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Quantum channels describe subsystem or open system evolution. Using the classical Koopman operator that evolves functions on phase space, 4 classical Koopman channels are identified that are analogs of the 4 possible quantum channels in a…

Quantum Physics · Physics 2024-07-22 Bidhi Vijaywargia , Arul Lakshminarayan

The characterization of errors in a quantum system is a fundamental step for two important goals. First, learning about specific sources of error is essential for optimizing experimental design and error correction methods. Second,…

Quantum Physics · Physics 2020-08-24 Hillary Dawkins , Joel Wallman , Joseph Emerson

We study the communication capabilities of a quantum channel under the most general channel model known as the one-shot model. Unlike classical channels that can only be used to transmit classical information (bits), a quantum channel can…

Information Theory · Computer Science 2020-10-02 Farzin Salek , Anurag Anshu , Min-Hsiu Hsieh , Rahul Jain , Javier R. Fonollosa

A model of quantum noisy channel with input encoding by a classical random vector is described. An equation of optimality is derived to determine a complete set of wave functions describing quantum decodings based on quasi-measurements…

Quantum Physics · Physics 2007-05-23 V. P. Belavkin , R. L. Stratonovich

We study the performance of a partially correlated amplitude damping channel acting on two qubits. We derive lower bounds for the single-shot classical capacity by studying two kinds of quantum ensembles, one which allows to maximize the…

Quantum Physics · Physics 2016-01-13 A. D'Arrigo , G. Benenti , G. Falci , C. Macchiavello

A strong converse theorem for channel capacity establishes that the error probability in any communication scheme for a given channel necessarily tends to one if the rate of communication exceeds the channel's capacity. Establishing such a…

Quantum Physics · Physics 2014-12-15 Mark M. Wilde , Andreas Winter

The quantum channel capacity gives the ultimate limit for the rate at which quantum data can be reliably transmitted through a noisy quantum channel. Degradable quantum channels are among the few channels whose quantum capacities are known.…

Quantum Physics · Physics 2011-03-31 Markus Grassl , Zhengfeng Ji , Zhaohui Wei , Bei Zeng

In this paper we propose a new model for arbitrarily varying classical-quantum channels. In this model a jammer has side information. We consider two scenarios. In the first scenario the jammer knows the channel input, while in the second…

Information Theory · Computer Science 2018-02-01 Holger Boche , Minglai Cai , Ning Cai

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

Recent experimental studies have shown that the relaxation time, $T_1$, and the dephasing time, $T_2$, of superconducting qubits fluctuate considerably over time. Time-varying quantum channel (TVQC) models have been proposed in order to…

Quantum Physics · Physics 2022-02-01 Josu Etxezarreta Martinez , Patricio Fuentes , Pedro Crespo , Javier Garcia-Frias

Quantum information science strives to leverage the quantum-mechanical nature of our universe in order to achieve large improvements in certain information processing tasks. In deep-space optical communications, current receivers for the…

Quantum Physics · Physics 2020-04-16 Narayanan Rengaswamy

Quantum entanglement, perhaps the most non-classical manifestation of quantum information theory, cannot be used to transmit information between remote parties. Yet, it can be used to reduce the amount of communication required to process a…

Quantum Physics · Physics 2015-06-29 Gilles Brassard , Anne Broadbent , Alain Tapp

We obtain strict upper bounds on the bit transmission rate for communication of Classical bit codewords over Quantum channels. Albeit previous arguments in arXiv: 1804.01797 which have demonstrated that lower bounds can be shown to hold for…

Quantum Physics · Physics 2025-07-08 Pete Rigas

In the simple quantum hypothesis testing problem, upper bound with asymmetric setting is shown by using a quite useful inequality by Audenaert et al, quant-ph/0610027, which was originally invented for symmetric setting. Using this upper…

Quantum Physics · Physics 2009-11-13 Masahito Hayashi

We define a new family of codes for symmetric classical-quantum channels and establish their optimality. To this end, we extend the classical notion of generalized perfect and quasi-perfect codes to channels defined over some finite…

Quantum Physics · Physics 2020-07-17 Andreu Blasco Coll , Gonzalo Vazquez-Vilar , Javier R. Fonollosa

The field of quantum metrology seeks to apply quantum techniques and/or resources to classical sensing approaches with the goal of enhancing the precision in the estimation of a parameter beyond what can be achieved with classical…

Fault-tolerant quantum computation requires non-destructive quantum measurements with classical feed-forward. Many experimental groups are actively working towards implementing such capabilities and so they need to be accurately evaluated.…

Quantum Physics · Physics 2023-06-14 Darian McLaren , Matthew A. Graydon , Joel J. Wallman

We propose and simulate a protocol to evolve a quantum particle forward in time such that its trajectory closely matches that of the particle's Newtonian counterpart. Using short bursts of Schr\"odinger time-evolution interleaved with…

Quantum Physics · Physics 2025-10-21 Youheng Zheng

One of the fundamental tasks in quantum information processing is to measure the quantum channels. Similar to measurements of quantum states, measurements of quantum channels are inherently stochastic, that is, quantum theory provides a…

Quantum Physics · Physics 2024-06-24 Taihei Kimoto , Takayuki Miyadera

In this work we analyze properties of generic quantum channels in the case of large system size. We use random matrix theory and free probability to show that the distance between two independent random channels converges to a constant…

Quantum Physics · Physics 2018-07-09 Ion Nechita , Zbigniew Puchała , Łukasz Pawela , Karol Życzkowski