1,710 research outputs found
EPR correlations and EPW distributions revisited
It is shown that Bell's proof of violation of local realism in phase space is
incorrect. Using Bell's approach, a violation can be derived also for
nonnegative Wigner distributions. The error is found to lie in the use of an
unnormalizable Wigner function.Comment: 7 pages, 1 figure, accepted to Phys. Lett.
Optimization of Bell's Inequality Violation For Continuous Variable Systems
Two mode squeezed vacuum states allow Bell's inequality violation (BIQV) for
all non-vanishing squeezing parameter . Maximal violation occurs at
when the parity of either component averages to zero. For a
given entangled {\it two spin} system BIQV is optimized via orientations of the
operators entering the Bell operator (cf. S. L. Braunstein, A. Mann and M.
Revzen: Phys. Rev. Lett. {\bf68}, 3259 (1992)). We show that for finite
in continuous variable systems (and in general whenever the dimensionality of
the subsystems is greater than 2) additional parameters are present for
optimizing BIQV. Thus the expectation value of the Bell operator depends, in
addition to the orientation parameters, on configuration parameters.
Optimization of these configurational parameters leads to a unique maximal BIQV
that depends only on The configurational parameter variation is used
to show that BIQV relation to entanglement is, even for pure state, not
monotonic.Comment: An example added; shows that the amount of Bell's inequality
violation as a measure of entanglement is doubtfu
Optimal States for Bell inequality Violations using Quadrature Phase Homodyne Measurements
We identify what ideal correlated photon number states are to required to
maximize the discrepancy between local realism and quantum mechanics when a
quadrature homodyne phase measurement is used. Various Bell inequality tests
are considered.Comment: 6 pages, 5 Figure
Why the Tsirelson bound?
Wheeler's question 'why the quantum' has two aspects: why is the world
quantum and not classical, and why is it quantum rather than superquantum,
i.e., why the Tsirelson bound for quantum correlations? I discuss a remarkable
answer to this question proposed by Pawlowski et al (2009), who provide an
information-theoretic derivation of the Tsirelson bound from a principle they
call 'information causality.'Comment: 17 page
Maximal violation of Bell inequality for any given two-qubit pure state
In the case of bipartite two qubits systems, we derive the analytical
expression of bound of Bell operator for any given pure state. Our result not
only manifest some properties of Bell inequality, for example which may be
violated by any pure entangled state and only be maximally violated for a
maximally entangled state, but also give the explicit values of maximal
violation for any pure state. Finally we point out that for two qubits systems
there is no mixed state which can produce maximal violation of Bell inequality.Comment: 3 pages, 1 figure
Maximal Bell's Inequality Violation for Non Maximal Entanglement
Bell's inequality violation (BIQV) for correlations of polarization is
studied for a {\it product} state of two two-mode squeezed vacuum (TMSV)
states. The violation allowed is shown to attain its maximal limit for all
values of the squeezing parameter, . We show via an explicit example
that a state whose entanglement is not maximal allow maximal BIQV. The Wigner
function of the state is non negative and the average value of either
polarization is nil.Comment: 8 pages, latex, no figure
General criterion for the entanglement of two indistinguishable particles
We relate the notion of entanglement for quantum systems composed of two
identical constituents to the impossibility of attributing a complete set of
properties to both particles. This implies definite constraints on the
mathematical form of the state vector associated with the whole system. We then
analyze separately the cases of fermion and boson systems, and we show how the
consideration of both the Slater-Schmidt number of the fermionic and bosonic
analog of the Schmidt decomposition of the global state vector and the von
Neumann entropy of the one-particle reduced density operators can supply us
with a consistent criterion for detecting entanglement. In particular, the
consideration of the von Neumann entropy is particularly useful in deciding
whether the correlations of the considered states are simply due to the
indistinguishability of the particles involved or are a genuine manifestation
of the entanglement. The treatment leads to a full clarification of the subtle
aspects of entanglement of two identical constituents which have been a source
of embarrassment and of serious misunderstandings in the recent literature.Comment: 18 pages, Latex; revised version: Section 3.2 rewritten, new Theorems
added, reference [1] corrected. To appear on Phys.Rev.A 70, (2004
Entangled qutrits violate local realism stronger than qubits - an analytical proof
In Kaszlikowski [Phys. Rev. Lett. {\bf 85}, 4418 (2000)], it has been shown
numerically that the violation of local realism for two maximally entangled
-dimensional () quantum objects is stronger than for two maximally
entangled qubits and grows with . In this paper we present the analytical
proof of this fact for N=3.Comment: 5 page
Parallel Repetition of Entangled Games with Exponential Decay via the Superposed Information Cost
In a two-player game, two cooperating but non communicating players, Alice
and Bob, receive inputs taken from a probability distribution. Each of them
produces an output and they win the game if they satisfy some predicate on
their inputs/outputs. The entangled value of a game is the
maximum probability that Alice and Bob can win the game if they are allowed to
share an entangled state prior to receiving their inputs.
The -fold parallel repetition of consists of instances of
where the players receive all the inputs at the same time and produce all
the outputs at the same time. They win if they win each instance of .
In this paper we show that for any game such that , decreases exponentially in . First, for
any game on the uniform distribution, we show that , where and are the sizes of the input
and output sets. From this result, we show that for any entangled game ,
where is the input distribution of and
. This implies parallel
repetition with exponential decay as long as for
general games. To prove this parallel repetition, we introduce the concept of
\emph{Superposed Information Cost} for entangled games which is inspired from
the information cost used in communication complexity.Comment: In the first version of this paper we presented a different, stronger
Corollary 1 but due to an error in the proof we had to modify it in the
second version. This third version is a minor update. We correct some typos
and re-introduce a proof accidentally commented out in the second versio
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Determining Item Screening Criteria Using Cost-Benefit Analysis
Successful testing programs rely on high-quality test items to produce reliable scores and defensible exams. However, determining what statistical screening criteria are most appropriate to support these goals can be daunting. This study describes and demonstrates cost-benefit analysis as an empirical approach to determining appropriate screening criteria for a given testing program and purpose. Using a certification exam’s item pool and simulation we illustrate how to examine a wide range of screening criteria and reach an acceptable balance between the number of items screened out (cost) and pass/fail classification accuracy (benefit). Accessed 699 times on https://pareonline.net from April 09, 2019 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right
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