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The safety of a quantum key distribution system relies on the fact that any eavesdropping attempt on the quantum channel creates errors in the transmission. For a given error rate, the amount of information that may have leaked to the…

Quantum Physics · Physics 2009-10-28 B. Huttner , N. Imoto , N. Gisin , T. Mor

Continuous-variable quantum key distribution (CV QKD) protocols with discrete modulation are interesting due to their experimental simplicity and their great potential for massive deployment in the quantum-secured networks, but their…

Quantum Physics · Physics 2020-01-01 Jie Lin , Twesh Upadhyaya , Norbert Lütkenhaus

We investigate the security against collective attacks of a continuous variable quantum key distribution scheme in the asymptotic key limit for a realistic setting. The quantum channel connecting the two honest parties is assumed to be…

Quantum Physics · Physics 2007-12-12 Matthias Heid , Norbert Lütkenhaus

Efficiency is a key issue in any real implementation of a cryptographic protocol since the physical resources are not unlimited. We will first show that Quantum Key Distribution is possible with an "Entanglement based" scheme with NPPT…

Quantum Physics · Physics 2015-03-17 Carles Rodó

We establish a lower bound on the asymptotic secret key rate of continuous-variable quantum key distribution with a discrete modulation of coherent states. The bound is valid against collective attacks and is obtained by formulating the…

Quantum Physics · Physics 2019-06-27 Shouvik Ghorai , Philippe Grangier , Eleni Diamanti , Anthony Leverrier

Discrete-modulated continuous-variable quantum key distribution protocols are promising candidates for large-scale deployment due to the large technological overlap with deployed modern optical communication devices. The security of…

Quantum Physics · Physics 2020-12-15 Jie Lin , Norbert Lütkenhaus

This is a Bachelor's thesis on quantum key distribution in the non-asymptotic regime submitted to the Leibniz Universit\"at Hannover, Germany. It deals with the question how to generate a key to encrypt messages between two honest parties…

Quantum Physics · Physics 2015-11-23 Ramona Wolf

Quantum conditional entropies play a fundamental role in quantum information theory. In quantum key distribution, they are exploited to obtain reliable lower bounds on the secret-key rates in the finite-size regime, against collective…

Quantum Physics · Physics 2026-03-05 Gabriele Staffieri , Giovanni Scala , Cosmo Lupo

We propose a new quantum key distribution scheme that is based on the optimum expectation values of maximally entangled Greenberger-Horne-Zeilinger states. Our protocol makes use of the degrees of freedom in continuously variable angles,…

Quantum Physics · Physics 2023-08-21 Hyung S. Choi , Ye Jin Han , Collin Kessinger , Qiaoren Wang

We consider continuous-variable quantum key distribution with discrete-alphabet encodings. In particular, we study protocols where information is encoded in the phase of displaced coherent (or thermal) states, even though the results can be…

Quantum Physics · Physics 2021-01-18 Panagiotis Papanastasiou , Stefano Pirandola

We consider two quantum cryptographic schemes relying on encoding the key into qudits, i.e. quantum states in a d-dimensional Hilbert space. The first cryptosystem uses two mutually unbiased bases (thereby extending the BB84 scheme), while…

Quantum Physics · Physics 2009-11-07 Nicolas J. Cerf , Mohamed Bourennane , Anders Karlsson , Nicolas Gisin

We give the first composable security proof for continuous-variable quantum key distribution with coherent states against collective attacks. Crucially, in the limit of large blocks the secret key rate converges to the usual value computed…

Quantum Physics · Physics 2015-03-06 Anthony Leverrier

Many papers proved the security of quantum key distribution (QKD) system, in the asymptotic framework. The degree of the security has not been discussed in the finite coding-length framework, sufficiently. However, to guarantee any…

Quantum Physics · Physics 2009-11-13 Masahito Hayashi

We introduce a new quantum key distribution protocol that uses d-level quantum systems to encode an alphabet with c letters. It has the property that the error rate introduced by an intercept-and-resend attack tends to one as the numbers c…

Quantum Physics · Physics 2009-10-15 Stephen Brierley

Quantum key distribution (QKD) seeks to provide a method of generating cryptographically-secure keys between remote parties while guaranteeing unconditional security. Implementations of high-dimensional QKD using dispersive-optics (DO-QKD)…

Quantum Physics · Physics 2024-03-15 Ariel Shlosberg , Alex Kwiatkowski , Akira Kyle , Graeme Smith

Quantum key distribution algorithms are considered secure because they leverage quantum phenomena to provide security. As such, eavesdroppers can be detected by analyzing the error rate in the shared key obtained by the parties performing…

Quantum Physics · Physics 2024-12-12 Christopher Dunne

We propose a new upper bound for the eavesdropper's information in the direct and reverse reconciliated coherent states quantum key distribution protocols with heterodyne detection. This bound is derived by maximizing the leaked information…

Quantum Physics · Physics 2009-02-17 Jerome Lodewyck , Philippe Grangier

We prove the security of a quantum key distribution scheme based on transmission of squeezed quantum states of a harmonic oscillator. Our proof employs quantum error-correcting codes that encode a finite-dimensional quantum system in the…

Quantum Physics · Physics 2009-11-06 Daniel Gottesman , John Preskill

Quantum Key Distribution (QKD) provides information-theoretic security by exploiting the principles of quantum mechanics. Among QKD protocols, the BB84 scheme remains the most widely adopted for both theoretical research and practical…

Quantum Physics · Physics 2026-03-31 Jaydeep Rath , Prajwal Panth , P. S. N. Bhaskar

A quantum key distribution protocol based on entanglement swapping is proposed. Through choosing particles by twos from the sequence and performing Bell measurements, two communicators can detect eavesdropping and obtain the secure key.…

Quantum Physics · Physics 2007-05-23 Fei Gao , Fenzhuo Guo , Qiaoyan Wen , Fuchen Zhu