16,237 research outputs found
Twisted Gauge Theory Model of Topological Phases in Three Dimensions
We propose an exactly solvable lattice Hamiltonian model of topological
phases in dimensions, based on a generic finite group and a
-cocycle over . We show that our model has topologically
protected degenerate ground states and obtain the formula of its ground state
degeneracy on the -torus. In particular, the ground state spectrum implies
the existence of purely three-dimensional looplike quasi-excitations specified
by two nontrivial flux indices and one charge index. We also construct other
nontrivial topological observables of the model, namely the
generators as the modular and matrices of the ground states, which
yield a set of topological quantum numbers classified by and
quantities derived from . Our model fulfills a Hamiltonian extension of
the -dimensional Dijkgraaf-Witten topological gauge theory with a gauge
group . This work is presented to be accessible for a wide range of
physicists and mathematicians.Comment: 37 pages, 9 figures, 4 tables; revised to improve the clarity;
references adde
LeNo: Adversarial Robust Salient Object Detection Networks with Learnable Noise
Pixel-wise predction with deep neural network has become an effective
paradigm for salient object detection (SOD) and achieved remakable performance.
However, very few SOD models are robust against adversarial attacks which are
visually imperceptible for human visual attention. The previous work robust
salient object detection against adversarial attacks (ROSA) shuffles the
pre-segmented superpixels and then refines the coarse saliency map by the
densely connected CRF. Different from ROSA that rely on various pre- and
post-processings, this paper proposes a light-weight Learnble Noise (LeNo) to
against adversarial attacks for SOD models. LeNo preserves accuracy of SOD
models on both adversarial and clean images, as well as inference speed. In
general, LeNo consists of a simple shallow noise and noise estimation that
embedded in the encoder and decoder of arbitrary SOD networks respectively.
Inspired by the center prior of human visual attention mechanism, we initialize
the shallow noise with a cross-shaped gaussian distribution for better defense
against adversarial attacks. Instead of adding additional network components
for post-processing, the proposed noise estimation modifies only one channel of
the decoder. With the deeply-supervised noise-decoupled training on
state-of-the-art RGB and RGB-D SOD networks, LeNo outperforms previous works
not only on adversarial images but also clean images, which contributes
stronger robustness for SOD.Comment: 8 pages, 5 figures, submitted to AAA
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