Finite-size general security for differential phase shift keying via variable-length quantum key distribution

TL;DR

This paper advances the security proof of differential phase shift keying (DPSK) in quantum key distribution by employing variable-length techniques and entropy accumulation, enabling practical, high-rate secure communication.

Contribution

It introduces a novel security proof for DPSK using entropy accumulation and conic optimization, overcoming previous limitations and demonstrating industrial-grade feasibility.

Findings

Achieves secret key rates with 10^5 signals beyond 12 dB

Provides a robust proof of experimental implementability of industrial-grade DPSK

Overcomes previous limitations in security proof constraints

Abstract

Differential phase shift keying (DPSK) constitutes a pathway towards practical quantum key distribution by using affordable commercial technologies, and robust theoretical foundations. Recent advances in the security of DPSK have proven its security against general adversaries, albeit requiring limitations, including strong repetition rate constraints at the security proof and costly statistical estimators. In this work, we overcome said limitations by leveraging recent techniques in variable-length general security by using entropy accumulation techniques based on R\'enyi leftover hashing, together with conic optimization methods. Our approach achieves secret key rates with $10^5$ signals beyond 12 dB, constituting a robust proof of the experimental implementability of industrial-grade DPSK.