# Finite-key analysis for twin-field quantum key distribution with composable security

## TL;DR

This paper presents a rigorous finite-key security proof for twin-field quantum key distribution, demonstrating its practicality over long distances with improved secret key rates in high-loss regimes.

## Contribution

It provides the first composable finite-key security analysis for coherent-state twin-field QKD against general attacks, with an optimized statistical fluctuation method.

## Key findings

- Security proof valid against general attacks.
- Enhanced secret key rate in high-loss regimes.
- Potential for practical long-distance quantum communication.

## Abstract

Long-distance quantum key distribution (QKD) has long time seriously relied on trusted relay or quantum repeater, which either has security threat or is far from practical implementation. Recently, a solution called twin-field (TF) QKD and its variants have been proposed to overcome this challenge. However, most security proofs are complicated, a majority of which could only ensure security against collective attacks. Until now, the full and simple security proof can only be provided with asymptotic resource assumption. Here, we provide a composable finite-key analysis for coherent-state-based TF-QKD with rigorous security proof against general attacks. Furthermore, we develop the optimal statistical fluctuation analysis method to significantly improve secret key rate in high-loss regime. The results show that coherent-state-based TF-QKD is practical and feasible, with the potential to apply over nearly one thousand kilometers.