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The bosonic quantum channels have recently attracted a growing interest, motivated by the hope that they open a tractable approach to the generally hard problem of evaluating quantum channel capacities. These studies, however, have always…

Quantum Physics · Physics 2007-05-23 Nicolas J. Cerf , Julien Clavareau , Chiara Macchiavello , Jeremie Roland

The optimal rate of reliable communication over a quantum channel can be enhanced by pre-shared entanglement. Whereas the enhancement may be unbounded in infinite-dimensional settings even when the input power is constrained, a…

A chain of interacting spin behaves like a quantum mediator (quantum link) which allows two distant parties that control the ends of the chain to exchange quantum messages. We show that over repeated uses without resetting the study of a…

Quantum Physics · Physics 2009-11-13 Vittorio Giovannetti , Daniel Burgarth , Stefano Mancini

The quantum capacity of a memoryless channel is often used as a single figure of merit to characterize its ability to transmit quantum information coherently. The capacity determines the maximal rate at which we can code reliably over…

Quantum Physics · Physics 2016-05-10 Marco Tomamichel , Mario Berta , Joseph M. Renes

We study universal quantum codes for entanglement-assisted quantum communication over compound quantum channels. In this setting, sender and receiver do not know the specific channel that will be used for communication, but only know the…

Quantum Physics · Physics 2017-04-28 Mario Berta , Hrant Gharibyan , Michael Walter

We construct a new entanglement-assisted quantum polar coding scheme which achieves the symmetric coherent information rate by synthesizing "amplitude" and "phase" channels from a given, arbitrary quantum channel. We first demonstrate the…

Quantum Physics · Physics 2012-09-04 Mark M. Wilde , Joseph M. Renes

Two photons can simultaneously share entanglement between several degrees of freedom such as polarization, energy-time, spatial mode and orbital angular momentum. This resource is known as hyperentanglement, and it has been shown to be an…

In this paper we study quantum communication channels with correlated noise effects, i.e., quantum channels with memory. We derive a model for correlated noise channels that includes a channel memory state. We examine the case where the…

Quantum Physics · Physics 2009-11-10 Garry Bowen , Stefano Mancini

A quantum communication network can be constructed by distributing a multipartite entangled state to space-separated nodes. Entangled optical beams with highest flying speed and measurable brightness can be used as carriers to convey…

Quantum Physics · Physics 2017-05-09 Xiaowei Deng , Caixing Tian , Xiaolong Su , Changde Xie

Entanglement and quantum information lie at the root of quantum theory. These remarkable resources are generally believed to diminish when systems carrying them interact with their environment. By contrast, we find that engaging a system…

Quantum Physics · Physics 2025-05-28 Vikesh Siddhu

We give a representation for entanglement-breaking channels in separable Hilbert space that generalizes the "Kraus decomposition with rank one operators" and use it to describe the complementary channels. We also give necessary and…

Quantum Physics · Physics 2010-11-23 A. S. Holevo

In this paper we initiate the study of entanglement-breaking (EB) superchannels. These are processes that always yield separable maps when acting on one side of a bipartite completely positive (CP) map. EB superchannels are a generalization…

Quantum Physics · Physics 2020-07-21 Senrui Chen , Eric Chitambar

Long-distance entanglement is pivotal for quantum communication, distributed quantum computing and sensing. Significant progresses have been made in extending the distribution distance of entangled photons, either in free space or fiber.…

The capability to reliably transmit and store quantum information is an essential building block for future quantum networks and processors. Gauging the ability of a communication link or quantum memory to preserve quantum correlations is…

Reservoir computing is a promising neuromorphic paradigm, and its quantum implementation using spin networks has shown some advantage when entanglement is present. Here, we consider a distributed scenario in which two distinct input time…

Quantum Physics · Physics 2025-11-10 Sareh Askari , Youssef Kora , Christoph Simon

A quantum communication channel can be put to many uses: it can transmit classical information, private classical information, or quantum information. It can be used alone, with shared entanglement, or together with other channels. For each…

Information Theory · Computer Science 2010-07-20 Graeme Smith

In communication networks many different channels must share a limited amount of resources. In order to allow for multiple simultaneous communications, multiple access techniques are routinely employed. With quantum communication, it is…

Quantum Physics · Physics 2007-05-23 Juan Carlos Garcia-Escartin , Pedro Chamorro-Posada

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

We show the equivalence of two different notions of quantum channel capacity: that which uses the entanglement fidelity as its criterion of success in transmission, and that which uses the minimum fidelity of pure states in a subspace of…

Quantum Physics · Physics 2016-11-18 H. Barnum , E. Knill , M. A. Nielsen

We investigate the usefulness of side entanglement in discriminating between two generic qubit channels, {\ up to unitary pre- and post-processing,} and determine exact conditions under which it does enhance (as well as conditions under…

Quantum Physics · Physics 2023-10-25 Samad Khabbazi Oskouei , Stefano Mancini , Milajiguli Rexiti