130,656 research outputs found
Image Retrieval using Histogram Factorization and Contextual Similarity Learning
Image retrieval has been a top topic in the field of both computer vision and
machine learning for a long time. Content based image retrieval, which tries to
retrieve images from a database visually similar to a query image, has
attracted much attention. Two most important issues of image retrieval are the
representation and ranking of the images. Recently, bag-of-words based method
has shown its power as a representation method. Moreover, nonnegative matrix
factorization is also a popular way to represent the data samples. In addition,
contextual similarity learning has also been studied and proven to be an
effective method for the ranking problem. However, these technologies have
never been used together. In this paper, we developed an effective image
retrieval system by representing each image using the bag-of-words method as
histograms, and then apply the nonnegative matrix factorization to factorize
the histograms, and finally learn the ranking score using the contextual
similarity learning method. The proposed novel system is evaluated on a large
scale image database and the effectiveness is shown.Comment: 4 page
Topological Superfluidity of Spin-Orbit Coupled Bilayer Fermi Gases
Topological superfluid, new quantum matter that possesses gapless exotic
excitations known as Majorana fermions, has attracted extensive attention
recently. These excitations, which can encode topological qubits, could be
crucial ingredients for fault-tolerant quantum computation. However, creating
and manipulating multiple Majorana fermions remain an ongoing challenge.
Loading a topologically protected system in multi-layer structures would be a
natural and simple way to achieve this goal. Here we investigate the system of
bilayer Fermi gases with spin-orbit coupling and show that the topological
condition is significantly influenced by the inter-layer tunneling, yielding
two novel topological phases, which support more Majorana Fermions. We
demonstrate the existence of such novel topological phases and associated
multiple Majorana fermions using bilayer Fermi gases trapped inside a harmonic
potential. This research pave a new way for generating multiple Majorana
fermions and would be a significant step towards topological quantum
computation.Comment: 34 pages, 5 figures, Comments welcom
Eigen-functional bosonization and Eikonal-type equations in one-dimensional strongly correlated electron system
With the eigen-functional bosonization method, we study one-dimensional
strongly correlated electron systems with large momentum ( and/or
) transfer term(s), and demonstrate that this kind of problems ends in
to solve the Eikonal-type equations, and these equations are universal, and
independent of whether or not the system is integrable. In contrast to usual
perturbation theory, this method is valid not only for weak electron
interaction, but also for strong electron interaction. Comparing with exact
solution of some integrable models, it can give correct results in one-loop
approximation. This method can also be used to study electron-phonon
interaction systems, and two coupled spin chain or quantum wire systems.Comment: latex, pages 24, no figure
Nuclear Bag Model and Nuclear Magnetic Moments
In 1991, we proposed a model in which nucleus is treated as a spherical
symmetric MIT bag and nucleon satisfies the MIT bag model boundary condition.
The model was employed to calculate nuclear magnetic moments. The results are
in good agreement with experiment data. Now, we found this model is still
interesting and illuminating.Comment: 5 pages, no figures, Late
Exact expression of the ground state energy of quantum many-particle systems as a functional of the particle density
By introducing a phase field and solving the eigen-functional equation of
particles, we obtain the exact expressions of the ground state energy as a
functional of the particle density for interacting electron/boson systems, and
a two-dimensional electron gas under an external magnetic field, respectively.
With the eigen-functionals of the particles, we can construct the ground state
wave-function of the systems. Moreover, with the expressions of the ground
state energy, we can exactly determine the ground state energy and the ground
state particle density of the systems by taking .Comment: 11 pages, latex fil
Unified theory of quantum many-particle systems
Using eigen-functional bosonization method, we study quantum many-particle
systems, and show that the quantum many-particle problems end in to solve the
differential equation of the phase fields which represent the particle
correlation strength. Thus, the physical properties of these systems are
completely determined by the differential equation of the phase fields. We
mainly focus on the study of D-dimensional electron gas with/without transverse
gauge fields, two-dimensional electron gas under an external magnetic field,
D-dimensional boson systems, a D-dimensional Heisenberg model and a one-band
Hubbard model on a square lattice, and give their exact (accurate for
Heisenberg model) functional expressions of the ground state energy and action,
and the eigen-functional wave functions of the fermions/bosons. With them, we
can calculate a variety of correlation functions of the systems, such as single
particle Green's functions and their ground state wave functions. In present
theoretical framework, we can unifiably represent the Landau Fermi liquid,
non-Fermi liquid () and Tomonaga-Luttinger liquid.Comment: 38 pages, RevTex, no figur
An exact expression of the collective excitation energy gap of fractional quantum Hall effect
We have exactly solved the eigenequation of a two-dimensional Dirac fermion
moving on the surface of a sphere under the influence of a radial magnetic
field B, and obtained an exact expression of the collective excitation energy
gap for the filling factors , m and p are non-zero integers,
which is very well agreement with the computing results.Comment: Revtex, 11 pages, no figure
Unified thoery of strongly correlated electron systems
In framework of eigen-functional bosonization method, we introduce an
imaginary phase field to uniquely represent electron correlation, and
demonstrate that the Landau Fermi liquid theory and the Tomonaga-Luttinger
liquid theory can be unified. It is very clear in this framework that the
Tomonaga-Luttinger liquid behavior of one-dimensional interacting electron
gases originates from their Fermi structure, and the non-Landau-Fermi liquid
behavior of 2D interacting electron gases is induced by the long-range electron
interaction, while 3D interacting electron gases generally show the Landau
Fermi liquid behavior.Comment: corrected some typos in eq. (13
The hierarchical Green function approach to the two-dimensional Hubbard model
By introducing multipe-site correlation functions, we propose a hierarchical
Green function approach, and apply it to study the characteristic properties of
a 2D square lattice Hubbard model by solving the equation of motions of a
one-particle Green function and related multipe-site correlation functions.
Under a cut-off approximation and taking the Fourier representation of
multipe-site correlation functions, we obtain an analytical expression of
one-particle Green function with static correlation functions. Then we
calculate the spectral density function of electrons, and obtain that besides
two main peaks corresponding to the lower and upper Hubbard bands in the
spectral density function, there emerge some novel states between these two
main peaks, and the total spectral weight of these emerged states is
proportional to the hole doping concentration . Meanwhile, there also emerge
some collective modes related to possible charge/spin density wave and/or
electronic pairing density wave ordering states. This calculation is completely
consistent with the spectroscopy observations of the cuprate superconductors in
normal states. On the other hand, the appearence of the static correlation
functions in the one-particle Green function can be used to describe the
intertwined orders observed in the normal state of the cuprate superconductors.Comment: 24p, no figuur
Electromagnetic fields, size, and copy of a single photon
Photons are almost involved in each field of science and daily life of
everyone. However, there are still some fundamental and puzzling questions such
as what a photon is.The expressions of electromagnetic fields of a photon are
here proposed. On the basis of the present expressions, we calculate the
energy, momentum, and spin angular momentum of a photon, derive the relations
between the photon size and wavelength, and reveal the differences between a
photon and its copy. The results show that the present expressions properly
describe the particle characteristics of a photon; the length of a photon is
half of the wavelength, and the radius is proportional to square root of the
wavelength; a photon can ionize a hydrogen atom at the ground state only if its
radius is less than the Bohr radius; a photon and its copy have the phase
difference of {\pi} and constitute a phase-entangled photon pair; the
phase-entangled n-photon train results from the sequential stimulated emissions
and belongs to the Fock state. A laser beam is an ensemble of the n-photon
trains and belongs to the coherent state. The threshold power of a laser is
equal to the power of the n-photon train. These provide a bridge between the
wave theory of light and quantum optics and will further advance research and
application of the related fields.Comment: 4 pages, crrected typos, improved some descriptions and reference
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