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A general quantum channel consisting of a decohering and a filtering element carries one qubit of an entangled photon pair. As we apply a local filter to the other qubit, some mutual quantum information between the two qubits is restored…

We test a general method to detect lower bounds of the quantum channel capacity for two-qubit correlated channels. We consider in particular correlated dephasing, depolarising and amplitude damping channels. We show that the method is…

Quantum Physics · Physics 2016-12-01 Chiara Macchiavello , Massimiliano F. Sacchi

The Petz recovery channel plays an important role in quantum information science as an operation that approximately reverses the effect of a quantum channel. The pretty good measurement is a special case of the Petz recovery channel, and it…

Quantum Physics · Physics 2022-06-03 András Gilyén , Seth Lloyd , Iman Marvian , Yihui Quek , Mark M. Wilde

We study binary discrimination of idempotent quantum channels. When the two channels share a common full-rank invariant state, we show that a simple image inclusion condition completely determines the asymptotic behavior: when it holds, a…

Quantum Physics · Physics 2026-03-31 Satvik Singh , Bjarne Bergh

We characterize entanglement subject to its definition over real and complex, composite quantum systems. In particular, a method is established to assess quantum correlations with respect to a selected number system, illuminating the deeply…

We formulate the notion of quantum channels in the framework of quantum tomography and address there the issue of whether such maps can be regarded as classical stochastic maps. In particular kernels of maps acting on probability…

Quantum Physics · Physics 2018-06-06 G. G. Amosov , S. Mancini , V. I. Man'ko

We address the following criterion for quantifying the quantum information resources: classically simulable {\it vs.} classically non-simulable information processing. This approach gives rise to existence of a deeper level of quantum…

Quantum Physics · Physics 2007-05-23 M. Dugic

The impressive pace of advance of quantum technology calls for robust and scalable techniques for the characterization and validation of quantum hardware. Quantum process tomography, the reconstruction of an unknown quantum channel from…

A secure quantum identification system combining a classical identification procedure and quantum key distribution is proposed. Each identification sequence is always used just once and new sequences are ``refuelled'' from a shared provably…

Quantum Physics · Physics 2009-10-31 Miloslav Dusek , Ondrej Haderka , Martin Hendrych , Robert Myska

We consider a scenario where a party, say, Alice prepares a pure two-qubit (either maximally entangled or non-maximally entangled) state and sends one half of this state to another distant party, say, Bob through a qubit (either unital or…

Quantum Physics · Physics 2021-05-19 Arkaprabha Ghosal , Debarshi Das , Subhashish Banerjee

We consider the problem of deterministically cloning quantum channels with respect to the best attainable rate and the highest quality, so-called optimal cloning. We demonstrate that cloning quantum states is, in-fact, equivalent to cloning…

We suggest that a certain one-to-one parametrization of completely positive maps on the matrix algebra might be useful in the study of quantum channels. This is illustrated in the case of binary quantum channels. While the algorithm is…

Operator Algebras · Mathematics 2007-05-23 T. Constantinescu

The possibility of quantum computing has been proposed decades ago, at least as far back as the 1980s, and distributed quantum computing has been studied around two decades ago. Recent times have seen experimental successes and advances in…

Distributed, Parallel, and Cluster Computing · Computer Science 2022-08-25 Seng W. Loke

This work presents a novel fundamental algorithm for for defining and training Neural Networks in Quantum Information based on time evolution and the Hamiltonian. Classical Neural Network algorithms (ANN) are computationally expensive. For…

Machine Learning · Computer Science 2020-03-24 Aditya Dendukuri , Blake Keeling , Arash Fereidouni , Joshua Burbridge , Khoa Luu , Hugh Churchill

Quantification is a supervised learning task that consists in predicting, given a set of classes C and a set D of unlabelled items, the prevalence (or relative frequency) p(c|D) of each class c in C. Quantification can in principle be…

Machine Learning · Computer Science 2021-09-22 Andrea Esuli , Alejandro Moreo Fernández , Fabrizio Sebastiani

We investigate the quantum channel consisting of two localized quantum systems that communicate through a scalar quantum field. We choose a scalar field rather than a tensor or vector field, such as the electromagnetic field, in order to…

Quantum Physics · Physics 2020-03-06 Petar Simidzija , Aida Ahmadzadegan , Achim Kempf , Eduardo Martin-Martinez

In addition to the need for stable and precisely controllable qubits, quantum computers take advantage of good readout schemes. Superconducting qubit states can be inferred from the readout signal transmitted through a dispersively coupled…

Significant efforts are being spent on building a quantum computer. At the same time, developments in quantum software are rapidly progressing. Insufficient quantum resources often are the problem when running quantum algorithms. New…

Quantum Physics · Physics 2025-10-06 Niels M. P. Neumann , Carlos M. R. Rocha , Jasper Verbree , Marc van Vliet

What is the ultimate performance for discriminating two arbitrary quantum channels acting on a finite-dimensional Hilbert space? Here we address this basic question by deriving a general and fundamental lower bound. More precisely, we…

Quantum Physics · Physics 2019-08-09 Stefano Pirandola , Riccardo Laurenza , Cosmo Lupo , Jason L. Pereira

Any potential application of quantum computing, once encoded as a quantum circuit, needs to be compiled in order to be executed on a quantum computer. Deciding which qubit technology, which device, which compiler, and which corresponding…

Quantum Physics · Physics 2024-06-25 Nils Quetschlich , Lukas Burgholzer , Robert Wille