Finite size analysis of measurement device independent quantum cryptography with continuous variables

TL;DR

This paper analyzes how finite data sizes affect the key rate in continuous-variable measurement-device-independent quantum key distribution, showing that larger block sizes improve performance and can achieve practical key rates over metropolitan distances.

Contribution

It adapts a parameter estimation technique to finite-size analysis of CV-MDI-QKD, providing realistic performance estimates under experimental conditions.

Findings

Larger block sizes improve key rate convergence.

Block sizes of 10^6 to 10^9 data points yield practical key rates.

Achieves key rate of ~10^-2 bits/use over metropolitan distances.

Abstract

We study the impact of finite-size effects on the key rate of continuous-variable (CV) measurement-device-independent (MDI) quantum key distribution (QKD). Inspired by the parameter estimation technique developed in [Rupert \textit{et al.} Phys. Rev. A \textbf{90}, 062310 (2014)]~we adapt it to study CV-MDI-QKD and, assuming realistic experimental conditions, we analyze the impact of finite-size effects on the key rate. We find that, increasing the block-size, the performance of the protocol converges towards the ideal one, and that block-sizes between $10^{6}$ and $10^{9}$ data points can already provide a key rate $\sim10^{-2}$ bit/use over metropolitan distances.