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The classical capacity of a quantum channel with arbitrary Markovian correlated noise is evaluated. For the general case of a channel with long-term memory, which corresponds to a Markov chain which does not converge to equilibrium, the…

Quantum Physics · Physics 2015-05-13 Nilanjana Datta , Tony Dorlas

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

Entangled inputs can enhance the capacity of quantum channels, this being one of the consequences of the celebrated result showing the non-additivity of several quantities relevant for quantum information science. In this work, we answer…

Quantum Physics · Physics 2015-05-20 Fernando G. S. L. Brandao , Jens Eisert , Michal Horodecki , Dong Yang

We give a non-technical introduction of the basic concepts of Quantum Information Theory along the distinction between possible and impossible machines. We then proceed to describe the mathematical framework of Quantum Information Theory.…

Quantum Physics · Physics 2007-05-23 R. F. Werner

As the hardware technology for quantum computing advances, its possible applications are actively searched and developed. However, such applications still suffer from the noise on quantum devices, in particular when using two-qubit gates…

Quantum Physics · Physics 2021-02-03 Kosuke Mitarai , Keisuke Fujii

In this paper we find, for a class of bipartite quantum states, a nontrivial lower bound on the entropy gain resulting from the action of a tensor product of identity channel with an arbitrary channel. By means of that we then estimate…

Quantum Physics · Physics 2015-06-22 Grigori G. Amosov

We investigate the classical communication over quantum channels when assisted by no-signaling (NS) and positive-partial-transpose-preserving (PPT) codes, for which both the optimal success probability of a given transmission rate and the…

Quantum Physics · Physics 2018-07-16 Xin Wang , Wei Xie , Runyao Duan

We consider the sequential quantum channel discrimination problem using adaptive and non-adaptive strategies. In this setting the number of uses of the underlying quantum channel is not fixed but a random variable that is either bounded in…

Information Theory · Computer Science 2022-10-21 Yonglong Li , Christoph Hirche , Marco Tomamichel

We investigate the dense coding in the case of non-symmetric Hilbert spaces of the sender and receiver's particles sharing the quantum maximally entangled state. The efficiency of classical information gain is also considered. We conclude…

Quantum Physics · Physics 2009-11-10 Fengli Yan , Meiyu Wang

Counter-intuitive to classical notions, quantum conditional entropy can be negative, playing a pivotal role in information-processing tasks. This article delves deeply into quantum channels, emphasizing negative conditional entropy breaking…

Quantum Physics · Physics 2024-11-06 PV Srinidhi , Indranil Chakrabarty , Samyadeb Bhattacharya , Nirman Ganguly

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

Evaluating the quantum capacity of quantum channels is an important but difficult problem, even for channels of low input and output dimension. Smith and Smolin showed that the quantum capacity of the Clifford-twirl of a qubit amplitude…

Quantum Physics · Physics 2021-10-12 Yingkai Ouyang

We investigate the capacity of three symmetric quantum states in three real dimensions to carry classical information. Several such capacities have already been defined, depending on what operations are allowed in the sending and receiving…

Quantum Physics · Physics 2007-05-23 Peter W. Shor

We establish a quantitative connection between the amount of lost classical information about a quantum state and the concomitant loss of entanglement. Using methods that have been developed for the optimal purification of mixed states we…

Quantum Physics · Physics 2013-09-03 J. Eisert , T. Felbinger , P. Papadopoulos , M. B. Plenio , M. Wilkens

The reliability of quantum channels for transmitting information is of profound importance from the perspective of quantum information. This naturally leads to the question as how well a quantum state is preserved when subjected to a…

Quantum Physics · Physics 2021-01-19 Javid Naikoo , Subhashish Banerjee , R. Srikanth

In this letter, we prove that the classical capacity of quantum channel for $M$ symmetric states is achieved by an uniform distribution on a priori probabilities. We also investigate non-symmetric cases such as a ternary amplitude shift…

Quantum Physics · Physics 2009-10-31 Kentaro Kato , Masao Osaki , Osamu Hirota

Recently there has been considerable activity on the subject of additivity of various quantum channel capacities. Here, we construct a family of channels with sharply bounded classical, hence private capacity. On the other hand, their…

Quantum Physics · Physics 2017-08-01 Ke Li , Andreas Winter , XuBo Zou , GuangCan Guo

Quantum communications using continuous variables are quite mature experimental techniques and the relevant theories have been extensively investigated with various methods. In this paper, we study the continuous variable quantum channels…

Quantum Physics · Physics 2009-11-11 Tao Qin , Meisheng Zhao , Yongde Zhang

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 establish the classical capacity of optical quantum channels as a sharp transition between two regimes---one which is an error-free regime for communication rates below the capacity, and the other in which the probability of correctly…

Quantum Physics · Physics 2015-03-17 Bhaskar Roy Bardhan , Raul Garcia-Patron , Mark M. Wilde , Andreas Winter