356 research outputs found
Experimental cyclic inter-conversion between Coherence and Quantum Correlations
Quantum resource theories seek to quantify sources of non-classicality that
bestow quantum technologies their operational advantage. Chief among these are
studies of quantum correlations and quantum coherence. The former to isolate
non-classicality in the correlations between systems, the latter to capture
non-classicality of quantum superpositions within a single physical system.
Here we present a scheme that cyclically inter-converts between these resources
without loss. The first stage converts coherence present in an input system
into correlations with an ancilla. The second stage harnesses these
correlations to restore coherence on the input system by measurement of the
ancilla. We experimentally demonstrate this inter-conversion process using
linear optics. Our experiment highlights the connection between
non-classicality of correlations and non-classicality within local quantum
systems, and provides potential flexibilities in exploiting one resource to
perform tasks normally associated with the other.Comment: 8 pages, 4 figures, comments welcom
Different phase leads to different transport behavior in PbCu(PO)O compounds
The recent claimed room-temperature superconductivity in Cu-doped lead
apatite at ambient pressure are under highly debate. To identify its physical
origin, we studied the crystal structures, energy band structures, lattice
dynamics and magnetic properties of the parent Pb(PO)O compound,
in which two different phases of the LK-99 compound are analyzed in detail. Our
results show that the Pb(PO)O compound is an indirect band gap
semiconductor, where Cu doping at the 4 site of Pb leads to a semiconducting
to half-metallic transition. Two half-filled flat bands spanning the Fermi
energy levels are present in the 4-phase of LK-99, which are mainly formed
by hybridization of the and orbitals of Cu with the 2
orbitals of O. In addition, 6-phase of LK-99 always has spin polarity at the
bottom of the conduction band and at the top of the valence band, making the
material a bipolar magnetic semiconductor. Our results are basically consistent
with the recent experimental transport properties of LK-99 posted on
arXiv:2308.05778.Comment: 6 pages and 4 figure
Compression with Bayesian Implicit Neural Representations
Many common types of data can be represented as functions that map
coordinates to signal values, such as pixel locations to RGB values in the case
of an image. Based on this view, data can be compressed by overfitting a
compact neural network to its functional representation and then encoding the
network weights. However, most current solutions for this are inefficient, as
quantization to low-bit precision substantially degrades the reconstruction
quality. To address this issue, we propose overfitting variational Bayesian
neural networks to the data and compressing an approximate posterior weight
sample using relative entropy coding instead of quantizing and entropy coding
it. This strategy enables direct optimization of the rate-distortion
performance by minimizing the -ELBO, and target different
rate-distortion trade-offs for a given network architecture by adjusting
. Moreover, we introduce an iterative algorithm for learning prior
weight distributions and employ a progressive refinement process for the
variational posterior that significantly enhances performance. Experiments show
that our method achieves strong performance on image and audio compression
while retaining simplicity.Comment: Preprin
PV-RCNN++: Point-Voxel Feature Set Abstraction With Local Vector Representation for 3D Object Detection
3D object detection is receiving increasing attention from both industry and
academia thanks to its wide applications in various fields. In this paper, we
propose Point-Voxel Region-based Convolution Neural Networks (PV-RCNNs) for 3D
object detection on point clouds. First, we propose a novel 3D detector,
PV-RCNN, which boosts the 3D detection performance by deeply integrating the
feature learning of both point-based set abstraction and voxel-based sparse
convolution through two novel steps, i.e., the voxel-to-keypoint scene encoding
and the keypoint-to-grid RoI feature abstraction. Second, we propose an
advanced framework, PV-RCNN++, for more efficient and accurate 3D object
detection. It consists of two major improvements: sectorized proposal-centric
sampling for efficiently producing more representative keypoints, and
VectorPool aggregation for better aggregating local point features with much
less resource consumption. With these two strategies, our PV-RCNN++ is about
faster than PV-RCNN, while also achieving better performance. The
experiments demonstrate that our proposed PV-RCNN++ framework achieves
state-of-the-art 3D detection performance on the large-scale and
highly-competitive Waymo Open Dataset with 10 FPS inference speed on the
detection range of 150m * 150m.Comment: Accepted by International Journal of Computer Vision (IJCV), code is
available at https://github.com/open-mmlab/OpenPCDe
Low CCL17 expression associates with unfavorable postoperative prognosis of patients with clear cell renal cell carcinoma
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