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Variational quantum computing offers a flexible computational paradigm with applications in diverse areas. However, a key obstacle to realizing their potential is the Barren Plateau (BP) phenomenon. When a model exhibits a BP, its parameter…

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

Barren plateau landscapes correspond to gradients that vanish exponentially in the number of qubits. Such landscapes have been demonstrated for variational quantum algorithms and quantum neural networks with either deep circuits or global…

Quantum Physics · Physics 2021-10-06 Andrew Arrasmith , M. Cerezo , Piotr Czarnik , Lukasz Cincio , Patrick J. Coles

Barren plateaus (BPs) are usually described by the exponential suppression of gradient variance, but the mechanism by which gradient signal disappears remains unclear. We show that this phenomenon can be understood as destructive…

Quantum Physics · Physics 2026-05-05 Pilsung Kang

Variational quantum algorithms (VQAs) have established themselves as a central computational paradigm in the Noisy Intermediate-Scale Quantum (NISQ) era. By coupling parameterized quantum circuits (PQCs) with classical optimization, they…

Vanishing gradients can pose substantial obstacles for high-dimensional optimization problems. Here we consider energy minimization problems for quantum many-body systems with extensive Hamiltonians and finite-range interactions, which can…

Quantum Physics · Physics 2025-03-26 Thomas Barthel , Qiang Miao

Ansatz selection is a key factor in the performance of variational quantum algorithms (VQAs). While much of the state-of-the-art still relies on heuristic choices, an inadequate circuit structure can compromise both the expressive power and…

Quantum Physics · Physics 2026-03-24 Rodrigo M. Sanz , Andreu Angles-Castillo , Eduard Alarcon , Carmen G Almudever

Quantum supervised learning, utilizing variational circuits, stands out as a promising technology for NISQ devices due to its efficiency in hardware resource utilization during the creation of quantum feature maps and the implementation of…

Quantum Physics · Physics 2023-11-15 Anton Simen Albino , Rodrigo Bloot , Otto M. Pires , Erick G. S. Nascimento

Variational quantum algorithms (VQAs) for combinatorial optimization routinely employ entangling gates as a default design choice, yet the role of entanglement, in its amount and structure, remains poorly understood. This gap is…

Solving hard optimization problems is one of the most promising application domains for quantum computers due to the ubiquity of such problems in industry and the availability of broadly applicable quantum speedups. However, the ability of…

Quantum Physics · Physics 2025-07-25 Zichang He , Rudy Raymond , Ruslan Shaydulin , Marco Pistoia

Scaling of variational quantum algorithms to large problem sizes requires efficient optimization of random parameterized quantum circuits. For such circuits with uncorrelated parameters, the presence of exponentially vanishing gradients in…

Quantum Physics · Physics 2021-01-28 Tyler Volkoff , Patrick J. Coles

The last decade has witnessed remarkable progress in the development of quantum technologies. Although fault-tolerant devices likely remain years away, the noisy intermediate-scale quantum devices of today may be leveraged for other…

The barren plateau phenomenon, where the gradients of parametrized quantum circuits become vanishingly small, poses a significant challenge in quantum machine learning. While previous studies attempted to explain the barren plateau…

Quantum Physics · Physics 2026-02-06 Yuhan Yao , Yoshihiko Hasegawa

In variational quantum algorithms the parameters of a parameterized quantum circuit are optimized in order to minimize a cost function that encodes the solution of the problem. The barren plateau phenomenon manifests as an exponentially…

Quantum Physics · Physics 2024-11-14 Marco Schumann , Frank K. Wilhelm , Alessandro Ciani

Variational quantum algorithms face a fundamental trainability crisis: barren plateaus render optimization exponentially difficult as system size grows. While recent Lie algebraic theory precisely characterizes when and why these plateaus…

Quantum Physics · Physics 2025-11-26 Mikhail Zubarev

The quantum approximate optimization algorithm (QAOA) has rapidly become a cornerstone of contemporary quantum algorithm development. Despite a growing range of applications, only a few results have been developed towards understanding the…

Quantum Physics · Physics 2020-03-11 V. Akshay , H. Philathong , M. E. S. Morales , J. Biamonte

Variational quantum-classical hybrid algorithms are seen as a promising strategy for solving practical problems on quantum computers in the near term. While this approach reduces the number of qubits and operations required from the quantum…

Quantum Physics · Physics 2022-03-07 Ali Rad , Alireza Seif , Norbert M. Linke

Variational quantum algorithms (VQAs) have demonstrated great potentials in the Noisy Intermediate Scale Quantum (NISQ) era. In the workflow of VQA, the parameters of ansatz are iteratively updated to approximate the desired quantum states.…

With rapid advances in quantum hardware, a central question is whether quantum devices with or without full error correction can outperform classical computers on practically relevant problems. Variational Quantum Algorithms (VQAs) have…

Quantum Physics · Physics 2025-09-09 Adelina Bärligea , Benedikt Poggel , Jeanette Miriam Lorenz

Combining classical optimization with parameterized quantum circuit evaluation, variational quantum algorithms (VQAs) are among the most promising algorithms in near-term quantum computing. Similar to neural networks (NNs), VQAs iteratively…

Quantum Physics · Physics 2025-11-18 Zhehao Yi , Yanying Liang , Haozhen Situ