Temporal steering and security of quantum key distribution with mutually-unbiased bases against individual attacks

TL;DR

This paper explores how temporal steering relates to quantum key distribution security, demonstrating that certain quantum correlations can ensure security against individual attacks in protocols like BB84 and B98.

Contribution

It introduces a temporal steerable weight and analyzes the role of temporal steering inequalities in quantum cryptography security.

Findings

Temporal steering inequalities relate to quantum bit error rates.

Temporal steerable weight reveals monogamy of correlations.

Security against individual attacks is guaranteed via temporal steering analysis.

Abstract

Temporal steering, which is a temporal analogue of Einstein-Podolsky-Rosen steering, refers to temporal quantum correlations between the initial and final state of a quantum system. Our analysis of temporal steering inequalities in relation to the average quantum bit error rates reveals the interplay between temporal steering and quantum cloning, which guarantees the security of quantum key-distribution based on mutually-unbiased bases against individual attacks. The key distributions analyzed here include the Bennett-Brassard 1984 protocol (BB84) and the six-state 1998 protocol by Bruss (B98). Moreover, we define a temporal steerable weight, which enables us to identify a kind of monogamy of temporal correlations that is essential to quantum cryptography and useful for analyzing various scenarios of quantum causality.