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Device-independent quantum key distribution (DI-QKD) provides the gold standard for secure key exchange. Not only it allows for information-theoretic security based on quantum mechanics, but it relaxes the need to physically model the…

Quantum Key Distribution (QKD) leverages the principles of quantum mechanics to provide theoretically unconditional security for cryptographic key sharing. However, practical implementations remain vulnerable due to non-ideal devices and…

Quantum Physics · Physics 2025-08-22 Cong Jiang , Xiao-Long Hu , Zong-Wen Yu , Hai Xu , Xiang-Bin Wang

A practical quantum key distribution (QKD) protocol necessarily runs in finite time and, hence, only a finite amount of communication is exchanged. This is in contrast to most of the standard results on the security of QKD, which only hold…

Quantum Physics · Physics 2009-01-08 Valerio Scarani , Renato Renner

Most security proofs of quantum key distribution (QKD) disregard the effect of information leakage from the users' devices, and, thus, do not protect against Trojan-horse attacks (THAs). In a THA, the eavesdropper injects strong light into…

Quantum Physics · Physics 2022-09-12 Álvaro Navarrete , Marcos Curty

We investigate the behavior of the maximal violations of the CHSH inequality and V$\grave{e}$rtesi's inequality under the local filtering operations. An analytical method has been presented for general two-qubit systems to compute the…

Quantum Physics · Physics 2017-04-27 Ming Li , Huihui Qin , Jing Wang , Shao-Ming Fei , Chang-Pu Sun

Recently it has been shown how the use of quantum entanglement can lead to the creation of real-time communication channels whose viability can be made location dependent. Such functionality leads to new security paradigms that are not…

Quantum Physics · Physics 2016-09-12 Robert A Malaney

Recently, in Sci. Rep. \textbf{6} (2016) 28767, Li et al., have proposed a scheme for quantum key distribution using Bell states. This comment provides a proof that the proposed scheme of Li et al., is insecure as it involves leakage of…

Quantum Physics · Physics 2016-09-26 Anirban Pathak , Kishore Thapliyal

It is widely believed that quantum key distribution (QKD) has been proved unconditionally secure for realistic models applicable to various current experimental schemes. Here we summarize briefly why this is not the case, from both the…

Quantum Physics · Physics 2015-05-30 Horace P. Yuen

Despite the enormous theoretical and experimental progress made so far in quantum key distribution (QKD), the security of most existing QKD implementations is not rigorously established yet. A critical obstacle is that almost all existing…

Two fault tolerant authenticated quantum dialogue (AQD) protocols are proposed in this paper by employing logical Bell states as the quantum resource, which combat the collective-dephasing noise and the collective-rotation noise,…

Quantum Physics · Physics 2022-05-06 Tian-Yu Ye

It is one of the most remarkable features of quantum physics that measurements on spatially separated systems cannot always be described by a locally causal theory. In such a theory, the outcomes of local measurements are determined in…

Quantum Physics · Physics 2016-09-08 Yeong-Cherng Liang

We provide an analysis of a new family of device independent quantum key distribution (QKD) protocols with several novel features: (a) The bits used for the secret key do not come from the results of the measurements on an entangled state…

Quantum Physics · Physics 2015-12-09 Ramij Rahaman , Matthew G. Parker , Piotr Mironowicz , Marcin Pawłowski

In device-independent quantum key distribution (DIQKD) the security is not based on any assumptions about the intrinsic properties of the devices and the quantum signals, but on the violation of a Bell inequality. We introduce a DIQKD…

Quantum Physics · Physics 2022-04-13 Sarnava Datta , Hermann Kampermann , Dagmar Bruß

A major application of quantum communication is the distribution of entangled particles for use in quantum key distribution (QKD). Due to noise in the communication line, QKD is in practice limited to a distance of a few hundred kilometres,…

Quantum Physics · Physics 2015-04-28 Stefan Bäuml , Matthias Christandl , Karol Horodecki , Andreas Winter

States that strongly violate Bell's inequalities are required in many quantum informational protocols as, for example, in cryptography, secret sharing and the reduction of communication complexity. We investigate families of such states…

Free-space Quantum key distribution (QKD) allows two parties to share a random key with unconditional security, between ground stations, between mobile platforms, and even in satellite-ground quantum communications. Atmospheric turbulence…

Quantum Physics · Physics 2018-04-04 Wenyuan Wang , Feihu Xu , Hoi-Kwong Lo

The security of quantum key distribution (QKD) is evaluated based on the secrecy of Alice's key and the correctness of the keys held by Alice and Bob. A practical method for ensuring correctness is known as error verification, in which…

Quantum Physics · Physics 2025-12-04 Toyohiro Tsurumaru , Akihiro Mizutani , Toshihiko Sasaki

Quantum key distribution (QKD) is a revolutionary cryptography response to the rapidly growing cyberattacks threat posed by quantum computing. Yet, the roadblock limiting the vast expanse of secure quantum communication is the exponential…

We report on a complete free-space field implementation of a modified Ekert91 protocol for quantum key distribution using entangled photon pairs. For each photon pair we perform a random choice between key generation and a Bell inequality.…

We present a generalized tomographic quantum key distribution protocol in which the two parties share a Bell diagonal mixed state of two qubits. We show that if an eavesdropper performs a coherent measurement on many quantum ancilla states…