3,986 research outputs found
Violating Bell's inequalities in the vacuum
We employ an approach wherein vacuum entanglement is directly probed in a
controlled manner. The approach consists of having a pair of initially
nonentangled detectors locally interact with the field for a finite duration,
such that the two detectors remain causally disconnected, and then analyzing
the resulting detector mixed state. It is demonstrated that the correlations
between arbitrarily far-apart regions of the vacuum of a relativistic free
scalar field cannot be reproduced by a local hidden-variable model, and that as
a function of the distance L between the regions, the entanglement decreases at
a slower rate than exp(-(L/cT)^3).Comment: 4 pages, 3 figures. A discussion has been added on the nature of the
relativistic corrections for the particle detectors. We argue that such
corrections do not affect the conclusion
A family of loss-tolerant quantum coin flipping protocols
We present a family of loss-tolerant quantum strong coin flipping protocols;
each protocol differing in the number of qubits employed. For a single qubit we
obtain a bias of 0.4, reproducing the result of Berl\'{i}n et al. [Phys. Rev. A
80, 062321 (2009)], while for two qubits we obtain a bias of 0.3975. Numerical
evidence based on semi-definite programming indicates that the bias continues
to decrease as the number of qubits is increased but at a rapidly decreasing
rate
Using complete measurement statistics for optimal device-independent randomness evaluation
The majority of recent works investigating the link between non-locality and
randomness, e.g. in the context of device-independent cryptography, do so with
respect to some specific Bell inequality, usually the CHSH inequality. However,
the joint probabilities characterizing the measurement outcomes of a Bell test
are richer than just the degree of violation of a single Bell inequality. In
this work we show how to take this extra information into account in a
systematic manner in order to optimally evaluate the randomness that can be
certified from non-local correlations. We further show that taking into account
the complete set of outcome probabilities is equivalent to optimizing over all
possible Bell inequalities, thereby allowing us to determine the optimal Bell
inequality for certifying the maximal amount of randomness from a given set of
non-local correlations.Comment: 12 pages, 4 figures. v2, v3, v4: minor corrections. See also the
related independent work arXiv:1309.389
Device-Independent Bit Commitment based on the CHSH Inequality
Bit commitment and coin flipping occupy a unique place in the
device-independent landscape, as the only device-independent protocols thus far
suggested for these tasks are reliant on tripartite GHZ correlations. Indeed,
we know of no other bipartite tasks, which admit a device-independent
formulation, but which are not known to be implementable using only bipartite
nonlocality. Another interesting feature of these protocols is that the
pseudo-telepathic nature of GHZ correlations -- in contrast to the generally
statistical character of nonlocal correlations, such as those arising in the
violation of the CHSH inequality -- is essential to their formulation and
analysis. In this work, we present a device-independent bit commitment protocol
based on CHSH testing, which achieves the same security as the optimal
GHZ-based protocol. The protocol is analyzed in the most general settings,
where the devices are used repeatedly and may have long-term quantum memory. We
also recast the protocol in a post-quantum setting where both honest and
dishonest parties are restricted only by the impossibility of signaling, and
find that overall the supra-quantum structure allows for greater security.Comment: 15 pages, 3 figure
Work-related basic need satisfaction as a predictor of work engagement among academic staff in Turkey
This study examines the relationship between work-related basic need satisfaction and work engagement. Data were obtained from a total of 203 academics who are employed in various universities of Turkey. In this research Work-Related Basic Need Satisfaction Scale and The Turkish Form of Utrecht Work Engagement Scale were utilized. The data were analysed through multiple regression and Pearson product-moment correlation coefficient analysis methods. The findings revealed that the sub-dimensions of work-related basic need satisfaction significantly predicted work engagement. Upper management should improve work conditions of their personnel, which are related with competency, autonomy, and relatedness needs of academics. This way, academic staff will have better efficiency in terms of work engagement, which will also result in higher work adaptation and participation.Keywords: academic staff, basic need satisfaction, work engagemen
Continuous input nonlocal games
We present a family of nonlocal games in which the inputs the players receive
are continuous. We study three representative members of the family. For the
first two a team sharing quantum correlations (entanglement) has an advantage
over any team restricted to classical correlations. We conjecture that this is
true for the third member of the family as well.Comment: Journal version, slight modification
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