66,223 research outputs found
Dynamical creation of entanglement by homodyne-mediated feedback
For two two-level atoms coupled to a single-mode cavity field that is driven
and heavily damped, the steady-state can be entangled by shining an
un-modulated driving laser on the system [S.Schneider, G. J. Milburn Phys. Rev
A 65, 042107, 2002]. We present a scheme to significantly increase the
steady-state entanglement by using homodyne-mediated feedback, in which the
driving laser is modulated by the homodyne photocurrent derived from the cavity
output. Such feedback can increase the nonlinear response to both the
decoherence process of the two-qubit system and the coherent evolution of
individual qubits. We present the properties of the entangled states using the
SO(3) Q function.Comment: 8 page
Monte Carlo Algorithm for Simulating Reversible Aggregation of Multisite Particles
We present an efficient and exact Monte Carlo algorithm to simulate
reversible aggregation of particles with dedicated binding sites. This method
introduces a novel data structure of dynamic bond tree to record clusters and
sequences of bond formations. The algorithm achieves a constant time cost for
processing cluster association and a cost between and
for processing bond dissociation in clusters with bonds.
The algorithm is statistically exact and can reproduce results obtained by the
standard method. We applied the method to simulate a trivalent ligand and a
bivalent receptor clustering system and obtained an average scaling of
for processing bond dissociation in acyclic
aggregation, compared to a linear scaling with the cluster size in standard
methods. The algorithm also demands substantially less memory than the
conventional method.Comment: 8 pages, 3 figure
Topological Weyl and Node-Line Semimetals in Ferromagnetic Vanadium-Phosphorous-Oxide -VOPO Compound
We propose that the topological semimetal features can co-exist with
ferromagnetic ground state in vanadium-phosphorous-oxide -VOPO
compound from first-principles calculations. In this magnetic system with
inversion symmetry, the direction of magnetization is able to manipulate the
symmetric protected band structures from a node-line type to a Weyl one in the
presence of spin-orbital-coupling. The node-line semimetal phase is protected
by the mirror symmetry with the reflection-invariant plane perpendicular to
magnetic order. Within mirror symmetry breaking due to the magnetization along
other directions, the gapless node-line loop will degenerate to only one pair
of Weyl points protected by the rotational symmetry along the magnetic axis,
which are largely separated in momentum space. Such Weyl semimetal phase
provides a nice candidate with the minimum number of Weyl points in a condensed
matter system. The results of surface band calculations confirm the non-trivial
topology of this proposed compound. This findings provide a realistic candidate
for the investigation of topological semimetals with time-reversal symmetry
breaking, particularly towards the realization of quantum anomalous Hall effect
in Weyl semimetals.Comment: 5 pages, 4 figure
Analysis of hadronic invariant mass spectrum in inclusive charmless semileptonic B decays
We make an analysis of the hadronic invariant mass spectrum in inclusive
charmless semileptonic B meson decays in a QCD-based approach. The decay width
is studied as a function of the invariant mass cut. We examine their
sensitivities to the parameters of the theory. The theoretical uncertainties in
the determination of from the hadronic invariant mass spectrum are
investigated. A strategy for improving the theoretical accuracy in the value of
is described.Comment: 13 pages, 5 Postscript figure
Analysis of Thermal Environment of Open Community Streets in Winter in Northern China
The long winter time and the harsh outdoor environment cause many inconveniences of the outdoor activities to urban residents in severe cold areas. Therefore, it is urgent to study and improve the thermal environment in urban residential streets. This paper focuses on winter thermal environment of streets in open communities of northern China, by carrying out field measurements according to the characteristics of cold climate and urban residential areas. The results show that the aspect ratios of streets can directly affect their thermal environment. With the aspect ratio increases, the air temperature decreases and the wind speed increases. At the same time, facade openings can make the average globe temperature significantly increased in the streets. This paper provides basic data for the further study of thermal environment in urban streets and the optimization design of street spaces
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