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Quantum key distribution (QKD) is a concept of secret key exchange supported by fundamentals of quantum physics. Its perfect realization offers unconditional key security, however, known practical schemes are potentially vulnerable if the…

Quantum Physics · Physics 2014-04-18 I. V. Radchenko , K. S. Kravtsov , S. P. Kulik , S. N. Molotkov

Due to the high noise caused by solar background radiation, the existing satellite-based free-space quantum key distribution (QKD) experiments are mainly carried out at night, hindering the establishment of a practical all-day real-time…

We present a practical method that can make quantum key distribution (QKD), for the first time, both ultra-long-distance and immune to all attacks in the detection system. This method is an important extension of the…

Quantum Physics · Physics 2013-08-22 Feihu Xu , Bing Qi , Zhongfa Liao , Hoi-Kwong Lo

Quantum Key Distribution (QKD) is a technology that ensures secure communication by leveraging the principles of quantum mechanics, such as the no-cloning theorem and quantum uncertainty. This chapter provides an overview of this quantum…

Quantum Physics · Physics 2026-02-27 Sebastian Kish , Josef Pieprzyk , Seyit Camtepe

An energy-time entanglement-based dispersive optics quantum key distribution (DO-QKD) is demonstrated experimentally over optical fibers of 20 km. In the experiment, the telecom band energy-time entangled photon pairs are generated through…

Quantum Physics · Physics 2019-04-30 Xu Liu , Xin Yao , Heqing Wang , Hao Li , Zhen Wang , Lixing You , Yidong Huang , Wei Zhang

Distributing secret keys with information-theoretic security is arguably one of the most important achievements of the field of quantum information processing and communications. The rapid progress in this field has enabled quantum key…

Quantum key distribution (QKD) is a method that enables two remote parties to share a secure key string. Clock synchronization between two parties is a crucial step in the normal operation of QKD. Qubit-based synchronization can achieve…

Quantum Physics · Physics 2024-04-24 Ye Chen , Chunfeng Huang , Shuyi Huang , Zhenrong Zhang , Kejin Wei

There is a big gap between theory and practice in quantum key distribution (QKD) because real devices do not satisfy the assumptions required by the security proofs. Here, we close this gap by introducing a simple and practical…

Quantum Physics · Physics 2021-03-31 Álvaro Navarrete , Margarida Pereira , Marcos Curty , Kiyoshi Tamaki

Device-independent quantum key distribution (QKD) can permit the superior security even with unknown devices. In practice, however, the realization of device-independent QKD is technically challenging because of its low noise tolerance. In…

Quantum Physics · Physics 2022-03-22 Feihu Xu , Yu-Zhe Zhang , Qiang Zhang , Jian-Wei Pan

In state-of-the-art quantum key distribution (QKD) systems, the main limiting factor in increasing the key generation rate is the timing resolution in detecting photons. Here, we present and experimentally demonstrate a strategy to overcome…

Quantum Physics · Physics 2021-07-29 Johannes Pseiner , Lukas Achatz , Lukas Bulla , Martin Bohmann , Rupert Ursin

Quantum communication over long distances is integral to information security and has been demonstrated in free space and fibre with two-dimensional polarisation states of light. Although increased bit rates can be achieved using…

The future envisaged global-scale quantum communication network will comprise various nodes interconnected via optical fibers or free-space channels, depending on the link distance. The free-space segment of such a network should guarantee…

Quantum key distribution (QKD) promises secure key agreement by using quantum mechanical systems. We argue that QKD will be an important part of future cryptographic infrastructures. It can provide long-term confidentiality for encrypted…

Quantum Physics · Physics 2010-01-25 Douglas Stebila , Michele Mosca , Norbert Lütkenhaus

We report on a complete experimental implementation of a quantum key distribution protocol through a free space link using polarization-entangled photon pairs from a compact parametric down-conversion source. Over 10 hours of uninterrupted…

Quantum Physics · Physics 2007-05-23 Ivan Marcikic , Antia Lamas-Linares , Christian Kurtsiefer

Free-space ground-to-ground links will be an integral part of future quantum communication networks. The implementation of free-space and fiber links in daylight inter-modal configurations are however still hard to achieve, due to the…

Quantum key distribution (QKD) refers to specific quantum strategies which permit the secure distribution of a secret key between two parties that wish to communicate secretly. Quantum cryptography has proven unconditionally secure in ideal…

Quantum Physics · Physics 2008-10-14 C. Rodó , O. Romero-Isart , K. Eckert , A. Sanpera

To prove the security of quantum key distribution (QKD) protocols, several assumptions have to be imposed on users' devices. From an experimental point of view, it is preferable that such theoretical requirements are feasible and the number…

Quantum Physics · Physics 2023-02-07 Akihiro Mizutani

Large-scale quantum communication networks are still a huge challenge due to the rate-distance limit of quantum key distribution (QKD). Recently, twin-field (TF) QKD has been proposed to overcome this limit. Here, we prove that…

Quantum Physics · Physics 2019-11-21 Hua-Lei Yin , Zeng-Bing Chen

Scattering of light by cloud, haze, and fog decreases the transmission efficiency of communication channels in quantum key distribution (QKD), reduces the system's practical security, and thus constrains the deployment of free-space QKD.…

A new scheme of quantum key distribution (QKD) using frequency and time coding is proposed, in which the security is based on the frequency-time uncertainty relation. In this scheme, the binary information sequence is encoded randomly on…

Quantum Physics · Physics 2015-05-18 Chang-hua Zhu , Chang-xing Pei , Dong-xiao Quan , Nan Chen , Yun-hui Yi