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In principle, quantum key distribution (QKD) offers information-theoretic security based on the laws of physics. In practice, however, the imperfections of realistic devices might introduce deviations from the idealized models used in…

Quantum Physics · Physics 2020-06-01 Feihu Xu , Xiongfeng Ma , Qiang Zhang , Hoi-Kwong Lo , Jian-Wei Pan

Measurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side-channels from quantum communication systems. The security proofs require, however, that certain assumptions on the sources are satisfied. This…

Quantum Physics · Physics 2021-01-20 Weilong Wang , Kiyoshi Tamaki , Marcos Curty

Quantum key distribution (QKD) promises information-theoretic security based on quantum mechanics and idealized device models. Practical implementations, however, deviate from these models due to unavoidable device imperfections, and…

Quantum Physics · Physics 2026-05-14 Álvaro Navarrete , Guillermo Currás-Lorenzo , Margarida Pereira , Marcos Curty

Interfering-or-not-interfering quantum key distribution (INI-QKD) is an innovative protocol whose performance surpasses existing twin-field protocol variants. In this study, we introduce an additional step of advantage distillation (AD)…

Quantum Physics · Physics 2024-10-02 Seyede Zahra Zarei , Fatemeh Tarighi Tabesh , Mehdi Abdi

Throughout history, every advance in encryption has been defeated by advances in hacking with severe consequences. Quantum cryptography holds the promise to end this battle by offering unconditional security when ideal single-photon sources…

Differential-phase-shift (DPS) quantum key distribution (QKD) is one of the major QKD protocols that can be implemented with a simple setup using a laser source and a passive detection unit. Recently, an information-theoretic security proof…

Quantum Physics · Physics 2023-06-01 Akihiro Mizutani , Yuki Takeuchi , Kiyoshi Tamaki

Quantum key distribution (QKD) offers the promise of absolutely secure communications. However, proofs of absolute security often assume perfect implementation from theory to experiment. Thus, existing systems may be prone to insidious…

Quantum Physics · Physics 2014-06-23 Samuel L. Braunstein , Stefano Pirandola

Device-independent quantum key distribution (DI-QKD) is a key application of the quantum internet. We report the realization of DI-QKD between two single-atom nodes linked by 100-km fibers. To improve the entangling rate, single-photon…

Beyond the foundational significance, the problem of bounding nonlocal correlations by reasonable physical principles has meaningful practical consequences, particularly for device-independent (DI) cryptographic security. In this work, we…

Quantum Physics · Physics 2025-10-02 Lucas Pollyceno , Anubhav Chaturvedi , Chithra Raj , Pedro R. Dieguez , Marcin Pawłowski

A prominent application of quantum cryptography is the distribution of cryptographic keys that are provably secure. Recently, such security proofs were extended by Vazirani and Vidick (Physical Review Letters, 113, 140501, 2014) to the…

Quantum Physics · Physics 2020-08-20 Rahul Jain , Carl A. Miller , Yaoyun Shi

The goal of quantum key distribution (QKD) is to establish a secure key between two parties connected by an insecure quantum channel. To use a QKD protocol in practice, one has to prove that a finite size key is secure against general…

Quantum Physics · Physics 2023-11-21 Tony Metger , Renato Renner

The Ekert 91 quantum key distribution (QKD) protocol appears to be secure whatever devices legitimate users adopt for the protocol, as long as the devices give a result that violates Bell's inequality. However, this is not the case if they…

Quantum Physics · Physics 2009-11-11 W. -Y. Hwang

Quantum key distribution(QKD) allows two remote parties to share information-theoretic secret keys. Many QKD protocols assume the phase of encoding state can be continuous randomized from 0 to 2 pi, which, however, may be questionable in…

Quantum Physics · Physics 2023-02-15 Rui Qiang Wang , Zhen Qiang yin , Rong Wang , Shuang Wang , Wei Chen , Guang can Guo , Zhen fu Han

Device-independent security is the gold standard for quantum cryptography: not only is security based entirely on the laws of quantum mechanics, but it holds irrespective of any a priori assumptions on the quantum devices used in a…

Quantum Physics · Physics 2025-06-09 Rotem Arnon , Renato Renner , Thomas Vidick

We present a measurement-device-independent quantum key distribution (MDI-QKD) using single photons in a linear superposition of three orthogonal time-bin states, for generating the key. The orthogonal states correspond to three distinct…

Quantum Physics · Physics 2021-02-24 Shashank Kumar Ranu , Anil Prabhakar , Prabha Mandayam

Quantum key distribution promises unconditionally secure communications. However, as practical devices tend to deviate from their specifications, the security of some practical systems is no longer valid. In particular, an adversary can…

Quantum Physics · Physics 2015-06-16 Marcos Curty , Feihu Xu , Wei Cui , Charles Ci Wen Lim , Kiyoshi Tamaki , Hoi-Kwong Lo

This study proposes a new lightweight quantum key distribution (LQKD) protocol based on the four-particle cluster state within a quantum-restricted environment. The protocol enables a quantum-capable user to simultaneously establish two…

Quantum Physics · Physics 2025-07-16 Mustapha Anis Younes , Sofia Zebboudj , Abdelhakim Gharbi

Cryptographic key exchange protocols traditionally rely on computational conjectures such as the hardness of prime factorisation to provide security against eavesdropping attacks. Remarkably, quantum key distribution protocols like the one…

Quantum Key Distribution (QKD) enables two distant users to exchange a secret key with information-theoretic security, based on the fundamental laws of quantum physics. While it is arguably the most mature application of quantum…

The malicious manipulation of quantum key distribution (QKD) hardware is a serious threat to its security, as, typically, neither end users nor QKD manufacturers can validate the integrity of every component of their QKD system in practice.…

Quantum Physics · Physics 2025-04-01 Víctor Zapatero , Marcos Curty