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The barren plateau phenomenon; where cost function gradients vanish exponentially with system size; remains a fundamental obstacle to training variational quantum circuits (VQCs) at scale. We demonstrate, both theoretically and numerically,…

Variational quantum circuits have recently gained much interest due to their relevance in real-world applications, such as combinatorial optimizations, quantum simulations, and modeling a probability distribution. Despite their huge…

Quantum Physics · Physics 2024-03-11 Chae-Yeun Park , Minhyeok Kang , Joonsuk Huh

Quantum architecture search (QAS) involves optimizing both the quantum parametric circuit configuration but also its parameters for a variational quantum algorithm. Thus, the problem is known to be multi-level as the performance of a given…

Quantum Physics · Physics 2024-07-30 Vicente P. Soloviev , Vedran Dunjko , Concha Bielza , Pedro Larrañaga , Hao Wang

We develop and implement a novel pulse-based ansatz, which we call PANSATZ, for more efficient and accurate implementations of variational quantum algorithms (VQAs) on today's noisy intermediate-scale quantum (NISQ) computers. Our approach…

Quantum Physics · Physics 2024-01-03 Dekel Meirom , Steven H. Frankel

Optimizing parameterized quantum circuits (PQCs) is the leading approach to make use of near-term quantum computers. However, very little is known about the cost function landscape for PQCs, which hinders progress towards quantum-aware…

Quantum Physics · Physics 2022-08-26 Andrew Arrasmith , Zoë Holmes , M. Cerezo , Patrick J. Coles

The barren plateau phenomenon, characterized by loss gradients that vanish exponentially with system size, poses a challenge to scaling variational quantum algorithms. Here we explore the potential of warm starts, whereby one initializes…

Quantum Physics · Physics 2025-03-04 Ricard Puig , Marc Drudis , Supanut Thanasilp , Zoë Holmes

The variational quantum eigensolver (VQE) is a hybrid quantum-classical algorithm used to find the ground state of a Hamiltonian using variational methods. In the context of this Lattice symposium, the procedure can be used to study lattice…

Quantum Physics · Physics 2021-12-02 Giovanni Iannelli , Karl Jansen

Variational quantum algorithms (VQAs) optimize the parameters $\vec{\theta}$ of a parametrized quantum circuit $V(\vec{\theta})$ to minimize a cost function $C$. While VQAs may enable practical applications of noisy quantum computers, they…

Quantum Physics · Physics 2021-03-23 M. Cerezo , Akira Sone , Tyler Volkoff , Lukasz Cincio , Patrick J. Coles

Variational Quantum Algorithms (VQAs) are critically threatened by the Barren Plateau (BP) phenomenon. In this work, we introduce the H-EFT Variational Ansatz (H-EFT-VA), an architecture inspired by Effective Field Theory (EFT). By…

Quantum Physics · Physics 2026-04-24 Eyad I. B Hamid

Parameterized quantum circuits (PQCs) have emerged as a foundational element in the development and applications of quantum algorithms. However, when initialized with random parameter values, PQCs often exhibit barren plateaus (BP). These…

Quantum Physics · Physics 2025-07-02 Muhammad Kashif , Muhammad Rashid , Saif Al-Kuwari , Muhammad Shafique

Quantum algorithms based on the variational principle have found applications in diverse areas with a huge flexibility. But as the circuit size increases the variational landscapes become flattened, causing the so-called Barren plateau…

Quantum Physics · Physics 2025-09-03 Fabio Tarocco , Davide Materia , Leonardo Ratini , Leonardo Guidoni

Variational algorithms are promising candidates to be implemented on near-term quantum computers. The variational quantum eigensolver (VQE) is a prominent example, where a parametrized trial state of the quantum mechanical wave function is…

Variational quantum algorithms (VQAs) have enabled a wide range of applications on near-term quantum devices. However, their scalability is fundamentally limited by barren plateaus, where the probability of encountering large gradients…

Quantum Physics · Physics 2025-07-22 Elias Zapusek , Ivan Rojkov , Florentin Reiter

Variational Quantum Algorithms (VQAs) may be a path to quantum advantage on Noisy Intermediate-Scale Quantum (NISQ) computers. A natural question is whether noise on NISQ devices places fundamental limitations on VQA performance. We…

Quantum Physics · Physics 2024-03-05 Samson Wang , Enrico Fontana , M. Cerezo , Kunal Sharma , Akira Sone , Lukasz Cincio , Patrick J. Coles

Variational quantum algorithms (VQAs), which classically optimize a parametrized quantum circuit to solve a computational task, promise to advance our understanding of quantum many-body systems and improve machine learning algorithms using…

Quantum Physics · Physics 2023-06-09 Roeland Wiersema , Cunlu Zhou , Juan Felipe Carrasquilla , Yong Baek Kim

In quantum chemistry, the variational quantum eigensolver (VQE) is a promising algorithm for molecular simulations on near-term quantum computers. However, VQEs using hardware-efficient circuits face scaling challenges due to the barren…

Quantum Physics · Physics 2024-09-27 Rui Mao , Guojing Tian , Xiaoming Sun

Variational quantum algorithms (VQAs) hold much promise but face the challenge of exponentially small gradients. Unmitigated, this barren plateau (BP) phenomenon leads to an exponential training overhead for VQAs. Perhaps the most…

Quantum Physics · Physics 2025-02-05 P. Singkanipa , D. A. Lidar

Variational quantum algorithms (VQAs) represent a promising pathway toward achieving practical quantum advantage on near-term hardware. Despite this promise, for generic, expressive ans\"atze, their scalability is critically hindered by…

Quantum Physics · Physics 2026-02-26 Chenfeng Cao , Yeqing Zhou , Swamit Tannu , Nic Shannon , Robert Joynt

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

Using tools from the representation theory of compact Lie groups, we formulate a theory of Barren Plateaus (BPs) for parameterized quantum circuits whose observables lie in their dynamical Lie algebra (DLA), a setting that we term Lie…