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Quantum channel capacities play a central role in quantum Shannon theory, a formalism built upon rigorous coding theorems for noisy channels. Evaluating exact capacity values for general quantum channels remains intractable due to…

Quantum Physics · Physics 2025-10-14 Zhen Wu , Si-Qi Zhou

Fast quantum data transmission faces several shortcomings such as the indistinguishability of some partly overlapping signals, the channel noises, and so on. Based on the encoded quantum data transmission protocol, an unconventional scheme…

Quantum Physics · Physics 2017-08-31 Weidong Tang , Sixia Yu

We consider the problem of coding for quantum channels with side information that is available ahead of time at the transmitter but not at the receiver. We find a single-letter expression for the entanglement-assisted quantum capacity of…

Quantum Physics · Physics 2017-08-14 Frédéric Dupuis

Quantum teleportation enables the deterministic exchange of qubits via lossy channels. While it is commonly believed that unconditional teleportation requires a preshared entangled qubit pair, here we demonstrate a protocol that is in…

The capacity of accelerated channel is investigated for different classes of initial states. It is shown that, the capacities of the travelling channels depend on the frame in which the accelerated channels are observed in and the initial…

Quantum Physics · Physics 2014-02-04 N. Metwally , A. Sagheer

Phase covariant qubit dynamics describes an evolution of a two-level system under simultaneous action of pure dephasing, energy dissipation, and energy gain with time-dependent rates $\gamma_z(t)$, $\gamma_-(t)$, and $\gamma_+(t)$,…

Quantum Physics · Physics 2020-04-24 S. N. Filippov , A. N. Glinov , L. Leppäjärvi

Quantum communications promises reliable transmission of quantum information, efficient distribution of entanglement and generation of completely secure keys. For all these tasks, we need to determine the optimal point-to-point rates that…

Quantum Physics · Physics 2017-04-27 Stefano Pirandola , Riccardo Laurenza , Carlo Ottaviani , Leonardo Banchi

We investigate phase transitions in the encoding of quantum information in a quantum many-body system due to the competing effects of unitary scrambling and boundary dissipation. Specifically, we study the fate of quantum information in a…

Quantum Physics · Physics 2023-04-07 Izabella Lovas , Utkarsh Agrawal , Sagar Vijay

Quantum mechanics provides a disembodied way to transfer quantum information from one quantum object to another. In theory, this quantum information transfer can occur between quantum objects of any dimension, yet the reported experiments…

Quantum Physics · Physics 2023-05-24 Tianfeng Feng , Qiao Xu , Linxiang Zhou , Maolin Luo , Wuhong Zhang , Xiaoqi Zhou

We prove that a broad array of capacities of a quantum channel are continuous. That is, two channels that are close with respect to the diamond norm have correspondingly similar communication capabilities. We first show that the classical…

Quantum Physics · Physics 2009-09-09 Debbie Leung , Graeme Smith

Dissipation can be used as a resource to control and simulate quantum systems. We discuss a modular model based on fast dissipation capable of performing universal quantum computation, and simulating arbitrary Lindbladian dynamics. The…

Quantum Physics · Physics 2016-12-01 Jeffrey Marshall , Lorenzo Campos Venuti , Paolo Zanardi

Quantum Information Processing (QIP) tasks can be efficiently formulated in terms of quantum dynamical maps, whose formalism is able to provide the appropriate mathematical representation of the evolution of open quantum systems. A key QIP…

Quantum states of light are the obvious choice for communicating quantum information. To date, encoding information into the polarisation states of single photons has been widely used as these states form an natural closed two state qubit.…

Quantum Physics · Physics 2015-01-08 Peter P. Rohde , Joseph F. Fitzsimons , Alexei Gilchrist

Quantum convolutional coding is a technique for encoding a stream of quantum information before transmitting it over a noisy quantum channel. Two important goals in the design of quantum convolutional encoders are to minimize the memory…

Quantum Physics · Physics 2013-01-21 Monireh Houshmand , Saied Hosseini-Khayat , Mark M. Wilde

As the rapidly evolving field of machine learning continues to produce incredibly useful tools and models, the potential for quantum computing to provide speed up for machine learning algorithms is becoming increasingly desirable. In…

Quantum Physics · Physics 2024-04-02 Anthony M. Smaldone , Gregory W. Kyro , Victor S. Batista

Quantum memory systems are vital in quantum information processing for dependable storage and retrieval of quantum states. Inspired by classical reliability theories that synthesize reliable computing systems from unreliable components, we…

Quantum Physics · Physics 2025-12-10 Anuj K. Nayak , Eric Chitambar , Lav R. Varshney

We consider quantum channels with two senders and one receiver. For an arbitrary such channel, we give multi-letter characterizations of two different two-dimensional capacity regions. The first region is comprised of the rates at which it…

Quantum Physics · Physics 2011-10-25 Jon Yard , Igor Devetak , Patrick Hayden

Quantum communication exploits non-classical correlations to achieve efficient and unconditionally secure exchange of information. In particular, the quantum teleportation protocol allows for a deterministic and secure transfer of unknown…

Quantum Physics · Physics 2025-12-30 W. K. Yam , M. Renger , S. Gandorfer , R. Gross , K. G. Fedorov

For any quantum transmission line, with smaller output dimension than its input, the number of classical symbols that can be reliably encoded is strictly suboptimal. In other words, if the channel outputs a lesser number of symbols than it…

Quantum Physics · Physics 2025-09-12 Snehasish Roy Chowdhury , Sutapa Saha , Subhendu B. Ghosh , Ranendu Adhikary , Tamal Guha

One of the main problems for the future of practical quantum computing is to stabilize the computation against unwanted interactions with the environment and imperfections in the applied operations. Existing proposals for quantum memories…

Quantum Physics · Physics 2007-05-23 Emanuel Knill , Raymond Laflamme