3,147 research outputs found
Difference of optical conductivity between one- and two-dimensional doped nickelates
We study the optical conductivity in doped nickelates, and find the dramatic
difference of the spectrum in the gap (\alt4 eV) between one- (1D)
and two-dimensional (2D) nickelates. The difference is shown to be caused by
the dependence of hopping integral on dimensionality. The theoretical results
explain consistently the experimental data in 1D and
2D nickelates, YCaBaNiO and LaSrNiO,
respectively. The relation between the spectrum in the X-ray aborption
experiments and the optical conductivity in LaSrNiO is
discussed.Comment: RevTeX, 4 pages, 4 figure
Normal modes and time evolution of a holographic superconductor after a quantum quench
We employ holographic techniques to investigate the dynamics of the order
parameter of a strongly coupled superconductor after a perturbation that drives
the system out of equilibrium. The gravity dual that we employ is the Soliton background at zero temperature. We first analyze the normal
modes associated to the superconducting order parameter which are purely real
since the background has no horizon. We then study the full time evolution of
the order parameter after a quench. For sufficiently a weak and slow
perturbation we show that the order parameter undergoes simple undamped
oscillations in time with a frequency that agrees with the lowest normal model
computed previously. This is expected as the soliton background has no horizon
and therefore, at least in the probe and large limits considered, the
system will never return to equilibrium. For stronger and more abrupt
perturbations higher normal modes are excited and the pattern of oscillations
becomes increasingly intricate. We identify a range of parameters for which the
time evolution of the order parameter become quasi chaotic. The details of the
chaotic evolution depend on the type of perturbation used. Therefore it is
plausible to expect that it is possible to engineer a perturbation that leads
to the almost complete destruction of the oscillating pattern and consequently
to quasi equilibration induced by superposition of modes with different
frequencies.Comment: 10 pages, 7 figures, corrected typos, expanded section on chaotic
oscillations and new results for other quenc
Object Detection in Foggy Scenes by Embedding Depth and Reconstruction into Domain Adaptation
Most existing domain adaptation (DA) methods align the features based on the
domain feature distributions and ignore aspects related to fog, background and
target objects, rendering suboptimal performance. In our DA framework, we
retain the depth and background information during the domain feature
alignment. A consistency loss between the generated depth and fog transmission
map is introduced to strengthen the retention of the depth information in the
aligned features. To address false object features potentially generated during
the DA process, we propose an encoder-decoder framework to reconstruct the
fog-free background image. This reconstruction loss also reinforces the
encoder, i.e., our DA backbone, to minimize false object features.Moreover, we
involve our target data in training both our DA module and our detection module
in a semi-supervised manner, so that our detection module is also exposed to
the unlabeled target data, the type of data used in the testing stage. Using
these ideas, our method significantly outperforms the state-of-the-art method
(47.6 mAP against the 44.3 mAP on the Foggy Cityscapes dataset), and obtains
the best performance on multiple real-image public datasets. Code is available
at: https://github.com/VIML-CVDL/Object-Detection-in-Foggy-ScenesComment: Accepted by ACC
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