4,200 research outputs found
Dynamics of entanglement in the transverse Ising model
We study the evolution of nearest-neighbor entanglement in the one
dimensional Ising model with an external transverse field. The system is
initialized as the so called "thermal ground state" of the pure Ising model. We
analyze properties of generation of entanglement for different regions of
external transverse fields. We find that the derivation of the time at which
the entanglement reaches its first maximum with respect to the reciprocal
transverse field has a minimum at the critical point. This is a new indicator
of quantum phase transition.Comment: To be published in PR
Low-Rank Discriminative Least Squares Regression for Image Classification
Latest least squares regression (LSR) methods mainly try to learn slack
regression targets to replace strict zero-one labels. However, the difference
of intra-class targets can also be highlighted when enlarging the distance
between different classes, and roughly persuing relaxed targets may lead to the
problem of overfitting. To solve above problems, we propose a low-rank
discriminative least squares regression model (LRDLSR) for multi-class image
classification. Specifically, LRDLSR class-wisely imposes low-rank constraint
on the intra-class regression targets to encourage its compactness and
similarity. Moreover, LRDLSR introduces an additional regularization term on
the learned targets to avoid the problem of overfitting. These two improvements
are helpful to learn a more discriminative projection for regression and thus
achieving better classification performance. Experimental results over a range
of image databases demonstrate the effectiveness of the proposed LRDLSR method
One-dimensional Quantum Spin Dynamics of Bethe String States
Quantum dynamics of strongly correlated systems is a challenging problem.
Although the low energy fractional excitations of one dimensional integrable
models are often well-understood, exploring quantum dynamics in these systems
remains challenging in the gapless regime, especially at intermediate and high
energies. Based on the algebraic Bethe ansatz formalism, we study spin dynamics
in a representative one dimensional strongly correlated model, {\it i.e. }, the
antiferromagnetic spin- XXZ chain with the Ising anisotropy, via
the form-factor formulae. Various excitations at different energy scales are
identified crucial to the dynamic spin structure factors under the guidance of
sum rules. At small magnetic polarizations, gapless excitations dominate the
low energy spin dynamics arising from the magnetic-field-induced
incommensurability. In contrast, spin dynamics at intermediate and high
energies is characterized by the two- and three-string states, which are
multi-particle excitations based on the commensurate N\'eel ordered background.
Our work is helpful for experimental studies on spin dynamics in both condensed
matter and cold atom systems beyond the low energy effective Luttinger liquid
theory. Based on an intuitive physical picture, we speculate that the dynamic
feature at high energies due to the multi-particle anti-bound state excitations
can be generalized to non-integrable spin systems.Comment: 15 pages, to appear in Phys. Rev.
VITON: An Image-based Virtual Try-on Network
We present an image-based VIirtual Try-On Network (VITON) without using 3D
information in any form, which seamlessly transfers a desired clothing item
onto the corresponding region of a person using a coarse-to-fine strategy.
Conditioned upon a new clothing-agnostic yet descriptive person representation,
our framework first generates a coarse synthesized image with the target
clothing item overlaid on that same person in the same pose. We further enhance
the initial blurry clothing area with a refinement network. The network is
trained to learn how much detail to utilize from the target clothing item, and
where to apply to the person in order to synthesize a photo-realistic image in
which the target item deforms naturally with clear visual patterns. Experiments
on our newly collected Zalando dataset demonstrate its promise in the
image-based virtual try-on task over state-of-the-art generative models
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