8,833 research outputs found
Scaling in directed dynamical small-world networks with random responses
A dynamical model of small-world network, with directed links which describe
various correlations in social and natural phenomena, is presented. Random
responses of every site to the imput message are introduced to simulate real
systems. The interplay of these ingredients results in collective dynamical
evolution of a spin-like variable S(t) of the whole network. In the present
model, global average spreading length \langel L >_s and average spreading time
_s are found to scale as p^-\alpha ln N with different exponents.
Meanwhile, S behaves in a duple scaling form for N>>N^*: S ~ f(p^-\beta
q^\gamma t'_sc), where p and q are rewiring and external parameters, \alpha,
\beta, \gamma and f(t'_sc) are scaling exponents and universal functions,
respectively. Possible applications of the model are discussed.Comment: 4 pages, 6 Figure
Rosen-Zener Transition in a Nonlinear Two-Level System
We study Rosen-Zener transition (RZT) in a nonlinear two-level system in
which the level energies depend on the occupation of the levels, representing a
mean-field type of interaction between the particles. We find that the
nonlinearity could affect the quantum transition dramatically. At certain
nonlinearity the 100% population transfer between two levels is observed and
found to be robust over a very wide range of external parameters. On the other
hand, the quantum transition could be completely blocked by a strong
nonlinearity. In the sudden and adiabatic limits we have derived analytical
expressions for the transition probability. Numerical explorations are made for
a wide range of parameters of the general case. Possible applications of our
theory to Bose-Einstern Condensates (BECs) are discussed.Comment: 8 pages, 8 figure
Topological Nature of the Phonon Hall Effect
We provide a topological understanding on phonon Hall effect in dielectrics
with Raman spinphonon coupling. A general expression for phonon Hall
conductivity is obtained in terms of the Berry curvature of band structures. We
find a nonmonotonic behavior of phonon Hall conductivity as a function of
magnetic field. Moreover, we observe a phase transition in phonon Hall effect,
which corresponds to the sudden change of band topology, characterized by the
altering of integer Chern numbers. This can be explained by touching and
splitting of phonon bands.Comment: 12 pages, 4 figures. Detailed supplementary file is include
Temperature dependence of the conductivity of the electronic crystal
We study the temperature dependence of the conductivity of the 2D electronic
solid. In realistic samples, a domain structure forms in the solid and each
domain randomly orients in the absence of the in-plane field. At higher
temperature, the electron transport is governed by thermal activation form of
. The impurities will localize the
electron states along the edges of the crystal domains. At sufficient low
temperature, another transport mechanism called Mott's variable range hopping
mechanism, similar to that in a disorder insulator takes effect. We show that
as the temperature decreases, a crossover from the fixed range hopping of the
transport to the variable range hopping of transport in the 2D electron system
may be experimentally observed.Comment: 4 pages,1 figure
Localized form of Fock terms in nuclear covariant density functional theory
In most of the successful versions of covariant density functional theory in
nuclei, the Fock terms are not included explicitly, which leads to local
functionals and forms the basis of their widespread applicability at present.
However, it has serious consequences for the description of Gamow-Teller
resonances (GTR) and spin-dipole resonances (SDR) which can only be cured by
adding further phenomenological parameters. Relativistic Hartree-Fock models do
not suffer from these problems. They can successfully describe the GTR and SDR
as well as the isovector part of the Dirac effective mass without any
additional parameters. However, they are non-local and require considerable
numerical efforts. By the zero-range reduction and the Fierz transformation, a
new method is proposed to take into account the Fock terms in local
functionals, which retains the simplicity of conventional models and provides
proper descriptions of the spin-isospin channels and the Dirac masses.Comment: 6 pages, 4 figures, Phys. Rev. C in pres
A network approach for managing and processing big cancer data in clouds
Translational cancer research requires integrative analysis of multiple levels of big cancer data to identify and treat cancer. In order to address the issues that data is decentralised, growing and continually being updated, and the content living or archiving on different information sources partially overlaps creating redundancies as well as contradictions and inconsistencies, we develop a data network model and technology for constructing and managing big cancer data. To support our data network approach for data process and analysis, we employ a semantic content network approach and adopt the CELAR cloud platform. The prototype implementation shows that the CELAR cloud can satisfy the on-demanding needs of various data resources for management and process of big cancer data
Adiabatic Fidelity for Atom-Molecule Conversion in a Nonlinear Three-Level \Lambda-system
We investigate the dynamics of the population transfer for atom-molecule
three-level -system on stimulated Raman adiabatic passage(STIRAP). We
find that the adiabatic fidelity for the coherent population trapping(CPT)
state or dark state, as the function of the adiabatic parameter, approaches to
unit in a power law. The power exponent however is much less than the
prediction of linear adiabatic theorem. We further discuss how to achieve
higher adiabatic fidelity for the dark state through optimizing the external
parameters of STIRAP. Our discussions are helpful to gain higher atom-molecule
conversion yield in practical experiments.Comment: 4 pages, 5 figure
Adiabatic Theory of Nonlinear Evolution of Quantum States
We present a general theory for adiabatic evolution of quantum states as
governed by the nonlinear Schrodinger equation, and provide examples of
applications with a nonlinear tunneling model for Bose-Einstein condensates.
Our theory not only spells out conditions for adiabatic evolution of
eigenstates, but also characterizes the motion of non-eigenstates which cannot
be obtained from the former in the absence of the superposition principle. We
find that in the adiabatic evolution of non-eigenstates, the Aharonov-Anandan
phases play the role of classical canonical actions.Comment: substantial revision, 5 pages and 3 figure
Transferring entanglement to the steady-state of flying qubits
The transfer of entanglement from optical fields to qubits provides a viable
approach to entangling remote qubits in a quantum network. In cavity quantum
electrodynamics, the scheme relies on the interaction between a photonic
resource and two stationary intracavity atomic qubits. However, it might be
hard in practice to trap two atoms simultaneously and synchronize their
coupling to the cavities. To address this point, we propose and study
entanglement transfer from cavities driven by an entangled external field to
controlled flying qubits. We consider two exemplary non-Gaussian driving
fields: NOON and entangled coherent states. We show that in the limit of long
coherence time of the cavity fields, when the dynamics is approximately
unitary, entanglement is transferred from the driving field to two atomic
qubits that cross the cavities. On the other hand, a dissipation-dominated
dynamics leads to very weakly quantum-correlated atomic systems, as witnessed
by vanishing quantum discord.Comment: 8 pages, 4 figures, RevTeX
Mutual selection in network evolution: the role of the intrinsic fitness
We propose a new mechanism leading to scale-free networks which is based on
the presence of an intrinsic character of a vertex called fitness. In our
model, a vertex is assigned a fitness , drawn from a given probability
distribution function . During network evolution, with rate we add a
vertex of fitness and connect to an existing vertex of fitness
selected preferentially to a linking probability function
which depends on the fitnesses of the two vertices involved and, with rate
we create an edge between two already existed vertices with fitnesses
and , with a probability also preferential to the connection
function . For the proper choice of , the resulting networks
have generalized power laws, irrespective of the fitness distribution of
vertices.Comment: ws-ijmpc.te
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