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When classical information is sent through a quantum channel of nonorthogonal states, there is a possibility that transmittable classical information exceeds a channel capacity in a single use of the initial channel by extending it into…

Quantum Physics · Physics 2009-10-30 Masahide Sasaki , Kentaro Kato , Masayuki Izutsu , Osamu Hirota

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

Using random Gaussian vectors and an information-uncertainty relation, we give a proof that the coherent information is an achievable rate for entanglement transmission through a noisy quantum channel. The codes are random subspaces…

Quantum Physics · Physics 2012-07-06 Patrick Hayden , Peter W. Shor , Andreas Winter

We define classical-quantum multiway channels for transmission of classical information, after recent work by Allahverdyan and Saakian. Bounds on the capacity region are derived in a uniform way, which are analogous to the classically known…

Quantum Physics · Physics 2016-11-15 Andreas Winter

A general formula for the capacity of arbitrary compound channels with the receiver channel state information is obtained using the information density approach. No assumptions of ergodicity, stationarity or information stability are made…

Information Theory · Computer Science 2016-04-07 Sergey Loyka , Charalambos D. Charalambous

Motivated by the gate set tomography we study quantum channels from the perspective of information which is invariant with respect to the gauge realized through similarity of matrices representing channel superoperators. We thus use the…

Quantum Physics · Physics 2018-04-13 Łukasz Rudnicki , Zbigniew Puchała , Karol Zyczkowski

We determine both the quantum and the private capacities of low-noise quantum channels to leading orders in the channel's distance to the perfect channel. It has been an open problem for more than 20 years to determine the capacities of…

Quantum Physics · Physics 2023-12-06 Felix Leditzky , Debbie Leung , Graeme Smith

We propose a categorical foundation for the connection between pure and mixed states in quantum information and quantum computation. The foundation is based on distributive monoidal categories. First, we prove that the category of all…

Logic in Computer Science · Computer Science 2019-04-25 Mathieu Huot , Sam Staton

A necessary condition for reversibility (sufficiency) of a quantum channel with respect to complete families of states with bounded rank is obtained. A full description (up to isometrical equivalence) of all quantum channels reversible with…

Quantum Physics · Physics 2015-06-04 M. E. Shirokov

In this paper, a channel that is contaminated by two independent Gaussian noises $S ~ N(0,Q)$ and $Z_0 ~ N(0,N_0)$ is considered. The capacity of this channel is computed when independent noisy versions of $S$ are known to the transmitter…

Information Theory · Computer Science 2008-06-18 Yong Peng , Dinesh Rajan

We look into the task of differentiating between any two quantum channels and reconstructing them from the obtained measurement statistics with possibly limited information about the experimental set-up. We employ the communication matrix…

Quantum Physics · Physics 2025-11-19 Samgeeth Puliyil , Leevi Leppäjärvi , Mário Ziman

We present a framework for quantifying information flow within general quantum processes. For this purpose, we introduce the signaling power of quantum channels and discuss its relevant operational properties. This function supports…

Quantum Physics · Physics 2025-08-08 Leonardo S. V. Santos , Zhen-Peng Xu , Jyrki Piilo , Otfried Gühne

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

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

A simple method to enhance the quality of communication is to send a carrier with its copies. Classical information theory says that information behaves quantitatively under copying. In other words, if a carrier is more informatic than…

Quantum Physics · Physics 2020-09-04 Jisho Miyazaki

The design of error-correcting codes used in modern communications relies on information theory to quantify the capacity of a noisy channel to send information [1]. This capacity can be expressed using the mutual information between input…

Quantum Physics · Physics 2019-07-17 M. B. Hastings

Transmission of classical information using quantum objects such as polarized photons is studied. The classical (Shannon) channel capacity and its relation to quantum (von Neumann) channel capacity is investigated for various receiver…

Quantum Physics · Physics 2007-05-23 Göran Einarsson

We derive a general limit on the fidelity of a quantum channel conveying an ensemble of pure states. Unlike previous results, this limit applies to arbitrary coding and decoding schemes, including nonunitary decoding. This establishes the…

Quantum Physics · Physics 2016-09-08 Howard Barnum , Christopher A. Fuchs , Richard Jozsa , Benjamin Schumacher

A recent method to certify the classical capacity of quantum communication channels is applied for general damping channels in finite dimension. The method compares the mutual information obtained by coding on the computational and a…

Quantum Physics · Physics 2020-10-23 Chiara Macchiavello , Massimiliano F. Sacchi , Tito Sacchi

Quantum reading refers to the task of reading out classical information stored in a read-only memory device. In any such protocol, the transmitter and receiver are in the same physical location, and the goal of such a protocol is to use…

Quantum Physics · Physics 2019-11-04 Siddhartha Das , Mark M. Wilde
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