3,800 research outputs found
An interpretation of Union-Find Decoder on Weighted Graphs
Union-Find (UF) and Minimum-Weight Perfect Matching (MWPM) are popular
decoder designs for surface codes. The former has significantly lower time
complexity than the latter but is considered somewhat inferior, in terms of
decoding accuracy. In this work we present an interpretation of UF decoders
that explains why UF and MWPM decoders perform closely in some cases: the UF
decoder is an approximate implementation of the blossom algorithm used for
MWPM. This interpretation allows a generalization of UF decoders for weighted
decoding graphs and explains why UF decoders achieve high accuracy for certain
surface codes
Scalable Quantum Error Correction for Surface Codes using FPGA
A fault-tolerant quantum computer must decode and correct errors faster than
they appear. The faster errors can be corrected, the more time the computer can
do useful work. The Union-Find (UF) decoder is promising with an average time
complexity slightly higher than . We report a distributed version of
the UF decoder that exploits parallel computing resources for further speedup.
Using an FPGA-based implementation, we empirically show that this distributed
UF decoder has a sublinear average time complexity with regard to , given
parallel computing resources. The decoding time per measurement round
decreases as increases, a first time for a quantum error decoder. The
implementation employs a scalable architecture called Helios that organizes
parallel computing resources into a hybrid tree-grid structure. Using Xilinx's
cycle-accurate simulator, we present cycle-accurate decoding time for up to
15, with the phenomenological noise model with . We are able to
implement up to 7 with a Xilinx ZC106 FPGA, for which an average decoding
time is 120 ns per measurement round. Since the decoding time per measurement
round of Helios decreases with , Helios can decode a surface code of
arbitrarily large without a growing backlog
Intermittent High Glucose Enhances Apoptosis in INS-1 Cells
To investigate the effect of intermittent high glucose (IHG) and sustained high glucose (SHG) on inducing β-cell apoptosis and the potential involved mechanisms, INS-1 beta cells were incubated for 72 h in the medium containing different glucose concentrations: control (5.5 mmol/L), SHG (33.3 mmol/L), and IHG (5.5 mmol/L and 33.3 mmol/L glucose alternating every 12 h). Cell viability, apoptosis rate, and oxidative-stress markers were determined. The results showed that the apoptosis induced by IHG was more obvious than that by SHG. Simultaneously, the intracellular level of oxidative stress was more significantly increased in INS-1 cells exposed to IHG. These findings suggest that intermittent high glucose could be more deleterious to β-cell than a constant high concentration of glucose, this may be due to the aggravation of oxidative stress triggered by intermittent high glucose
Hybrid Topological Superconductivity and Hinge Majorana Flat Band in Type-II Dirac Semimetals
Type-II Dirac semimetals (DSMs) have a distinct Fermi surface topology, which
allows them to host novel topological superconductivity (TSC) different from
type-I DSMs. Depending on the relationship between intra- and inter-orbital
electron-electron interactions, the phase diagram of superconductivity is
obtained in type-II DSMs. We find that when the inter-orbital attraction is
dominant, an unconventional inter-orbital intra-spin superconducting (SC) state
( and pairing channels of point group) is realized,
yielding hybrid TSC, i.e., first- and second-order TSC exists at the same time.
Further analysis reveals the Majorana flat bands on the -directed hinges,
which penetrate through the whole hinge Brillouin zone and link the projections
of the surface helical Majorana cones at time-reversal-invariant momenta. These
higher-order hinge modes are symmetry-protected and can even host strong
stability against finite rotation symmetry-breaking order. We suggest
that experimental realization of these findings can be explored in transition
metal dichalcogenides
More on QCD Ghost Dark Energy
The difference between vacuum energy of quantum fields in Minkowski space and
in Friedmann-Robterson-Walker universe might be related to the observed dark
energy. The vacuum energy of the Veneziano ghost field introduced to solve the
problem in QCD is of the form, . Based on this, we
study the dynamical evolution of a phenomenological dark energy model whose
energy density is of the form . In this model, the universe
approaches to a de Sitter phase at late times. We fit the model with current
observational data including SnIa, BAO, CMB, BBN, Hubble parameter and growth
rate of matter perturbation. It shows that the universe begins to accelerate at
redshift and this model is consistent with current data. In
particular, this model fits the data of growth factor well as the
model.Comment: 14 pages, 4 figures, 2 table
Inert Higgs Dark Matter for New CDF W-boson Mass and Detection Prospects
The -boson mass, which was recently measured at FermiLab, suggests the
presence of new multiplets beyond the Standard Model (SM). One of the minimal
extensions of the SM is to introduce an additional scalar doublet, in which the
non-SM scalars can enhance -boson mass via the loop corrections. On the
other hand, with a proper discrete symmetry, the lightest new scalar in the
doublet can be stable and play the role of dark matter particle. We show that
the inert two Higgs doublet model can naturally handle the new -boson mass
without violating other constraints, and the preferred dark matter mass is
between and GeV. We identify three feasible parameter regions for the
thermal relic density: the co-annihilation, the Higgs resonance, and the
annihilation. We find that the first region can be fully tested
by the HL-LHC, the second region will be tightly constrained by direct
detection experiments, and the third region could yield detectable GeV
gamma-ray and antiproton signals in the Galaxy that may have been observed by
Fermi-LAT and AMS-02.Comment: 8 pages, 5 figure
Real-time Local Feature with Global Visual Information Enhancement
Local feature provides compact and invariant image representation for various
visual tasks. Current deep learning-based local feature algorithms always
utilize convolution neural network (CNN) architecture with limited receptive
field. Besides, even with high-performance GPU devices, the computational
efficiency of local features cannot be satisfactory. In this paper, we tackle
such problems by proposing a CNN-based local feature algorithm. The proposed
method introduces a global enhancement module to fuse global visual clues in a
light-weight network, and then optimizes the network by novel deep
reinforcement learning scheme from the perspective of local feature matching
task. Experiments on the public benchmarks demonstrate that the proposal can
achieve considerable robustness against visual interference and meanwhile run
in real time.Comment: 6 pages, 5 figures, 2 tables. Accepted by ICIEA 202
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