Pre-Privacy Amplification: A Post-Processing Technique for Quantum Key Distribution with Application to the Simplified Trusted Relay
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Date
2023-04-26
Authors
Burniston, John
Journal Title
Journal ISSN
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Publisher
University of Waterloo
Abstract
Until quantum repeaters and quantum error correcting codes can be made commercially
viable, long distance quantum key distribution (QKD) will continue to rely on trusted
relay satellites. Strongly constrained by weight and power efficiency, little room is left
for raw computational power, lowering the key rate per second. Efforts to reduce the
computational burden on satellites, such as the simplified trusted relay (which does
not participate in privacy amplification), come at a significant cost to their key rate per
bit sent and maximum tolerable error rate. We construct a post processing technique,
that acts as a sort of pre-privacy amplification that is performed before the usual error
correction and privacy amplification steps. Loosely speaking, it provides a way to scale
between the simplified trusted relay and the usual full trusted relay. For the asymptotic
qubit six-state protocol, we demonstrate an increase in the maximum tolerable error rate
from ∼12.62% to ∼12.83% for the full trusted relay, and from ∼9.05% to ∼11.7% for the
simplified trusted relay. We also provide several sufficient conditions to determine when
unique reduction matrices will yield identical key rates.
Description
Keywords
quantum key distribution, six-state, post processing, QKD, trusted relay, simplified trusted relay, full trusted relay