38,529 research outputs found
Some remarks on Bell non-locality and Einstein-Podolsky-Rosen steering of bipartite states
Bell nonlocality and Einstein-Podolsky-Rosen (EPR) steering are every
important quantum correlations of a composite quantum system. Bell nonlocality
of a bipartite state is a quantum correlation demonstrated by some local
quantum measurements, while EPR steering is another form of quantum
correlations, observed firstly by Schrodinger in the context of famous EPR
paradox. In this paper, we give some remarks on Bell nonlocality and EPR
steering of bipartite states, including mathematical definitions and
characterizations of these two quantum correlations, the convexity and
closedness of the set of all Bell local states and the set of all EPR
unsteerable states. We also derive a EPR-steering criteria, with which the EPR
steerability of the maximally entangled states are checked
The role of in production
We study the near-threshold production mechanism in nucleon-nucleon
and collisions under the assumption that sub-threshold resonance
is predominant. In an effective Lagrangian approach which gives a
reasonable description to the and
reactions, it is found that t-channel exchange make the dominate
contribution to the process, and a value of 6.5 for the
ratio of to is
predicted. A strong coupling strength of to () is extracted from a combined analysis to and , and the possible implication to the intrinsic
component of is explored.Comment: 12pp + 5fig
Harnack Estimates for Conjugate Heat Kernel on Evolving Manifolds
In this article we derive Harnack estimates for conjugate heat kernel in an
abstract geometric flow. Our calculation involves a correction term D. When D
is nonnegative, we are able to obtain a Harnack inequality. Our abstract
formulation provides a unified framework for some known results, in particular
including corresponding results of Ni, Perelman, and Tran as special cases.
Moreover it leads to new results in the setting of Ricci-Harmonic flow and mean
curvature flow in Lorentzian manifolds with nonnegative sectional curvature.Comment: 16
Hyper-Graph Based Database Partitioning for Transactional Workloads
A common approach to scaling transactional databases in practice is
horizontal partitioning, which increases system scalability, high availability
and self-manageability. Usu- ally it is very challenging to choose or design an
optimal partitioning scheme for a given workload and database. In this
technical report, we propose a fine-grained hyper-graph based database
partitioning system for transactional work- loads. The partitioning system
takes a database, a workload, a node cluster and partitioning constraints as
input and out- puts a lookup-table encoding the final database partitioning
decision. The database partitioning problem is modeled as a multi-constraints
hyper-graph partitioning problem. By deriving a min-cut of the hyper-graph, our
system can min- imize the total number of distributed transactions in the
workload, balance the sizes and workload accesses of the partitions and satisfy
all the partition constraints imposed. Our system is highly interactive as it
allows users to im- pose partition constraints, watch visualized partitioning
ef- fects, and provide feedback based on human expertise and indirect domain
knowledge for generating better partition- ing schemes
Approximation of Mean Field Games to N-Player Stochastic Games, with Singular Controls
This paper establishes that -player stochastic games with singular
controls, either of bounded velocity or of finite variation, can both be
approximated by mean field games (MFGs) with singular controls of bounded
velocity. More specifically, it shows i) the optimal control to an MFG with
singular controls of a bounded velocity is shown to be an
-NE to an -player game with singular controls of the bounded
velocity, with , and (ii) the optimal
control to this MFG is an -NE to an
-player game with singular controls of finite variation, where
is an error term that depends on .
This work generalizes the classical result on approximation -player games
by MFGs, by allowing for discontinuous controls
Topological textures and their bifurcation processes in 2D ferromagnetic thin films
In this paper, by the use of the topological current theory, the topological
structures and the dynamic processes in thin-film ferromagnetic systems are
investigated directly from viewpoint of topology. It is found that the
topological charge of a thin-film ferromagnetic system can be changed by
annihilation or creation processes of opposite polarized vortex-antivortex
pairs taking place at space-time singularities of the normalized magnetization
vector field of the system, the variation of the topological charge is integer
and can further be expressed in terms of the Hopf indices and Brouwer degrees
of the magnetization vector field around the singularities. Moreover, the
change of the topological charge of the system is crucial to vortex core
reversal processes in ferromagnetic thin films. With the help of the
topological current theory and implicit function theorem, the processes of
vortex merging, splitting as well as vortex coreComment: 10 pages, 8 figure
New approach for fabrication germanene with Dirac electrons preserved: A first principle study
How to obtain germanene with Dirac electrons preserved is still an open
challenge. Here we report a sandwich-dehydrogenation approach, i.e., to
fabricate germanene through dehydrogenating germanane in a sandwiched
structure. The dehydrogenation can spontaneously occur for the sandwiched
structure, which overcomes the problem of amorphization in the heating
dehydrogenation approach. The obtained germanene preserve the Dirac electronic
properties very well. Moreover, the Fermi velocity of germanene can be
efficiently manipulated through controlling the interlayer spacing between
germanane and the sandwiching surfaces. Our results indicate a guideline for
fabrication of prefect two-dimensional materials.Comment: 23 pages,6 figure
Generalization Bounds for Metric and Similarity Learning
Recently, metric learning and similarity learning have attracted a large
amount of interest. Many models and optimisation algorithms have been proposed.
However, there is relatively little work on the generalization analysis of such
methods. In this paper, we derive novel generalization bounds of metric and
similarity learning. In particular, we first show that the generalization
analysis reduces to the estimation of the Rademacher average over
"sums-of-i.i.d." sample-blocks related to the specific matrix norm. Then, we
derive generalization bounds for metric/similarity learning with different
matrix-norm regularisers by estimating their specific Rademacher complexities.
Our analysis indicates that sparse metric/similarity learning with -norm
regularisation could lead to significantly better bounds than those with
Frobenius-norm regularisation. Our novel generalization analysis develops and
refines the techniques of U-statistics and Rademacher complexity analysis.Comment: 20 page
Ultrafast Manipulation of a Double Quantum Dot via Lyapunov Control Method
For a double quantum dot (DQD) system, here we propose alternative ultrafast
manipulate approach: Lyapunov control method, to transfer the state from R to L
on the picosecond scale, orders of magnitude faster and transfer probability
higher than the previously measured electrically controlled charge- or
spin-based quits. The control laws are composed of two-direction components,
one is used to eliminate the dissipation in the system, another is used to
transfer the state. The control theory's stability ensures the system can be
transferred to the target state in high probability, and the coefficients in
control laws leads very fast convergence. The role of eliminating the
dissipation plays the suppression of decoherence effect. Numerical simulation
results show that under the realistic implementation conditions, the transfer
probability and fidelity can be increased up to 98.79% and 98.97%,
respectively. This is the first result directly applicable to a DQD system's
state transferring using the Lyapunov control method. We also give specific
experimental realization scheme.Comment: 8 pages, 4 figure
Uniqueness of planar vortex patch in incompressible steady flow
We investigate a steady planar flow of an ideal fluid in a bounded simple
connected domain and focus on the vortex patch problem with prescribed
vorticity strength. There are two methods to deal with the existence of
solutions for this problem: the vorticity method and the stream function
method. A long standing open problem is whether these two entirely different
methods result in the same solution. In this paper, we will give a positive
answer to this problem by studying the local uniqueness of the solutions.
Another result obtained in this paper is that if the domain is convex, then the
vortex patch problem has a unique solution.Comment: 36 page
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