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The set of quantum Gaussian channels acting on one bosonic mode can be classified according to the action of the group of Gaussian unitaries. We look for bounds on the classical capacity for channels belonging to such a classification.…

Quantum Physics · Physics 2011-03-03 Cosmo Lupo , Stefano Pirandola , Paolo Aniello , Stefano Mancini

Communication over a random-parameter quantum channel when the decoder is required to reconstruct the parameter sequence is considered. We study scenarios that include either strictly-causal, causal, or non-causal channel side information…

Information Theory · Computer Science 2021-09-28 Uzi Pereg

We show that no source encoding is needed in the definition of the capacity of a quantum channel for carrying quantum information. This allows us to use the coherent information maximized over all sources and and block sizes, but not…

Quantum Physics · Physics 2011-07-19 H. Barnum , J. A. Smolin , B. M. Terhal

We study quantum channels that vary on time in a deterministic way, that is, they change in an independent but not identical way from one to another use. We derive coding theorems for the classical entanglement assisted and unassisted…

Quantum Physics · Physics 2021-02-05 Samad Khabbazi Oskouei , Stefano Mancini

We present an upper bound for the quantum channel capacity that is both additive and convex. Our bound can be interpreted as the capacity of a channel for high-fidelity quantum communication when assisted by a family of channels that have…

Quantum Physics · Physics 2008-08-28 Graeme Smith , John A. Smolin , Andreas Winter

We consider the additivity of the minimal output entropy and the classical information capacity of a class of quantum channels. For this class of channels the norm of the output is maximized for the output being a normalized projection. We…

Quantum Physics · Physics 2009-11-10 M. M. Wolf , J. Eisert

We consider the problem of transmitting classical information over a time-invariant channel with memory. A popular class of time-invariant channels with memory are finite-state-machine channels, where a \emph{classical} state evolves over…

Information Theory · Computer Science 2022-07-22 Michael X. Cao , Pascal O. Vontobel

Quantum capacity quantifies the amount of quantum information that can be transmitted by a quantum channel with an arbitrary small probability of error. Mathematically, the quantum capacity is given by an asymptotic formula involving the…

Quantum Physics · Physics 2025-12-30 Zhen Wu , Zhihao Ma , James Fullwood

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

The quantum capacity of thermal noise channel is studied. The extremal input state is obtained at the postulation that the coherent information is convex or concave at its vicinity. When the input energy tends to infinitive, it is verified…

Quantum Physics · Physics 2007-05-23 Xiao-yu Chen

The fundamental limits of channels with mismatched decoding are addressed. A general formula is established for the mismatch capacity of a general channel, defined as a sequence of conditional distributions with a general decoding metrics…

Information Theory · Computer Science 2013-10-01 Anelia Somekh-Baruch

The zero-error classical capacity of a quantum channel is the asymptotic rate at which it can be used to send classical bits perfectly, so that they can be decoded with zero probability of error. We show that there exist pairs of quantum…

Quantum Physics · Physics 2012-01-31 Toby S. Cubitt , Jianxin Chen , Aram W. Harrow

For any quantum discrete memoryless channel, we define a quantity called quantum entanglement capacity with classical feedback ($E_B$), and we show that this quantity lies between two other well-studied quantities. These two quantities -…

Quantum Physics · Physics 2009-11-13 Alan W. Leung

We define the direct and reverse secret-key capacities of a memoryless quantum channel as the optimal rates that entanglement-based quantum key distribution protocols can reach by using a single forward classical communication (direct…

Quantum Physics · Physics 2009-02-09 Stefano Pirandola , Raul Garcia-Patron , Samuel L. Braunstein , Seth Lloyd

It is shown that the capacity of a classical-quantum channel with arbitrary (possibly mixed) states equals to the maximum of the entropy bound with respect to all apriori distributions. This completes the recent result of Hausladen, Jozsa,…

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

Quantum communication channels and quantum memories are the fundamental building blocks of large-scale quantum communication networks. Estimating their capacity to transmit and store quantum information is crucial in order to assess the…

Quantum Physics · Physics 2022-12-01 Ya-Dong Wu , Giulio Chiribella

There are different inequivalent ways to define the R\'enyi capacity of a channel for a fixed input distribution $P$. In a 1995 paper Csisz\'ar has shown that for classical discrete memoryless channels there is a distinguished such quantity…

Quantum Physics · Physics 2023-01-18 Milán Mosonyi , Tomohiro Ogawa

A method is proposed to characterize a high-dimensional quantum channel with the aid of classical light. It uses a single nonseparable input optical field that contains correlations between spatial modes and wavelength to determine the…

Quantum Physics · Physics 2018-01-17 Chemist M. Mabena , Filippus S. Roux

The entanglement-assisted classical capacity of a noisy quantum channel is the amount of information per channel use that can be sent over the channel in the limit of many uses of the channel, assuming that the sender and receiver have…

Quantum Physics · Physics 2007-05-23 Charles H. Bennett , Peter W. Shor , John A. Smolin , Ashish V. Thapliyal

Given a quantum Markovian noise model, we study the maximum dimension of a classical or quantum system that can be stored for arbitrarily large time. We show that, unlike the fixed time setting, in the limit of infinite time, the classical…

Quantum Physics · Physics 2025-02-27 Omar Fawzi , Mizanur Rahaman , Mostafa Taheri