How not to discard half of the cases in QKD

TL;DR

This paper introduces QKD protocols that avoid discarding data when bases differ, increasing efficiency and security, and providing new insights into quantum cryptography's fundamental limits.

Contribution

It presents novel QKD protocols that do not require discarding results or announcing bases, enhancing capacity and security.

Findings

Protocols as secure as standard ones

Increased communication channel capacity

Elimination of certain eavesdropping strategies

Abstract

All known QKD protocols require the parties to discard the results when they have chosen differen bases. In this paper we show that it is not necessary. We give examples of QKD protocols that are as safe as standard ones but do not involve the discarding the results when the bases are different or even that do not require the announcement of the bases. This leads to greater communication channel capacities and render some eavesdropping strategies useless but the most important thing is that they provide us better insight into the general structures that underlie the quantum cryptography and help to establish the boundaries of what is possible and what is not.