4,000 research outputs found
Local vertical measurements and violation of Bell inequality
For two qubits belonging to Alice and Bob, we derive an approach to setup the
bound of Bell operator in the condition that Alice and Bob continue to perform
local vertical measurements. For pure states we find that if the entanglement
of the two qubits is less than 0.2644 (measured with von Neumann entropy) the
violation of the Bell inequality will never be realized, and only when the
entanglement is equal to 1 the maximal violation () can occur. For
specific form of mixed states, we prove that the bound of the Bell inequality
depends on the concurrence. Only when the concurrence is greater than 0.6 the
violation of the Bell inequality can occur, and the maximal violation can never
be achieved. We suggest that the bound of the Bell operator in the condition of
local vertical measurements may be used as a measure of the entanglement.Comment: 4 pages, 3 figure
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
Target-searching on the percolation
We study target-searching processes on a percolation, on which a hunter
tracks a target by smelling odors it emits. The odor intensity is supposed to
be inversely proportional to the distance it propagates. The Monte Carlo
simulation is performed on a 2-dimensional bond-percolation above the
threshold. Having no idea of the location of the target, the hunter determines
its moves only by random attempts in each direction. For lager percolation
connectivity , it reveals a scaling law for the searching time
versus the distance to the position of the target. The scaling exponent is
dependent on the sensitivity of the hunter. For smaller , the scaling law is
broken and the probability of finding out the target significantly reduces. The
hunter seems trapped in the cluster of the percolation and can hardly reach the
goal.Comment: 5 figure
Electronic Structure in Gapped Graphene with Coulomb Potential
In this paper, we numerically study the bound electron states induced by long
range Coulomb impurity in gapped graphene and the quasi-bound states in
supercritical region based on the lattice model. We present a detailed
comparison between our numerical simulations and the prediction of the
continuum model which is described by the Dirac equation in (2+1)-dimensional
Quantum Electrodynamics (QED). We also use the Fano's formalism to investigate
the quasi-bound state development and design an accessible experiments to test
the decay of the supercritical vacuum in the gapped graphene.Comment: 5 page, 4 figure
Enhanced Strong Coupling between Spin Ensemble and non-Hermitian Topological Edge States
Light-matter interaction is crucial to both understanding fundamental
phenomena and developing versatile applications. Strong coupling, robustness,
and controllability are the three most important aspects in realizing
light-matter interactions. Topological and non-Hermitian photonics, have
provided frameworks for robustness and extensive control freedom, respectively.
How to engineer the properties of the edge state such as photonic density of
state, scattering parameters by using non-Hermitian engineering while ensuring
topological protection has not been fully studied. Here we construct a
parity-time-symmetric dimerized photonic lattice and generate complex-valued
edge states via spontaneous PT-symmetry breaking. The enhanced strong coupling
between the topological photonic edge mode and magnon mode in a ferromagnetic
spin ensemble is demonstrated. Our research reveals the subtle non-Hermitian
topological edge states and provides strategies for realizing and engineering
topological light-matter interactions.Comment: 6 pages, 4 figure
TransCORALNet: A Two-Stream Transformer CORAL Networks for Supply Chain Credit Assessment Cold Start
This paper proposes an interpretable two-stream transformer CORAL networks
(TransCORALNet) for supply chain credit assessment under the segment industry
and cold start problem. The model aims to provide accurate credit assessment
prediction for new supply chain borrowers with limited historical data. Here,
the two-stream domain adaptation architecture with correlation alignment
(CORAL) loss is used as a core model and is equipped with transformer, which
provides insights about the learned features and allow efficient
parallelization during training. Thanks to the domain adaptation capability of
the proposed model, the domain shift between the source and target domain is
minimized. Therefore, the model exhibits good generalization where the source
and target do not follow the same distribution, and a limited amount of target
labeled instances exist. Furthermore, we employ Local Interpretable
Model-agnostic Explanations (LIME) to provide more insight into the model
prediction and identify the key features contributing to supply chain credit
assessment decisions. The proposed model addresses four significant supply
chain credit assessment challenges: domain shift, cold start, imbalanced-class
and interpretability. Experimental results on a real-world data set demonstrate
the superiority of TransCORALNet over a number of state-of-the-art baselines in
terms of accuracy. The code is available on GitHub
https://github.com/JieJieNiu/TransCORALN .Comment: 13 pages, 7 figure
Quantum Dot in Z-shaped Graphene Nanoribbon
Stimulated by recent advances in isolating graphene, we discovered that
quantum dot can be trapped in Z-shaped graphene nanoribbon junciton. The
topological structure of the junction can confine electronic states completely.
By varying junction length, we can alter the spatial confinement and the number
of discrete levels within the junction. In addition, quantum dot can be
realized regardless of substrate induced static disorder or irregular edges of
the junction. This device can be used to easily design quantum dot devices.
This platform can also be used to design zero-dimensional functional nanoscale
electronic devices using graphene ribbons.Comment: 4 pages, 3 figure
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