publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2001-01-24 | Coupling of Nonlocal Potentials to Electromagnetic Fields | Nonlocal Hamiltonians are used widely in first-principles quantum
calculations; the nonlocality stems from eliminating undesired degrees of
freedom, e.g. core electrons. To date, attempts to couple nonlocal systems to
external electromagnetic (EM) fields have been heuristic or limited to weak or
long wavelength fields.... | 0101383v3 |
2001-01-29 | Dynamics of order parameters for a population of globally coupled oscillators | Using an expansion in order parameters, the equation of motion for the
centroid of globally coupled oscillators with natural frequencies taken from a
distribution is obtained for the case of high coupling, low dispersion of
natural frequencies and any number of oscillators. To the first order, the
system can be approxi... | 0101441v1 |
2001-03-27 | Beyond Eliashberg superconductivity in MgB2: anharmonicity, two-phonon scattering, and multiple gaps | Density-functional calculations of the phonon spectrum and electron-phonon
coupling in MgB$_2$ are presented. The $E_{2g}$ phonons, which involve in-plane
B displacements, couple strongly to the $p_{x,y}$ electronic bands. The
isotropic electron-phonon coupling constant is calculated to be about 0.8.
Allowing for diffe... | 0103570v1 |
2001-04-02 | Decoherence and dephasing in coupled Josephson-junction qubits | We investigate the decoherence and dephasing of two coupled Josephson qubits.
With the interaction between the qubits being generated by current-current
correlations, two different situations in which the qubits are coupled to the
same bath, or to two independent baths, are considered. Upon focussing on
dissipation bei... | 0104023v1 |
2001-05-14 | Charge spectrometry with a strongly coupled superconducting single-electron transistor | We have used a superconducting single-electron transistor as a
DC-electrometer that is strongly coupled to the metal island of another
transistor. With this set-up, it is possible to directly measure the charge
distribution on this island. The strong capacitive coupling was achieved by a
multilayer fabrication techniqu... | 0105263v1 |
2001-07-20 | Raman Response in Antiferromagnetic Two-Leg S=1/2 Heisenberg Ladders | The Raman response in the antiferromagnetic 2-leg S=1/2 Heisenberg ladder is
calculated for various couplings by continuous unitary transformations. For leg
couplings above 80% of the rung coupling a characteristic 2-peak structure
occurs with a point of zero intensity within the continuum. Experimental data
for CaV_2O... | 0107431v1 |
2001-07-27 | Nonlinear coupling between scissors modes of a Bose-Einstein condensate | We explore the nonlinear coupling of the three scissors modes of an
anisotropic Bose-Einstein condensate. We show that only when the frequency of
one of the scissors modes is twice the frequency of another scissors mode,
these two modes can be resonantly coupled and a down conversion can occur. We
perform the calculati... | 0107567v1 |
2001-09-19 | Charge transport through quantum dots via time-varying tunnel couplings | We describe a novel mechanism for charge pumping through tunnel-coupled
quantum dots in the regime of strong Coulomb blockade. The quantum state of an
additional electron within the structure is steered by changing the tunneling
couplings between neighbouring dots. Appropriate tailoring of the interdot
tunneling rates ... | 0109335v1 |
2001-11-09 | Strong-Coupling Effects in "Dirty" Superfluid $^3He$ | The contribution of the strong-coupling effects to the free energy of the
"dirty" superfluid $^3He$ is estimated using a simple model. It is shown that
the strong-coupling effects are less susceptible to the quasiparticle
scattering events in comparison to the weak-coupling counterpart. This supports
the conclusion abo... | 0111161v2 |
2001-12-06 | Aharonov-Bohm oscillations of a particle coupled to dissipative environments | The amplitude of the Bohm-Aharonov oscillations of a particle moving around a
ring threaded by a magnetic flux and coupled to different dissipative
environments is studied. The decay of the oscillations when increasing the
radius of the ring is shown to depend on the spatial features of the coupling.
When the environme... | 0112099v2 |
2001-12-18 | System size resonance in coupled noisy systems and in the Ising model | We consider an ensemble of coupled nonlinear noisy oscillators demonstrating
in the thermodynamic limit an Ising-type transition. In the ordered phase and
for finite ensembles stochastic flips of the mean field are observed with the
rate depending on the ensemble size. When a small periodic force acts on the
ensemble, ... | 0112338v1 |
2002-04-16 | Charge Pumping in Mesoscopic Systems coupled to a Superconducting Lead | We derive a general scattering-matrix formula for the pumped current through
a mesoscopic region attached to a normal and a superconducting lead. As
applications of this result we calculate the current pumped through (i) a pump
in a wire, (ii) a quantum dot in the Coulomb blockade regime, and (iii) a
ballistic double-b... | 0204340v1 |
2002-06-16 | Frequency behavior of Raman coupling coefficient in glasses | Low-frequency Raman coupling coefficient of 11 different glasses is
evaluated. It is found that the coupling coefficient demonstrates a universal
linear frequency behavior near the boson peak maximum and a superlinear
behavior at very low frequencies. The last observation suggests vanishing of
the coupling coefficient ... | 0206295v1 |
2002-07-18 | Disentangling the exchange coupling of entangled donors in the Si quantum computer architecture | We develop a theory for micro-Raman scattering by single and coupled
two-donor states in silicon. We find the Raman spectra to have significant
dependence on the donor exchange splitting and the relative spatial positions
of the two donor sites. In particular, we establish a strong correlation
between the temperature d... | 0207455v2 |
2002-08-22 | Spin-Orbit Coupling, Antilocalization, and Parallel Magnetic Fields in Quantum Dots | We investigate antilocalization due to spin-orbit coupling in ballistic GaAs
quantum dots. Antilocalization that is prominent in large dots is suppressed in
small dots, as anticipated theoretically. Parallel magnetic fields suppress
both antilocalization and also, at larger fields, weak localization, consistent
with ra... | 0208436v2 |
2002-08-26 | Characterization of the stretched exponential trap-time distributions in one-dimensional coupled map lattices | Stretched exponential distributions and relaxation responses are encountered
in a wide range of physical systems such as glasses, polymers and spin glasses.
As found recently, this type of behavior occurs also for the distribution
function of certain trap time in a number of coupled dynamical systems. We
analyze a one-... | 0208487v1 |
2002-09-21 | Dynamical spin-electric coupling in a quantum dot | Due to the spin-orbital coupling in a semiconductor quantum dot, a freely
precessing electron spin produces a time-dependent charge density. This creates
a sizeable electric field outside the dot, leading to promising applications in
spintronics. The spin-electric coupling can be employed for non-invasive single
spin d... | 0209507v1 |
2002-10-27 | Effect of Pr doping on the superconductivity and interlayer coupling of Bi2Sr2-xPrxCa1Cu2Oy system | The effect of Pr substitution on the superconductivity and interlayer
coupling of Bi2212 system is investigated. Magnetic and transport measurements
were performed for purposes of characterization. The superconducting transition
temperature Tc first increased and then decreased till it became zero at x=0.6.
The effecti... | 0210595v1 |
2002-10-31 | Coexistence of Coherence and Incoherence in Nonlocally Coupled Phase Oscillators | The phase oscillator model with global coupling is extended to the case of
finite-range nonlocal coupling. Under suitable conditions, peculiar patterns
emerge in which a quasi-continuous array of identical oscillators separates
sharply into two domains, one composed of mutually synchronized oscillators
with unique freq... | 0210694v1 |
2003-01-07 | Noise-induced macroscopic bifurcations in populations of globally coupled maps | Populations of globally coupled identical maps subject to additive,
independent noise are studied in the regimes of strong coupling. Contrary to
each noisy population element, the mean field dynamics undergoes qualitative
changes when the noise strength is varied. In the limit of infinite population
size, these macrosc... | 0301056v1 |
2003-01-23 | Mode Repulsion and Mode Coupling in Random Lasers | We studied experimentally and theoretically the interaction of lasing modes
in random media. In a homogeneously broadened gain medium, cross gain
saturation leads to spatial repulsion of lasing modes. In an inhomogeneously
broadened gain medium, mode repulsion occurs in the spectral domain. Some
lasing modes are couple... | 0301461v1 |
2003-03-24 | Electron-phonon interaction and coupled phonon--plasmon modes | The theory of Raman scattering by the electron--phonon coupled system in
metals and heavily doped semiconductors is developed taking into account the
Coulomb screening and the electron--phonon deformation interaction. The
Boltzmann equation for carriers is applied. Phonon frequencies and optic
coupling constants are re... | 0303503v1 |
2003-03-28 | Effect of Antiferromagnetic Interlayer Coupling on Current-Assisted Magnetization Switching | We compare magnetization switching in Co/Cu/Co nanopillars with uncoupled and
dipole-field coupled Co layers. In uncoupled nanopillars, current-driven
switching is hysteretic at low magnetic field H and changes to reversible,
characterized by telegraph noise, at high H. We show that dipolar coupling both
affects the sw... | 0303614v1 |
2003-04-12 | Effect of Interlayer Coupling on Current-Assisted Magnetization Switching in Nanopillars | We show that dipole-field induced antiferromagnetic coupling, or RKKY
ferromagnetic coupling, between Co layers can strongly affect the low magnetic
field switching behavior of Co/Cu/Co nanopillars. Whereas current-assisted
switching at low fields in uncoupled nanopillars is always hysteretic, strong
coupling of either... | 0304299v1 |
2003-04-28 | Ferromagnetism and Superconductivity in the multi-orbital Hubbard Model: Hund's Rule Coupling versus Crystal-Field Splitting | The multi-orbital Hubbard model in one dimension is studied using the
numerical diagonalization method. Due to the effect of the crystal-field
splitting $\Delta$, the fully polarized ferromagnetism which is observed in the
strong coupling regime becomes unstable against the partially polarized
ferromagnetism when the H... | 0304620v1 |
2003-05-01 | Negative differential resistance due to the resonance coupling of a quantum-dot dimer | Electron tunneling through a coupled quantum-dot dimer under a dc-bias is
investigated. We find that a peak in the $I$-$V$ curve appears at low
temperature when two discrete electronic states in the two quantum dots are
aligned with each other -- resonance coupling. This leads to a negative
differential resistance. The... | 0305018v1 |
2003-06-11 | Relative phase fluctuations of two coupled one-dimensional condensates | We study the relative phase fluctuations of two one-dimensional condensates
coupled along their whole extension with a local single-atom interaction. The
thermal equilibrium is defined by the competition between independent
longitudinal thermally excited phase fluctuations and the coupling between the
condensates which... | 0306282v2 |
2003-06-13 | Controllable manipulation and entanglement of macroscopic quantum states in coupled charge qubits | We present an experimentally implementable method to couple Josephson charge
qubits and to generate and detect macroscopic entangled states. A
large-junction superconducting quantum interference device is used in the qubit
circuit for both coupling qubits and implementing the readout. Also, we
explicitly show how to ac... | 0306363v2 |
2003-07-02 | Ferromagnetic phase transition and Bose-Einstein condensation in spinor Bose gases | Phase transitions in spinor Bose gases with ferromagnetic (FM) couplings are
studied via mean-field theory. We show that an infinitesimal value of the
coupling can induce a FM phase transition at a finite temperature always above
the critical temperature of Bose-Einstein condensation. This contrasts sharply
with the ca... | 0307063v1 |
2003-08-22 | Intriguing Heat Conduction of a Polymer Chain | We study heat conduction in a one-dimensional chain of particles with
longitudinal as well as transverse motions. The particles are connected by
two-dimensional harmonic springs together with bending angle interactions.
Using equilibrium and nonequilibrium molecular dynamics, three types of thermal
conducting behaviors... | 0308445v1 |
2003-10-20 | Spin Blockade in Capacitively Coupled Quantum Dots | We present transport measurements on a lateral double dot produced by
combining local anodic oxidation and electron beam lithography. We investigate
the tunability of our device and demonstrate, that we can switch between
capacitive and tunnel coupling. In the regime of capacitive coupling we observe
the phenomenon of ... | 0310469v1 |
2003-11-14 | Spin-orbit coupling and Berry phase with ultracold atoms in 2D optical lattices | We show how spin-orbit coupling and Berry phase can appear in two-dimensional
optical lattices by coupling atoms' internal degrees of freedom to radiation.
The Rashba Hamiltonian, a standard description of spin-orbit coupling for
two-dimensional electrons, is obtained for the atoms under certain
circumstances. We discu... | 0311356v2 |
2003-12-04 | Generalized scaling relations for unidirectionally coupled nonequilibrium systems | Unidirectionally coupled systems which exhibit phase transitions into an
absorbing state are investigated at the multicritical point. We find that for
initial conditions with isolated particles, each hierarchy level exhibits an
inhomogeneous active region, coupled and uncoupled respectively. The particle
number of each... | 0312136v1 |
2004-02-10 | First-order Synchronization Transition in Locally Coupled Maps | We study a family of diffusively coupled chaotic maps on periodic
d-dimensional square lattices. Even and odd sub-lattices are updated
alternately, introducing an effective delay. As the coupling strength is
increased, the system undergoes a first order phase transition from a
multi-stable to a synchronized phase. Furt... | 0402283v1 |
2004-02-27 | Coupling Josephson qubits via a current-biased information bus | Josephson qubits without direct interaction can be effectively coupled by
sequentially connecting them to an information bus: a current-biased large
Josephson junction treated as an oscillator with adjustable frequency. The
coupling between any qubit and the bus can be controlled by modulating the
magnetic flux applied... | 0402678v2 |
2004-06-02 | Multi-terminal transport through a quantum dot in the Coulomb blockade regime | Three terminal tunnelling experiments on quantum dots in the Coulomb blockade
regime allow a quantitative determination of the coupling strength of
individual quantum states to the leads. Exploiting this insight we have
observed independent fluctuations of the coupling strengths as a function of
electron number and mag... | 0406046v1 |
2004-10-04 | Dephasing of coupled spin qubit system during gate operations due to background charge fluctuations | It has been proposed that a quantum computer can be constructed based on
electron spins in quantum dots or based on a superconducting nanocircuit.
During two-qubit operations, the fluctuation of the coupling parameters is a
critical factor. One source of such fluctuation is the stirring of the
background charges. We fo... | 0410060v1 |
2004-10-11 | Electron Correlations in a Quantum Dot with Bychkov-Rashba Coupling | We report on a theoretical approach developed to investigate the influence of
Bychkov-Rashba interaction on a few interacting electrons confined in a quantum
dot. We note that the spin-orbit coupling profoundly influences the energy
spectrum of interacting electrons in a quantum dot. Inter-electron interaction
causes l... | 0410248v1 |
2004-11-06 | Rectification in single molecular dimers with strong polaron effect | We study theoretically the transport properties of a molecular two level
system with large electron-vibron coupling in the Coulomb blockade regime. We
show that when the electron-vibron coupling induces polaron states, the
current-voltage characteristic becomes strongly asymmetric because, in one
current direction, one... | 0411173v2 |
2004-11-10 | Maxwell Equation for the Coupled Spin-Charge Wave Propagation | We show that the dissipationless spin current in the ground state of the
Rashba model gives rise to a reactive coupling between the spin and charge
propagation, which is formally identical to the coupling between the electric
and the magnetic fields in the 2+1 dimensional Maxwell equation. This analogy
leads to a remar... | 0411276v1 |
2004-12-16 | Magnetoelastic Coupling in the Spin-Dimer System TlCuCl$_3$ | We present high-resolution measurements of the thermal expansion and the
magnetostriction of TlCuCl$_{3}$ which shows field-induced antiferromagnetic
order. We find pronounced anomalies in the field and temperature dependence of
different directions of the lattice signaling a large magnetoelastic coupling.
The phase bo... | 0412451v1 |
2005-01-25 | Time evolution and decoherence of entangled states realized in coupled superconducting flux qubits | We study theoretically how decoherence affects superposition states composed
of entangled states in inductively coupled two superconducting flux-qubits. We
discover that the quantum fluctuation of an observable in a coupled flux-qubit
system plays a crucial role in decoherence when the expectation value of the
observab... | 0501581v2 |
2005-02-09 | Bridge-mediated Donor-Acceptor Effective Coupling: Exact theoretical description | An exact expression of the bridge-mediated donor-acceptor effective coupling,
is derived. For systems represented by a tight-binding Hamiltonian with
nearest-neighbor interactions, we show that the effective coupling, is equal to
the product over all square of nearest-neighbor couplings divided by an
appropriate produc... | 0502242v1 |
2005-03-09 | Theoretical Study of Fano Resonance in Single-Walled Carbon Nanotubes | Electrical transport through single-walled carbon nanotubes (SWNTs) is
investigated by using the nearest-neighbor tight-binding model coupled with two
electron reservoirs. When the SWNT-electrode coupling is not axially symmetric,
asymmetric resonance peaks are found in the conductance and are considered to
be due to t... | 0503200v1 |
2005-03-16 | Exciton-optical-phonon coupling: comparison with experiments for ZnO quantum wells | The temperature-dependent linewidths of excitons in ZnO quantum wells were
studied by measuring absorption spectra from 5 K to room temperature. We
deduced experimentally the exciton-longitudinal-optical (LO) phonon coupling
strength, which showed reduction of coupling with decrease in well width. This
reduction was ex... | 0503386v1 |
2005-04-22 | Rashba interaction in quantum wires with in-plane magnetic fields | We analyze the spectral and transport properties of ballistic quasi
one-dimensional systems in the presence of spin-orbit coupling and in-plane
agnetic fields. Our results demonstrate that Rashba precession and intersubband
coupling must be treated on equal footing for wavevectors near the magnetic
field induced gaps. ... | 0504578v2 |
2005-05-27 | Charge fluctuations in coupled systems: ring coupled to a wire or ring | Coupled systems in mesoscopic regime are of interest as charge fluctuation
between the sub-systems will depend on electron-electron interactions and will
play a dominant role in determining their thermodynamic properties. We study
some simple systems like a stub or a bubble strongly coupled to a ring. We show
that for ... | 0505672v2 |
2005-06-30 | Magnon transport and spin current switching through quantum dots | We study the nonequilibrium spin current through a quantum dot consisting of
two localized spin-1/2 coupled to two ferromagnetic insulators. The influence
of an intra-dot magnetic field and exchange coupling, different dot-reservoir
coupling configurations, and the influence of magnon chemical potential
differences vs.... | 0506806v1 |
2005-07-24 | A framework for public-channel cryptography using chaotic lasers | Two mutually coupled chaotic diode lasers with individual external feedback,
are shown to establish chaos synchronization in the low-frequency fluctuations
regime. A third laser with identical external feedback but coupled
unidirectionally to one of the pair does not synchronize. Both experiments and
simulations reveal... | 0507554v1 |
2005-07-29 | Quasiclassical frustration | We study the dissipative properties of a harmonic oscillator subject to two
independent heat baths, one of which couples to its position and the other one
to its momentum. This model describes a large spin impurity in a ferromagnet.
We find that some effects of the two heat baths partially cancel each other.
Most notab... | 0507726v1 |
2005-08-02 | Interaction of a surface acoustic wave with a two-dimensional electron gas | When a surface acoustic wave propagates on the surface of a GaAs
semiconductor, coupling between electrons in the two-dimensional electron gas
beneath the interface and the elastic host crystal through piezoelectric
interaction will attenuate the SAW. The coupling coefficient is calculated for
the SAW propagating along... | 0508065v1 |
2005-09-28 | About low field memory and negative magnetization in semiconductors and polymers | Ginzburg-Landau bulk magnetization of itinerant electrons can provide a
negative effective field in the Weiss model by coupling to localized magnetic
moments. The coupling enforces remnant magnetization, which can be negative or
positive depending on the sample magnetic history. Stable magnetic
susceptibility of couple... | 0509712v1 |
2005-09-30 | Parametric coupling for superconducting qubits | We propose a scheme to couple two superconducting charge or flux qubits
biased at their symmetry points with unequal energy splittings. Modulating the
coupling constant between two qubits at the sum or difference of their two
frequencies allows to bring them into resonance in the rotating frame.
Switching on and off th... | 0509799v2 |
2005-10-03 | Electron-vibron coupling in suspended nanotubes | We consider the electron-vibron coupling in suspended nanotube quantum dots.
Modelling the tube as an elastic medium, we study the possible coupling
mechanism for exciting the stretching mode in a single-electron-transistor
setup. Both the forces due to the longitudinal and the transverse fields are
included. The effec... | 0510044v1 |
2005-10-03 | Spin relaxation in quantum dots with random spin-orbit coupling | We investigate the longitudinal spin relaxation arising due to spin-flip
transitions accompanied by phonon emission in quantum dots where the strength
of the Rashba spin-orbit coupling is a random function of the lateral
(in-plane) coordinate on the spatial nanoscale. In this case the Rashba
contribution to the spin-or... | 0510050v1 |
2005-10-05 | Multibranch Bogoliubov-Bloch spectrum of a cigar shaped Bose condensate in an optical lattice | We study properties of excited states of an array of weakly coupled
quasi-two-dimensional Bose condensates by using the hydrodynamic theory. The
spectrum of the axial excited states strongly depends on the coupling among the
various discrete radial modes in a given symmetry. By including mode-coupling
within a given sy... | 0510096v1 |
2005-12-08 | The universality of synchrony: critical behavior in a discrete model of stochastic phase coupled oscillators | We present the simplest discrete model to date that leads to synchronization
of stochastic phase-coupled oscillators. In the mean field limit, the model
exhibits a Hopf bifurcation and global oscillatory behavior as coupling crosses
a critical value. When coupling between units is strictly local, the model
undergoes a ... | 0512171v1 |
2005-12-29 | Theory of phonon-induced spin relaxation in laterally coupled quantum dots | Phonon-induced spin relaxation in coupled lateral quantum dots in the
presence of spin-orbit coupling is calculated. The calculation for single dots
is consistent with experiment. Spin relaxation in double dots at useful
interdot couplings is dominated by spin hot spots that are strongly
anisotropic. Spin hot spots are... | 0512713v2 |
2006-02-14 | Collective dynamics in coupled maps on a lattice with quenched disorder | It is investigated how a spatial quenched disorder modifies the dynamics of
coupled map lattices. The disorder is introduced via the presence or absence of
coupling terms among lattice sites. Two nonlinear maps have been considered
embodying two paradigmatic dynamics. The Miller and Huse map can be associated
with an I... | 0602338v1 |
2006-03-09 | Generalized coupling in the Kuramoto model | We propose a modification of the Kuramoto model to account for the effective
change in the coupling constant among the oscillators, as suggested by some
experiments on Josephson junction, laser arrays and mechanical systems, where
the active elements are turned on one by one. The resulting model is
analytically tractab... | 0603241v1 |
2006-03-18 | Long-range spin-qubit interaction mediated by microcavity polaritons | We study the optically-induced coupling between spins mediated by polaritons
in a planar micro-cavity. In the strong coupling regime, the vacuum Rabi
splitting introduces anisotropies in the spin coupling. Moreover, due to their
photon-like mass, polaritons provide an extremely long spin coupling range.
This suggests t... | 0603472v1 |
2006-03-23 | Intense terahertz laser fields on a quantum dot with Rashba spin-orbit coupling | We investigate the effects of the intense terahertz laser field and the
spin-orbit coupling on single electron spin in a quantum dot. The laser field
and the spin-orbit coupling can strongly affect the electron density of states
and can excite a magnetic moment.
The direction of the magnetic moment depends on the sym... | 0603614v2 |
2006-03-27 | Quantum Hall droplets in coupled lateral quantum dots | We present a theory and Coulomb and Spin Blockade spectroscopy experiments on
quantum Hall droplets with controlled electron numbers (N1,N2) in laterally
coupled gated quantum dots. The theory is based on the configuration
interaction method (CI) coupled with the unrestricted Hartree-Fock (URHF)
basis. It allows us to ... | 0603723v1 |
2006-05-04 | Sparse repulsive coupling enhances synchronization in complex networks | Through the last years, different strategies to enhance synchronization in
complex networks have been proposed. In this Letter, we show that the
synchronization in a small-world network of attractively coupled non-identical
neurons is strongly improved by adding a tiny fraction of phase-repulsive
couplings. By a purely... | 0605115v1 |
2006-05-19 | Switchable resonant coupling of flux qubits | We propose a coupling scheme, where two or more flux qubits with different
eigenfrequencies share Josephson junctions with a coupler loop devoid of its
own quantum dynamics. Switchable two-qubit coupling is realized by tuning the
frequency of the AC magnetic flux through the coupler to a combination
frequency of two of... | 0605484v3 |
2006-06-07 | An Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System | Spin-orbit coupled systems generally break the spin rotation symmetry.
However, for a model with equal Rashba and Dresselhauss coupling constant (the
ReD model), and for the $[110]$ Dresselhauss model, a new type of SU(2) spin
rotation symmetry is discovered. This symmetry is robust against
spin-independent disorder an... | 0606196v1 |
2006-07-22 | Exchange interaction and stability diagram of coupled quantum dots in magnetic fields | The charge stability diagram for two coupled quantum dots containing up to
two electrons is computed in magnetic fields. One- and two-particle
Schroedinger equations are solved by exact diagonalization to obtain the
chemical potentials and exchange energy in these systems. By analyzing the
chemical potentials variation... | 0607571v1 |
2006-07-26 | Inelastic effects in Aharonov-Bohm molecular interferometer | Inelastic effects arising from electron-phonon coupling in molecular
Aharonov-Bohm (AB) interferometers are studied using the nonequilibrium Green's
function method. Results for the magnetoconductance are compared for different
values of the electron-phonon coupling strength. At low bias voltages, the
coupling to the p... | 0607686v1 |
2006-08-01 | Coherent magnetotransport spectroscopy in an edge-blocked double quantum wire with window and resonator coupling | We propose an electronic double quantum wire system that contains a pair of
edge blocking potential and a coupling element in the middle barrier between
two ballistic quantum wires. A window and a resonator coupling control between
the parallel wires are discussed and compared for the enhancement of the
interwire trans... | 0608027v1 |
2006-09-25 | Spectroscopy of three strongly coupled flux qubits | We have carried out spectroscopic measurements of a system of three strongly
coupled four-junction flux qubits. The samples studied cover a wide range of
parameters with the coupling energy between neighboring qubits varying between
0.75 GHz and 6.05 GHz. The observed complicated spectra agree well with
eight-level the... | 0609627v1 |
2006-12-19 | Effect of spin-orbit coupling on the excitation spectrum of Andreev billiards | We consider the effect of spin-orbit coupling on the low energy excitation
spectrum of an Andreev billiard (a quantum dot weakly coupled to a
superconductor), using a dynamical numerical model (the spin Andreev map).
Three effects of spin-orbit coupling are obtained in our simulations: In zero
magnetic field: (1) the n... | 0612501v1 |
2007-01-20 | Stability of longitudinal coupling for Josephson charge qubits | For inductively coupled superconducting quantum bits, we determine the
conditions when the coupling commutes with the single-qubit terms. We show that
in certain parameter regimes such longitudinal coupling can be stabilized with
respect to variations of the circuit parameters. In addition, we analyze its
stability aga... | 0701499v2 |
2007-01-25 | Spin-Hall effect and spin-coherent excitations in a strongly confined two-dimensional hole gas | Based on a rigorous quantum-kinetic approach, spin-charge coupled
drift-diffusion equations are derived for a strongly confined two-dimensional
hole gas. An electric field leads to a coupling between the spin and charge
degrees of freedom. For weak spin-orbit interaction, this coupling gives rise
to the intrinsic spin-... | 0701612v1 |
2007-03-30 | Sensitivity of Global Dynamics on the microscopic details of a network of dynamically coupled maps | Here we analyze the behavior of dynamically coupled maps, based on those
introduced in a series of papers by Ito and Kaneko (Phys. Rev. Lett. 88:028701,
2002 and Phys. Rev. E 67:046226, 2003). We show how the microscopic coupling
mechanism changes the behavior of the system both by affecting the stability of
fixed poin... | 0703804v1 |
2005-12-23 | Low-Energy Sensor Network Time Synchronization as an Emergent Property | The primary contribution of this work is to examine the energy efficiency of
pulse coupled oscillation for time synchronization in a realistic wireless
network environment and to explore the impact of mobility on convergence rate.
Energy coupled oscillation is susceptible to interference; this approach uses
reception a... | 0512094v1 |
1994-10-17 | The Dipole Coupling of Atoms and Light in Gravitational Fields | The dipole coupling term between a system of N particles with total charge
zero and the electromagnetic field is derived in the presence of a weak
gravitational field. It is shown that the form of the coupling remains the same
as in flat space-time if it is written with respect to the proper time of the
observer and to... | 9410019v1 |
1996-01-15 | New no-scalar-hair theorem for black-holes | A new no-hair theorem is formulated which rules out a very large class of
non-minimally coupled finite scalar dressing of an asymptotically flat, static,
and spherically symmetric black-hole. The proof is very simple and based in a
covariant method for generating solutions for non-minimally coupled scalar
fields starti... | 9601021v1 |
1998-11-03 | On the non-minimal coupling of Riemann-flat Klein-Gordon | On the non-minimal coupling of Riemann-flat Klein-Gordon Fields to Space-time
torsion} The energy spectrum of Klein-Gordon particles is obtained via the
non-minimal coupling of Klein-Gordon fields to Cartan torsion in the
approximation of Riemann-flatness and constant torsion.When the mass squared is
proportional to to... | 9811010v1 |
2001-07-31 | A note on wavemap-tensor cosmologies | We examine theories of gravity which include finitely many coupled scalar
fields with arbitrary couplings to the curvature (wavemaps). We show that the
most general scalar-tensor $\sigma$-model action is conformally equivalent to
general relativity with a minimally coupled wavemap with a particular target
metric. Infla... | 0107100v1 |
2002-02-02 | Nonminimal coupling, equivalence principle and exact Foldy-Wouthuysen transformation | It is shown that the exact Foldy-Wouthuysen transformation for spin-0
particles on spacetimes described by the metrics $ds^2 = V^2 dt^2 - W^2 d
{\bf{x}}^2$, where $V=V({\bf{x}})$ and $W=W({\bf{x}})$, only exists if the
scalar field is nonminimally coupled to the Ricci scalar field with a coupling
constant equal to 1/6.... | 0202006v1 |
2002-09-22 | Modification of the Doppler Effect due to the Helicity-Rotation Coupling | The helicity-rotation coupling and its current empirical basis are examined.
The modification of the Doppler effect due to the coupling of photon spin with
the rotation of the observer is considered in detail in connection with its
applications in the Doppler tracking of spacecraft. Further implications of
this couplin... | 0209079v2 |
2003-04-01 | Dirac spinor fields in the teleparallel gravity: comment on "Metric-affine approach to teleparallel gravity" | We show that the coupling of a Dirac spinor field with the gravitational
field in the teleparallel equivalent of general relativity is consistent. For
an arbitrary SO(3,1) connection there are two possibilities for the coupling of
the spinor field with the gravitational field. The problems of consistency
raised by Y. N... | 0304005v1 |
2003-06-05 | Constraints on non-minimally coupled curved space electrodynamics from astrophysical observations | We study interactions of electro-magnetic fields with the curvature tensor of
the form $\lambda R_{\mu \nu \alpha \beta}F^{\mu \nu}F^{\alpha \beta}$. Such
coupling terms though are invariant under general coordinate transformation and
CPT, however violate the Einstein equivalence principle. These couplings do not
cause... | 0306021v1 |
2004-04-17 | Coupled oscillators as models of phantom and scalar field cosmologies | We study a toy model for phantom cosmology recently introduced in the
literature and consisting of two oscillators, one of which carries negative
kinetic energy. The results are compared with the exact phase space picture
obtained for similar dynamical systems describing, respectively, a massive
canonical scalar field ... | 0404078v1 |
2004-09-03 | Asymptotic quasinormal modes of a coupled scalar field in the Garfinkle-Horowitz-Strominger dilaton spacetime | The analytic forms of the asymptotic quasinormal frequencies of a coupled
scalar field in the Garfinkle-Horowitz-Strominger dilaton spacetime is
investigated by using the monodromy technique proposed by Motl and Neitzke. It
is found that the asymptotic quasinormal frequencies depend not only on the
structure parameters... | 0409013v1 |
2005-03-19 | Metric-scalar gravity with torsion and the measurability of the non-minimal coupling | The "measurability" of the non-minimal coupling is discussed by considering
the correction to the Newtonian static potential in the semi-classical
approach. The coefficient of the "gravitational Darwin term" (GDT) gets
redefined by the non-minimal torsion-scalar couplings. Based on a similar
analysis of the GDT in the ... | 0503084v3 |
2005-09-02 | Nonmetricity and torsion induced by dilaton gravity in two dimension | We develop a theory in which there are couplings amongst Dirac spinor,
dilaton and non-Riemannian gravity and explore the nature of connection-induced
dilaton couplings to gravity and Dirac spinor when the theory is reformulated
in terms of the Levi-Civita connection. After presenting some exact solutions
without spino... | 0509010v3 |
1999-03-30 | Scalar and Tensor Couplings in Kaon Decays | In the past few years charged kaon experiments have indicated possible scalar
and tensor couplings in semileptonic kaon decays(K --> pi e nu). These
couplings, if correct, are not predicted by the Standard Model and may indicate
the onset of new physics. We present a summary of the existing data and a new,
precision me... | 9903069v2 |
1999-10-02 | Measurement of Triple-Gauge-Boson Couplings of the W Boson at LEP | We report on measurements of the triple-gauge-boson couplings of the W boson
in e+e- collisions with the L3 detector at LEP. W-pair, single-W and
single-photon events are analysed in a data sample corresponding to a total
luminosity of 76.7 pb^{-1} collected at centre-of-mass energies between 161 GeV
and 183 GeV. CP-co... | 9910008v1 |
2002-01-23 | Anomalous couplings at LEP2 | In its second phase, LEP has allowed to study four fermion processes never
observed before. Results are presented on the charged triple gauge boson
couplings (TGC) from the W-pair, Single W and Single gamma production. The
anomalous quartic gauge couplings (QGC) are constrained using production of
WWgamma, nunubargamma... | 0201035v1 |
2004-10-05 | Measurement of triple gauge boson couplings a an e-gamma collider | If no light Higgs boson exists, the interaction among the gauge bosons
becomes strong at high energies (~1TeV). The effects of strong electroweak
symmetry breaking (SEWSB) could manifest themselves indirectly as anomalous
couplings before they give rise to new physical states like resonances. Here a
study of the measur... | 0410011v2 |
2005-06-22 | Boson Gauge Couplings at LEP | The review of the measurements of the gauge couplings in the boson sector at
LEP is presented. The measurements of the charged triple gauge couplings (cTGC)
parameters from the four LEP experiments are combined and the results are in
good agreement with the Standard Model predictions, proving the non-abelian
structure ... | 0506048v1 |
2005-07-11 | Trilinear Gauge Couplings from gamma/gamma to WW | If there is no the Standard Model Higgs boson, the interaction among the
gauge bosons becomes strong at high energies (~ 1TeV). The effects of strong
electroweak symmetry breaking could manifest themselves indirectly through the
vertices as anomalous gauge boson couplings before they give rise to new
physical states li... | 0507050v1 |
1992-06-01 | Renormalization group and triviality in noncompact lattice QED with light fermions | In the framework of noncompact lattice QED with light fermions, we derive the
functional dependence of the average energy per plaquette on the bare
parameters using block-spin Renormalization Group arguments and assuming that
the renormalized coupling vanishes. Our numerical results for this quantity in
$8^4$ and $10^4... | 9205030v1 |
1992-07-18 | Fermion Interactions in the Wilson Yukawa Approach for Lattice Chiral Gauge Theories | We consider fermion-gauge couplings in the Wilson-Yukawa approach for lattice
chiral gauge theories. At the leading order of a fermionic hopping parameter
expansion we find that the fermion-gauge coupling has a chiral and tree-like
structure. We argue that this fermion-gauge coupling remains non-zero in the
continuum l... | 9207018v1 |
1992-11-26 | No strong coupling regime in the fermion-Higgs sector of the standard model | We present results for the renormalized quartic self-coupling $\lm_R$ and the
renormalized Yukawa coupling $y_R$ in a fermion-Higgs model with two SU(2)
doublets, indicating that these couplings are not very strong. | 9211061v1 |
1993-09-13 | A Precise Determination of the Running Coupling in the SU(3) Yang-Mills Theory | A non-perturbative finite-size scaling technique is used to study the
evolution of the running coupling (in a certain adapted scheme) in the SU(3)
Yang-Mills theory. At low energies contact is made with the fundamental
dynamical scales, such as the string tension K, while at larger energies the
coupling is shown to evo... | 9309005v1 |
1994-11-15 | Do Wilson Fermions Induce an Adjoint Gauge Coupling? | Expansions of the Wilson determinant in lattice QCD with quarks produce gauge
action terms which shift the coupling constant of the fundamental
representation plaquette action and induce an adjoint representation plaquette
action. We study the magnitude of these induced couplings with two flavors of
Wilson fermions. We... | 9411025v1 |
1994-11-30 | The SU(3) running coupling from lattice gluons | We provide numerical results for the running coupling in $SU(3)$ Yang-Mills
theory as determined from an analysis of lattice two and three-point gluon
correlation functions. The coupling is evaluated directly, from first
principles, by defining suitable renormalisation constants from the lattice
triple gluon vertex and... | 9411085v1 |
1994-12-16 | Numerical Simulations of an SU(2)_L x SU(2)_R-symmetric Higgs-Yukawa Model on the QUADRICS Q16 | We report on our work on the SU(2)_L x SU(2)_R symmetric Higgs Yukawa Model
with mirror fermion action. Our model describes a fermion Higgs system in the
limit of vanishing gauge coupling. Setting the bare Yukawa coupling of the
mirror fermions G_\chi to zero, we want to determine the triviality bounds on
the renormali... | 9412082v1 |
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