publicationDate stringlengths 1 2.79k | title stringlengths 1 36.5k ⌀ | abstract stringlengths 1 37.3k ⌀ | id stringlengths 9 47 |
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2005-05-03 | A coupled-channel analysis of $KΛ$ production in the nucleon resonance region | A unitary coupled-channel effective Lagrangian model is applied to the
combined analysis of the $(\pi,\gamma) N \to K\Lambda$ reactions in the energy
region up to 2 GeV. To constrain the resonance couplings to the $K\Lambda$
final state the recent photoproduction data obtained by the SAPHIR, SPring-8,
and CLAS groups a... | 0505010v1 |
2005-09-29 | Parity violation in $pp$ scattering and vector-meson weak-coupling constants | We calculate the parity-nonconserving longitudinal asymmetry in the elastic
$\vec{p} p$ scattering at the energies where experimental data are available.
In addition to the standard one-meson exchange weak potential, the variation of
the strong-coupling constants and the non-standard effects such as form factors
and $2... | 0509090v1 |
2005-10-28 | Comparison between two methods of solution of coupled equations for low-energy scattering | Cross sections from low-energy neutron-nucleus scattering have been evaluated
using a coupled channel theory of scattering. Both a coordinate-space and a
momentum-space formalism of that coupled-channel theory are considered.A simple
rotational model of the channel interaction potentials is used to find results
using t... | 0510085v1 |
2006-03-23 | The nucleon-sigma coupling constant in QCD Sum Rules | The external-field QCD Sum Rules method is used to evaluate the coupling
constant of the light isoscalar-scalar meson (``$\sigma$'' or \epsilon) to the
nucleon. The contributions that come from the excited nucleon states and the
response of the continuum threshold to the external field are calculated. The
obtained valu... | 0603056v1 |
2006-05-24 | Covariant theory of particle-vibrational coupling and its effect on the single-particle spectrum | The Relativistic Mean Field (RMF) approach describing the motion of
independent particles in effective meson fields is extended by a microscopic
theory of particle vibrational coupling. It leads to an energy dependence of
the relativistic mass operator in the Dyson equation for the single-particle
propagator. This equa... | 0605060v1 |
2006-11-29 | On the sign of the pi-rho-omega coupling constant | It is shown that the relative sign between the $NN\omega$ and $\pi\rho\omega$
coupling constants can be determined most sensitively from $\omega$ production
processes in $NN$ collisions. Recent data on these reactions clearly favor the
sign of the $\pi\rho\omega$ coupling constant which is opposite to that
inferred fro... | 0611101v2 |
2007-01-24 | The Unitary Clothing Transformation Method in Quantum Field Theory. Renormalization of Coupling Constant | Applying the unitary clothing transformation method in the model of charged
spinless nucleons and neutral mesons interacting via the three-linear
Yukawa-type coupling, the expression for the charge shift in the third order in
the coupling constant is derived. Being determined off the energy shell, the
ex-pression can b... | 0701071v1 |
2007-03-13 | Relativistic mean-field model with density-dependent meson-nucleon couplings | Within the relativistic mean-field approach, we extend the Miyazaki model,
where the NN$\sigma$ and NN$\omega$ interactions are modified to suppress the
couplings between positive- and negative-energy states of a nucleon in matter.
Assuming appropriate density-dependence of the meson-nucleon couplings, we
study nuclear... | 0703039v1 |
1995-11-07 | Existence and Stability of Steady Fronts in Bistable CML | We prove the existence and we study the stability of the kink-like fixed
points in a simple Coupled Map Lattice for which the local dynamics has two
stable fixed points. The condition for the existence allows us to define a
critical value of the coupling parameter where a (multi) generalized
saddle-node bifurcation occ... | 9511001v1 |
1998-09-01 | Tunable Pinning of Burst-Waves in Extended Systems with Discrete Sources | We study the dynamics of waves in a system of diffusively coupled discrete
nonlinear sources. We show that the system exhibits burst waves which are
periodic in a traveling-wave reference frame. We demonstrate that the burst
waves are pinned if the diffusive coupling is below a critical value. When the
coupling crosses... | 9809002v1 |
1999-09-21 | All Optical Flip-Flop Based on Coupled Laser Diodes | An all optical set-reset flip flop is presented that is based on two coupled
identical laser diodes. The lasers are coupled so that when one of the lasers
lases it quenches lasing in the other laser. The state of the flip flop is
determined by which laser is currently lasing. Rate equations are used to model
the flip f... | 9909039v1 |
2000-09-17 | Convergence improvement for coupled cluster calculations | Convergence problems in coupled-cluster iterations are discussed, and a new
iteration scheme is proposed. Whereas the Jacobi method inverts only the
diagonal part of the large matrix of equation coefficients, we invert a matrix
which also includes a relatively small number of off-diagonal coefficients,
selected accordi... | 0009060v1 |
2001-03-26 | Instability of Shear Waves in an Inhomogeneous Strongly Coupled Dusty Plasma | It is demonstrated that low frequency shear modes in a strongly coupled,
inhomogeneous, dusty plasma can grow on account of an instability involving the
dynamical charge fluctuations of the dust grains. The instability is driven by
the gradient of the equilibrium dust charge density and is associated with the
finite ch... | 0103081v1 |
2001-04-20 | Synchronization and multi-mode dynamics of mutually coupled semiconductor lasers | Dynamics of coupled semiconductor lasers is investigated by numerical
simulations. A realistic laser simulation engine is used to study the
synchronization and dynamical regime in two mutually coupled Fabry-Perot and/or
DFB lasers. Both, single- and multi-mode operation regimes are studied with
emphasis on the role of ... | 0104060v1 |
2002-10-07 | Frictional coupling between sliding and spinning motion | We show that the friction force and torque, acting at a dry contact of two
objects moving and rotating relative to each other, are inherently coupled. As
a simple test system, a sliding and spinning disk on a horizontal flat surface
is considered. We calculate, and also measure, how the disk is slowing down,
and find t... | 0210024v1 |
2002-12-19 | Robustness and Enhancement of Neural Synchronization by Activity-Dependent Coupling | We study the synchronization of two model neurons coupled through a synapse
having an activity-dependent strength. Our synapse follows the rules of
Spike-Timing Dependent Plasticity (STDP). We show that this plasticity of the
coupling between neurons produces enlarged frequency locking zones and results
in synchronizat... | 0212070v1 |
2003-03-13 | Interchannel coupling effects in the spin polarization of energetic photoelectrons | Effects of the interchannel coupling on the spin polarization of energetic
photoelectrons emitted from atomic Ne valence subshells are examined. Like
previously obtained results for cross sections and angular distributions, the
photoelectron spin polarization parameters too are found considerably
influenced by the coup... | 0303056v1 |
2003-05-13 | Generalization of the coupled dipole method to periodic structures | We present a generalization of the coupled dipole method to the scattering of
light by arbitrary periodic structures. This new formulation of the coupled
dipole method relies on the same direct-space discretization scheme that is
widely used to study the scattering of light by finite objects. Therefore, all
the knowled... | 0305051v1 |
2003-11-03 | Efficient input and output fiber coupling to a photonic crystal waveguide | The efficiency of evanescent coupling between a silica optical fiber taper
and a silicon photonic crystal waveguide is studied. A high reflectivity mirror
on the end of the photonic crystal waveguide is used to recollect, in the
backwards propagating fiber mode, the optical power that is initially coupled
into the phot... | 0311006v1 |
2004-03-04 | Phase Synchronization and Polarization Ordering of Globally-Coupled Oscillators | We introduce a prototype model for globally-coupled oscillators in which each
element is given an oscillation frequency and a preferential oscillation
direction (polarization), both randomly distributed. We found two collective
transitions: to phase synchronization and to polarization ordering. Introducing
a global-pha... | 0403038v2 |
2004-03-25 | Inference of stochastic nonlinear oscillators with applications to physiological problems | A new method of inferencing of coupled stochastic nonlinear oscillators is
described. The technique does not require extensive global optimization,
provides optimal compensation for noise-induced errors and is robust in a broad
range of dynamical models. We illustrate the main ideas of the technique by
inferencing a mo... | 0403121v1 |
2004-04-04 | Spin-orbit coupling and magnetic spin states in cylindrical quantum dots | We make detailed analysis of each possible spin-orbit coupling of zincblende
narrow-gap cylindrical quantum dots built in two-dimensional electron gas.
These couplings are related to both bulk (Dresselhaus) and structure (Rashba)
inversion asymmetries. We study the competition between electron-electron and
spin-orbit i... | 0404017v1 |
2004-05-13 | Analytical expressions for special cases of LS-jj transformation matrices for a shell of equivalent electrons | Transformation matrices of the weights of the atomic wave functions in jj
coupling to the relevant weights of LS coupling are considered for a shell of
equivalent electrons. Their use allows one to preserve main part of
relativistic effects but to classify the energy levels of an atom or an ion
considered with the help... | 0405060v1 |
2004-07-19 | Polarization control and sensing with two-dimensional coupled photonic crystal microcavity arrays | We have experimentally studied polarization properties of the two-dimensional
coupled photonic crystal microcavity arrays, and observed a strong polarization
dependence of the transmission and reflection of light from the structures -
the effects that can be employed in building miniaturized polarizing optical
componen... | 0407103v2 |
2004-12-31 | Enhanced diffraction by a rectangular grating made of a negative phase--velocity (or negative index) material | The diffraction of electromagnetic plane waves by a rectangular grating
formed by discrete steps in the interface of a homogeneous, isotropic, linear,
negative phase--velocity (negative index) material with free space is studied
using the semi--analytic C method. When a nonspecular diffracted order is of
the propagatin... | 0501001v1 |
2005-05-03 | Quantum Solution to Scalar Field Theory Models | Amplitudes $A_n$ in $d$-dimensional scalar field theory are generated, to all
orders in the coupling constant and at $n$-point. The amplitudes are expressed
as a series in the mass $m$ and coupling $\lambda$. The inputs are the
classical scattering, and these generate, after the integrals are performed,
the series expa... | 0505018v3 |
2005-09-22 | Highly charged ions in a weakly coupled plasma: an exact solution | The ion sphere model introduced long ago by Salpeter is placed in a rigorous
theoretical setting. The leading corrections to this model for very highly
charged but dilute ions in thermal equilibrium with a weakly coupled,
one-component background plasma are explicitly computed, and the subleading
corrections are shown ... | 0509191v1 |
2006-01-19 | Convergent close-coupling calculations of two-photon double ionization of helium | We apply the convergent close-coupling (CCC) formalism to the problem of
two-photon double ionization of helium. The electron-photon interaction is
treated perturbatively whereas the electron-electron interaction is included in
full. The integrated two-photon double ionization cross-section is
substantially below non-p... | 0601137v1 |
2006-02-14 | Nonlinear interaction between three kinetic Alfvén waves | Using Hall-MHD theory, we focus on the resonant interaction between three
kinetic Alfv\'{e}n waves. We thus derive three coupled equations which govern
this process. It turns out that these equations contain the same coupling
coefficient, directly showing that they satisfy the Manley-Rowe relations. The
coupling coeffi... | 0602090v1 |
2006-03-16 | On the Possibility of Large Upconversions and Mode Coupling between Frohlich States and Visible Photons in Biological Systems | At least two significant roles for large scale quantum coherence in living
systems have been suggested: Herbert Fr\"{o}hlich's coherent excitations of
nonlinearly coupled ensembles of large polarizable molecules, with frequencies
in the microwave region, and Fritz Popp's coherent visible photon emission
arising from me... | 0603137v1 |
2006-06-22 | Polarization rotation enhancement by high-order waveguide mode coupling in magnetophotonic crystals | Inter-modal coupling in photonic bandgap optical channels in magnetic films
is used to leverage the transverse-electric (TE) to transverse-magnetic (TM)
mode conversion due to the Faraday Effect. The underlying mechanism is traced
to the dependence of the grating coupling-constant on the modal refractive
index and the ... | 0606200v1 |
2006-10-13 | Efficient Photonic Crystal Cavity-Waveguide Couplers | Coupling of photonic crystal (PC) linear three-hole defect cavities (L3) to
PC waveguides is theoretically and experimentally investigated. The systems are
designed to increase the overlap between the evanescent cavity field and the
waveguide mode, and to operate in the linear dispersion region of the
waveguide. Our si... | 0610105v1 |
2006-11-14 | Optical fiber taper coupling and high-resolution wavelength tuning of microdisk resonators at cryogenic temperatures | A system for studying microcavity resonators at cryogenic temperatures (~10
K) through evanescent coupling via optical fiber taper waveguides is reported,
and efficient fiber coupling to AlGaAs microdisk cavities with embedded quantum
dots is demonstrated. As an immediate application of this tool, we study
high-resolut... | 0611127v1 |
2006-12-19 | Electron-impact ionization of the metastable excited states of Li+ | Electron-impact ionization cross sections for the 1s2s 1S and 1s2s 3S
metastable states of Li+ are calculated using both perturbative distorted-wave
and non-perturbative close-coupling methods. Term-resolved distorted-wave
calculations are found to be approximately 15% above term-resolved R-matrix
with pseudostates cal... | 0612188v1 |
2007-01-11 | Differentiation of functionals with variables coupled by constraints: Analysis through a fluid-dynamical model | Analysing an application in liquid film dynamics, a guide for obtaining the
corresponding constrained functional derivatives for constraints coupling the
functional variables is given. The use of constrained derivatives makes the
proper account for constraints possible in time-dependent, nonequilibrium
physical theorie... | 0701145v2 |
2004-04-19 | Pulse-coupled resonate-and-fire models | We analyze two pulse-coupled resonate-and-fire neurons. Numerical simulation
reveals that an anti-phase state is an attractor of this model. We can
analytically explain the stability of anti-phase states by means of a return
map of firing times, which we propose in this paper. The resultant stability
condition turns ou... | 0404021v1 |
2004-09-09 | How to compute using globally coupled oscillators | Synchronization is known to play a vital role within many highly connected
neural systems such as the olfactory systems of fish and insects. In this paper
we show how one can robustly and effectively perform practical computations
using small perturbations to a very simple globally coupled network of coupled
oscillator... | 0409012v1 |
2007-01-09 | Elastic Correlations in Nucleosomal DNA Structure | The structure of DNA in the nucleosome core particle is studied using an
elastic model that incorporates anisotropy in the bending energetics and
twist-bend coupling. Using the experimentally determined structure of
nucleosomal DNA [T.J. Richmond and C.A. Davey, Nature {\bf 423}, 145 (2003)],
it is shown that elastic c... | 0701014v1 |
1995-03-13 | Relation between energy shifts and relaxation rates for a small system coupled to a reservoir | For a small system the coupling to a reservoir causes energy shifts as well
as transitions between the system's energy levels. We show for a general
stationary situation that the energy shifts can essentially be reduced to the
relaxation rates. The effects of reservoir fluctuations and self reaction are
treated separat... | 9503012v1 |
1995-11-13 | Coupling ``Classical'' and Quantum Variables | Experimentally, certain degrees of freedom may appear classical because their
quantum fluctuations are smaller than the experimental error associated with
measuring them. An approximation to a fully quantum theory is described in
which the self-interference of such ``quasiclassical'' variables is neglected
so that they... | 9511014v1 |
1996-09-28 | Convergence Behavior of Variational Perturbation Expansions | Variational weak-coupling perturbation theory yields converging
approximations, uniformly in the coupling strength. This allows us to calculate
directly the coefficients of `strong-coupling' expansions. For the anharmonic
oscillator we explain the physical origin of the empirically observed
convergence behavior which i... | 9609027v1 |
1997-01-21 | Coupled Q-oscillators as a model for vibrations of polyatomic molecules | The system of two $Q$-deformed oscillators coupled so that the total
Hamiltonian has the su$_Q$(2) symmetry is proved to be equivalent, to lowest
order approximation, to a system of two identical Morse oscillators coupled by
the cross-anharmonicity usually used empirically in describing vibrational
spectra of triatomic... | 9701025v1 |
1997-08-04 | Engineering two-mode interactions in ion traps | We describe how two vibrational degrees of freedom of a single trapped ion
can be coupled through the action of suitably-chosen laser excitation. We
concentrate on a two-dimensional ion trap with dissimilar vibrational
frequencies in the x- and y-directions of motion, and derive from first
principles a variety of quant... | 9708008v1 |
1998-01-30 | Quantum Langevin Equations and Stability | Different quantum Langevin equations obtained by coupling a particle to a
field are examined. Instabilities or violations of causality affect the motion
of a point charge linearly coupled to the electromagnetic field. In contrast,
coupling a scatterer with a reflection cut-off to radiation pressure leads to
stable and ... | 9801072v1 |
1998-08-11 | Dephasing of Josephson oscillations between two coupled Bose-Einstein condensates | We study the dynamics of the relative phase between two Bose-Einstein
condensates coupled via collisions and via a Josephson-like coupling. We derive
the equations of the motion for the relative phase and the relative number
operators from the second quantized Hamiltonian of the system using a quantum
field theoretical... | 9808017v1 |
1999-01-19 | Effective mass in quantum effects of radiation pressure | We study the quantum effects of radiation pressure in a high-finesse cavity
with a mirror coated on a mechanical resonator. We show that the optomechanical
coupling can be described by an effective susceptibility which takes into
account every acoustic modes of the resonator and their coupling to the light.
At low freq... | 9901057v2 |
1999-06-24 | The influence of density of modes on dark lines in spontaneous emission | We study two distinct multi-level atomic models in which one transition is
coupled to a Markovian reservoir, while another linked transition is coupled to
a non-Markovian reservoir. We show that by choosing appropriately the density
of modes of the non-Markovian reservoir the spontaneous emission to the
Markovian reser... | 9906093v2 |
1999-09-29 | Quantum systems coupled to a structured reservoir with multiple excitations | We present a method for dealing with quantum systems coupled to a structured
reservoir with any density of modes and with more than one excitation. We apply
the method to a two-level atom coupled to the edge of a photonic band gap and a
defect mode. Results pertaining to this system, provide the solution to the
problem... | 9909088v1 |
1999-12-06 | Strong coupling theory for driven tunneling and vibrational relaxation | We investigate on a unified basis tunneling and vibrational relaxation in
driven dissipative multistable systems described by their N lowest lying
unperturbed levels. By use of the discrete variable representation we derive a
set of coupled non-Markovian master equations. We present analytical treatments
that describe ... | 9912024v3 |
2000-09-08 | One- and two-dimensional N-qubit systems in capacitively coupled quantum dots | Coulomb blockade effects in capacitively coupled quantum dots can be utilized
for constructing an N-qubit system with antiferromagnetic Ising interactions.
Starting from the tunneling Hamiltonian, we theoretically show that the
Hamiltonian for a weakly coupled quantum-dot array is reduced to that for
nuclear magnetic r... | 0009030v3 |
2001-01-29 | Rotational invariance and the Pauli exclusion principle | In this article, the rotational invariance of entangled quantum states is
investigated as a possible cause of the Pauli exclusion principle. First, it is
shown that a certain class of rotationally invariant states can only occur in
pairs. This will be referred to as the coupling principle. This in turn
suggests a natur... | 0101135v1 |
2001-10-26 | Jahn-Teller Anharmonic Coupling for an Octahedral System | The coupling between doubly degenerate electronic states and doubly
degenerate vibrations is analysed for an octahedral system on the basis of the
introduction of an anharmonic Morse potential for the vibronic part. The
vibrations are described by anharmonic coherent states and their linear
coupling with the electronic... | 0110153v1 |
2001-11-29 | Conditional Spin Resonance with Trapped Ions | Internal states of different ions in an electrodynamic trap are coupled when
a static magnetic field is applied -- analogous to spin-spin coupling in
molecules used for NMR. This spin-spin interaction can be used, for example, to
implement quantum logic operations in ion traps using NMR methods. The
collection of trapp... | 0111158v1 |
2001-12-01 | Path integral for a pair of time-dependent coupled and driven oscillators | The propagator for a certain class of two time-dependent coupled and driven
harmonic oscillators with time-varying angular frequencies and masses is
evaluated by path integration. This is simply done through suitably chosen
generalized canonical transformations and without presupposing the knownledge
of any auxiliary e... | 0112003v1 |
2001-12-06 | The power of entangled quantum channels | All communication channels are at bottom quantum mechanical. Quantum
mechanics contributes both obstacles to communication in the form of noise, and
opportunities in the use of intrinsically quantum representations for
information. This paper investigates the trade-off between power and
communication rate for coupled q... | 0112034v1 |
2002-03-15 | Ergodic Properties of Local Spectral Density for a Conservative System of Coupled Quantum States | The shape and the inverse participation ratio (IPR) of local spectral density
(LSD) are studied for a generic isolated system of coupled quantum states, the
Hamiltonian of which is represented by a band random matrix with the disordered
leading diagonal. We find for the matrices with arbitrary small band that the
lack ... | 0203071v1 |
2002-03-29 | Quantum computation with coupled-quantum-dots embedded in optical microcavities | Based on an idea that spatial separation of charge states can enhance quantum
coherence, we propose a scheme for quantum computation with quantum bit (qubit)
constructed from two coupled quantum dots. Quantum information is stored in
electron-hole pair state with the electron and hole locating in different dots,
which ... | 0203145v1 |
2002-05-31 | Invitation to quantum dynamical semigroups | The theory of quantum dynamical semigroups within the mathematically rigorous
framework of completely positive dynamical maps is reviewed. First, the
axiomatic approach which deals with phenomenological constructions and general
mathematical structures is discussed. Then basic derivation schemes of the
constructive app... | 0205188v1 |
2002-09-11 | Decoherence in a spin--spin-bath model with environmental self-interaction | A low temperature model system consisting of a central spin coupled to a
spin-bath is studied to determine whether interaction among bath spins has an
effect on central spin dynamics. In the absence of intra-environmental
coupling, decoherence of the central spin is fast and irreversible. Strong
intra-environmental int... | 0209079v1 |
2002-10-02 | Cole-Hopf Like Transformation for a Class of Coupled Nonlinear Schroedinger Equations | In this paper we consider a class of coupled nonlinear Schroedinger equations
for the fields $\psi_i$ containing complex nonlinearities, that has been
obtained by requiring that the norms $|\psi_i|^2$ are conserved densities. For
this class of equations we introduce a Cole-Hopf like transformation, whose
effect is to r... | 0210016v1 |
2003-01-10 | NMR experimental realization of seventh-order coupling transformations and the seven-qubit modified Deutsch-Jozsa algorithm | We propose a scalable method on the basis of nth-order coupling operators to
construct f-dependent phase transformations in the n-qubit modified
Deutsch-Jozsa (D-J) quantum algorithm. The novel n-qubit entangling
transformations are easily implemented via J-couplings between neighboring
spins. The seven-qubit modified ... | 0301041v1 |
2003-03-12 | Exploring quantum dynamics in an open many-body system: Transition to superradiance | We study the dynamics of a complex open quantum many-body system. The
coupling to external degrees of freedom can be viewed as a coupling to a
radiation field, to continuum states or to a measuring apparatus. This
perturbation is treated in terms of an effective non-Hermitian Hamiltonian. The
influence of such coupling... | 0303078v1 |
2003-03-20 | Effective fiber-coupling of entangled photons for quantum communication | We report on theoretical and experimental demonstration of high-efficiency
coupling of two-photon entangled states produced in the nonlinear process of
spontaneous parametric down conversion into a single-mode fiber. We determine
constraints for the optimal coupling parameters. This result is crucial for
practical impl... | 0303126v1 |
2003-05-08 | Broadband Geodesic Pulses for Three Spin Systems: Time-Optimal Realization of Effective Trilinear Coupling Terms and Indirect SWAP Gates | Broadband implementations of time-optimal geodesic pulse elements are
introduced for the efficient creation of effective trilinear coupling terms for
spin systems consisting of three weakly coupled spins 1/2. Based on these pulse
elements, the time-optimal implementation of indirect SWAP operations is
demonstrated expe... | 0305041v1 |
2003-06-24 | Weak-Coupling-Like Time Evolution of Driven Four-Level Systems in the Strong-Coupling Regime | It is shown analytically that there exists a natural basis in terms of which
the nonperturbative time evolution of an important class of driven four-level
systems in the strong-coupling regime decouples and essentially reduces to the
corresponding time evolution in the weak-field regime, exhibiting simple Rabi
oscillat... | 0306165v1 |
2003-08-22 | Qubit Assisted Probing of Coherence Between States of a Macroscopic Apparatus | I present a general scheme through which the evidence of a superposition
involving distinct classical-like states of a macroscopic system can be probed.
The scheme relies on a qubit being coupled to a macroscopic harmonic oscillator
in such a way that it can be used to both prepare and probe a macroscopic
superposition... | 0308122v1 |
2003-09-17 | Perfect state transfer in quantum spin networks | We propose a class of qubit networks that admit perfect transfer of any
quantum state in a fixed period of time. Unlike many other schemes for quantum
computation and communication, these networks do not require qubit couplings to
be switched on and off. When restricted to N-qubit spin networks of identical
qubit coupl... | 0309131v2 |
2003-11-17 | Ultrafast deterministic generation of entanglement in a time-dependent asymmetric two-qubit-cavity system | We present an efficient scheme for the controlled generation of pure
two-qubit states possessing {\em any} desired degree of entanglement and a {\em
prescribed} symmetry in two cavity QED based systems, namely, cold trapped ions
and flying atoms. This is achieved via on-resonance ion/atom-cavity couplings
which are tim... | 0311111v1 |
2003-12-10 | Disentanglement by Dissipative Open System Dynamics | This paper investigates disentanglement as a result of evolution according to
a class of master equations which include dissipation and interparticle
interactions. Generalizing an earlier result of Di\'{o}si, the time taken for
complete disentanglement is calculated (i.e. for disentanglement from any other
system). The... | 0312099v1 |
2004-01-07 | Phase Transitions in Generalised Spin-Boson (Dicke) Models | We consider a class of generalised single mode Dicke Hamiltonians with
arbitrary boson coupling in the pseudo-spin $x$-$z$ plane. We find exact
solutions in the thermodynamic, large-spin limit as a function of the coupling
angle, which allows us to continuously move between the simple dephasing and
the original Dicke H... | 0401029v1 |
2004-02-18 | Preparation of pseudopure state in a cluster of dipolar-coupled spins with "unresolved" spectrum | A method of creating pseudopure spin states in large clusters of coupled
spins is described. It is based on filtering multiple-quantum coherence of the
highest order followed by a time-reversal period and partial saturation.
Experimental demonstration is presented for a cluster of six dipolar-coupled
proton spins of a ... | 0402132v1 |
2004-04-23 | An approximation to $δ'$ couplings on graphs | We discuss a general parametrization for vertices of quantum graphs and show,
in particular, how the $\delta'_s$ and $\delta'$ coupling at an $n$ edge vertex
can be approximated by means of $n+1$ couplings of the $\delta$ type provided
the latter are properly scaled. | 0404136v2 |
2004-05-04 | Decay rate and decoherence control in coupled dissipative cavities | We give a detailed account of the derivation of a master equation for two
coupled cavities in the presence of dissipation. The analytical solution is
presented and physical limits of interest are discussed. Firstly we show that
the decay rate of initial coherent states can be significantly modified if the
two cavities ... | 0405022v1 |
2004-05-08 | Effect of inter-subsystem couplings on the evolution of composite systems | The effect of inter-subsystem coupling on the adiabaticity of composite
systems and that of its subsystems is investigated. Similar to the adiabatic
evolution defined for pure states, non-transitional evolution for mixed states
is introduced; conditions for the non-transitional evolution are derived and
discussed. An e... | 0405040v2 |
2004-05-16 | Size effects in the electronic properties of finite arrays of exchange coupled quantum dots: A renormalization group approach | Transport properties of arrays of metallic quantum dots are governed by the
distance-dependent exchange coupling between the dots. It is shown that the
effective value of the exchange coupling, as measured by the charging energy
per dot, depends monotonically on the size of the array. The effect saturates
for hexagonal... | 0405088v1 |
2004-05-22 | Spatial weak-light solitons in an electro-magnetically induced nonlinear waveguide | We show that a weak probe light beam can form spatial solitons in an
electro-magnetically induced transparency (EIT) medium composed of four-level
atoms and a coupling light field. We find that the coupling light beam can
induce a highly controllable nonlinear waveguide and exert very strong effects
on the dynamical be... | 0405132v1 |
2004-07-28 | Single-atom detection using whispering gallery modes of microdisk resonators | We investigate the possibility of using dielectric microdisk resonators for
the optical detection of single atoms trapped and cooled in magnetic microtraps
near the surface of a substrate. The bound and evanescent fields of optical
whispering gallery modes are calculated and the coupling to straight waveguides
is inves... | 0407229v1 |
2004-09-02 | On the Harmonic approximation for large Josephson junction coupling charge qubits | We revisit the harmonic approximation (HA) for a large Josephson junction
interacting with some charge qubits through the variational approach for the
quantum dynamics of the junction-qubit coupling system. By making use of
numerical calculation and analytical treatment, the conditions under which HA
works well can be ... | 0409013v2 |
2004-11-26 | Berry's phase with quantized field driving: effects of inter-subsystem coupling | The effect of inter-subsystem couplings on the Berry phase of a composite
system as well as that of its subsystem is investigated in this paper. We
analyze two coupled spin-$\frac 1 2 $ particles with one driven by a quantized
field as an example, the pure state geometric phase of the composite system as
well as the mi... | 0411186v1 |
2004-12-14 | Entanglement and the Einstein-Podolsky-Rosen paradox with coupled intracavity optical downconverters | We show that two evanescently coupled $\chi^{(2)}$ parametric downconverters
inside a Fabry-Perot cavity provide a tunable source of quadrature squeezed
light, Einstein-Podolsky-Rosen correlations and quantum entanglement. Analysing
the operation in the below threshold regime, we show how these properties can
be contro... | 0412106v1 |
2005-02-13 | A minimal coupling method for investigating one dimensional dissipative quantum systems | Quantum mechanics of a general one dimensional dissipative system
investigated by it's coupling to a Klein-Gordon field as the environment using
a minimal coupling method. Heisenberg equation for such a dissipative system
containing a dissipative term proportional to velocity obtained. As an example,
quantum dynamics o... | 0502076v2 |
2005-05-13 | Unmodulated spin chains as universal quantum wires | We study a quantum state transfer between two qubits interacting with the
ends of a quantum wire consisting of linearly arranged spins coupled by an
excitation conserving, time-independent Hamiltonian. We show that if we control
the coupling between the source and the destination qubits and the ends of the
wire, the ev... | 0505097v1 |
2005-05-27 | Mesoscopic continuous and discrete channels for quantum information transfer | We study the possibility of realizing perfect quantum state transfer in
mesoscopic devices. We discuss the case of the Fano-Anderson model extended to
two impurities. For a channel with an infinite number of degrees of freedom, we
obtain coherent behavior in the case of strong coupling or in weak coupling
off-resonance... | 0505205v2 |
2005-10-18 | Possibility of Inhomogeneous Coupling Leading to Decoherence in an Electromagnetically-Induced-Transparency Quantum-Memory Process | The effect of inhomogeneous coupling between three-level atoms and external
light fields is studied in the electromagnetically induced transparency (EIT)
quantum memory techqnique. By introducing a subensemble-atomic system to deal
with present inhomogeneous coupling case, we find there is a non-symmetric
dark-state su... | 0510141v1 |
2005-10-28 | Dipole induced transparency in drop-filter cavity-waveguide systems | We show that a waveguide that is normally opaque due to interaction with a
drop-filter cavity can be made transparent when the drop filter is also coupled
to a dipole. A transparency condition is derived between the cavity lifetime
and vacuum Rabi frequency of the dipole. This condition is much weaker than
strong coupl... | 0510228v2 |
2005-11-03 | Dephasing due to Intermode Coupling in Superconducting Stripline Resonators | The nonlinearity exhibited by the kinetic inductance of a superconducting
stripline couples stripline resonator modes together in a manner suitable for
quantum non-demolition measurement of the number of photons in a given
resonator mode. Quantum non-demolition measurement is accomplished by
coherently driving another ... | 0511033v2 |
2005-11-09 | Coupled-channel version of PT-symmetric square well | Coupled pair of PT-symmetric square wells is studied as a prototype of a
quantum system characterized by two manifestly non-Hermitian commuting
observables. We demonstrate that there exists a domain of couplings where both
the respective sets of eigenvalues (viz., energies and spin projections) remain
real and where th... | 0511085v1 |
2006-01-08 | Universal destabilization and slowing of spin transfer functions by a bath of spins | We investigate the effect of a spin bath on the spin transfer functions of a
permanently coupled spin system. When each spin is coupled to a seperate
environment, the effect on the transfer functions in the first excitation
sector is amazingly simple: the group velocity is slowed down by a factor of
two, and the fideli... | 0601047v2 |
2006-01-16 | Multichannel coupling with supersymmetric quantum mechanics and exactly-solvable model for Feshbach resonance | A new type of supersymmetric transformations of the coupled-channel radial
Schroedinger equation is introduced, which do not conserve the vanishing
behavior of solutions at the origin. Contrary to usual transformations, these
``non-conservative'' transformations allow, in the presence of thresholds, the
construction of... | 0601101v2 |
2006-02-22 | Geometric phase in open systems: beyond the Markov approximation and weak coupling limit | Beyond the quantum Markov approximation and the weak coupling limit, we
present a general theory to calculate the geometric phase for open systems with
and without conserved energy. As an example, the geometric phase for a
two-level system coupling both dephasingly and dissipatively to its environment
is calculated. Co... | 0602181v1 |
2006-03-10 | Finite-dimensional states and entanglement generation for a nonlinear coupler | We discuss a system comprising two nonlinear (Kerr-like) oscillators coupled
mutually by a nonlinear interaction. The system is excited by an external
coherent field that is resonant to the frequency of one of the oscillators. We
show that the coupler evolution can be closed within a finite set of $n$-photon
states, an... | 0603090v1 |
2006-04-18 | Universal decoherence induced by an environmental quantum phase transition | Decoherence induced by coupling a system with an environment may display
universal features. Here we demostrate that when the coupling to the system
drives a quantum phase transition in the environment, the temporal decay of
quantum coherences in the system is Gaussian with a width independent of the
system-environment... | 0604136v1 |
2006-05-02 | The Super-Strong Coupling Regime of Cavity Quantum Electrodynamics | We describe a qualitatively new regime of cavity quantum electrodynamics, the
super strong coupling regime. This regime is characterized by atom-field
coupling strengths of the order of the free spectral range of the cavity,
resulting in a significant change in the spatial mode functions of the light
field. It can be r... | 0605020v3 |
2006-06-13 | Cooling to the Ground State of Axial Motion for One Atom Strongly Coupled to an Optical Cavity | Localization to the ground state of axial motion is demonstrated for a
single, trapped atom strongly coupled to the field of a high finesse optical
resonator. The axial atomic motion is cooled by way of coherent Raman
transitions on the red vibrational sideband. An efficient state detection
scheme enabled by strong cou... | 0606104v1 |
2006-08-26 | Relaxation- and Decoherence-free subspaces in networks of weakly and strongly coupled resonators | We consider a network of interacting resonators and analyze the physical
ingredients that enable the emergence of relaxation-free and decoherence-free
subspaces. We investigate two different situations: i) when the whole network
interacts with a common reservoir and ii) when each resonator, strongly coupled
to each oth... | 0608204v1 |
2006-09-18 | Spontaneous emergence of angular momentum Josephson oscillations in coupled annular Bose-Einstein condensates | We investigate the nonlinear dynamics of two coupled annular Bose-Einstein
condensates (BECs). For certain values of the coupling strength the nonrotating
ground state is unstable with respect to fluctuations in the higher angular
momentum modes. The two branched Bogoliubov spectrum exhibits distinct regions
of instabi... | 0609133v2 |
2006-09-29 | Use of dynamical coupling for improved quantum state transfer | We propose a method to improve quantum state transfer in transmission lines.
The idea is to localize the information on the last qubit of a transmission
line, by dynamically varying the coupling constants between the first and the
last pair of qubits. The fidelity of state transfer is higher then in a chain
with fixed ... | 0609235v1 |
2006-10-10 | Effective Quantum Dynamics of Interacting Systems with Inhomogeneous Coupling | We study the quantum dynamics of a single mode/particle interacting
inhomogeneously with a large number of particles and introduce an effective
approach to find the accessible Hilbert space where the dynamics takes place.
Two relevant examples are given: the inhomogeneous Tavis-Cummings model (e.g.,
N atomic qubits cou... | 0610078v2 |
2006-10-17 | Dissipation in Quantum Mechanics, Scalar and Vector Field Theory | A new minimal coupling method is introduced. A general dissipative quantum
system is investigated consistently and systematically. Some coupling functions
describing the interaction between the system and the environment are
introduced. Based on coupling functions, some susceptibility functions are
attributed to the en... | 0610133v1 |
2006-11-15 | Non-exponential decay via tunneling in tight-binding lattices and the optical Zeno effect | An exactly-solvable model for the decay of a metastable state coupled to a
semi-infinite tight-binding lattice, showing large deviations from exponential
decay in the strong coupling regime, is presented. An optical realization of
the lattice model, based on discrete diffraction in a semi-infinite array of
tunneling-co... | 0611164v1 |
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