Four-state continuous variable quantum key distribution with two accelerating partners.

The field of quantum communication has gradually expanded to include satellites in Earth's orbit. However, for long-distance communication protocols, gravity and its effect on quantum states must be taken into account. By applying the equivalence principle, we can consider that the gravitational effects are equivalent to the acceleration that observers possess. A comprehensive method is proposed to find out the effect of gravity on the performance of the four-state continuous-variable quantum key distribution (CV-QKD) protocol. Finally, the effects of gravity on the QKD of each protocol are discussed, and the associated factors are also analyzed. The performance of the CV-QKD protocol under the effects of gravity is deeply analyzed by taking acceleration into consideration. Both the asymptotic key rate and the finite-size key rate are analyzed in this paper. Furthermore, significant room exists for improving the security and efficiency of space quantum communication. • The effects of gravity have a significant negative impact on the QKD protocols. • Performance differences between asymptotic and finite-size key rates under the influence of acceleration. • Discrete modulation QKD scheme breaks through the limitations of transmission over long distances. [ABSTRACT FROM AUTHOR]