25,615 research outputs found
Work Function of Single-wall Silicon Carbide Nanotube
Using first-principles calculations, we study the work function of single
wall silicon carbide nanotube (SiCNT). The work function is found to be highly
dependent on the tube chirality and diameter. It increases with decreasing the
tube diameter. The work function of zigzag SiCNT is always larger than that of
armchair SiCNT. We reveal that the difference between the work function of
zigzag and armchair SiCNT comes from their different intrinsic electronic
structures, for which the singly degenerate energy band above the Fermi level
of zigzag SiCNT is specifically responsible. Our finding offers potential
usages of SiCNT in field-emission devices.Comment: 3 pages, 3 figure
A Probabilistic Embedding Clustering Method for Urban Structure Detection
Urban structure detection is a basic task in urban geography. Clustering is a
core technology to detect the patterns of urban spatial structure, urban
functional region, and so on. In big data era, diverse urban sensing datasets
recording information like human behaviour and human social activity, suffer
from complexity in high dimension and high noise. And unfortunately, the
state-of-the-art clustering methods does not handle the problem with high
dimension and high noise issues concurrently. In this paper, a probabilistic
embedding clustering method is proposed. Firstly, we come up with a
Probabilistic Embedding Model (PEM) to find latent features from high
dimensional urban sensing data by learning via probabilistic model. By latent
features, we could catch essential features hidden in high dimensional data
known as patterns; with the probabilistic model, we can also reduce uncertainty
caused by high noise. Secondly, through tuning the parameters, our model could
discover two kinds of urban structure, the homophily and structural
equivalence, which means communities with intensive interaction or in the same
roles in urban structure. We evaluated the performance of our model by
conducting experiments on real-world data and experiments with real data in
Shanghai (China) proved that our method could discover two kinds of urban
structure, the homophily and structural equivalence, which means clustering
community with intensive interaction or under the same roles in urban space.Comment: 6 pages, 7 figures, ICSDM201
Alternative scheme for two-qubit conditional phase gate by adiabatic passage under dissipation
We check a recent proposal [H. Goto and K. Ichimura Phys. Rev. A 70, 012305
(2004)] for controlled phase gate through adiabatic passage under the influence
of spontaneous emission and the cavity decay. We show a modification of above
proposal could be used to generate the necessary conditional phase gates in the
two-qubit Grover search. Conditioned on no photon leakage either from the
atomic excited state or from the cavity mode during the gating period, we
numerically analyze the success probability and the fidelity of the two-qubit
conditional phase gate by adiabatic passage. The comparison made between our
proposed gating scheme and a previous one shows that Goto and Ichimura's scheme
is an alternative and feasible way in the optical cavity regime for two-qubit
gates and could be generalised in principle to multi-qubit gates.Comment: to appear in J. Phys.
Temperature - pressure phase diagram of the superconducting iron pnictide LiFeP
Electrical-resistivity and magnetic-susceptibility measurements under
hydrostatic pressure up to p = 2.75 GPa have been performed on superconducting
LiFeP. A broad superconducting (SC) region exists in the temperature - pressure
(T-p) phase diagram. No indications for a spin-density-wave transition have
been found, but an enhanced resistivity coefficient at low pressures hints at
the presence of magnetic fluctuations. Our results show that the
superconducting state in LiFeP is more robust than in the isostructural and
isoelectronic LiFeAs. We suggest that this finding is related to the nearly
regular [FeP_4] tetrahedron in LiFeP.Comment: 4 pages, 4 figure
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