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Quantum key distribution (QKD) offers information-theoretic security based on the fundamental laws of physics. However, device imperfections, such as those in active modulators, may introduce side-channel leakage, thus compromising…

Quantum Physics · Physics 2023-05-10 Chengqiu Hu , Wenyuan Wang , Kai-Sum Chan , Zhenghan Yuan , Hoi-Kwong Lo

We present a new technique for proving the security of quantum key distribution (QKD) protocols. It is based on direct information-theoretic arguments and thus also applies if no equivalent entanglement purification scheme can be found.…

Quantum Physics · Physics 2009-11-11 R. Renner , N. Gisin , B. Kraus

Quantum coherence was recently formalized as a physical resource to measure the strength of superposition. Based on the resource theory, we present a systematic framework that connects a coherence measure to the security of quantum key…

Quantum Physics · Physics 2019-06-25 Jiajun Ma , You Zhou , Xiao Yuan , Xiongfeng Ma

In realistic continuous variable quantum key distribution protocols, an eavesdropper may exploit the additional Gaussian noise generated during transmission to mask her presence. We present a theoretical framework for a post-selection based…

Continuous-variable quantum key distribution (CV-QKD) enables two remote parties to establish information-theoretically secure keys and offers high practical feasibility due to its compatibility with mature coherent optical communication…

Quantum Physics · Physics 2025-12-18 Yanhao Sun , Jiayu Ma , Xiangyu Wang , Song Yu , Ziyang Chen , Hong Guo

We address the applicability of quantum key distribution with continuous-variable coherent and squeezed states over long-distance satellite-based links, considering low Earth orbits and taking into account strong varying channel…

Quantum Physics · Physics 2021-01-25 Ivan Derkach , Vladyslav C Usenko

Entanglement swapping between photon pairs is a fundamental building block in schemes using quantum relays or quantum repeaters to overcome the range limits of long-distance quantum key distribution. We develop a closed-form solution for…

Quantum Physics · Physics 2010-06-01 Artur Scherer , Regina B. Howard , Barry C. Sanders , Wolfgang Tittel

The stochastic evolution of quantum systems during measurement is arguably the most enigmatic feature of quantum mechanics. Measuring a quantum system typically steers it towards a classical state, destroying any initial quantum…

Mesoscale and Nanoscale Physics · Physics 2013-10-18 D. Ristè , M. Dukalski , C. A. Watson , G. de Lange , M. J. Tiggelman , Ya. M. Blanter , K. W. Lehnert , R. N. Schouten , L. DiCarlo

We present three quantum key distribution protocols using entangled state. In the first two protocols, all Einstein-Podolsky-Rosen pairs are used to distribute a secret key except those chosen for eavesdropping check, because the…

Quantum Physics · Physics 2007-05-23 Jian Wang , Quan Zhang , Chao-jing Tang

We explore possibilities of entangling two distant material qubits with the help of an optical radiation field in the regime of strong quantum electrodynamical coupling with almost resonant interaction. For this purpose the optimum…

Quantum Physics · Physics 2025-10-10 J. Z. Bernád , G. Alber

We review and discuss the potential of using measurement-based elements in quantum communication schemes, where certain tasks are realized with the help of entangled resource states that are processed by measurements. We consider long-range…

Quantum Physics · Physics 2016-09-27 M. Zwerger , H. J. Briegel , W. Dür

We consider the security of continuous-variable quantum key distribution using thermal (or noisy) Gaussian resource states. Specifically, we analyze this against collective Gaussian attacks using direct and reverse reconciliation where both…

Quantum Physics · Physics 2013-04-17 Christian Weedbrook , Stefano Pirandola , Timothy C. Ralph

Complementarity and entanglement are fundamental features of Quantum Mechanics that were recently related in triality equalities that involve quantum coherence, the wave aspect of a qubit, and quantum predictability and quantum…

Quantum Physics · Physics 2022-09-09 Marcos L. W. Basso , Jonas Maziero

We report an experimental investigation of the role of measurement in quantum metrology when the states of the probes are mixed. In particular, we investigated optimized local measurements and general global projective measurements,…

Quantum Physics · Physics 2021-02-22 R. S. Piera , S. P. Walborn , G. H. Aguilar

Quantum key distribution (QKD) based on entangled photon pairs holds the potential for repeater-based quantum networks connecting clients over long distance. We demonstrate long-distance entanglement distribution by means of…

Entanglement-assisted quantum communication employs pre-shared entanglement between sender and receiver as a resource. We apply the same framework to quantum metrology, introducing shared entanglement between the preparation and the…

Quantum Physics · Physics 2016-07-06 Zixin Huang , Chiara Macchiavello , Lorenzo Maccone

Continuous-variable quantum key distribution (CVQKD) using coherent states and heterodyne detection enables secure quantum communication based on technology that has large similarities to coherent optical telecommunication. Yet, practical…

We prove the security of a high-capacity quantum key distribution protocol over noisy channels. By using entanglement purification protocol, we construct a modified version of the protocol in which we separate it into two consecutive…

Quantum Physics · Physics 2007-05-23 Xiao-Wei Zhang , Kai Wen , Gui Lu Long

Continuous-variable (CV) quantum key distribution (QKD) employs the quadratures of a bosonic mode to establish a secret key between two remote parties, and this is usually achieved via a Gaussian modulation of coherent states. The resulting…

Studies of quantum metrology have shown that the use of many-body entangled states can lead to an enhancement in sensitivity when compared to product states. In this paper, we quantify the metrological advantage of entanglement in a setting…