15,456 research outputs found
Inhomogeneous states with checkerboard order in the t-J Model
We study inhomogeneous states in the t-J model using an unrestricted
Gutzwiller approximation. We find that checkerboard order, where
is a doping dependent number, emerges from Fermi surface instabilities of
both the staggered flux phase and the Fermi liquid state with realistic band
parameters. In both cases, the checkerboard order develops at wave vectors
, that are tied to the peaks of the
wave-vector dependent susceptibility, and is of the Lomer-Rice-Scott type. The
properties of such periodic, inhomogeneous states are discussed in connection
to the checkerboard patterns observed by STM in underdoped cuprates.Comment: Published Versio
Kondo Signatures of a Quantum Magnetic Impurity in Topological Superconductors
We study the Kondo physics of a quantum magnetic impurity in two-dimensional topological superconductors (TSCs), either intrinsic or induced on the surface of a bulk topological insulator, using a numerical renormalization group technique. We show that, despite sharing the p+ip pairing symmetry, intrinsic and extrinsic TSCs host different physical processes that produce distinct Kondo signatures. Extrinsic TSCs harbor an unusual screening mechanism involving both electron and orbital degrees of freedom that produces rich and prominent Kondo phenomena, especially an intriguing pseudospin Kondo singlet state in the superconducting gap and a spatially anisotropic spin correlation. In sharp contrast, intrinsic TSCs support a robust impurity spin doublet ground state and an isotropic spin correlation. These findings advance fundamental knowledge of novel Kondo phenomena in TSCs and suggest experimental avenues for their detection and distinction
Coupling of Rolling Tachyon to Closed Strings
We study the late time behavior of the boundary state representing the
rolling tachyon constructed by Sen. It is found that the coupling of the
rolling tachyon to massive modes of the closed string grows exponentially as
the system evolves. We argue that the description of rolling tachyon by a
boundary state is valid during the finite time determined by string coupling,
and that energy could be dissipated to the bulk beyond this time. We also
comment on the relation between the rolling tachyon boundary state and the
spacelike D-brane boundary state.Comment: 18 pages, no figure; v2, reference added, minor corrections; v3,
final version that appeared in Nucl.Phys.
DeepSLAM: A Robust Monocular SLAM System with Unsupervised Deep Learning
In this paper, we propose DeepSLAM, a novel unsupervised deep learning-based visual Simultaneous Localization and Mapping (SLAM) system. The DeepSLAM training is fully unsupervised since it only requires stereo imagery instead of annotating ground-truth poses. Its testing takes a monocular image sequence as the input. Therefore, it is a monocular SLAM paradigm. DeepSLAM consists of several essential components, including Mapping-Net, Tracking-Net, Loop-Net and a graph optimization unit. Specifically, the Mapping-Net is an encoder and decoder architecture for describing the 3D structure of the environment while the Tracking-Net is a Recurrent Convolutional Neural Network (RCNN) architecture for capturing the camera motion. The Loop-Net is a pre-trained binary classifier for detecting loop closures. DeepSLAM can simultaneously generate pose estimate, depth map and outlier rejection mask. We evaluate its performance on various datasets, and find that DeepSLAM achieves good performance in terms of pose estimation accuracy, and is robust in some challenging scenes
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