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We propose a distributed quantum dense coding protocol that uses a control system to superpose two dense coding processes, allowing us to simultaneously and coherently encode and non-classically route the sender's single-qubit system to two…

Quantum Physics · Physics 2025-03-21 Pratham Hullamballi , Aparajita Bhattacharyya , Ujjwal Sen

Weak measurements may result in extra quantity of quantumness of correlations compared with standard projective measurement on a bipartite quantum state. We show that the quantumness of correlations by weak measurements can be consumed for…

Quantum Physics · Physics 2014-03-18 Lin-Ping Huai , Bo Li , Shi-Xian Qu , Heng Fan

Dynamics of coded information over Bloch channels is investigated for different values of the channel's parameters. We show that, the suppressing of the travelling coded information over Bloch channel can be increased by decreasing the…

Quantum Physics · Physics 2015-05-19 Nasser Metwally

Conventional absorption spectroscopy relies on coherent laser sources, and in turn suffers from the inherent limitation of shot noise, especially in estimating weak absorption. Here we propose a measurement strategy with correlated photons…

Quantum Physics · Physics 2025-04-17 Zhucheng Zhang , Xue Zhang , Jing Liu , Hui Dong

Entanglement offers substantial advantages in quantum information processing, but loss and noise hinder its applications in practical scenarios. Although it has been well known for decades that the classical communication capacity over…

Quantum Physics · Physics 2020-03-16 Haowei Shi , Zheshen Zhang , Quntao Zhuang

The quantum analog of the classical erasure channel provides a simple example of a channel whose asymptotic capacity for faithful transmission of intact quantum states, with and without the assistance of a two-way classical side channel,…

Quantum Physics · Physics 2008-11-26 Charles H. Bennett , David P. DiVincenzo , John A. Smolin

We discuss the estimation of channel parameters for a noisy quantum channel - the so-called Pauli channel - using finite resources. It turns out that prior entanglement considerably enhances the fidelity of the estimation when we compare it…

Quantum Physics · Physics 2009-11-07 Dietmar G. Fischer , Holger Mack , Markus A. Cirone , Matthias Freyberger

Quantum optical systems are typically affected by two types of noise: photon loss and dephasing. Despite extensive research on each noise process individually, a comprehensive understanding of their combined effect is still lacking. A…

Quantum Physics · Physics 2024-07-26 Francesco Anna Mele , Farzin Salek , Vittorio Giovannetti , Ludovico Lami

We report measurements of the cross-correlation between current noise fluctuations in two capacitively coupled quantum dots in the Coulomb blockade regime. The sign of the cross-spectral density is found to be tunable by gate voltage and…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 D. T. McClure , L. DiCarlo , Y. Zhang , H. -A. Engel , C. M. Marcus , M. P. Hanson , A. C. Gossard

Mixed state can be used in dense coding. We have analyzed here that maximally entangled mixed states like Werner state is dense codeable for a certain range of state parameter whereas for some wider range of the state parameter the state is…

Quantum Physics · Physics 2023-01-25 Sovik Roy

We construct a class of quantum channels in arbitrary dimensions for which entanglement improves the performance of the channel. The channels have correlated noise and when the level of correlation passes a critical value we see a sharp…

Quantum Physics · Physics 2009-11-13 V. Karimipour , L. Memarzadeh

The qubit depolarizing channel with noise parameter $\eta$ transmits an input qubit perfectly with probability $1-\eta$, and outputs the completely mixed state with probability $\eta$. We show that its complementary channel has positive…

Quantum Physics · Physics 2018-10-03 Debbie Leung , John Watrous

Decoherence is one of the most important obstacles that must be overcome in quantum information processing. It depends on the qubit-environment coupling strength, but also on the spectral composition of the noise generated by the…

Quantum Physics · Physics 2011-12-02 Gonzalo A. Alvarez , Dieter Suter

Estimating the information transmission capability of a quantum channel remains one of the fundamental problems in quantum information processing. In contrast to classical channels, the information-carrying capability of quantum channels is…

Quantum Physics · Physics 2024-07-26 Aditya Nema , Ananda G. Maity , Sergii Strelchuk , David Elkouss

The capacity of discrete-time, non-coherent, multipath fading channels is considered. It is shown that if the delay spread is large in the sense that the variances of the path gains do not decay faster than geometrically, then capacity is…

Information Theory · Computer Science 2016-11-18 Tobias Koch , Amos Lapidoth

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 consider the problem of reliable communication over multiple-access channels (MAC) where the channel is driven by an independent and identically distributed state process and the encoders and the decoder are provided with various degrees…

Information Theory · Computer Science 2012-01-20 Nevroz Şen , Fady Alajaji , Serdar Yüksel , Giacomo Como

Channel capacity bounds are derived for a point-to-point indoor visible light communications (VLC) system with signal-dependent Gaussian noise. Considering both illumination and communication, the non-negative input of VLC is constrained by…

Information Theory · Computer Science 2020-11-03 Jin-Yuan Wang , Xian-Tao Fu , Rong-Rong Lu , Jun-Bo Wang , Min Lin , Julian Cheng

Non-adaptive joint source network coding of correlated sources is discussed in this paper. By studying the information flow in the network, we propose quantized network coding as an alternative for packet forwarding. This technique has both…

Information Theory · Computer Science 2012-12-24 Mahdy Nabaee , Fabrice Labeau

The capacities of noisy quantum channels capture the ultimate rates of information transmission across quantum communication lines, and the quantum capacity plays a key role in determining the overhead of fault-tolerant quantum computation…

Quantum Physics · Physics 2024-09-04 Ludovico Lami , Mark M. Wilde