4,289 research outputs found
Quantum key distribution without alternative measurements and rotations
A quantum key distribution protocol based on entanglement swapping is
proposed. Through choosing particles by twos from the sequence and performing
Bell measurements, two communicators can detect eavesdropping and obtain the
secure key. Because the two particles measured together are selected out
randomly, we need neither alternative measurements nor rotations of the Bell
states to obtain security.Comment: 11 pages, no figures, a modified version of quant-ph/0412014, add a
security proof and delete the identification par
Historical and interpretative aspects of quantum mechanics: a physicists' naive approach
Many theoretical predictions derived from quantum mechanics have been
confirmed experimentally during the last 80 years. However, interpretative
aspects have long been subject to debate. Among them, the question of the
existence of hidden variables is still open. We review these questions, paying
special attention to historical aspects, and argue that one may definitively
exclude local realism on the basis of present experimental outcomes. Other
interpretations of Quantum Mechanics are nevertheless not excluded.Comment: 30 page
No-relationship between impossibility of faster-than-light quantum communication and distinction of ensembles with the same density matrix
It has been claimed in the literature that impossibility of faster-than-light
quantum communication has an origin of indistinguishability of ensembles with
the same density matrix. We show that the two concepts are not related. We
argue that: 1) even with an ideal single-atom-precision measurement, it is
generally impossible to produce two ensembles with exactly the same density
matrix; or 2) to produce ensembles with the same density matrix, classical
communication is necessary. Hence the impossibility of faster-than-light
communication does not imply the indistinguishability of ensembles with the
same density matrix.Comment: 4 pages and 3 figure
Playing games with EPR-type experiments
An approach towards quantum games is proposed that uses the unusual
probabilities involved in EPR-type experiments directly in two-player games.Comment: Submitted to the J. Phys. A: Maths & Gen., revised in the light of
referees' comments, 14 pages, no figur
Event-by-event Simulation of Quantum Cryptography Protocols
We present a new approach to simulate quantum cryptography protocols using
event-based processes. The method is validated by simulating the BB84 protocol
and the Ekert protocol, both without and with the presence of an eavesdropper
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