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We investigate entanglement-based quantum key distribution protocols, with particular emphasis on their efficiency under realistic conditions of satellite quantum communications, where performance is limited by the low power of a received…

Quantum Physics · Physics 2026-05-21 Vera Uzunova , Marcin Jarzyna

A protocol of quantum dense coding protection of two qubits is proposed in amplitude damping (AD) channel using weak measurement and reversal measurement. It is found that the capacity of quantum dense coding under the weak measurement and…

Quantum Physics · Physics 2018-03-16 Mao-Bin Tian , Guo-Feng Zhang

Quantum memories can be regarded as quantum channels that transmit information through time without moving it through space. Aiming at a reliable storage of information we may thus not only encode at the beginning and decode at the end, but…

Quantum Physics · Physics 2015-03-23 Alexander Müller-Hermes , David Reeb , Michael M. Wolf

We propose two types of quantum dense coding communication networks with optical continuous variables, in which a quadripartite entangled state of the optical field with totally three-party correlations of quadrature amplitudes is utilized.…

Quantum Physics · Physics 2015-05-14 Heng Shen , Xiaolong Su , Xiaojun Jia , Changde Xie

Channel capacities quantify the optimal rates of sending information reliably over noisy channels. Usually, the study of capacities assumes that the circuits which sender and receiver use for encoding and decoding consist of perfectly…

Quantum Physics · Physics 2024-04-15 Paula Belzig , Matthias Christandl , Alexander Müller-Hermes

A quantum bit encoding converter between qubits of different forms is experimentally demonstrated, paving the way to efficient networks for optical quantum computing and communication.

Quantum Physics · Physics 2023-02-14 Hyunseok Jeong

An important distinction in our understanding of capacities of classical versus quantum channels is marked by the following question: is there an algorithm which can compute (or even efficiently compute) the capacity? While there is…

Quantum Physics · Physics 2026-03-31 Archishna Bhattacharyya , Arthur Mehta , Yuming Zhao

A recent method to certify the classical capacity of quantum communication channels is applied for general damping channels in finite dimension. The method compares the mutual information obtained by coding on the computational and a…

Quantum Physics · Physics 2020-10-23 Chiara Macchiavello , Massimiliano F. Sacchi , Tito Sacchi

Recent years have seen rapid development in the subject of quantum coding theory, with breakthroughs on many exciting classes of codes, including quantum LDPC codes, quantum locally testable codes, and quantum codes with interesting…

Quantum Physics · Physics 2026-03-06 Adam Wills , Ting-Chun Lin , Rachel Yun Zhang , Min-Hsiu Hsieh

A controlled quantum dense coding scheme is investigated with a four-particle non-maximal quantum channel. The amount of classical information is shown to be capable of being controlled by the controllers through adjustments of the local…

Quantum Physics · Physics 2007-05-23 Chang-Bao Fu , Yan Xia , Bo-Xue Liu , Shou Zhang , Kyu-Hwang Yeon , Chung-In Um

The complexity of large-scale 6G-and-beyond networks demands innovative approaches for multi-objective optimization over vast search spaces, a task often intractable. Quantum computing (QC) emerges as a promising technology for efficient…

Networking and Internet Architecture · Computer Science 2025-09-10 Sebastian Macaluso , Giovanni Geraci , Elías F. Combarro , Sergi Abadal , Ioannis Arapakis , Sofia Vallecorsa , Eduard Alarcón

Quantum Machine Learning (QML) holds the promise of enhancing machine learning modeling in terms of both complexity and accuracy. A key challenge in this domain is the encoding of input data, which plays a pivotal role in determining the…

We give a scheme for loss tolerantly building a linear optical quantum memory which itself is tolerant to qubit loss. We use the encoding recently introduced in [Phys. Rev. Lett. 97, 120501, (2006)] and give a method for efficiently…

Quantum Physics · Physics 2007-09-12 Michael Varnava , Daniel Browne , Terry Rudolph

We derive explicit formulas for the capacity of multimode quantum Gaussian channels which serve as a fundamental model for optical version of multiple-input multiple-output channels. We show that it is always optimal to increase the number…

Quantum Physics · Physics 2026-05-20 Maria Popławska , Marcin Jarzyna

We present a formalism for encoding the logical basis of a qubit into subspaces of multiple physical levels. The need for this multilevel encoding arises naturally in situations where the speed of quantum operations exceeds the limits…

Quantum Physics · Physics 2007-05-23 Matthew Grace , Constantin Brif , Herschel Rabitz , Ian Walmsley , Robert Kosut , Daniel Lidar

The quantum computing paradigm in photonics currently relies on the multi-port interference in linear optical devices, which is intrinsically based on probabilistic measurements outcome and thus non-deterministic. Devising a fully…

Quantum Physics · Physics 2024-05-10 Francesco Scala , Davide Nigro , Dario Gerace

A wide variety of communication channels employ the quantized electromagnetic field to convey information. Their communication capacity crucially depends on losses associated to spatial characteristics of the channel such as diffraction and…

Quantum Physics · Physics 2012-06-21 Cosmo Lupo , Vittorio Giovannetti , Stefano Pirandola , Stefano Mancini , Seth Lloyd

For any quantum transmission line, with smaller output dimension than its input, the number of classical symbols that can be reliably encoded is strictly suboptimal. In other words, if the channel outputs a lesser number of symbols than it…

Quantum Physics · Physics 2025-09-12 Snehasish Roy Chowdhury , Sutapa Saha , Subhendu B. Ghosh , Ranendu Adhikary , Tamal Guha

We analyze the quantum capacity of a unital quantum channel, using ideas from the proof of near-optimality of Petz recovery map [Barnum and Knill 2000] and give an upper bound on the quantum capacity in terms of regularized output $2$-norm…

Quantum Physics · Physics 2018-03-07 Anurag Anshu

Adopting quantum communication to modern networking requires transmitting quantum information through fiber-based infrastructure. We report the first demonstration of superdense coding over optical fiber links, taking advantage of a…

Quantum Physics · Physics 2017-02-08 Brian P. Williams , Ronald J. Sadlier , Travis S. Humble