetic {\it and}
antiferromagnetic coupling),... | 9502044v3 |
1995-03-08 | Screening effect of interlayer coupling on electronic transport properties of layered high-$T_c$ oxides | We have investigated the effect of thermal fluctuation on the interlayer
coupling of three-dimensional Josephson-junction arrays with anisotropic
interactions as a model of layered high-$T_c$ oxides, focusing on non-Ohmic
current-voltage characteristics. Langevin dynamic simulations were performed
for various Josephson... | 9503039v1 |
1995-07-18 | Electron-phonon coupling close to a metal-insulator transition in one dimension | We consider a one-dimensional system of electrons interacting via a
short-range repulsion and coupled to phonons close to the metal-insulator
transition at half filling. We argue that the metal-insulator transition can be
described as a standard one dimensional incommensurate to commensurate
transition, even if the ele... | 9507070v1 |
1995-09-06 | Band spectra of rectangular graph superlattices | We consider rectangular graph superlattices of sides l1, l2 with the
wavefunction coupling at the junctions either of the delta type, when they are
continuous and the sum of their derivatives is proportional to the common value
at the junction with a coupling constant alpha, or the "delta-prime-S" type
with the roles o... | 9509027v1 |
1995-11-30 | Fermi surface evolution in underdoped cuprates | We consider a two-dimensional Fermi liquid coupled to low-energy commensurate
spin fluctuations. At small coupling, the hole Fermi surface is large and
centered around $(\pi,\pi)$. We show that as the coupling increases, the shape
of the Fermi surface undergoes a substantial evolution, and at strong coupling,
the hole ... | 9511138v2 |
1996-01-15 | Mode coupling and renormalization group results for the noisy Burgers equation | We investigate the noisy Burgers equation (Kardar--Parisi--Zhang equation in
1+1 dimensions) using the dynamical renormalization group (to two--loop order)
and mode--coupling techniques. The roughness and dynamic exponent are fixed by
Galilean invariance and a fluctuation--dissipation theorem. The fact that there
are n... | 9601049v1 |
1996-03-06 | The London penetration depth of strongly coupled isotropic superconductors : low temperature behaviour | We proceed to a systematic exploration of the low temperature dependence of
the London penetration depth of isotropic superconductors within strong
coupling theory in the clean limit. For a sizeable range of parameters, we find
that strong coupling effects can reasonably simulate a power law dependence,
sometimes with ... | 9603040v1 |
1996-04-04 | Friedel transition in a modified XY model | Weakly coupled superconducting layers are described by the three-dimensional
XY model with strong coupling in two directions and weak coupling in the third
direction. For the usual Josephson-type interplane coupling the coherence
between the layers is lost at the same temperature as that within the layers.
Thus a low-t... | 9604028v1 |
1996-07-25 | Polaronic optical absorption of the Holstein and Su-Schrieffer-Heeger models | The optical conductivity of a polaronic charge carrier in the intermediate
and strong-coupling regimes is calculated for a tight-binding electron using
exact diagonalization. Two different simple models of the electron-phonon
coupling are considered: the Holstein model, with coupling of the lattice
displacement to the ... | 9607179v1 |
1996-09-11 | Exchange Coupling Between Iron Layers Separated by BCC Copper | The exchange coupling between Fe layers separated by BCC Cu is calculated for
Fe/Cu/Fe (001) trilayers. It is shown that the coupling is basically regulated
by three extrema of the bulk BCC Cu Fermi surface. The contributions from those
extrema are all of the same order of magnitude, but that associated with the
``bell... | 9609104v1 |
1997-01-28 | Electronic structure of underdoped cuprates | We consider a two-dimensional Fermi liquid coupled to low-energy commensurate
spin fluctuations. At small coupling, the hole Fermi surface is large and
centered around $Q =(\pi,\pi)$. We show that as the coupling increases, the
shape of the quasiparticle Fermi surface and the spin-fermion vertex undergo a
substantial e... | 9701196v1 |
1997-02-15 | Spin Gap in a Doped Kondo Chain | We show that the Kondo chain away from half-filling has a spin gap upon the
introduction of an additional direct Heisenberg coupling between localized
spins. This is understood in the weak-Kondo-coupling limit of the
Heisenberg-Kondo lattice model by bosonization and in the strong-coupling limit
by a mapping to a modif... | 9702143v3 |
1997-06-17 | Generalized calculation of magnetic coupling constants for Mott-Hubbard insulators: Application to ferromagnetic Cr compounds | Using a Rayleigh-Schr\"odinger perturbation expansion of multi-band Hubbard
models, we present analytic expressions for the super-exchange coupling
constants between magnetic transition metal ions of arbitrary separation in
Mott-Hubbard insulators. The only restrictions are i) all ligand ions are
closed shell anions an... | 9706175v1 |
1997-10-18 | Breakdown of Migdal's theorem and intensity of electron-phonon coupling in high-Tc superconductors | In this article we quantify the possible effects of the breakdown of Migdal's
theorem on the electron-phonon (e-p) coupling constant, on the critical
temperature and on the superconducting gap by examining different kinds of
superconducting materials either with low and high critical temperature. We use
the theoretical... | 9710189v1 |
1997-10-29 | Solving the Holstein molecular crystal model | We present selected results for the Holstein molecular crystal model in one
space dimension as determined by the Global-Local variational method, including
complete polaron energy bands, ground state energies, and effective masses. We
juxtapose our results with specific comparable results of numerous other
methodologie... | 9710321v2 |
1997-12-29 | Ferromagnetic transition and phase diagram of the one-dimensional Hubbard model with next-nearest-neighbor hopping | We study the phase diagram of the one-dimensional Hubbard model with
next-nearest-neighbor hopping using exact diagonalization, the density-matrix
renormalization group, the Edwards variational ansatz, and an adaptation of
weak-coupling calculations on the two-chain Hubbard model. We find that a
substantial region of t... | 9712310v1 |
1998-03-04 | Exactly solvable phase oscillator models with synchronization dynamics | Populations of phase oscillators interacting globally through a general
coupling function $f(x)$ have been considered. In the absence of precessing
frequencies and for odd-coupling functions there exists a Lyapunov functional
and the probability density evolves toward stable stationary states described
by an equilibriu... | 9803055v1 |
1998-04-28 | An Analytical Study of Coupled Two-State Stochastic Resonators | The two-state model of stochastic resonance is extended to a chain of coupled
two-state elements governed by the dynamics of Glauber's stochastic Ising
model. Appropriate assumptions on the model parameters turn the chain into a
prototype system of coupled stochastic resonators. In a weak-signal limit
analytical expres... | 9804305v1 |
1998-05-25 | Scalar potential effect in an integrable Kondo model | To study the impurity potential effect to the Kondo problem in a Luttinger
liquid, we propose an integrable model of two interacting half-chains coupled
with a single magnetic impurity ferromagnetically. It is shown that the scalar
potential effectively reconciles the spin dynamics at low temperatures.
Generally, there... | 9805322v2 |
1998-05-29 | Scaling theory of magnetic ordering in the Kondo lattices with anisotropic exchange interactions | The lowest-order scaling consideration of the magnetic state formation in the
Kondo lattices is performed within the $s-f$ model with inclusion of anisotropy
for both the $f-f$ coupling and $s-f$ exchange interaction. The Kondo
renormalizations of the effective transverse and longitudinal $s-f$ coupling
parameters, spi... | 9805390v2 |
1998-10-05 | The microscopic spin-phonon coupling constants in CuGeO_3 | Using RPA results, mean field theory, and refined data for the polarization
vectors we determine the coupling constants of the four Peierls-active phonon
modes to the spin chains of CuGeO_3. We then derive the values of the coupling
of the spin system to the linear ionic displacements, the bond lengths and the
angles b... | 9810038v2 |
1998-10-17 | Many-body spectral statistics of interacting Fermions | We have studied the appearance of chaos in the many-body spectrum of
interacting Fermions. The coupling of a single state to the Fermi sea is
considered. This state is coupled to a hierarchy of states corresponding to one
or several particle-hole excitations. We have considered various couplings
between two successive ... | 9810211v1 |
1999-06-28 | Theory of Pseudogap Phenomena in High-Tc Cuprates Based on the Strong Coupling Superconductivity | In this paper we study the effects of the strong coupling superconductivity
on the normal state electronic structure. We point out that the pseudogap
phenomena in High-T_c cuprates are naturally explained as a precursor of the
strong coupling superconductivity.
We expand the reciprocal of the T-matrix with respect to... | 9906418v1 |
1999-07-09 | Hidden non-Fermi liquid behavior due to crystal field quartet | We study a realistic Kondo model for crystal field quartet ground states
having magnetic and non-magnetic (quadrupolar) exchange couplings with
conduction electrons, using the numerical renormalization group method. We
focus on a local effect dependent on singlet excited states coupled to the
quartet, which reduces the... | 9907137v1 |
1999-07-19 | Renormalization of the Spin-Peierls Transition due to Phonon Dynamics | We report results from a systematic strong-coupling expansion of a spin-1/2
Heisenberg chain coupled to Einstein phonons. In the non-adiabatic regime this
model is used to describe zero temperature properties of CuGeO3. The linked
cluster expansion allows the determination of observables in the thermodynamic
limit pres... | 9907266v1 |
1999-07-23 | Coupling of carbon nanotubes to metallic contacts | The modeling of carbon nanotube-metal contacts is important from both basic
and applied view points. For many applications, it is important to design
contacts such that the transmission is dictated by intrinsic properties of the
nanotube rather than by details of the contact. In this paper, we calculate the
electron tr... | 9907357v2 |
1999-09-27 | Minimal model to describe the magnetism of $CuGeO_{3}$ | We show that to describe properly the low energy excitations of $CuGeO_{3}$
one must include the effects of a transverse antiferromagnetic coupling, which
is estimated to be $J_{\perp}=0.15 J$. Owing to this coupling the frustration
in the chains is significantly lower than recent 1D estimates based on purely
one-dimen... | 9909375v1 |
1999-10-21 | Metal-insulator transitions: Influence of lattice structure, Jahn-Teller effect, and Hund's rule coupling | We study the influence of the lattice structure, the Jahn-Teller effect and
the Hund's rule coupling on a metal-insulator transition in AnC60 (A= K, Rb).
The difference in lattice structure favors A3C60 (fcc) being a metal and A4C60
(bct) being an insulator, and the coupling to Hg Jahn-Teller phonons favors
A4C60 being... | 9910319v1 |
1999-11-17 | Dynamic modulation of electron correlation by intramolecular modes in charge transfer compounds | Electron-phonon and electron-electron interactions are in competition in
determining the properties of molecular charge transfer conductors and
superconductors. The direct influence of phonons on the electron-electron
interaction was not before considered and in the present work the coupling of
intramolecular modes to ... | 9911259v1 |
1999-11-17 | Magnetic order in ferromagnetically coupled spin ladders | A model of coupled antiferromagnetic spin-1/2 Heisenberg ladders is studied
with numerical techniques. In the case of ferromagnetic interladder coupling we
find that the dynamic and static structure factor has a peak at $(\pi,\pi/2)$
where the first (second) direction is along (transversal) to the ladders.
Besides, we ... | 9911271v2 |
2000-01-01 | Strong Coupling Approach to the Supersymmetric Kondo Model | We carry out the strong coupling expansion for the SU(N) Kondo model where
the impurity spin is represented by a L-shaped Young tableau. Using second
order perturbation theory around the strong coupling fixed point it is shown
that when the antisymmetric component of the Young-tableau contains more than
N/2 entries, th... | 0001002v3 |
2000-01-03 | Dissipative Landau-Zener Tunneling at Marginal Coupling | The Landau-Zener transition in a two level system can be suppressed or
enhanced by coupling to an environment, depending on the temperature and the
environment spectral function. We consider the marginal spectral function, when
the dissipation effects are important for arbitrarily slow motion. Landau-Zener
transition r... | 0001012v1 |
2000-08-18 | Entangled states in a Josephson charge qubit coupled to a superconducting resonator | We study the dynamics of a quantum superconducting circuit which is the
analogue of an atom in a high-Q cavity. The circuit consists of a Josephson
charge qubit coupled to a superconducting resonator. The charge qubit can be
treated as a two level quantum system whose energy separation is split by the
Josephson energy ... | 0008275v1 |
2000-09-27 | Validity of the zero-thermodynamic law in off-equilibrium coupled harmonic oscillators | In order to describe the thermodynamics of the glassy systems it has been
recently introduced an extra parameter also called effective temperature which
generalizes the fluctuation-dissipation theorem (FDT) to systems
off-equilibrium and supposedly describes thermal fluctuations around the aging
state. Here we investig... | 0009428v2 |
2000-10-20 | Interlayer coupling and the c-axis quasiparticle transport in high-$T_{c}$ cuprates | The c-axis quasiparticle conductivity shows different behavior depending on
the nature of the interlayer coupling. For coherent coupling with a constant
hopping amplitude $t_{\perp}$, the conductivity at zero frequency and zero
temperature $\sigma(0,0)$ depends on the direction of the magnetic field, but
it does not fo... | 0010314v2 |
2000-12-04 | Spike-Train Responses of a Pair of Hodgkin-Huxley Neurons with Time-Delayed Couplings | Model calculations have been performed on the spike-train response of a pair
of Hodgkin-Huxley (HH) neurons coupled by recurrent excitatory-excitatory
couplings with time delay. The coupled, excitable HH neurons are assumed to
receive the two kinds of spike-train inputs: the transient input consisting of
$M$ impulses f... | 0012033v1 |
2000-12-25 | Slow Switching in Globally Coupled Oscillators: Robustness and Occurrence through Delayed Coupling | The phenomenon of slow switching in populations of globally coupled
oscillators is discussed. This characteristic collective dynamics, which was
first discovered in a particular class of the phase oscillator model, is a
result of the formation of a heteroclinic loop connecting a pair of clustered
states of the populati... | 0012456v2 |
2001-02-08 | Mechanisms of Decoherence at Low Temperatures | We briefly review the oscillator and spin bath models of quantum
environments, which can be used to describe the low-energy dynamics of open
quantum systems. We then use them to discuss both the mechanisms causing
decoherence at low $T$, and the dynamics of this decoherence. This is done
first for a central 2-level sys... | 0102156v2 |
2001-02-20 | Spinwaves and large electron-phonon coupling near the metal-insulator transition in hole-doped high-T$_C$ oxides | A theory for spin and lattice couplings to the electronic states in
high-T$_C$ oxides is presented, with HgBa$_2$CuO$_4$ as an example. A simple
analytical model suggests that the barrel band is sensitive to potential
perturbations with long-range Fourier components, and that gaps can be opened
at the Fermi energy. Thi... | 0102343v1 |
2001-04-05 | Kondo effect in coupled quantum dots under magnetic fields | The Kondo effect in coupled quantum dots is investigated theoretically under
magnetic fields. We show that the magnetoconductance (MC) illustrates peak
structures of the Kondo resonant spectra. When the dot-dot tunneling coupling
$V_C$ is smaller than the dot-lead coupling $\Delta$ (level broadening), the
Kondo resonan... | 0104091v1 |
2001-06-22 | Quantum phase transitions in models of coupled magnetic impurities | We discuss models of interacting magnetic impurities coupled to a metallic
host. If twice the sum of the impurity spins is larger than the total number of
host screening channels, the system shows one or more quantum phase transitions
where the ground-state spin changes as a function of the inter-impurity
couplings. Th... | 0106458v2 |
2001-07-01 | Coupling and Dissociation in Artificial Molecules | We show that the spin-and-space unrestricted Hartree-Fock method, in
conjunction with the companion step of the restoration of spin and space
symmetries via Projection Techniques (when such symmetries are broken), is able
to describe the full range of couplings in two-dimensional double quantum dots,
from the strong-co... | 0107014v1 |
2001-09-14 | Boundary dependence of the coupling constant and the mass in the vector N-component $(λφ^{4})_{D}$ theory | Using the Matsubara formalism, we consider the massive $(\lambda
\phi^{4})_{D}$ vector $N$-component model in the large $N$ limit, the system
being confined between two infinite paralell planes. We investigate the
behavior of the coupling constant as a function of the separation $L$ between
the planes. For the Wick-ord... | 0109259v1 |
2001-10-15 | Spin-Phonon Chains with Bond Coupling | We investigate the antiadiabatic limit of an antiferromagnetic S=1/2
Heisenberg chain coupled to Einstein phonons via a bond coupling. The flow
equation method is used to decouple the spin and the phonon part of the
Hamiltonian. In the effective spin model longer range spin-spin interactions
are generated. The effectiv... | 0110298v2 |
2001-10-22 | Magnetoconductance of a two-dimensional metal in the presence of spin-orbit coupling | We show that in the metallic phase of a two dimensional electron gas the
spin-orbit coupling due to structure inversion asymmetry leads to a
characteristic anisotropy in the magnetoconductance. Within the assumption that
the metallic phase can be described by a Fermi liquid, we compute the
conductivity in the presence ... | 0110454v1 |
2001-10-23 | Dissipative effects on quantum glassy systems | We discuss the behavior of a quantum glassy system coupled to a bath of
quantum oscillators. We show that the system localizes in the absence of
interactions when coupled to a subOhmic bath. When interactions are switched on
localization disappears and the system undergoes a phase transition towards a
glassy phase. We ... | 0110497v1 |
2001-12-07 | Universality of coupled Potts models | We study systems of M Potts models coupled by their local energy density.
Each model is taken to have a distinct number of states, and the permutational
symmetry S_M present in the case of identical coupled models is thus broken
initially. The duality transformations within the space of 2^M-1 multi-energy
couplings are... | 0112120v1 |
2001-12-31 | Kondo effect and anti-ferromagnetic correlation in transport through tunneling-coupled double quantum dots | We propose to study the transport through tunneling-coupled double quantum
dots (DQDs) connected in series to leads, using the finite-$U$ slave-boson mean
field approach developed initially by Kotliar and Ruckenstein [Phys. Rev. Lett.
{\bf 57}, 1362 (1986)]. This approach treats the dot-lead coupling and the
inter-dot ... | 0112500v2 |
2002-04-18 | Emergence of Quantum-Classical Dynamics in an Open Quantum Environment | The conditions under which an open quantum mechanical system may be described
by mixed quantum-classical dynamics are investigated. Decoherence is studied
using influence functional methods in a model composite quantum system
comprising two coupled systems, A and C, interacting with a harmonic bath with
Ohmic and super... | 0204388v2 |
2002-06-09 | Quasi-spin Model for Macroscopic Quantum Tunnelling between Two Coupled Bose-Einstein Condensates | The macroscopic quantum tunneling between two coupled Bose-Einstein
condensates (BEC) (radio-frequency coupled two-component BECs or two BECs
confined in a double-well potential) is mapped onto the tunneling of an
uniaxial spin with an applied magnetic field. The tunneling exponent is
calculated with an imaginary-time ... | 0206134v3 |
2002-08-12 | Control of interlayer exchange coupling in Fe/Cr/Fe trilayers by ion beam irradiation | The manipulation of the antiferromagnetic interlayer coupling in the
epitaxial Fe/Cr/Fe(001) trilayer system by moderate 5 keV He ion beam
irradiation has been investigated experimentally. It is shown that even for
irradiation with very low fluences (10^14 ions/cm^2) a drastic change in
strength of the coupling appears... | 0208218v1 |
2002-08-27 | Coupling to haloform molecules in intercalated C60? | For field-effect-doped fullerenes it was reported that the superconducting
transition temperature Tc is markedly larger for C60.2CHX_3 (X=Cl, Br)
crystals, than for pure C60. Initially this was explained by the expansion of
the volume per C60-molecule and the corresponding increase in the density of
states at the Fermi... | 0208509v1 |
2002-12-17 | Transition from a strong-coupling fixed point to an intermediate-coupling fixed point in a single-channel SU(N) Kondo model: role of the filling and two-stage screening | We study an extended SU(N) single-impurity Kondo model in which the impurity
spin is described by a combination of Abrikosov fermions and Schwinger bosons.
Our aim is to describe both the quasiparticle-like excitations and the locally
critical modes observed in various physical situations, including non-Fermi
liquid be... | 0212429v1 |
2002-12-18 | Acoustical-Mode-Driven Electron-Phonon Coupling in Transition-Metal Diborides | We show that the electron-phonon coupling in the transition-metal diborides
NbB2 and TaB2 is dominated by the longitudinal acoustical (LA) mode, in
contrast to the optical E_{2g} mode dominated coupling in MgB2. Our ab initio
results, described in terms of phonon dispersion, linewidth, and partial
electron-phonon coupl... | 0212443v1 |
2003-01-10 | Quantum Spin Chains with Nonlocally-Correlated Random Exchange Coupling and Random-Mass Dirac Fermions | S=1/2 quantum spin chains and ladders with random exchange coupling are
studied by using an effective low-energy field theory and transfer matrix
methods. Effects of the nonlocal correlations of exchange couplings are
investigated numerically. In particular we calculate localization length of
magnons, density of states... | 0301139v2 |
2003-05-07 | Coupling of Josephson current qubits using a connecting loop | We propose a coupling scheme for the three-Josephson junction qubits which
uses a connecting loop, but not mutual inductance. Present scheme offers the
advantages of a large and tunable level splitting in implementing the
controlled-NOT (CNOT) operation. We calculate the switching probabilities of
the coupled qubits in... | 0305127v3 |
2003-05-15 | Josephson effect between superconducting nanograins with discrete energy levels | We investigate the Josephson effect between two coupled superconductors,
coupled by the tunneling of pairs of electrons, in the regime that their energy
level spacing is comparable to the bulk superconducting gap, but neglecting any
charging effects. In this regime, BCS theory is not valid, and the notion of a
supercon... | 0305361v1 |
2003-06-05 | Electron-phonon vertex in the two-dimensional one-band Hubbard model | Using quantum Monte Carlo techniques, we study the effects of electronic
correlations on the effective electron-phonon (el-ph) coupling in a
two-dimensional one-band Hubbard model. We consider a momentum-independent bare
ionic el-ph coupling. In the weak- and intermediate-correlation regimes, we
find that the on-site C... | 0306131v3 |
2003-06-11 | The effect of electromechanical coupling on the strain in AlGaN/GaN heterojunction field effect transistors | The strain in AlGaN/GaN heterojunction field-effect transistors (HFETs) is
examined theoretically in the context of the fully-coupled equation of state
for piezoelectric materials. Using a simple analytical model, it is shown that,
in the absence of a two-dimensional electron gas (2DEG), the out-of-plane
strain obtaine... | 0306297v1 |
2003-07-11 | Hydrodynamic coupling of two rotating spheres trapped in harmonic potentials | We theoretically study in detail the hydrodynamic coupling of two equal-sized
colloidal spheres at low Reynolds numbers assuming the particles to be
harmonically trapped with respect to both their positions and orientations. By
taking into account the rotational motion, we obtain a rich spectrum of
collective eigen mod... | 0307282v2 |
2003-07-17 | Coherent oscillations of electrons in tunnel-coupled wells under ultrafast intersubband excitation | Ultrafast intersubband excitation of electrons in tunnell-coupled wells is
studied depending on the structure parameters, the duration of the infrared
pump and the detuning frequency. The temporal dependencies of the photoinduced
concentration and dipole moment are obtained for two cases of transitions: from
the single... | 0307417v1 |
2003-09-01 | The Origin of Magnetic Interactions in Ca3Co2O6 | We investigate the microscopic origin of the ferromagnetic and
antiferromagnetic spin exchange couplings in the quasi one-dimensional cobalt
compound Ca3Co2O6. In particular, we establish a local model which stabilizes a
ferromagnetic alignment of the S=2 spins on the cobalt sites with trigonal
prismatic symmetry, for ... | 0309031v2 |
2003-09-05 | Equilibrium currents in quantum double ring system: A non-trivial role of system-reservoir coupling | Amperes law states that the magnetic moment of a ring is given by current
times the area enclosed. Also from equilibrium statistical mechanics it is
known that magnetic moment is the derivative of free energy with respect to
magnetic field. In this work we analyze a quantum double ring system
interacting with a reservo... | 0309133v2 |
2003-09-11 | Criticality in coupled quantum spin-chains with competing ladder-like and two-dimensional couplings | Motivated by the geometry of spins in the material CaCu$_2$O$_3$, we study a
two-layer, spin-half Heisenberg model, with nearest-neighbor exchange couplings
J and \alpha*J along the two axes in the plane and a coupling J_\perp
perpendicular to the planes. We study these class of models using the
Stochastic Series Expan... | 0309268v1 |
2003-09-23 | Kondo effect in a two-level quantum dot coupled to an external fermionic reservoir | We investigate theoretically the linear conductance of a two-level quantum
dot as a function of the gate voltage and different strength of coupling to the
external electronic system (the reservoir). Apart from the weak coupling
regime, characterized by the Kondo-enhancement of the conductance in the
spinful ground stat... | 0309525v1 |
2003-10-14 | Spin-Hall and spin-diagonal conductivity in the presence of Rashba and Dresselhaus spin-orbit coupling | We investigate the spin-current linear response conductivity tensor to an
electric field in a paramagnetic two dimensonal electron gas with both Rashba
and Dresselhaus spin-orbit coupling in the weak scattering regime. In the
ususal case where both spin-orbit-split bands are occupied, we find that the
spin-Hall conduct... | 0310315v1 |
2003-10-16 | Spin Hall effect and Berry phase in two dimensional electron gas | The spin Hall effect is investigated in a high mobility two dimensional
electron system with the spin-orbital coupling of both the Rashba and the
Dresselhaus types. A spin current perpendicular to the electric field is
generated by either the Rashba or the Dresselhaus coupling. The spin Hall
conductance is independent ... | 0310368v3 |
2003-12-24 | Dynamic generation of spin orbit coupling | Spin-orbit coupling plays an important role in determining the properties of
solids, and is crucial for spintronics device applications. Conventional
spin-orbit coupling arises microscopically from relativistic effects described
by the Dirac equation, and is described as a single particle band effect. In
this work, we ... | 0312632v4 |
2004-04-16 | Superconductor-insulator transition driven by local dephasing | We consider a system where localized bound electron pairs form an array of
"Andreev"-like scattering centers and are coupled to a fermionic subsystem of
uncorrelated electrons. By means of a path-integral approach, which describes
the bound electron pairs within a coherent pseudospin representation, we derive
and analy... | 0404394v1 |
2004-04-22 | Atomic quantum dots coupled to BEC reservoirs | We study the dynamics of an atomic quantum dot, i.e. a single atom in a tight
optical trap which is coupled to a superfluid reservoir via laser transitions.
Quantum interference between the collisional interactions and the laser induced
coupling to the phase fluctuations of the condensate results in a tunable
coupling ... | 0404533v1 |
2004-06-24 | Understanding Mechanochemical Coupling in Kinesins Using First-Passage Time Processes | Kinesins are processive motor proteins that move along microtubules in a
stepwise manner, and their motion is powered by the hydrolysis of ATP. Recent
experiments have investigated the coupling between the individual steps of
single kinesin molecules and ATP hydrolysis, taking explicitly into account
forward steps, bac... | 0406578v1 |
2004-06-25 | Super-poissonian noise, negative differential conductance, and relaxation effects in transport through molecules, quantum dots and nanotubes | We consider charge transport through a nanoscopic object, e.g. single
molecules, short nanotubes, or quantum dots, that is weakly coupled to metallic
electrodes. We account for several levels of the molecule/quantum dot with
level-dependent coupling strengths, and allow for relaxation of the excited
states. The current... | 0406647v2 |
2004-07-09 | Effect of electron-phonon interaction range on lattice polaron dynamics: a continuous-time quantum Monte Carlo study | We present the numerically exact ground state energy, effective mass, and
isotope exponents of a one-dimensional lattice polaron, valid for any range of
electron-phonon interaction, applying a new continuous-time Quantum Monte Carlo
(QMC) technique in a wide range of coupling strength and adiabatic ratio. The
QMC metho... | 0407250v2 |
2004-07-23 | Single-photon exchange interaction in a semiconductor microcavity | We consider the effective coupling of localized spins in a semiconductor
quantum dot embedded in a microcavity. The lowest cavity mode and the quantum
dot exciton are coupled and close in energy, forming a polariton. The fermions
forming the exciton interact with localized spins via exchange. Exact
diagonalization of a... | 0407639v1 |
2004-08-24 | Pairing interactions and pairing mechanism in high temperature copper oxide superconductors | The polaron binding energy E_{p} in undoped parent cuprates has been
determined to be about 1.0 eV from the unconventional oxygen-isotope effect on
the antiferromagnetic ordering temperature. The deduced value of E_{p} is in
quantitative agreement with that estimated from independent optical data and
that estimated the... | 0408520v3 |
2004-08-26 | BCS-BEC crossover of collective excitations in two-band superfluids | We use the functional integral approach to study low energy collective
excitations in a continuum model of neutral two-band superfluids at T=0 for all
couplings with a separable pairing interaction. In the long wavelength and low
frequency limit, we recover Leggett's analytical results in weak coupling (BCS)
for s-wave... | 0408586v2 |
2004-08-27 | Long-range dynamics of magnetic impurities coupled to a two-dimensional Heisenberg antiferromagnet | We consider a two-dimensional Heisenberg antiferromagnet on a square lattice
with weakly coupled impurities, i.e. additional spins interacting with the host
magnet by a small dimensionless coupling constant g<<1. Using linear spin-wave
theory, we find that the magnetization disturbance at distance r from a single
impur... | 0408598v2 |
2004-09-13 | Properties of the superconducting state in a two-band model | Eliashberg theory is used to investigate the range of thermodynamic
properties possible within a two-band model for s-wave superconductivity and to
identify signatures of its two-band nature. We emphasize dimensionless BCS
ratios (those for the energy gaps, the specific heat jump and the negative of
its slope near Tc, ... | 0409335v2 |
2004-11-03 | Long-range radiative interaction between semiconductor quantum dots | We develop a Maxwell-Schroedinger formalism in order to describe the
radiative interaction mechanism between semiconductor quantum dots. We solve
the Maxwell equations for the electromagnetic field coupled to the polarization
field of a quantum dot ensemble through a linear non-local susceptibility and
compute the pola... | 0411087v1 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.