General theory of decoy-state quantum cryptography with source errors

TL;DR

This paper develops a robust decoy-state quantum cryptography theory that remains secure despite source errors, simplifying practical implementation without needing to correct small pulse errors.

Contribution

It introduces a new theoretical framework for decoy-state quantum cryptography that accounts for source errors, ensuring unconditional security in realistic conditions.

Findings

Security is maintained despite source errors.

Final key length is slightly reduced but secure.

Practical implementation is simplified.

Abstract

The existing theory of decoy-state quantum cryptography assumes the exact control of each states from Alice's source. Such exact control is impossible in practice. We develop the theory of decoy-state method so that it is unconditionally secure even there are state errors of sources, if the range of a few parameters in the states are known. This theory simplifies the practical implementation of the decoy-state quantum key distribution because the unconditional security can be achieved with a slightly shortened final key, even though the small errors of pulses are not corrected.