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BB84 Quantum Key Distribution: Difference between revisions
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# Sifting: the BB84 protocol can also be described in a symmetric way. This means that the inputs <math>0</math> and <math>1</math> are chosen with the same probability. In that case only <math>1/2</math> of the generated bits are discarded during the sifting process. Indeed, in the symmetric protocol, Alice and Bob measure in the same basis in about half of the rounds. | # Sifting: the BB84 protocol can also be described in a symmetric way. This means that the inputs <math>0</math> and <math>1</math> are chosen with the same probability. In that case only <math>1/2</math> of the generated bits are discarded during the sifting process. Indeed, in the symmetric protocol, Alice and Bob measure in the same basis in about half of the rounds. | ||
# [https://dl.acm.org/citation.cfm?id=1058094 LCA05] the asymmetric protocol was introduced to make this more efficient protocol presented in this article. | # [https://dl.acm.org/citation.cfm?id=1058094 LCA05] the asymmetric protocol was introduced to make this more efficient protocol presented in this article. | ||
# A post-processing of the key using 2-way classical communication, denoted [[Advantage distillation]], can increase the QBER tolarance up to <math>18.9\%</math> (3). | |||
# We remark that in [[BB84 Quantum Key Distribution#Pseudo Code|Pseudo Code]], the QBER in the <math>Z</math> basis is not estimated during the protocol. Instead Alice and Bob make use of a previous estimate for the value of <math>Q_Z</math> and the error correction step, Step 4 in the pseudo-code, will make sure that this estimation is correct. Indeed, if the real QBER is higher than the estimated value <math>Q_Z</math>, [[BB84 Quantum Key Distribution#Pseudo Code|Pseudo Code]] will abort in the Step 4 with very high probability. | |||
# The BB84 can be equivalently implemented by distributing [[EPR pairs]] and Alice and Bob making measurements in the <math>Z</math> and <math>X</math> basis, however this required a [[entanglement distribution]] network stage. | |||