2024-04-03 デンマーク工科大学(DTU)
デンマーク工科大学（DTU）の研究者たちは、連続変数量子鍵分配（CV QKD）と呼ばれる手法を用いて、量子安全な鍵を記録的な100kmの距離で配布に成功しました。この手法は既存のインターネットインフラに適用可能であり、古典的なアルゴリズムに基づく暗号化を脅かす量子コンピュータの脅威に対抗するために開発されました。CV QKD技術では、光子の量子状態の滑らかな特性を測定し、既存のインフラに組み込むことができます。これにより、より広範囲での安全な鍵分配が可能になり、データの安全な送信が保証されます。
＜関連情報＞
- https://www.dtu.dk/english/newsarchive/2024/04/100-kilometres-of-quantum-encrypted-transfer
- https://www.science.org/doi/10.1126/sciadv.adi9474
局所局部発振器を用いた100kmファイバーでの長距離の連続可変量子鍵分散法 Long-distance continuous-variable quantum key distribution over 100-km fiber with local local oscillator
ADNAN A. E. HAJOMER , IVAN DERKACH , NITIN JAIN , HOU-MAN CHIN , […], AND TOBIAS GEHRING
Science Advances Published:3 Jan 2024
DOI:https://doi.org/10.1126/sciadv.adi9474
Abstract
Quantum key distribution (QKD) enables two remote parties to share encryption keys with security based on the laws of physics. Continuous-variable (CV) QKD with coherent states and coherent detection integrates well with existing telecommunication networks. Thus far, long-distance CV-QKD has only been demonstrated using a highly complex scheme where the local oscillator is transmitted, opening security loopholes for eavesdroppers and limiting potential applications. Here, we report a long-distance CV-QKD experiment with a locally generated local oscillator over a 100-kilometer fiber channel with a total loss of 15.4 decibels. This record-breaking distance is achieved by controlling the phase noise–induced excess noise through a machine learning framework for carrier recovery and optimizing the modulation variance. We implement the full CV-QKD protocol and demonstrate the generation of keys secure against collective attacks in the finite-size regime. Our results mark a substantial milestone for realizing CV quantum access networks with a high loss budget and pave the way for large-scale deployment of secure QKD.
