14,903 research outputs found
Localization of electric field distribution in graded core-shell metamaterials
The local electric field distribution has been investigated in a core-shell
cylindrical metamaterial structure under the illumination of a uniform incident
optical field. The structure consists of a homogeneous dielectric core, a shell
of graded metal-dielectric metamaterial, embedded in a uniform matrix. In the
quasi-static limit, the permittivity of the metamaterial is given by the graded
Drude model. The local electric potentials and hence the electric fields have
been derived exactly and analytically in terms of hyper-geometric functions.
Our results showed that the peak of the electric field inside the cylindrical
shell can be confined in a desired position by varying the frequency of the
optical field and the parameters of the graded profiles. Thus, by fabricating
graded metamaterials, it is possible to control electric field distribution
spatially. We offer an intuitive explanation for the gradation-controlled
electric field distribution
Free boson representation of at level one
We construct a realization of the central extension of super-Yangian double
at level-one in terms of free boson fields with
a continuous parameter.Comment: 9 pages, latex, reference revise
-wave chiral superfluidity from an -wave interacting atomic Fermi gas
Chiral -wave superfluids are fascinating topological quantum states of
matter that have been found in the liquid He-A phase and arguably in the
electronic SrRuO superconductor. They are shown fundamentally related
to the fractional quantum Hall state which supports fractional exotic
excitations. A common understanding is that such states require spin-triplet
pairing of fermions due to -wave interaction. Here we report by controlled
theoretical approximation that a center-of-mass Wannier -wave chiral
superfluid state can arise from spin-singlet pairing for an -wave
interacting atomic Fermi gas in an optical lattice. Despite a conceptually
different origin, it shows topological properties similar to the conventional
chiral -wave state. These include a non-zero Chern number and the appearance
of chiral fermionic zero modes bounded to domain walls. Several signature
quantities are calculated for the cold atom experimental condition.Comment: 16 pages and 7 figures including supplementary material
Fast Poisson Noise Removal by Biorthogonal Haar Domain Hypothesis Testing
Methods based on hypothesis tests (HTs) in the Haar domain are widely used to
denoise Poisson count data. Facing large datasets or real-time applications,
Haar-based denoisers have to use the decimated transform to meet limited-memory
or computation-time constraints. Unfortunately, for regular underlying
intensities, decimation yields discontinuous estimates and strong "staircase"
artifacts. In this paper, we propose to combine the HT framework with the
decimated biorthogonal Haar (Bi-Haar) transform instead of the classical Haar.
The Bi-Haar filter bank is normalized such that the p-values of Bi-Haar
coefficients (pBH) provide good approximation to those of Haar (pH) for
high-intensity settings or large scales; for low-intensity settings and small
scales, we show that pBH are essentially upper-bounded by pH. Thus, we may
apply the Haar-based HTs to Bi-Haar coefficients to control a prefixed false
positive rate. By doing so, we benefit from the regular Bi-Haar filter bank to
gain a smooth estimate while always maintaining a low computational complexity.
A Fisher-approximation-based threshold imple- menting the HTs is also
established. The efficiency of this method is illustrated on an example of
hyperspectral-source-flux estimation
A New Approach to Linear/Nonlinear Distributed Fusion Estimation Problem
Disturbance noises are always bounded in a practical system, while fusion
estimation is to best utilize multiple sensor data containing noises for the
purpose of estimating a quantity--a parameter or process. However, few results
are focused on the information fusion estimation problem under bounded noises.
In this paper, we study the distributed fusion estimation problem for linear
time-varying systems and nonlinear systems with bounded noises, where the
addressed noises do not provide any statistical information, and are unknown
but bounded. When considering linear time-varying fusion systems with bounded
noises, a new local Kalman-like estimator is designed such that the square
error of the estimator is bounded as time goes to . A novel
constructive method is proposed to find an upper bound of fusion estimation
error, then a convex optimization problem on the design of an optimal weighting
fusion criterion is established in terms of linear matrix inequalities, which
can be solved by standard software packages. Furthermore, according to the
design method of linear time-varying fusion systems, each local nonlinear
estimator is derived for nonlinear systems with bounded noises by using Taylor
series expansion, and a corresponding distributed fusion criterion is obtained
by solving a convex optimization problem. Finally, target tracking system and
localization of a mobile robot are given to show the advantages and
effectiveness of the proposed methods.Comment: 9 pages, 3 figure
Detecting -phase superfluids with -wave symmetry in a quasi-1D optical lattice
We propose an experimental protocol to study -wave superfluidity in a
spin-polarized cold Fermi gas tuned by an -wave Feshbach resonance. A
crucial ingredient is to add a quasi-1D optical lattice and tune the fillings
of two spins to the and band, respectively. The pairing order parameter
is confirmed to inherit -wave symmetry in its center-of-mass motion. We find
that it can further develop into a state of unexpected -phase modulation
in a broad parameter regime. Measurable quantities are calculated, including
time-of-flight distributions, radio-frequency spectra, and in situ
phase-contrast imaging in an external trap. The -phase -wave superfluid
is reminiscent of the -state in superconductor-ferromagnet
heterostructures but differs in symmetry and origin. If observed, it would
represent another example of -wave pairing, first discovered in He-3
liquids.Comment: 5 pages, 5 figure
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