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Quantum key distribution (QKD) provides information-theoretic security guaranteed by the laws of quantum mechanics, making it resistant to future computational threats, including quantum computers. While QKD technology shows great promise,…

Quantum Physics · Physics 2025-04-14 Si Qi Ng , Florian Kanitschar , Gong Zhang , Chao Wang

The non-Gaussian operation can be used not only to enhance and distill the entanglement between Gaussian entangled states, but also to improve quantum communications. In this paper, we propose an non-Gaussian continuous-variable quantum key…

Quantum Physics · Physics 2019-03-27 Ying Guo , Wei Ye , Hai Zhong , Qin Liao

Here, we demonstrate that a practical Continuous Variables Quantum Key Distribution (CVQKD) protocol relying on the Gaussian modulation of coherent states features secret key rates that cannot be achieved with standard qubit Discrete…

Quantum Physics · Physics 2014-10-24 Paul Jouguet , David Elkouss , Sébastien Kunz-Jacques

We assess the security of a quantum key distribution protocol relying on the transmission of Gaussian-modulated coherent states and homodyne detection. This protocol is shown to be equivalent to a squeezed state protocol based on a CSS code…

Quantum Physics · Physics 2009-11-10 S. Iblisdir , G. Van Assche , N. J. Cerf

The capacity of the quantum dense key distribution (QDKD) [Phys. Rev. A69, 032310 (2004)] is doubled by introducing the dense coding. The security of the improved QDKD against eavesdropping is pointed out to be easily proven. In both the…

Quantum Physics · Physics 2007-05-23 Z. J. Zhang , Z. X. Man

The security of measurement device-independent quantum key distribution (MDI QKD) relies on a thorough characterization of one's optical source output, especially any noise in the state preparation process. Here, we provide an extension of…

Quantum Physics · Physics 2021-01-04 J. Eli Bourassa , Ignatius William Primaatmaja , Charles Ci Wen Lim , Hoi-Kwong Lo

Quantum Key Distribution (QKD) enables secret key exchange between two remote parties with information-theoretic security rooted in the laws of quantum physics. Encoding key information in continuous variables (CV), such as the values of…

Quantum Key Distribution (QKD) offers unconditional security in principle. Many QKD protocols have been proposed and demonstrated to ensure secure communication between two authenticated users. Continuous variable (CV) QKD offers many…

We have developed a method to calculate a secret key rate of a continuous-variable quantum-key-distribution scheme using four coherent states and postselection for a general model of Gaussian attacks. We assume that the transmission line…

Quantum Physics · Physics 2018-10-30 Ryo Namiki , Akira Kitagawa , Takuya Hirano

Quantum key distribution (QKD) represents a cornerstone of secure communication in the quantum era. While discrete-variable QKD (DV-QKD) protocols were historically the first to demonstrate secure key exchange, continuous-variable QKD…

Quantum Physics · Physics 2025-06-30 Mobin Motaharifar , Mahmood Hasani , Hassan Kaatuzian

We study the secrecy properties of Gaussian states under Gaussian operations. Although such operations are useless for quantum distillation, we prove that it is possible to distill a secret key secure against any attack from sufficiently…

Quantum Physics · Physics 2012-04-30 M. Navascues , J. Bae , J. I. Cirac , M. Lewenstein , A. Sanpera , A. Acin

Entanglement is a well-known resource in quantum information, in particular it can be exploited for quantum key distribution (QKD). In this paper we define a two-way QKD scheme employing GHZ-type states of three qubits obtaining an…

Quantum Physics · Physics 2020-04-07 Davide Pastorello

We use single homodyne detector to accomplish Continuous-Variable quantum key distribution(CV QKD) in a laboratory and urban environment free-space channel. This is based on Gaussian modulation with coherent-states in the polarization…

Quantum Physics · Physics 2019-07-24 Shi-Yang Shen , Ming-Wei Dai , Xue-Tao Zheng , Qi-Yao Sun , Bing Zhu , Guang-Can Guo , Zheng-Fu Han

It is known that quantum scissors, as non-deterministic amplifiers, can enhance the performance of Gaussian-modulated continuous-variable quantum key distribution (CV-QKD) in noisy and long-distance regimes of operation. Here, we extend…

Quantum Physics · Physics 2020-04-06 Masoud Ghalaii , Carlo Ottaviani , Rupesh Kumar , Stefano Pirandola , Mohsen Razavi

Quantum key distribution (QKD) allows two distant parties to share secret keys with the proven security even in the presence of an eavesdropper with unbounded computational power. Recently, GHz-clock decoy QKD systems have been realized by…

While the objective of conventional quantum key distribution (QKD) is to secretly generate and share the classical bits concealed in the form of maximally mixed quantum states, that of private quantum channel (PQC) is to secretly transmit…

Quantum Physics · Physics 2015-09-15 Kabgyun Jeong , Jaewan Kim , Su-Yong Lee

The unconditional security of continuous-variable quantum key distribution is established for all schemes based on the estimation of the channel loss and excess noise. It is proved that, in the limit of large keys, Gaussian attacks are…

Quantum Physics · Physics 2010-12-15 Anthony Leverrier , Evgueni Karpov , Philippe Grangier , Nicolas J. Cerf

Quantum key distribution (QKD) exploits the quantum nature of light to share provably secure keys, allowing secure communication in the presence of an eavesdropper. The first QKD schemes used photons encoded in two states, such as…

Continuous-variable quantum key distribution (CVQKD) offers the specific advantage of sharing keys remotely by the use of standard telecom components, thereby promoting cost-effective and high-performance metropolitan applications.…

Quantum Physics · Physics 2023-03-30 Ziyang Chen , Xiangyu Wang , Song Yu , Zhengyu Li , Hong Guo

In the Gaussian-modulated coherent state quantum key distribution (QKD) protocol, the sender first generates Gaussian distributed random numbers and then encodes them on weak laser pulses actively by performing amplitude and phase…