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Quantum key distribution is on the verge of real world applications, where perfectly secure information can be distributed among multiple parties. Several quantum cryptographic protocols have been theoretically proposed and independently…

We propose two quantum key distribution (QKD) protocols based on Bell's inequality, which can be considered as modified time-reversed E91 protocol. Similar to the measurement-device-independent quantum key distribution (MDI-QKD) protocol,…

Quantum Physics · Physics 2014-07-29 Hua-Lei Yin , Yao Fu , Yan-Lin Tang , Yuan Li , Teng-Yun Chen , Zeng-Bing Chen

Quantum key distribution (QKD) promises everlasting security based on the laws of physics. Most common protocols are grouped into two distinct categories based on the degrees of freedom used to carry information, which can be either…

Quantum Physics · Physics 2024-02-28 Jasminder S. Sidhu , Rocco Maggi , Saverio Pascazio , Cosmo Lupo

Counterfactual quantum key distribution (QKD) enables two parties to share a secret key using an interaction-free measurement. Here, we point out that the efficiency of counterfactual QKD protocols can be enhanced by including…

Quantum Physics · Physics 2021-09-07 Vinod N. Rao , R. Srikanth

Contextuality, a key resource for quantum advantage, describes systems in which the outcome of a measurement is not independent of other compatible measurements, in contrast to classical hidden-variable descriptions. We investigate the…

Quantum Physics · Physics 2025-12-08 Caroline Lima , María Rosa Preciado-Rivas , Sanchit Srivastava

We present a complete protocol for BB84 quantum key distribution for a realistic setting (noise, loss, multi-photon signals of the source) that covers many of todays experimental implementations. The security of this protocol is shown…

Quantum Physics · Physics 2007-07-10 Hitoshi Inamori , Norbert Lütkenhaus , Dominic Mayers

Quantum key distribution allows two parties, traditionally known as Alice and Bob, to establish a secure random cryptographic key if, firstly, they have access to a quantum communication channel, and secondly, they can exchange classical…

Quantum Physics · Physics 2007-05-23 Matthias Christandl , Renato Renner , Artur Ekert

Quantum computers promise dramatic advantages over their classical counterparts, but the answer to the most basic question "What is the source of the power in quantum computing?" has remained elusive. Here we prove a remarkable equivalence…

Quantum Physics · Physics 2014-10-16 Mark Howard , Joel J. Wallman , Victor Veitch , Joseph Emerson

We reveal that the entropic uncertainty relation with a quantum memory is able to intrinsically connect local generic contextuality addressed in the pioneering work by Spekkens and nonlocal quantum resources such as entanglement and Bell…

Quantum Physics · Physics 2026-05-01 Wei Li , Min-Xuan Zhou , Yun-Hao Shi , Z. D. Wang , Heng Fan , Yan-Kui Bai

Quantum coherence plays a fundamental and operational role in different areas of physics. A resource theory has been developed to characterize the coherence of distinguishable particles systems. Here we show that indistinguishability of…

All the currently available unconditional security proofs on quantum key distribution, in particular for the BB84 protocol and its variants including continuous-variable ones, are invalid or incomplete at many points. In this paper we…

Quantum Physics · Physics 2013-10-23 Horace P. Yuen

Quantum contextuality is a key nonclassical feature underlying advantages in quantum computation and communication. We introduce a new method to study contextuality in quantum information-processing tasks and protocols, relying solely on…

Quantum Physics · Physics 2026-03-03 Mina Doosti , Theodoros Yianni , Farid Shahandeh

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.…

Key distribution plays a fundamental role in cryptography. Currently, the quantum scheme stands as the only known method for achieving unconditionally secure key distribution. This method has been demonstrated over distances of 508 and 1002…

Quantum Physics · Physics 2024-08-27 Hua-Lei Yin

Quantum Cryptography or Quantum key distribution (QKD) is a technique that allows the secure distribution of a bit string, used as key in cryptographic protocols. When it was noted that quantum computers could break public key cryptosystems…

Cryptography and Security · Computer Science 2010-07-15 Mohamed Elboukhari , Mostafa Azizi , Abdelmalek Azizi

The Kochen-Specker theorem demonstrates that it is not possible to reproduce the predictions of quantum theory in terms of a hidden variable model where the hidden variables assign a value to every projector deterministically and…

Quantum Physics · Physics 2015-09-16 Ravi Kunjwal , Robert W. Spekkens

Device-independent randomness generation and quantum key distribution protocols rely on a fundamental relation between the non-locality of quantum theory and its random character. This relation is usually expressed in terms of a trade-off…

Quantum Physics · Physics 2018-03-20 Olmo Nieto-Silleras , Cédric Bamps , Jonathan Silman , Stefano Pironio

In the original BB84 protocol by Bennett and Brassard, an eavesdropper is detected because his attempts to intercept information result in a quantum bit error rate (QBER) of at least 25%. Here we design an alternative quantum key…

Quantum Physics · Physics 2015-05-13 Muhammad Mubashir Khan , Michael Murphy , Almut Beige

We investigate a new strategy for incoherent eavesdropping in Ekert's entanglement based quantum key distribution protocol. We show that under certain assumptions of symmetry the effectiveness of this strategy reduces to that of the…

Quantum Physics · Physics 2009-11-07 Hitoshi Inamori , Luke Rallan , Vlatko Vedral

Quantum Key Distribution (QKD) is a technique that enables secure communication between two parties by sharing a secret key. One of the most well-known QKD protocols is the BB84 protocol, proposed by Charles Bennett and Gilles Brassard in…

Quantum Physics · Physics 2023-12-12 SujayKumar Reddy M , Chandra Mohan B