1,584 research outputs found
Topological phases protected by point group symmetry
We consider symmetry protected topological (SPT) phases with crystalline
point group symmetry, dubbed point group SPT (pgSPT) phases. We show that such
phases can be understood in terms of lower-dimensional topological phases with
on-site symmetry, and can be constructed as stacks and arrays of these
lower-dimensional states. This provides the basis for a general framework to
classify and characterize bosonic and fermionic pgSPT phases, that can be
applied for arbitrary crystalline point group symmetry and in arbitrary spatial
dimension. We develop and illustrate this framework by means of a few examples,
focusing on three-dimensional states. We classify bosonic pgSPT phases and
fermionic topological crystalline superconductors with (reflection)
symmetry, electronic topological crystalline insulators (TCIs) with symmetry, and bosonic pgSPT phases with symmetry,
which is generated by two perpendicular mirror reflections. We also study
surface properties, with a focus on gapped, topologically ordered surface
states. For electronic TCIs we find a classification, where
the corresponds to known states obtained from non-interacting electrons,
and the corresponds to a "strongly correlated" TCI that requires strong
interactions in the bulk. Our approach may also point the way toward a general
theory of symmetry enriched topological (SET) phases with crystalline point
group symmetry.Comment: v2: Minor changes/additions to introduction and discussion sections,
references added, published version. 21 pages, 11 figure
Investigation of Langdon effect on the nonlinear evolution of SRS from the early-stage inflation to the late-stage development of secondary instabilities
In a laser-irradiated plasma, the Langdon effect can result in a
super-Gaussian electron energy distribution function (EEDF), imposing
significant influences on the stimulated backward Raman scattering (SRS). In
this work, the influence of a super-Gaussian EEDF on the nonlinear evolution of
SRS is investigated by three wave model simulation and Vlasov-Maxwell
simulation for plasma parameters covering a wide range of k{\lambda}De from
0.19 to 0.48 at both high and low intensity laser drives. In the early-stage of
SRS evolution, it is found that besides the kinetic effects due to electron
trapping [Phys. Plasmas 25, 100702 (2018)], the Langdon effect can also
significantly widen the parameter range for the absolute growth of SRS, and the
time for the absolute SRS to reach saturation is greatly shorten by Langdon
effect within certain parameter region. In the late-stage of SRS, when
secondary instabilities such as decay of the electron plasma wave to beam
acoustic modes, rescattering, and Langmuir decay instability become important,
the Langdon effect can influence the reflectivity of SRS by affecting the
secondary processes. The comprehension of Langdon effect on nonlinear evolution
and saturation of SRS would contribute to a better understanding and prediction
of SRS in inertial confinement fusion
Ground-Challenge: A Multi-sensor SLAM Dataset Focusing on Corner Cases for Ground Robots
High-quality datasets can speed up breakthroughs and reveal potential
developing directions in SLAM research. To support the research on corner cases
of visual SLAM systems, this paper presents Ground-Challenge: a challenging
dataset comprising 36 trajectories with diverse corner cases such as aggressive
motion, severe occlusion, changing illumination, few textures, pure rotation,
motion blur, wheel suspension, etc. The dataset was collected by a ground robot
with multiple sensors including an RGB-D camera, an inertial measurement unit
(IMU), a wheel odometer and a 3D LiDAR. All of these sensors were
well-calibrated and synchronized, and their data were recorded simultaneously.
To evaluate the performance of cutting-edge SLAM systems, we tested them on our
dataset and demonstrated that these systems are prone to drift and fail on
specific sequences. We will release the full dataset and relevant materials
upon paper publication to benefit the research community. For more information,
visit our project website at https://github.com/sjtuyinjie/Ground-Challenge
Stability of Strutinsky Shell Correction Energy in Relativistic Mean Field Theory
The single-particle spectrum obtained from the relativistic mean field (RMF)
theory is used to extract the shell correction energy with the Strutinsky
method. Considering the delicate balance between the plateau condition in the
Strutinsky smoothing procedure and the convergence for the total binding
energy, the proper space sizes used in solving the RMF equations are
investigated in detail by taking 208Pb as an example. With the proper space
sizes, almost the same shell correction energies are obtained by solving the
RMF equations either on basis space or in coordinate space.Comment: 9 pages, 4 figure
Multi-microjoule GaSe-based mid-infrared optical parametric amplifier with an ultra-broad idler spectrum covering 4.2-16 {\mu}m
We report a multi-microjoule, ultra-broadband mid-infrared optical parametric
amplifier based on a GaSe nonlinear crystal pumped at ~2 {\mu}m. The generated
idler pulse has a flat spectrum spanning from 4.5 to 13.3 {\mu}m at -3 dB and
4.2 to 16 {\mu}m in the full spectral range, with a central wavelength of 8.8
{\mu}m. The proposed scheme supports a sub-cycle Fourier-transform-limited
pulse width. A (2+1)-dimensional numerical simulation is employed to reproduce
the obtained idler spectrum. To our best knowledge, this is the broadest -3 dB
spectrum ever obtained by optical parametric amplifiers in this spectral
region. The idler pulse energy is ~3.4 {\mu}J with a conversion efficiency of
~2% from the ~2 {\mu}m pump to the idler pulse.Comment: 5 pages, 5 figure
Targeted absolute quantitative proteomics with SILAC internal standards and unlabeled full‐length protein calibrators (TAQSI)
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116918/1/rcm7482.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/116918/2/rcm7482_am.pd
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