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Quantum machine learning techniques have been proposed as a way to potentially enhance performance in machine learning applications. In this paper, we introduce two new quantum methods for neural networks. The first one is a quantum…

Entanglement is a key quantity for characterizing quantum correlations in particle scattering processes, but its direct evaluation is computationally demanding on quantum hardware. In this work, we investigate whether fermion density…

Quantum Physics · Physics 2026-04-08 Hala Elhag , Yahui Chai

Access to quantum computing is steadily increasing each year as the speed advantage of quantum computers solidifies with the growing number of usable qubits. However, the inherent noise encountered when running these systems can lead to…

Quantum Physics · Physics 2024-09-24 Jon Gardeazabal-Gutierrez , Erik B. Terres-Escudero , Pablo García Bringas

Image classification, a pivotal task in multiple industries, faces computational challenges due to the burgeoning volume of visual data. This research addresses these challenges by introducing two quantum machine learning models that…

Quantum Physics · Physics 2024-03-29 Arsenii Senokosov , Alexandr Sedykh , Asel Sagingalieva , Basil Kyriacou , Alexey Melnikov

In many physical situations the behavior of a quantum system is affected by interaction with a larger environment. We develop, using the method of influence functional, how to deduce the density matrix of the quantum system incorporating…

High Energy Physics - Phenomenology · Physics 2009-10-28 M. Hotta , I. Joichi , Sh. Matsumoto , M. Yoshimura

Classical machine learning theory and theory of quantum computations are among of the most rapidly developing scientific areas in our days. In recent years, researchers investigated if quantum computing can help to improve classical machine…

Quantum Physics · Physics 2019-06-26 D. V. Fastovets , Yu. I. Bogdanov , B. I. Bantysh , V. F. Lukichev

Quantum state tomography, the ability to deduce the density matrix of a quantum system from measured data, is of fundamental importance for the verification of present and future quantum devices. It has been realized in systems with few…

Quantum Physics · Physics 2010-02-22 M. Cramer , M. B. Plenio

Machine learning techniques are essential tools to compute efficient, yet accurate, force fields for atomistic simulations. This approach has recently been extended to incorporate quantum computational methods, making use of variational…

Entanglement is a defining property of quantum systems. For a subsystem of a larger quantum system, one can formally define an operator known as the modular Hamiltonian, which is closely linked to the entanglement properties of that…

Quantum Physics · Physics 2025-08-26 Ian T. Lim , Isaac H. Kim

A quantum finite multi-barrier system, with a periodic potential, is considered and exact expressions for its plane wave amplitudes are obtained using the Transfer Matrix method [10]. This quantum model is then associated with a stochastic…

Statistical Mechanics · Physics 2019-06-26 Emilio N. M. Cirillo , Matteo Colangeli , Lamberto Rondoni

Quantum estimation theory is a reformulation of random statistical theory with the modern language of quantum mechanics. In fact, the density operator plays a role similar to that of probability distribution functions in classical…

Quantum Physics · Physics 2022-11-15 Bakmou Lahcen , Daoud Mohammed

The density matrix of a two-level system (spin, atom) is usually determined by measuring the three non-commuting components of the Pauli vector. This density matrix can also be obtained via the measurement data of two commuting variables,…

Quantum Physics · Physics 2012-05-25 B. Mehmani , A. E. Allahverdyan , Th. M. Nieuwenhuizen

Quantum noise fundamentally limits the utility of near-term quantum devices, making error mitigation essential for practical quantum computation. While traditional quantum error correction codes require substantial qubit overhead and…

Quantum Physics · Physics 2025-09-23 Karan Kendre

Quantum machine learning has attracted significant interest in recent years. Most existing approaches, however, are variational in nature and require extensive parameter optimization subroutines. Here, we propose a conceptually distinct…

Quantum Physics · Physics 2026-04-22 Kristina Kirova , Monika Doerfler , Franz Luef , Richard Kueng

We clarify different definitions of the density matrix by proposing the use of different names, the full density matrix for a single-closed quantum system, the compressed density matrix for the averaged single molecule state from an…

Quantum Physics · Physics 2007-05-23 Gui Lu Long , Yi-Fan Zhou , Jia-Qi Jin , Yang Sun , Hai-Woong Lee

We study quantum anomaly detection with density estimation and multivariate Gaussian distribution. Both algorithms are constructed using the standard gate-based model of quantum computing. Compared with the corresponding classical…

Quantum Physics · Physics 2019-06-26 Jin-Ming Liang , Shu-Qian Shen , Ming Li , Lei Li

We present error mitigation (EM) techniques for noisy intermediate-scale quantum computers (QC) based on density matrix purification and perturbative corrections to the target energy. We incorporate this scheme into the variational quantum…

Quantum Physics · Physics 2019-12-04 T. D. Morris , Z. P. Parks , A. J. McCaskey , J. Jakowski , R. C. Pooser

A major bottleneck in the quest for scalable many-body quantum technologies is the difficulty in benchmarking their preparations, which suffer from an exponential `curse of dimensionality' inherent to their quantum states. We present an…

Quantum Physics · Physics 2019-07-31 Juan Carrasquilla , Giacomo Torlai , Roger G. Melko , Leandro Aolita

Quantum computers are projected to handle the Gibbs sampling and the related inference on Markov networks effectively. Apart from noting the background information useful for those starting the explorations in this important thread of…

Quantum Physics · Physics 2020-06-23 S Ashutosh , Deepankar Sarmah , Sayantan Pramanik , M Girish Chandra

Estimating quantum amplitude, or the overlap between two quantum states, is a fundamental task in quantum computing and underpins numerous quantum algorithms. In this work, we introduce a novel algorithmic framework for quantum amplitude…

Quantum Physics · Physics 2025-02-27 Zhong-Xia Shang , Qi Zhao