16,088 research outputs found
Large Magnetoresistance in Compensated Semimetals TaAs and NbAs
We report large magnetoresistance (MR) at low temperatures in
single-crystalline nonmagnetic compounds TaAs and NbAs. Both compounds
exhibit parabolic-field-dependent MR larger than in a magnetic
field of 9 Tesla at 2 K. The MR starts to deviate from parabolic dependence
above 10 T and intends to be saturated in 45 T for TaAs at 4.2 K. The Hall
resistance measurements and band structural calculations reveal their
compensated semimetal characteristics. The large MR at low temperatures is
ascribed to a resonance effect of the balanced electrons and holes with large
mobilities. We also discuss the relation of the MR and samples' quality for
TaAs and other semimetals. We found that the magnitudes of MR are strongly
dependent on the samples' quality for different compounds.Comment: 26 pages, 11 figures, 2 table
Dual-Stage Approach Toward Hyperspectral Image Super-Resolution
Hyperspectral image produces high spectral resolution at the sacrifice of
spatial resolution. Without reducing the spectral resolution, improving the
resolution in the spatial domain is a very challenging problem. Motivated by
the discovery that hyperspectral image exhibits high similarity between
adjacent bands in a large spectral range, in this paper, we explore a new
structure for hyperspectral image super-resolution (DualSR), leading to a
dual-stage design, i.e., coarse stage and fine stage. In coarse stage, five
bands with high similarity in a certain spectral range are divided into three
groups, and the current band is guided to study the potential knowledge. Under
the action of alternative spectral fusion mechanism, the coarse SR image is
super-resolved in band-by-band. In order to build model from a global
perspective, an enhanced back-projection method via spectral angle constraint
is developed in fine stage to learn the content of spatial-spectral
consistency, dramatically improving the performance gain. Extensive experiments
demonstrate the effectiveness of the proposed coarse stage and fine stage.
Besides, our network produces state-of-the-art results against existing works
in terms of spatial reconstruction and spectral fidelity
Water and salt movement in different soil textures under various negative irrigating pressures
AbstractThis study examined the effect of different negative pressures and soil textures on water and salt movement to improve the efficiency of negative pressure irrigation (NPI). Four soil textures of varying fineness (Loamy Sand, Loam, Silty Loam, and Sandy Loam) and three negative pressure values (0, –5, and –10 kPa) were used. As irrigation time increased, wetting front movement speeds decreased, and as negative pressure increased, wetting front size decreased. Coarse soils had the smallest wetting front under greater negative pressure. Next, water infiltration rate decreased as irrigation time increased, and coarse soils had the lowest average infiltration rate under greater negative pressure. Finally, salt content increased with distance from the irrigation emitter and with increased negative pressure. Further, coarse soils were found to have decreased desalination under greater negative pressure. Thus, soil texture has a strong effect on NPI efficiency. However, by adjusting pressure values in accordance with soil texture, soil water content can be controlled and maintained. These findings are important to the improvement of NPI systems, increasing their practicality for agricultural use
Tip induced unconventional superconductivity on Weyl semimetal TaAs
Weyl fermion is a massless Dirac fermion with definite chirality, which has
been long pursued since 1929. Though it has not been observed as a fundamental
particle in nature, Weyl fermion can be realized as low-energy excitation
around Weyl point in Weyl semimetal, which possesses Weyl fermion cones in the
bulk and nontrivial Fermi arc states on the surface. As a firstly discovered
Weyl semimetal, TaAs crystal possesses 12 pairs of Weyl points in the momentum
space, which are topologically protected against small perturbations. Here, we
report for the first time the tip induced superconductivity on TaAs crystal by
point contact spectroscopy. A conductance plateau and sharp double dips are
observed in the point contact spectra, indicating p-wave like unconventional
superconductivity. Furthermore, the zero bias conductance peak in low
temperature regime is detected, suggesting potentially the existence of
Majorana zero modes. The experimentally observed tunneling spectra can be
interpreted with a novel mirror-symmetry protected topological superconductor
induced in TaAs, which can exhibit zero bias and double finite bias peaks, and
double conductance dips in the measurements. Our work can open a broad avenue
in search for new topological superconducting phases from topological Weyl
materials and trigger intensive investigations for pursuing Majorana fermions
Robust interface between flying and topological qubits
Hybrid architectures, consisting of conventional and topological qubits, have
recently attracted much attention due to their capability in consolidating the
robustness of topological qubits and the universality of conventional qubits.
However, these two kinds of qubits are normally constructed in significantly
different energy scales, and thus this energy mismatch is a major obstacle for
their coupling that supports the exchange of quantum information between them.
Here, we propose a microwave photonic quantum bus for a direct strong coupling
between the topological and conventional qubits, in which the energy mismatch
is compensated by the external driving field via the fractional ac Josephson
effect. In the framework of tight-binding simulation and perturbation theory,
we show that the energy splitting of the topological qubits in a finite length
nanowire is still robust against local perturbations, which is ensured not only
by topology, but also by the particle-hole symmetry. Therefore, the present
scheme realizes a robust interface between the flying and topological qubits.
Finally, we demonstrate that this quantum bus can also be used to generate
multipartitie entangled states with the topological qubits.Comment: Accepted for publication in Scientific Report
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