Recent progress in Continuous Variable Quantum Key Distribution

Takuya Hirano

E. Llanos, Samael Sarmiento, Jeison Tabares +13 more

Quantum key distribution (QKD) enables secure secret key exchange with information-theoretic security by leveraging the principles of quantum mechanics. Continuous-variable QKD (CV-QKD), which utilizes coherent states and coherent detection, has gained attention as a promising approach due to its seamless integration with existing telecommunications networks. CV-QKD systems, which are built with standard telecommunication components, open the door—through photonic integration technology—to the development of devices that are more affordable, compact, and energy efficient. This paper reviews the current state of the art and highlights our recent progress toward fully integrated CV-QKD systems.

Romain Alléaume

Yongmin Li, Xuyang Wang, Zengliang Bai +3 more

Quantum key distribution enables unconditionally secure key distribution between two legitimate users. The information-theoretic security is guaranteed by the fundamental laws of quantum physics. Initially, the quantum key distribution protocol was proposed based on the qubits. Later on, it was found that quantum continuous variables can also be exploited for this target. The continuous variable quantum key distribution can build upon standard telecommunication technology and exhibits a higher secret key rate per pulse at a relatively short distance due to the possibility of encoding more than 1 bit per pulse. In this article, we review the current status of the continuous variable quantum key distribution research, including its basic principle, experimental implementations, security and future directions; the experimental progress in this field made by our group is also presented.

Chenyang Li, Li Qian, Hoi‐Kwong Lo

Abstract Despite tremendous theoretical and experimental progress in continuous variable (CV) quantum key distribution (QKD), the security has not been rigorously established for most current continuous variable quantum key distribution systems that have imperfections. Among these imperfections, intensity fluctuation is one of the principal problems affecting security. In this paper, we provide simple security proofs for continuous variable quantum key distribution systems with intensity fluctuating sources. Specifically, depending on device assumptions in the source, the imperfect systems are divided into two general cases for security proofs. In the most conservative case, we prove the security based on the tagging idea, which is a main technique for the security proof of discrete variable quantum key distribution. Our proofs are simple to implement without any hardware adjustment for current continuous variable quantum key distribution systems. Also, we show that our proofs are able to provide secure secret keys in the finite-size scenario.

Aida Garcia-Callejo, Andrés Ruiz-Chamorro, Daniel Cano +1 more