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Quantum noise is currently limiting efficient quantum information processing and computation. In this work, we consider the tasks of reconstructing and classifying quantum states corrupted by the action of an unknown noisy channel using…

Quantum Physics · Physics 2025-04-01 Angela Rosy Morgillo , Stefano Mangini , Marco Piastra , Chiara Macchiavello

Dynamics of many-qubit systems, that may correspond to computational processing with quantum systems, can be efficiently and generally approximated by a sequence of two- and single-qubit gates. In practical applications, however, a quantum…

Quantum Physics · Physics 2018-12-06 Joonwoo Bae , Tanmay Singal

According to the statistical interpretation of quantum theory, quantum computers form a distinguished class of probabilistic machines (PMs) by encoding n qubits in 2n pbits (random binary variables). This raises the possibility of a…

Quantum Physics · Physics 2007-05-23 P. Gralewicz

We introduce a construction that turns a category of pure state spaces and operators into a category of observable algebras and superoperators. For example, it turns the category of finite-dimensional Hilbert spaces into the category of…

Quantum Physics · Physics 2014-09-17 Bob Coecke , Chris Heunen , Aleks Kissinger

We investigate decoherence channels that are modelled as a sequence of collisions of a quantum system (e.g., a qubit) with particles (e.g., qubits) of the environment. We show that collisions induce decoherence when a bi-partite interaction…

Quantum Physics · Physics 2009-11-11 Mario Ziman , Vladimir Buzek

We study mixed unitary quantum channels generated by irreducible projective unitary representations of finite groups. Under some assumptions on the probability distribution determining a mixture the classical capacity of the channel is…

Quantum Physics · Physics 2022-05-26 Grigori Amosov

A characterization of qubit quantum channels is introduced. In analogy to what happens in the context of Bosonic channels we exploit the possibility of representing the states of the system in terms of characteristic function. The latter…

Quantum Physics · Physics 2007-10-25 Filippo Caruso , Vittorio Giovannetti

The efficiency of parameter estimation of quantum channels is studied in this paper. We introduce the concept of programmable parameters to the theory of estimation. It is found that programmable parameters obey the standard quantum limit…

Quantum Physics · Physics 2010-03-17 Zhengfeng Ji , Guoming Wang , Runyao Duan , Yuan Feng , Mingsheng Ying

We study a particular class of trace-preserving completely positive maps, called PQ-channels, for which classical and quantum evolutions are isolated in a certain sense. By combining open quantum random walks with a notion of recurrence, we…

Mathematical Physics · Physics 2015-06-26 Carlos F. Lardizabal , Rafael R. Souza

Quantum convolutional neural networks (QCNNs) have gathered attention as one of the most promising algorithms for quantum machine learning. Reduction in the cost of training as well as improvement in performance is required for practical…

In recent years semiconducting qubits have undergone a remarkable evolution, making great strides in overcoming decoherence as well as in prospects for scalability, and have become one of the leading contenders for the development of…

Mesoscale and Nanoscale Physics · Physics 2021-02-24 Anasua Chatterjee , Paul Stevenson , Silvano De Franceschi , Andrea Morello , Nathalie de Leon , Ferdinand Kuemmeth

Machine Learning provides powerful tools for a variety of applications, including disease diagnosis through medical image classification. In recent years, quantum machine learning techniques have been put forward as a way to potentially…

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

Quantum information processing is expressed using quantum bits (qubits) and quantum gates which are arranged in the terms of quantum circuits. Here, each qubit is associated to a quantum circuit wire which is used to conduct the desired…

Quantum Physics · Physics 2016-10-26 Alexandru Paler , Robert Wille , Simon J. Devitt

We define the binding entanglement channel as the quantum channel through which quantum information cannot be reliably transmitted, but which can be used to share bound entanglement. We provide a characterization of such class of channels.…

Quantum Physics · Physics 2015-06-26 Pawel Horodecki , Michal Horodecki , Ryszard Horodecki

Product states are always considered as the states that don't contain quantum correlation. We discuss here when a quantum channel sends the product states to themselves. The exact forms of such channels are proposed. It is shown that such a…

Quantum Physics · Physics 2015-05-12 Yu Guo , Zhaofang Bai , Shuanping Du , Xiulan Li

An important distinction in our understanding of capacities of classical versus quantum channels is marked by the following question: is there an algorithm which can compute (or even efficiently compute) the capacity? While there is…

Quantum Physics · Physics 2026-03-31 Archishna Bhattacharyya , Arthur Mehta , Yuming Zhao

A special class of quantum channels, named subspace local (SL), are defined and investigated. The proposed definition of subspace locality of quantum channels is an attempt to answer the question of what kind of restriction should be put on…

Quantum Physics · Physics 2007-05-23 Johan Åberg

In this brief note, I clarify the crucial differences between three different protocols of quantum channel discrimination, after some confusion has appeared in recent literature.

Quantum Physics · Physics 2021-03-08 Stefano Pirandola

The simplest building blocks for quantum computations are the qubit-qubit quantum channels. In this paper, we analyze the structure of these channels via their Choi representation. The restriction of a quantum channel to the space of…

Mathematical Physics · Physics 2023-07-24 Attila Lovas , Attila Andai