168 research outputs found
Universal characteristics of one-dimensional non-Hermitian superconductors
We establish a non-Bloch band theory for one-dimensional(1D) non-Hermitian
topological superconductors. The universal physical properties of non-Hermitian
topological superconductors are revealed based on the theory. According to the
particle-hole symmetry, there exist reciprocal particle and hole loops of
generalized Brillouin zone (GBZ). The critical point of quantum phase
transition, where the energy gap closes, appears when the particle and hole
loops intersect and their values of GBZ satisfy |\beta| = 1. If the
non-Hermitian system has skin modes, these modes should be Z2 style, i.e., the
corresponding eigenstates of particle and hole localize at opposite ends of an
open chain, respectively. The non-Bloch band theory is applied to two examples,
non-Hermitian p- and s-wave topological superconductors. Topological phase
transitions occur at \beta_{c}= \pm 1 in the two systems. In terms of Majorana
Pfaffian, a Z2 non-Bloch topological invariant is defined to establish the
non-Hermitian bulk-boundary correspondence in non-Hermitian superconductors.Comment: 6 pages, 4 figure
A New Non-Abelian Topological Phase of Cold Fermi Gases in Anisotropic and Spin-Dependent Optical Lattices
To realize non-Abelian s-wave topological superfluid (TS) of cold Fermi
gases, generally a Zeeman magnetic field larger than superfluid pairing gap is
necessary. In this paper we find that using an anisotropic and spin-dependent
optical lattice (ASDOL) to trap gases, a new non-Abelian TS phase appears, in
contrast to an isotropic and spin-independent optical lattice. A characteristic
of this new non-Abelian TS is that Zeeman magnetic field can be smaller than
the superfluid pairing gap. By self-consistently solving pairing gap equation
and considering the competition against normal state and phase separation, this
new phase is also stable. Thus an ASDOL supplies a convenient route to realize
TS. We also investigate edge states and the effects of a harmonic trap
potential
Ab Initio Studies on Interactions in KC under High Pressure
Fullerene solids doped with alkali metals (AC, A = K, Rb, Cs)
exhibit a superconducting transition temperature () as high as 40 K, and
their unconventional superconducting properties have been a subject of debate.
With application of high pressure on KC and RbC, the
experiments demonstrate the decrease of . In this paper, we focus on
KC and derive the structure of KC under different
pressures based on first-principles calculations, exploring the trends of
Coulomb interactions at various pressures. By utilizing the Maximally Localized
Wannier function approach, Constrained Density Functional Perturbation Theory
(cDFPT), and Constrained Random Phase Approximation (cRPA), we construct a
microscopic low-energy model near the Fermi level. Our results strongly
indicate that, in the KC system, as pressure increases, the effect
of phonons is the key to intraorbital electron pairing. There is a dominance of
the phonon-driven superconducting mechanism at high pressure
Improving the Transferability of Adversarial Samples by Path-Augmented Method
Deep neural networks have achieved unprecedented success on diverse vision
tasks. However, they are vulnerable to adversarial noise that is imperceptible
to humans. This phenomenon negatively affects their deployment in real-world
scenarios, especially security-related ones. To evaluate the robustness of a
target model in practice, transfer-based attacks craft adversarial samples with
a local model and have attracted increasing attention from researchers due to
their high efficiency. The state-of-the-art transfer-based attacks are
generally based on data augmentation, which typically augments multiple
training images from a linear path when learning adversarial samples. However,
such methods selected the image augmentation path heuristically and may augment
images that are semantics-inconsistent with the target images, which harms the
transferability of the generated adversarial samples. To overcome the pitfall,
we propose the Path-Augmented Method (PAM). Specifically, PAM first constructs
a candidate augmentation path pool. It then settles the employed augmentation
paths during adversarial sample generation with greedy search. Furthermore, to
avoid augmenting semantics-inconsistent images, we train a Semantics Predictor
(SP) to constrain the length of the augmentation path. Extensive experiments
confirm that PAM can achieve an improvement of over 4.8% on average compared
with the state-of-the-art baselines in terms of the attack success rates.Comment: 10 pages + appendix, CVPR 202
Mutational Profile and Potential Molecular Therapeutic Targets of Pheochromocytoma
PurposePheochromocytoma/paraganglioma (PCC/PGL; collectively known as PPGL) can be driven by germline and somatic mutations in susceptibility genes. We aimed to investigate the mutation profile and clinical features of pathogenic genes in highly genetically heterogeneous PPGL and to preliminary explore molecular therapeutic targets in PPGL.MethodsWe established a panel of 260 genes, including susceptibility genes of PPGL and other important tumorigenic genes to sequence 107 PPGL tissues.ResultsOverall, 608 genomic mutations were identified in 107 PPGL tissues. Almost 57% of PPGL tissue samples exhibited pathogenic mutations, and the most frequently mutated gene was SDHB (15/107, 14%). SDHB and HRAS were the most commonly mutated genes in germline-mutated PPGL (25/107, 23%) and nongermline-mutated PPGL (36/107, 34%), respectively. In addition, novel pathogenic mutations were detected in sporadic PPGL. PPGL with mutations in the hypoxia pathway had an earlier onset and higher norepinephrine level than those in the kinase pathway. Receptor tyrosine kinase (RTK; 22%, 24/107), mitogen-activated protein kinase (MAPK; 14%, 15/107), and tyrosine kinase (TK; 2%, 2/107) pathways were the most frequently mutated pathways in PPGL.ConclusionOur results provided the genetic mutation profile in PPGL tissues. Genetic mutations in PPGL were mainly concentrated in the RTK, TK, and MAPK pathways, suggesting potential molecular therapeutic targets for PPGL
- …