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The quantum capacity captures the value of a quantum channel for transmitting quantum information, establishing the fundamental limits on quantum communication. In spite of its central role in quantum information theory, the quantum…

We consider the transfer of classical and quantum information through a memory amplitude damping channel. Such a quantum channel is modeled as a damped harmonic oscillator, the interaction between the information carriers - a train of…

Quantum Physics · Physics 2012-06-15 A. D'Arrigo , G. Benenti , G. Falci

We consider various forms of a process, which we call {\em gluing}, for combining two or more complementary quantum channel pairs $(\mathcal{B},\mathcal{C})$ to form a composite. One type of gluing combines a perfect channel with a second…

Quantum Physics · Physics 2021-10-07 Vikesh Siddhu , Robert B. Griffiths

We study the identification capacity of classical-quantum channels ("cq-channels"), under channel uncertainty and privacy constraints. To be precise, we consider first compound memoryless cq-channels and determine their identification…

Quantum Physics · Physics 2020-04-07 Holger Boche , Christian Deppe , Andreas Winter

Quantum capacity, as the key figure of merit for a given quantum channel, upper bounds the channel's ability in transmitting quantum information. Identifying different type of channels, evaluating the corresponding quantum capacity and…

Quantum Physics · Physics 2023-03-08 Changchun Zhong , Changhun Oh , Liang Jiang

Quantum information theory predicts that when the transmission resource is doubled in quantum channels, the amount of information transmitted can be increased more than twice by quantum channel coding technique, whereas the increase is at…

Quantum Physics · Physics 2009-11-10 M. Takeoka , M. Fujiwara , J. Mizuno , M. Sasaki

Quantum addition channels have been recently introduced in the context of deriving entropic power inequalities for finite dimensional quantum systems. We prove a reverse entropy power equality which can be used to analytically prove an…

Quantum Physics · Physics 2026-04-13 Chiranjib Mukhopadhyay , Arun Kumar Pati , Sk Sazim

We consider quantum channels with two senders and one receiver. For an arbitrary such channel, we give multi-letter characterizations of two different two-dimensional capacity regions. The first region characterizes the rates at which it is…

Information Theory · Computer Science 2011-10-25 Jon Yard , Igor Devetak , Patrick Hayden

The capacity of quantum channel with product input states was formulated by the quantum coding theorem. However, whether entangled input states can enhance the quantum channel is still open. It turns out that this problem is reduced to…

Quantum Physics · Physics 2007-05-23 Susumu Osawa , Hiroshi Nagaoka

We investigate multiparty communication scenarios where information is sent from several sender to several receivers. We establish a relation between the quantum capacity of multiparty communication channels and their distillability…

Quantum Physics · Physics 2009-11-10 W. Dür , J. I. Cirac , P. Horodecki

We exhibit discrete memoryless quantum channels whose quantum capacity assisted by two-way classical communication, $Q_2$, exceeds their unassisted one-shot Holevo capacity $C_H$. These channels may be thought of as having a data input and…

Quantum Physics · Physics 2007-05-23 Charles H. Bennett , Igor Devetak , Peter W. Shor , John A. Smolin

The superactivation of zero-capacity quantum channels makes it possible to use two zero-capacity quantum channels with a positive joint capacity for their output. Currently, we have no theoretical background to describe all possible…

Quantum Physics · Physics 2012-08-28 Laszlo Gyongyosi , Sandor Imre

We develop an approximation approach to infinite dimensional quantum channels based on detailed investigation of the continuity properties of entropic characteristics of quantum channels and operations (trace-nonincreasing completely…

Quantum Physics · Physics 2008-12-17 M. E. Shirokov , A. S. Holevo

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

We study optimal rates for quantum communication over a single use of a channel, which itself can correspond to a finite number of uses of a channel with arbitrarily correlated noise. The corresponding capacity is often referred to as the…

Quantum Physics · Physics 2010-03-19 Francesco Buscemi , Nilanjana Datta

Activation of quantum capacity is a surprising phenomenon according to which the quantum capacity of a certain channel may increase by combining it with another channel with zero quantum capacity. Superactivation describes an even more…

Quantum Physics · Physics 2019-03-29 Youngrong Lim , Ryuji Takagi , Gerardo Adesso , Soojoon Lee

The purpose of this work is to extend the result of previous papers quant-ph/9611023, quant-ph/9703013 to quantum channels with additive constraints onto the input signal, by showing that the capacity of such channel is equal to the…

Quantum Physics · Physics 2007-05-23 A. S. Holevo

We provide lower and upper bounds on the information transmission capacity of one single use of a classical-quantum channel. The lower bound is expressed in terms of the Hoeffding capacity, that we define similarly to the Holevo capacity,…

Quantum Physics · Physics 2009-07-24 Milan Mosonyi , Nilanjana Datta

In this paper we show how \emph{the metric theory of tensor products} developed by Grothendieck perfectly fits in the study of channel capacities, a central topic in \emph{Shannon's information theory}. Furthermore, in the last years…

Functional Analysis · Mathematics 2015-02-10 Marius Junge , Carlos Palazuelos

We study mixed unitary quantum channels generated by irreducible projective unitary representations of finite groups. Under some assumptions on the probability distribution determining a mixture the classical capacity of the channel is…

Quantum Physics · Physics 2022-05-26 Grigori Amosov