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Major obstacles against efficient long distance quantum communication are photon losses during transmission and the probabilistic nature of Bell measurement causing exponential scaling in time and resource with distance. To overcome these…

Quantum Physics · Physics 2019-11-05 Seung-Woo Lee , Timothy C. Ralph , Hyunseok Jeong

At the fundamental level, quantum communication is ultimately limited by noise. For instance, quantum signals cannot be amplified without the introduction of noise in the amplified states. Furthermore, photon loss reduces the…

Quantum entanglement is an indispensable resource for many significant quantum information processing tasks. However, because of the noise in quantum channels, it is difficult to distribute quantum entanglement over a long distance in…

Quantum Physics · Physics 2018-01-31 Zhaofeng Su , Ji Guan , Lvzhou Li

In the absence of quantum repeaters, quantum communication proved to be nearly impossible across optical fibres longer than $\gtrsim 20\text{ km}$ due to the drop of transmissivity below the critical threshold of $1/2$. However, if the…

Quantum Physics · Physics 2025-12-29 Francesco Anna Mele , Ludovico Lami , Vittorio Giovannetti

In quantum mechanics, a fundamental law prevents quantum communications to simultaneously achieve high rates and long distances. This limitation is well known for point-to-point protocols, where two parties are directly connected by a…

Quantum Physics · Physics 2020-04-06 Stefano Pirandola

The information capacity of an optical channel under power constraints is ultimately limited by the quantum nature of transmitted signals. We discuss currently available and emerging photonic technologies whose combination can be shown…

Quantum Physics · Physics 2020-05-18 Konrad Banaszek , Ludwig Kunz , Marcin Jarzyna , Michał Jachura

Photon loss is the fundamental issue towards the development of quantum communication. We present a proposal to mitigate photon loss even at large distances and hence to create a global-scale quantum communication architecture. In this…

Quantum Physics · Physics 2023-09-01 Sumit Goswami , Sayandip Dhara

Reliable preparation of entanglement between distant systems is an outstanding problem in quantum information science and quantum communication. In practice, this has to be accomplished via noisy channels (such as optical fibers) that…

Quantum Physics · Physics 2007-11-01 Liang Jiang , Jacob M. Taylor , Navin Khaneja , Mikhail D. Lukin

Quantum communication is at the forefront of quantum technology, enabling the development of absolutely secure encryption, distributed quantum computing, teleportation and more. Whilst quantum communication has been experimentally…

Quantum Physics · Physics 2017-05-24 Scott E. Vinay , Pieter Kok

For more than a century, the diffraction limit has defined the resolution achievable by passive optical imaging systems. Although some resolution improvement can be gained through classical data processing of the image, it is limited by the…

Quantum Physics · Physics 2026-05-12 A. I. Lvovsky , Michael R. Grace , Saikat Guha , Mankei Tsang , Gerardo Adesso , Nicolas Treps

Quantum communications promises reliable transmission of quantum information, efficient distribution of entanglement and generation of completely secure keys. For all these tasks, we need to determine the optimal point-to-point rates that…

Quantum Physics · Physics 2017-04-27 Stefano Pirandola , Riccardo Laurenza , Carlo Ottaviani , Leonardo Banchi

We present an experiment demonstrating entanglement-enhanced classical communication capacity of a quantum channel with correlated noise. The channel is modelled by a fiber optic link exhibiting random birefringence that fluctuates on a…

Quantum Physics · Physics 2007-05-23 K. Banaszek , A. Dragan , W. Wasilewski , C. Radzewicz

Classical free-space optical (FSO) communication promises massive data throughput rates relative to traditional wireless technologies - an attractive outcome now being pursued in the context of satellite-ground, inter-satellite and…

Quantum Physics · Physics 2024-05-16 Nicholas Zaunders , Ziqing Wang , Timothy C. Ralph , Ryan Aguinaldo , Robert Malaney

Quantum Key Distribution (QKD) is maturing quickly. However, the current approaches to its application in optical networks make it an expensive technology. QKD networks deployed to date are designed as a collection of point-to-point,…

Quantum repeaters create long-distance entanglement between quantum systems while overcoming difficulties such as the attenuation of single photons in a fiber. Recently, an implementation of a repeater protocol based on single qubits in…

Quantum Physics · Physics 2007-07-03 L. Jiang , J. M. Taylor , M. D. Lukin

Precise synchronization between transmitter and receiver is crucial for quantum communication protocols, such as Quantum Key Distribution (QKD), to efficiently correlate the transmitted and received signals and increase the signal-to-noise…

We investigate theoretically the efficiency of deep-space optical communication in the presence of background noise. With decreasing average signal power spectral density, a scaling gap opens up between optimized simple-decoded pulse…

Quantum Physics · Physics 2018-02-20 Marcin Jarzyna , Wojciech Zwoliński , Michał Jachura , Konrad Banaszek

We propose a projection measurement onto encoded Bell states with a static network of linear optical elements. By increasing the size of the quantum error correction code, both Bell measurement efficiency and photon-loss tolerance can be…

Quantum Physics · Physics 2016-11-23 Fabian Ewert , Marcel Bergmann , Peter van Loock

Dynamic quantum circuits generate states that depend on the measurement results obtained during circuit execution. To date such a quantum computing model has mainly been implemented with qubit-based superconducting hardware utilizing reset…

We study the problem of joint communication and sensing for data transmission systems using optimal quantum instruments in order to transmit data and, at the same time, estimate environmental parameters. In particular we consider the…

Quantum Physics · Physics 2024-11-19 Pere Munar-Vallespir , Janis Nötzel