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Quantum machine learning (QML) holds promise for accelerating pattern recognition, optimization, and data analysis, but the conditions under which it can truly outperform classical approaches remain unclear. Existing research often…

Quantum Physics · Physics 2025-09-23 Christophe Pere

While all quantum algorithms can be expressed in terms of single-qubit and two-qubit gates, more expressive gate sets can help reduce the algorithmic depth. This is important in the presence of gate errors, especially those due to…

Noise in quantum systems is a major obstacle to implementing many quantum algorithms on large quantum circuits. In this work, we study the effects of noise on the Rademacher complexity of quantum circuits, which is a measure of statistical…

Quantum Physics · Physics 2021-03-05 Kaifeng Bu , Dax Enshan Koh , Lu Li , Qingxian Luo , Yaobo Zhang

We introduce a quantum version for the statistical complexity measure, in the context of quantum information theory, and use it as a signalling function of quantum order-disorder transitions. We discuss the possibility for such transitions…

Quantum computers have now appeared in our society and are utilized for the investigation of science and engineering. At present, they have been built as intermediate-size computers containing about fifty qubits and are weak against noise…

Quantum Physics · Physics 2020-12-07 Yusuke Hama

Flexible characterization techniques that identify and quantify experimental imperfections under realistic assumptions are crucial for the development of quantum computers. Gate set tomography is a characterization approach that…

Quantum Physics · Physics 2023-03-31 Raphael Brieger , Ingo Roth , Martin Kliesch

Variational quantum circuits (VQCs) are a central component of many quantum machine learning algorithms, offering a hybrid quantum-classical framework that, under certain aspects, can be considered similar to classical deep neural networks.…

Quantum Physics · Physics 2025-07-16 Nicola Assolini , Luca Marzari , Isabella Mastroeni , Alessandra di Pierro

In recent years, there is considerable experimental effort using cold atoms to study strongly correlated many-body systems. One class of phenomena of particularly interests is quantum critical (QC) phenomena. While prevalent in many…

Quantum Gases · Physics 2015-05-19 Qi Zhou , Tin-Lun Ho

In this paper, we propose a low complexity quantum principal component analysis (qPCA) algorithm. Similar to the state-of-the-art qPCA, it achieves dimension reduction by extracting principal components of the data matrix, rather than all…

Quantum Physics · Physics 2021-01-14 Chen He , Jiazhen Li , Weiqi Liu , Z. Jane Wang

Parametric quantum circuits play a crucial role in the performance of many variational quantum algorithms. To successfully implement such algorithms, one must design efficient quantum circuits that sufficiently approximate the solution…

Quantum Physics · Physics 2021-05-05 Lena Funcke , Tobias Hartung , Karl Jansen , Stefan Kühn , Paolo Stornati

Density-functional theory (DFT) has revolutionized computer simulations in chemistry and material science. A faithful implementation of the theory requires self-consistent calculations. However, this effort involves repeatedly diagonalizing…

Quantum Physics · Physics 2023-07-17 Taehee Ko , Xiantao Li , Chunhao Wang

Quantum coherence is a fundamental property of quantum systems, separating quantum from classical physics. Recently, there has been significant interest in the characterization of quantum coherence as a resource, investigating how coherence…

We establish a direct connection between spread complexity and quantum circuit complexity by demonstrating that spread complexity emerges as a limiting case of a circuit complexity framework built from two fundamental operations:…

High Energy Physics - Theory · Physics 2026-05-19 Cameron Beetar , Eric L Graef , Jeff Murugan , Horatiu Nastase , Hendrik J R Van Zyl

Quantitative aspects of computation are related to the use of both physical and mathematical quantities, including time, performance metrics, probability, and measures for reliability and security. They are essential in characterizing the…

Programming Languages · Computer Science 2020-01-22 Alessandro Aldini

Quantum computing is an emerging field that utilizes the unique principles of quantum mechanics to offer significant advantages in algorithm execution over classical approaches. This potential is particularly promising in the domain of…

Human-Computer Interaction · Computer Science 2025-04-15 Anja Heim , Thomas Lang , Alexander Gall , Eduard Gröller , Christoph Heinzl

Efficiently simulating quantum circuits on classical computers is a fundamental challenge in quantum computing. This paper presents a novel theoretical approach that achieves substantial speedups over existing simulators for a wide class of…

Quantum Physics · Physics 2026-02-10 Daksh Shami

Communication complexity is a fundamental aspect of information science, concerned with the amount of communication required to solve a problem distributed among multiple parties. The standard quantification of one-way communication…

Quantum Physics · Physics 2024-12-25 Satyaki Manna , Anubhav Chaturvedi , Debashis Saha

We develop a classical shadow tomography protocol utilizing the randomized measurement scheme based on hybrid quantum circuits, which consist of layers of two-qubit random unitary gates mixed with single-qubit random projective…

Quantum Physics · Physics 2023-09-26 Ahmed A. Akhtar , Hong-Ye Hu , Yi-Zhuang You

We present a novel quantum algorithm for classification of images. The algorithm is constructed using principal component analysis and von Neuman quantum measurements. In order to apply the algorithm we present a new quantum representation…

Quantum Physics · Physics 2016-03-24 Mateusz Ostaszewski , Przemysław Sadowski , Piotr Gawron

Parameterized quantum circuits play a key role in quantum computing. Measuring the suitability of such a circuit for solving a class of problems is needed. One such promising measure is the expressivity of a circuit, which is defined in two…

Quantum Physics · Physics 2025-09-09 Johanna Barzen , Frank Leymann