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A series of recent works has shown that placing communication channels in a coherent superposition of alternative configurations can boost their ability to transmit information. Instances of this phenomenon are the advantages arising from…

Quantum Physics · Physics 2021-09-28 Hlér Kristjánsson , Giulio Chiribella , Sina Salek , Daniel Ebler , Matthew Wilson

Transmitting data reliably over noisy communication channels is one of the most important applications of information theory, and well understood when the channel is accurately modelled by classical physics. However, when quantum effects…

In a variant of communication complexity tasks, two or more separated parties cooperate to compute a function of their local data, using a limited amount of communication. It is known that communication of quantum systems and shared…

Quantum Physics · Physics 2015-12-21 Adrien Feix , Mateus Araújo , Časlav Brukner

Superactivation is the property that two channels with zero quantum capacity can be used together to yield positive capacity. Here we demonstrate that this effect exists for a wide class of inequivalent channels, none of which can simulate…

Quantum Physics · Physics 2012-01-27 Fernando G. S. L. Brandão , Jonathan Oppenheim , Sergii Strelchuk

The quantum switch, a process enabling a coherent superposition of different orders of quantum channels, has garnered significant attention due to its ability to enable noiseless communications through noisy channels, such as…

Quantum Physics · Physics 2026-01-13 Claudio Pellitteri , Marcello Caleffi , Angela Sara Cacciapuoti

We determine the capacity of compound classical-quantum channels. As a consequence we obtain the capacity formula for the averaged classical-quantum channels. The capacity result for compound channels demonstrates, as in the classical…

Quantum Physics · Physics 2009-02-16 Igor Bjelakovic , Holger Boche

We prove that a broad array of capacities of a quantum channel are continuous. That is, two channels that are close with respect to the diamond norm have correspondingly similar communication capabilities. We first show that the classical…

Quantum Physics · Physics 2009-09-09 Debbie Leung , Graeme Smith

Quantum capacities are fundamental quantities that are notoriously hard to compute and can exhibit surprising properties such as superadditivity. Thus, a vast amount of literature is devoted to finding tight and computable bounds on these…

Quantum Physics · Physics 2023-03-02 Christoph Hirche , Felix Leditzky

We consider a communication scenario over a discrete memoryless interference channel or multiple access channel without feedback, where transmitters exploit classical, quantum, or no-signaling cooperation. In this scenario, several previous…

Quantum Physics · Physics 2026-01-05 Seung-Hyun Nam , Hyun-Young Park , Jiyoung Yun , Ashutosh Rai , Si-Hyeon Lee , Joonwoo Bae

A formula for the capacity of a quantum channel for transmitting private classical information is derived. This is shown to be equal to the capacity of the channel for generating a secret key, and neither capacity is enhanced by forward…

Quantum Physics · Physics 2007-05-23 I. Devetak

Quantum mechanics allows for situations where the relative order between two processes is entangled with a quantum degree of freedom. Here we show that such entanglement can enhance the ability to transmit quantum information over noisy…

Quantum Physics · Physics 2018-09-20 Sina Salek , Daniel Ebler , Giulio Chiribella

Quantum capacity, as the ultimate transmission rate of quantum communication, is characterized by regularized coherent information. In this work, we reformulate approximations of the quantum capacity by operator space norms and give both…

Quantum Physics · Physics 2019-11-06 Li Gao , Marius Junge , Nicholas LaRacuente

Prior entanglement between sender and receiver, which exactly doubles the classical capacity of a noiseless quantum channel, can increase the classical capacity of some noisy quantum channels by an arbitrarily large constant factor…

Quantum Physics · Physics 2009-01-23 Charles H. Bennett , Peter W. Shor , John A. Smolin , Ashish V. Thapliyal

Quantum communication channels differ from their classical counterparts because their capacities can be superadditive. The principle of monogamy of entanglement suggests that superadditive improvements in the transmission capacity of a…

Quantum Physics · Physics 2025-11-06 Satvik Singh , Sergii Strelchuk

In this paper we address the issue of universal or robust communication over quantum channels. Specifically, we consider memoryless communication scenario with channel uncertainty which is an analog of compound channel in classical…

Quantum Physics · Physics 2009-11-13 I. Bjelakovic , H. Boche , J. Noetzel

Classical communication through quantum channels may be enhanced by sharing entanglement. Superdense coding allows the encoding, and transmission, of up to two classical bits of information in a single qubit. In this paper, the maximum…

Quantum Physics · Physics 2009-11-07 G. Bowen

Quantum channels are known to provide qualitatively better information transfer capacities over their classical counterparts. Examples include quantum cryptography, quantum dense coding, and quantum teleportation. This is a short review on…

Quantum Physics · Physics 2015-03-19 Aditi Sen De , Ujjwal Sen

Recent studies have shown that quantum information may be effectively transmitted by a finite collection of completely depolarizing channels in a coherent superposition of different orders, via an operation known as the quantum $\tt…

Quantum Physics · Physics 2024-07-04 Zhen Wu , James Fullwood , Zhihao Ma , Siqi Zhou , Qi Zhao , Giulio Chiribella

Communication over a noisy quantum channel introduces errors in the transmission that must be corrected. A fundamental bound on quantum error correction is the quantum capacity, which quantifies the amount of quantum data that can be…

Quantum Physics · Physics 2009-02-20 Graeme Smith , Jon Yard

Quantum channel capacity is a fundamental quantity in order to understand how good can quantum information be transmitted or corrected when subjected to noise. However, it is generally not known how to compute such quantities, since the…

Quantum Physics · Physics 2023-09-20 Josu Etxezarreta Martinez , Antonio deMarti iOlius , Pedro M. Crespo