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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

One of the most promising applications of noisy intermediate-scale quantum computers is the simulation of molecular Hamiltonians using the variational quantum eigensolver. We show that encoding symmetries of the simulated Hamiltonian in the…

Finding solid and practical quantum advantages via noisy quantum devices without error correction is a critical but challenging problem. Conversely, comprehending the fundamental limitations of the state-of-the-art is equally crucial. In…

Quantum Physics · Physics 2026-03-25 Yuxuan Yan , Zhenyu Du , Junjie Chen , Xiongfeng Ma

Quantum Neural Networks (QNNs) offer a promising framework for integrating quantum computing principles into machine learning, yet their practical capabilities and limitations remain insufficiently studied. In this work, we systematically…

Quantum Physics · Physics 2026-03-31 Martyna Czuba , Patrick Holzer , Hein Zay Yar Oo

Quantum machine learning is an approach that aims to improve the performance of machine learning methods by leveraging the properties of quantum computers. In quantum circuit learning (QCL), a supervised learning method that can be…

Implementing many important sub-circuits on near-term quantum devices remains a challenge due to the high levels of noise and the prohibitive depth on standard nearest-neighbour topologies. Overcoming these barriers will likely require…

Quantum Physics · Physics 2024-11-06 Angus Mingare , Anastasia Moroz , Marcell D Kovacs , Andrew G Green

While variational quantum algorithms (VQAs) have demonstrated considerable success in unconstrained optimization, their application to constrained combinatorial problems face a trade-off. Penalty-based methods, despite their circuit…

Quantum Physics · Physics 2026-03-09 Hui-Min Li , Yuan-Liang Han , Zhi-Xi Wang , Shao-Ming Fei

Quantum computation, a completely different paradigm of computing, benefits from theoretically proven speed-ups for certain problems and opens up the possibility of exactly studying the properties of quantum systems. Yet, because of the…

Quantum metrology and sensing seek advantage in estimating an unknown parameter of some quantum state or channel, using entanglement such as spin squeezing produced by one-axis twists or other quantum resources. In particular, qubit phase…

Quantum Physics · Physics 2024-05-29 Tyler G. Thurtell , Akimasa Miyake

The number of measurements demanded by hybrid quantum-classical algorithms such as the variational quantum eigensolver (VQE) is prohibitively high for many problems of practical value. For such problems, realizing quantum advantage will…

Quantum Physics · Physics 2021-03-24 Guoming Wang , Dax Enshan Koh , Peter D. Johnson , Yudong Cao

The Hadamard test is a standard quantum primitive for estimating inner products and expectation values, but in data-processing settings its practical utility is often limited by the cost of preparing amplitude-encoded quantum states. In…

Quantum Physics · Physics 2026-04-20 Hiroshi Ohno

The variational quantum eigensolver (VQE) is a method that uses a hybrid quantum-classical computational approach to find eigenvalues and eigenvalues of a Hamiltonian. VQE has been proposed as an alternative to fully quantum algorithms such…

Quantum Physics · Physics 2021-09-01 Dmitry A. Fedorov , Bo Peng , Niranjan Govind , Yuri Alexeev

Quantum error correction is capable of digitizing quantum noise and increasing the robustness of qubits. Typically, error correction is designed with the target of eliminating all errors - making an error so unlikely it can be assumed that…

Quantum Physics · Physics 2022-05-20 Salonik Resch , Ulya R. Karpuzcu

Quantum chemistry is one of the most promising applications of quantum computers in the near future. For noisy intermediate-scale quantum devices, the quantum-classical hybrid framework based on the variational quantum eigensolver (VQE) has…

To harness the potential of noisy intermediate-scale quantum devices, it is paramount to find the best type of circuits to run hybrid quantum-classical algorithms. Key candidates are parametrized quantum circuits that can be effectively…

Quantum Physics · Physics 2022-02-28 Tobias Haug , Kishor Bharti , M. S. Kim

The study of out-of-equilibrium quantum many-body dynamics remains one of the most exciting research frontiers of physics, standing at the crossroads of our understanding of complex quantum phenomena and the realization of quantum…

Quantum Physics · Physics 2025-11-24 Matteo D'Anna , Yuxuan Zhang , Roeland Wiersema , Manuel S. Rudolph , Juan Carrasquilla

Recently we find several candidates of quantum algorithms that may be implementable in near-term devices for estimating the amplitude of a given quantum state, which is a core sub- routine in various computing tasks such as the Monte Carlo…

Quantum Physics · Physics 2021-10-12 Tomoki Tanaka , Yohichi Suzuki , Shumpei Uno , Rudy Raymond , Tamiya Onodera , Naoki Yamamoto

The variational quantum eigensolver (VQE) algorithm recently became a popular method to compute quantum chemical properties of molecules on noisy intermediate scale quantum (NISQ) devices. In order to avoid noise accumulation from the NISQ…

Quantum Physics · Physics 2023-08-29 Seyed Ehsan Ghasempouri , Gerhard W. Dueck , Stijn De Baerdemacker

Existing quantum discrete adiabatic approaches are hindered by circuit depth that increases linearly with the number of evolution steps, a significant challenge for current quantum hardware with limited coherence times. To address this, we…

Quantum Physics · Physics 2025-06-02 Boxuan Ai , Shuo He , Xiang Zhao , Lin Yang , Guozhen Liu , Pengfei Gao , Hongbao Liu , Tao Tang , Jiecheng Yang , Jie Wu

Higher-dimensional quantum systems (qudits) offer advantages in information encoding, error resilience, and compact gate implementations, and naturally arise in platforms such as superconducting and solid-state systems. However, realistic…

Quantum Physics · Physics 2025-06-17 Yule Mayevsky , Akram Youssry , Ritik Sareen , Gerardo A. Paz-Silva , Alberto Peruzzo