Optimal ratio between phase basis and bit basis in QKD

TL;DR

This paper investigates the optimal ratio of phase to bit basis in the BB84 quantum key distribution protocol to maximize key rate while considering security constraints.

Contribution

It derives the optimal basis ratio in BB84 under security constraints, improving the understanding of basis choice for enhanced key generation.

Findings

Optimal basis ratio derived for security constraints

Enhanced key rate potential identified

Framework for basis ratio optimization established

Abstract

In the original BB84 protocol, the bit basis and the phase basis are used with equal probability. Lo et al (J. of Cryptology, 18, 133-165 (2005)) proposed to modify the ratio between the two bases by increasing the final key generation rate. However, the optimum ratio has not been derived. In this letter, in order to examine this problem, the ratio between the two bases is optimized for exponential constraints given Eve's information distinguishability and the final error probability.