21,152 research outputs found
Formation of Long Single Quantum Dots in High Quality InSb Nanowires Grown by Molecular Beam Epitaxy
We report on realization and transport spectroscopy study of single quantum
dots (QDs) made from InSb nanowires grown by molecular beam epitaxy (MBE). The
nanowires employed are 50-80 nm in diameter and the QDs are defined in the
nanowires between the source and drain contacts on a Si/SiO substrate. We
show that highly tunable QD devices can be realized with the MBE-grown InSb
nanowires and the gate-to-dot capacitance extracted in the many-electron
regimes is scaled linearly with the longitudinal dot size, demonstrating that
the devices are of single InSb nanowire QDs even with a longitudinal size of
~700 nm. In the few-electron regime, the quantum levels in the QDs are resolved
and the Land\'e g-factors extracted for the quantum levels from the
magnetotransport measurements are found to be strongly level-dependent and
fluctuated in a range of 18-48. A spin-orbit coupling strength is extracted
from the magnetic field evolutions of a ground state and its neighboring
excited state in an InSb nanowire QD and is on the order of ~300 eV. Our
results establish that the MBE-grown InSb nanowires are of high crystal quality
and are promising for the use in constructing novel quantum devices, such as
entangled spin qubits, one-dimensional Wigner crystals and topological quantum
computing devices.Comment: 19 pages, 5 figure
Quantum Information Approach to Bose-Einstein Condensate in a Tilted Double-Well System
We study the ground state properties of bosons in a tilted double-well
system. We use fidelity susceptibility to identify the possible ground state
transitions under different tilt values. For a very small tilt (for example
), two transitions are found. For a moderate tilt (for example
), only one transition is found. For a large tilt (for example
), no transition is found. We explain this by analyzing the spectrum
of the ground state. The quantum discord and total correlation of the ground
state under different tilts are also calculated to indicate those transitions.
In the transition region, both quantities have peaks decaying exponentially
with particle number . This means for a finite-size system the transition
region cannot be explained by the mean-field theory, but in the large- limit
it can be.Comment: 5 pages, 5 figures, slightly different from the published versio
A Coarse-to-Fine Algorithm for Registration in 3D Street-View Cross-Source Point Clouds
© 2016 IEEE. With the development of numerous 3D sensing technologies, object registration on cross-source point cloud has aroused researchers' interests. When the point clouds are captured from different kinds of sensors, there are large and different kinds of variations. In this study, we address an even more challenging case in which the differently-source point clouds are acquired from a real street view. One is produced directly by the LiDAR system and the other is generated by using VSFM software on image sequence captured from RGB cameras. When it confronts to large scale point clouds, previous methods mostly focus on point-to-point level registration, and the methods have many limitations.The reason is that the least mean error strategy shows poor ability in registering large variable cross-source point clouds. In this paper, different from previous ICP-based methods, and from a statistic view, we propose a effective coarse-to-fine algorithm to detect and register a small scale SFM point cloud in a large scale Lidar point cloud. Seen from the experimental results, the model can successfully run on LiDAR and SFM point clouds, hence it can make a contribution to many applications, such as robotics and smart city development
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