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The endeavour to develop quantum networks gave rise to a rapidly developing field with far reaching applications such as secure communication and the realisation of distributed computing tasks. This ultimately calls for the creation of…

Quantum Physics · Physics 2016-11-28 J. Wallnöfer , M. Zwerger , C. Muschik , N. Sangouard , W. Dür

Probabilistic quantum non-demolition (QND) measurements can be performed using linear optics and post-selection. Here we show how QND devices of this kind can be used in a straightforward way to implement a quantum relay, which is capable…

Quantum Physics · Physics 2009-11-07 B. C. Jacobs , T. B. Pittman , J. D. Franson

A complete degradability analysis of one-mode Gaussian Bosonic channels is presented. We show that apart from the class of channels which are unitarily equivalent to the channels with additive classical noise, these maps can be…

Quantum Physics · Physics 2009-11-13 F. Caruso , V. Giovannetti , A. S. Holevo

Long distance quantum communication will require the use of quantum repeaters to overcome the exponential attenuation of signal with distance. One class of such repeaters utilizes quantum error correction to overcome losses in the…

Quantum Physics · Physics 2024-07-31 Filip Rozpędek , Kaushik P. Seshadreesan , Paul Polakos , Liang Jiang , Saikat Guha

The purpose of this work is to extend the result of previous papers quant-ph/9611023, quant-ph/9703013 to quantum channels with additive constraints onto the input signal, by showing that the capacity of such channel is equal to the…

Quantum Physics · Physics 2007-05-23 A. S. Holevo

We present an algorithm for calculation of the Gaussian classical capacity of a quantum bosonic memory channel with additive Gaussian noise. The algorithm, restricted to Gaussian input states, is applicable to all channels with noise…

Quantum Physics · Physics 2015-03-17 Joachim Schäfer , Evgueni Karpov , Nicolas J. Cerf

A large scale quantum network requires the distribution of high-fidelity end-to-end entanglement. To overcome the range limitations inherent to terrestrial fiber, a leading architecture has emerged: satellite-based sources transmitting…

For a quantum channel of additive Gaussian noise with loss, in the general case of $n$ copies input, we show that up to first order perturbation, any non-Gaussian perturbation to the product thermal state input has a less quantum…

Quantum Physics · Physics 2007-10-03 Xiao-yu Chen

Quantum communications capacity using direct transmission over length-$L$ optical fiber scales as $R \sim e^{-\alpha L}$, where $\alpha$ is the fiber's loss coefficient. The rate achieved using a linear chain of quantum repeaters equipped…

Quantum Physics · Physics 2021-11-22 Prajit Dhara , Ashlesha Patil , Hari Krovi , Saikat Guha

Global-scale entanglement distribution has been a formidable challenge due to the unavoidable losses in communication channels. Here, we propose a novel backbone channel for quantum network based on balloon-based aerial relays. We…

Quantum Physics · Physics 2026-02-24 Pei-Xi Liu , Yu-Ping Lin , Zong-Quan Zhou , Chuan-Feng Li , Guang-Can Guo

Upper bounds on the secret-key-agreement capacity of a quantum channel serve as a way to assess the performance of practical quantum-key-distribution protocols conducted over that channel. In particular, if a protocol employs a quantum…

Quantum Physics · Physics 2018-03-13 Eneet Kaur , Mark M. Wilde

While Quantum Key Distribution (QKD) has been proven in lab environments, large-scale implementation requires integration with existing infrastructure. This paper proposes an opportunistic QKD framework that takes advantage of idle spectral…

Quantum Physics · Physics 2026-04-15 Sumit Chaudhary , Pere Munar Vallespir , Alonso Viladomat Jasso , Janis Nötzel

Quantum key distribution (QKD) takes advantage of fundamental properties of quantum physics to allow two distant parties to share a secret key; however, QKD is hampered by a distance limitation of a few hundred kilometers on earth. The most…

A feasible route towards implementing long-distance quantum key distribution (QKD) systems relies on probabilistic schemes for entanglement distribution and swapping as proposed in the work of Duan, Lukin, Cirac, and Zoller (DLCZ) [Nature…

Quantum Physics · Physics 2015-03-17 Jeyran Amirloo , Mohsen Razavi , A. Hamed Majedi

Standard upper and lower bounds on the capacity of relay channels are cut-set (CS), decode-forward (DF), and quantize-forward (QF) rates. For real additive white Gaussian noise (AWGN) multicast relay channels with one source node and one…

Information Theory · Computer Science 2019-01-28 Mohit Thakur , Gerhard Kramer

In Shannon information theory the capacity of a memoryless communication channel cannot be increased by the use of feedback from receiver to sender. In this paper the use of classical feedback is shown to provide no increase in the…

Quantum Physics · Physics 2007-05-23 Garry Bowen , Rajagopal Nagarajan

Quantum repeater networks that allow long-distance entanglement distribution will be the backbone of distributed quantum information processing. In this paper we explore entanglement distribution using quantum repeaters with optimized…

The employ of a noiseless linear amplifier (NLA) has been proven as a useful tool for mitigating imperfections in quantum channels. Its analysis is usually conducted within specific frameworks, for which the set of input states for a given…

Quantum Physics · Physics 2015-06-10 Rémi Blandino , Marco Barbieri , Philippe Grangier , Rosa Tualle-Brouri

Quantum networks, capable of transmitting arbitrary quantum states, provide a foundation for a wide range of quantum applications, including distributed quantum computing, distributed quantum sensing, and quantum communication. Photons are…

Quantum Physics · Physics 2025-08-28 Tian-Xiang Zhu , Xiao Liu , Zong-Quan Zhou , Chuan-Feng Li

With the emergence of the Quantum Internet, the need for advanced quantum networking techniques has significantly risen. Various models of quantum repeaters have been presented, each delineating a unique strategy to ensure quantum…

Networking and Internet Architecture · Computer Science 2024-01-19 Zebo Yang , Ali Ghubaish , Raj Jain , Hassan Shapourian , Alireza Shabani