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The efficient certification of classically intractable quantum devices has been a central research question for some time. However, to observe a "quantum advantage", it is believed that one does not need to build a large scale universal…

Quantum Physics · Physics 2018-03-05 Daniel Mills , Anna Pappa , Theodoros Kapourniotis , Elham Kashefi

We show that all quantum states that do not have a positive partial transpose are distillable via channels, which preserve the positivity of the partial transpose. The question whether NPT bound entanglement exist is therefore closely…

Quantum Physics · Physics 2009-11-07 Tilo Eggeling , Karl Gerd H. Vollbrecht , Reinhard F. Werner , Michael M. Wolf

In this paper, we prove that it is impossible to construct a convariant quantum feedback control instruments which aim to correct the channel noise imposed on an unknown qubit. The proof is based on the searching for the optimal quantum…

Quantum Physics · Physics 2008-11-21 ShengLi Zhang , XuBo Zou , Chuanfeng Li , ChenHui Jin , GuangCan Guo

A quantum channel is sufficient with respect to a set of input states if it can be reversed on this set. In the approximate version, the input states can be recovered within an error bounded by the decrease of the relative entropy under the…

Quantum Physics · Physics 2024-11-14 Anna Jenčová

With the advent of quantum cloud computing, the security of delegated quantum computation has become of utmost importance. While multiple statistically secure blind verification schemes in the prepare-and-send model have been proposed, none…

Quantum Physics · Physics 2026-04-16 Theodoros Kapourniotis , Dominik Leichtle , Luka Music , Harold Ollivier

Completely depolarising channels are often regarded as the prototype of physical processes that are useless for communication: any message that passes through them along a well-defined trajectory is completely erased. When two such channels…

Quantum Physics · Physics 2021-11-10 Giulio Chiribella , Matt Wilson , H. F. Chau

We study the problem of decoding classical information encoded on quantum states at the output of a quantum channel, with particular focus on increasing the communication rates towards the maximum allowed by Quantum Mechanics. After a brief…

Quantum Physics · Physics 2017-10-25 Matteo Rosati

Long-distance optical quantum channels are necessarily lossy, leading to errors in transmitted quantum information, entanglement degradation and, ultimately, poor protocol performance. Quantum states carrying information in the channel can…

In the absence of any efficient classical schemes for verifying a universal quantum computer, the importance of limiting the required quantum resources for this task has been highlighted recently. Currently, most of efficient quantum…

Quantum Physics · Physics 2015-06-24 Theodoros Kapourniotis , Vedran Dunjko , Elham Kashefi

The optimal rate at which information can be sent through a quantum channel when the transmitted signal must simultaneously carry some minimum amount of energy is characterized. To do so, we introduce the quantum-classical analogue of the…

Quantum Physics · Physics 2025-01-10 Bishal Kumar Das , Lav R. Varshney , Vaibhav Madhok

A quantum computer -- i.e., a computer capable of manipulating data in quantum superposition -- would find applications including factoring, quantum simulation and tests of basic quantum theory. Since quantum superpositions are fragile, the…

Quantum Physics · Physics 2007-05-23 Ben W. Reichardt

The presence of noise in quantum computers hinders their effective operation. Even though quantum error correction can theoretically remedy this problem, its practical realization is still a challenge. Testing and benchmarking noisy,…

Quantum Physics · Physics 2023-02-15 Adrian Ortega , Orsolya Kálmán , Tamás Kiss

We study the use of entanglement purification for quantum communication over long distances. For distances much longer than the coherence length of a corresponding noisy quantum channel, the fidelity of transmission is usually so low that…

Quantum Physics · Physics 2008-12-18 W. Dür , H. - J. Briegel , J. I. Cirac , P. Zoller

Accurately estimating high-order moments of quantum states is an elementary precondition for many crucial tasks in quantum computing, such as entanglement spectroscopy, entropy estimation, spectrum estimation, and predicting non-linear…

Quantum Physics · Physics 2024-05-16 Benchi Zhao , Mingrui Jing , Lei Zhang , Xuanqiang Zhao , Yu-Ao CHen , Kun Wang , Xin Wang

Quantum process tomography, the standard procedure to characterize any quantum channel in nature, is affected by a circular argument: in order to characterize the channel, the tomographic preparation and measurement need in turn to be…

Quantum Physics · Physics 2016-06-13 Michele Dall'Arno , Sarah Brandsen , Francesco Buscemi

Transmitting information about quantum states over classical noisy channels is an important problem with applications to science, computing, and sensing. This task, however, poses fundamental challenges due to the exponential scaling of…

Quantum Physics · Physics 2025-12-08 Nikhitha Nunavath , Jiechen Chen , Osvaldo Simeone , Riccardo Bassoli , Frank H. P. Fitzek

Quantum hypothesis testing plays a pivotal role in quantum technologies, making decisions or drawing conclusions about quantum systems based on observed data. Recently, quantum control techniques have been successfully applied to quantum…

Quantum Physics · Physics 2025-10-16 Han Xu , Benran Wang , Haidong Yuan , Xin Wang

Estimating the information transmission capability of a quantum channel remains one of the fundamental problems in quantum information processing. In contrast to classical channels, the information-carrying capability of quantum channels is…

Quantum Physics · Physics 2024-07-26 Aditya Nema , Ananda G. Maity , Sergii Strelchuk , David Elkouss

A key challenge in fault-tolerant quantum computing is synthesising and optimising circuits in a noisy environment, as traditional techniques often fail to account for the effect of noise on circuits. In this work, we propose and…

Quantum Physics · Physics 2026-04-02 Benjamin Rodatz , Boldizsár Poór , Aleks Kissinger

Quantum computing's potential is immense, promising super-polynomial reductions in execution time, energy use, and memory requirements compared to classical computers. This technology has the power to revolutionize scientific applications…

Quantum Physics · Physics 2024-05-01 Samudra Dasgupta
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