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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 However, as practical devices tend to deviate from their specifications, the security of some practical systems is no longer valid.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

Establishing scalable, secure quantum networks requires advancing beyond conventional point-to-point quantum key distribution (QKD) protocols toward point-to-multipoint QKD protocols. Here, we generalize a well-established…

Rigorous mathematical proofs of the security of continuous-variable quantum key distribution (CV QKD) have been obtained recently. Unfortunately, these security proofs rely on assumptions that are hardly met in experimental practice. Here I…

Quantum Physics · Physics 2020-09-01 Cosmo Lupo

Quantum key distribution (QKD) provides information-theoretic security grounded in the fundamental laws of physics. Nevertheless, practical imperfections can introduce side channels that expose QKD systems to quantum hacking, especially…

We present a composable security proof, valid against arbitrary attacks and including finite-size effects, for a high dimensional time-frequency quantum key distribution (TFQKD) protocol based upon spectrally entangled photons. Previous…

Quantum Physics · Physics 2016-09-30 Nathan Walk , Jonathan Barrett , Joshua Nunn

We address continuous variable quantum key distribution (QKD) in non-Markovian lossy channels and show how the non-Markovian features may be exploited to enhance security and/or to detect the presence and the position of an eavesdropper…

Quantum Physics · Physics 2015-05-20 Ruggero Vasile , Stefano Olivares , Matteo G A Paris , Sabrina Maniscalco

Using the generalized Bell states and controlled not gates, we introduce an enatanglement-based quantum key distribution (QKD) of d-level states (qudits). In case of eavesdropping, Eve's information gain is zero and a quantum error rate of…

Quantum Physics · Physics 2009-11-07 Vahid Karimipour , Saber Bagherinezhad , Alireza Bahraminasab

The goal of this paper is to extend the framework of finite size analysis recently developed for quantum key distribution to continuous-variable protocols. We do not solve this problem completely here, and we mainly consider the finite size…

Quantum Physics · Physics 2010-06-29 Anthony Leverrier , Frédéric Grosshans , Philippe Grangier

Continuous-variable quantum key distribution protocols, based on Gaussian modulation of the quadratures of coherent states, have been implemented in recent experiments. A present limitation of such systems is the finite efficiency of the…

A beam emitted by a displaced thermal source, incident on a beam splitter, is used as the source in a central broadcast quantum key distribution protocol. These displaced thermal states have parallels to signals produced through phase-shift…

Quantum Physics · Physics 2022-02-04 Adam Walton , Anne Ghesquière , David Jennings , Benjamin Varcoe

We address the security of continuous-variable quantum key distribution with squeezed states upon realistic conditions of noisy and lossy environment and limited reconciliation efficiency. Considering the generalized preparation scheme and…

Quantum Physics · Physics 2011-11-10 Vladyslav C. Usenko , Radim Filip

Unconditionally secure non-relativistic bit commitment is known to be impossible in both the classical and the quantum worlds. But when committing to a string of n bits at once, how far can we stretch the quantum limits? In this paper, we…

Quantum Physics · Physics 2008-08-18 Harry Buhrman , Matthias Christandl , Patrick Hayden , Hoi-Kwong Lo , Stephanie Wehner

We present two experimental schemes to perform continuous variable (2,3) threshold quantum secret sharing on the quadratures amplitudes of bright light beams. Both schemes require a pair of entangled light beams. The first scheme utilizes…

Quantum Physics · Physics 2009-11-07 A. M. Lance , T. Symul , W. P. Bowen , T. Tyc , B. C. Sanders , P. K. Lam

In theory, quantum key distribution (QKD) allows secure communications between two parties based on physical laws. However, most of the security proofs of QKD today make unrealistic assumptions and neglect many relevant device…

Quantum Physics · Physics 2019-08-06 Margarida Pereira , Marcos Curty , Kiyoshi Tamaki

We illustrate using a quantum system the principle of a cryptographic switch, in which a third party (Charlie) can control to a continuously varying degree the amount of information the receiver (Bob) receives, after the sender (Alice) has…

Modern communication strives towards provably secure systems which can be widely deployed. Quantum key distribution provides a methodology to verify the integrity and security of a key exchange based on physical laws. However, physical…

Quantum Physics · Physics 2020-04-01 Henry Semenenko , Philip Sibson , Andy Hart , Mark G. Thompson , John G. Rarity , Chris Erven

We present protocols for quantum key distribution in a prepare-and-measure setup with an asymmetric level of trust. While the device of the sender (Alice) is partially characterized, the receiver's (Bob's) device is treated as a black-box.…

In quantum weak oblivious transfer, Alice sends Bob two bits and Bob can learn one of the bits at his choice. It was found that the security of such a protocol is bounded by $2P_{Alice}^{\ast }+P_{Bob}^{\ast }\geq 2$, where $P_{Alice}^{\ast…

Quantum Physics · Physics 2015-06-15 Guang Ping He

There are two main factors limiting the performance of quantum key distribution --- channel transmission loss and noise. Previously, a linear bound was believed to put an upper limit on the rate-transmittance performance. Remarkably, the…

Quantum Physics · Physics 2020-07-01 Pei Zeng , Weijie Wu , Xiongfeng Ma

A new class of quantum cryptography (QC) protocols that are robust against the most general photon number splitting attacks in a weak coherent pulse implementation has been recently proposed. In this article we give a quite exhaustive…

Quantum Physics · Physics 2009-11-10 Antonio Acin , Nicolas Gisin , Valerio Scarani