3,781 research outputs found
Monte Carlo approach to the evaluation of the security of device-independent quantum key distribution
We present a generic study on the information-theoretic security of
multi-setting device-independent quantum key distribution protocols, i.e., ones
that involve more than two measurements (or inputs) for each party to perform,
and yield dichotomic results (or outputs). The approach we develop, when
applied in protocols with either symmetric or asymmetric Bell experiments,
yields nontrivial estimates of the secure key rates, along with those of the
minimum detection efficiencies of the measuring devices. The results imply that
increasing the number of measurements may lower the minimum efficiency required
by the security criterion. The improvement, however, depends on (i) the choice
of multi-setting Bell inequalities chosen to be tested in a protocol, and (ii)
either a symmetric or asymmetric Bell experiment is considered. Our results
serve as an advance toward the quest for evaluating security and reducing
efficiency requirement of applying device-independent quantum key distribution
in scenarios without heralding.Comment: 10 pages, 10 figures, 3 tables; minor changes, close to the submitted
manuscrip
Demonstrating quantum contextuality of indistinguishable particles by a single family of noncontextuality inequalities
Quantum theory has the intriguing feature that is inconsistent with
noncontextual hidden variable models, for which the outcome of a measurement
does not depend on which other compatible measurements are being performed
concurrently. While various proofs of such contextual behavior of quantum
systems have been established, relatively little is known concerning the
possibility to demonstrate this intriguing feature for indistinguishable
particles. Here, we show in a simple and systematic manner that with projective
measurements alone, it is possible to demonstrate quantum contextuality for
such systems of arbitrary Hilbert space dimensions, including those
corresponding to a qubit. Our demonstration is applicable to a single fermion
as well as multiple fermions, and thus also a composite boson formed from an
even number of fermions. In addition, our approach gives a clear demonstration
of the intimate connection between complementarity and contextuality, two
seemingly unrelated aspects of quantum theory.Comment: 9 pages, no figure; Major changes; More changes. Accepted in
Scientific Report
State-independent contextuality sets for a qutrit
We present a generalized set of complex rays for a qutrit in terms of
parameter , a -th root of unity. Remarkably, when ,
the set reduces to two well known state-independent contextuality (SIC) sets:
the Yu-Oh set and the Bengtsson-Blanchfield-Cabello set. Based on the
Ramanathan-Horodecki criterion and the violation of a noncontextuality
inequality, we have proven that the sets with and are SIC, while
the set with is not. Our generalized set of rays will theoretically
enrich the study of SIC proof, and experimentally stimulate the novel
application to quantum information processing.Comment: 4 pages, 2 figures; revised versio
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