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We show that it is possible for the so-called weak locking capacity of a quantum channel [Guha et al., PRX 4:011016, 2014] to be much larger than its private capacity. Both reflect different ways of capturing the notion of reliable…

Quantum Physics · Physics 2017-01-06 Andreas Winter

We study the regularized average Renyi output entropy $\bar{S}_{r}^{\reg}$ of quantum channels. This quantity gives information about the average noisiness of the channel output arising from a typical, highly entangled input state in the…

Quantum Physics · Physics 2015-05-28 Christopher King , David K. Moser

In this paper a notion of entropy transmission of quantum channels is introduced as a natural extension of Ohya's entropy. Here by quantum channel is meant unital completely positive mappings (ucp) of $B(H)$ into itself, where $H$ is an…

Quantum Physics · Physics 2007-11-21 Nasir Ganikhodjaev , Farrukh Mukhamedov

We prove that all R\'enyi entanglement entropies of spin-chains described by generic (gapped), translational invariant matrix product states (MPS) are extensive for disconnected sub-systems: All R\'enyi entanglement entropy densities of the…

Quantum Physics · Physics 2020-08-31 Alberto Rolandi , Henrik Wilming

The super-additivity of quantum channel capacity is an important feature of quantum information theory different from classical theory, which has been attracting attention. Recently a special channel called ``platypus channel'' exhibits…

Quantum Physics · Physics 2025-06-02 Zhen Wu , Qi Zhao , Zhihao Ma

The thermodynamic resourcefulness of quantum channels primarily depends on their underlying causal structure and their ability to generate quantum correlations. We quantify this interplay within the resource theory of athermality for…

Quantum Physics · Physics 2026-04-02 Himanshu Badhani , Siddhartha Das

This paper introduces a method for calculating the quantum relative entropy of channels, an essential quantity in quantum channel discrimination and resource theories of quantum channels. By building on recent developments in the…

Quantum Physics · Physics 2026-04-16 Gereon Koßmann , Mark M. Wilde

The chain rule for the classical relative entropy ensures that the relative entropy between probability distributions on multipartite systems can be decomposed into a sum of relative entropies of suitably chosen conditional distributions on…

Quantum Physics · Physics 2020-03-18 Kun Fang , Omar Fawzi , Renato Renner , David Sutter

We investigate the possibility of dividing quantum channels into concatenations of other channels, thereby studying the semigroup structure of the set of completely-positive trace-preserving maps. We show the existence of 'indivisible'…

Mathematical Physics · Physics 2015-06-26 Michael M. Wolf , J. Ignacio Cirac

One of most important issues in quantum information theory concerns transmission of information through noisy quantum channels. We discuss few channel characteristics expressed by means of generalized entropies. Such characteristics can…

Quantum Physics · Physics 2013-08-19 Alexey E. Rastegin

We define and investigate a notion of entropy for quantum error correcting codes. The entropy of a code for a given quantum channel has a number of equivalent realisations, such as through the coefficients associated with the Knill-Laflamme…

Quantum Physics · Physics 2009-02-24 David W. Kribs , Aron Pasieka , Karol Zyczkowski

We obtained the estimation from below for the output entropy of a tensor product of the quantum phase-damping channel with an arbitrary channel. It is shown that from this estimation immediately follows that the strong superadditivity of…

Quantum Physics · Physics 2015-02-02 Grigori Amosov

We discuss several aspects concerning the asymptotic dynamics of dicrete-time semigroups associated with a quantum channel. By using an explicit expression of the asymptotic map, which describes the action of the quantum channel on its…

Quantum Physics · Physics 2023-06-13 Daniele Amato , Paolo Facchi , Arturo Konderak

Most quantum divergences derive their structure from classical f-divergences or Renyi-type constructions, a dependence that obscures several quantum geometric effects. We introduce a quantum relative-alpha-entropy that extends Umegaki's…

Quantum Physics · Physics 2026-04-09 Sayantan Roy , Atin Gayen , Aditi Kar Gangopadhyay , Sugata Gangopadhyay

In this article, we investigate the additivity phenomenon in the dynamic capacity of a quantum channel for trading classical communication, quantum communication and entanglement. Understanding such additivity property is important if we…

Quantum Physics · Physics 2017-08-17 Elton Yechao Zhu , Quntao Zhuang , Min-Hsiu Hsieh , Peter W. Shor

In the problem of binary quantum channel discrimination with product inputs, the supremum of all type II error exponents for which the optimal type I errors go to zero is equal to the Umegaki channel relative entropy, while the infimum of…

Quantum Physics · Physics 2025-08-12 Milán Mosonyi , Fumio Hiai

The quantum data processing inequality asserts that two quantum states become harder to distinguish when a noisy channel is applied. On the other hand, a reverse quantum data processing inequality characterizes whether distinguishability is…

Quantum Physics · Physics 2025-11-03 Paula Belzig , Li Gao , Graeme Smith , Peixue Wu

Selfcomplementary quantum channels are characterized by such an interaction between the principal quantum system and the environment that leads to the same output states of both interacting systems. These maps can describe approximate…

Quantum Physics · Physics 2018-03-20 Marek Smaczynski , Wojciech Roga , Karol Zyczkowski

For a given quantum channel we consider two optimal sets of states, related to the Holevo capacity and to the minimal output entropy of this channel. Some properties of these sets as well as the necessary and sufficient condition for their…

Quantum Physics · Physics 2008-12-17 M. E. Shirokov

We define the quantum-incoherent relative entropy of coherence ($\mathcal{QI}$ REC) of quantum channels in the framework of the resource theory by using the Choi-Jamiolkowsky isomorphism. Coherence-breaking channels are introduced as free…

Quantum Physics · Physics 2020-06-30 F. H. Kamin , F. T. Tabesh , S. Salimi , F. Kheirandish