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We experimentally investigate the viability of a variational quantum gate optimization protocol informed by the underlying physical Hamiltonian of fixed-frequency transmon qubits. The utility of the scheme is demonstrated through the…

Quantum Physics · Physics 2024-07-02 Sean Greenaway , Francesco Petiziol , Hongzheng Zhao , Florian Mintert

Variational quantum algorithms (VQAs) utilize a hybrid quantum-classical architecture to recast problems of high-dimensional linear algebra as ones of stochastic optimization. Despite the promise of leveraging near- to intermediate-term…

Quantum Physics · Physics 2022-11-08 Oliver Knitter , James Stokes , Shravan Veerapaneni

A large ongoing research effort focuses on Variational Quantum Algorithms (VQAs), representing leading candidates to achieve computational speed-ups on current quantum devices. The scalability of VQAs to a large number of qubits, beyond the…

In the era of noisy intermediate-scale quantum (NISQ), variational quantum circuits (VQCs) have been widely applied in various domains, demonstrating the potential advantages of quantum circuits over classical models. Similar to classic…

Quantum Physics · Physics 2025-08-26 Jun Zhuang , Jack Cunningham , Chaowen Guan

Classical optimization is a cornerstone of the success of variational quantum algorithms, which often require determining the derivatives of the cost function relative to variational parameters. The computation of the cost function and its…

Quantum Physics · Physics 2025-07-15 Muhammad Umer , Eleftherios Mastorakis , Dimitris G. Angelakis

The training of a parameterized model largely depends on the landscape of the underlying loss function. In particular, vanishing gradients are a central bottleneck in the scalability of variational quantum algorithms (VQAs), and are known…

Quantum Physics · Physics 2024-09-26 Alistair Letcher , Stefan Woerner , Christa Zoufal

Variational quantum eigensolvers are touted as a near-term algorithm capable of impacting many applications. However, the potential has not yet been realized, with few claims of quantum advantage and high resource estimates, especially due…

Solving optimisation problems is a promising near-term application of quantum computers. Quantum variational algorithms leverage quantum superposition and entanglement to optimise over exponentially large solution spaces using an…

Quantum Physics · Physics 2022-10-13 Edric Matwiejew , Jason Pye , Jingbo B. Wang

Variational quantum approaches have shown great promise in finding near-optimal solutions to computationally challenging tasks. Nonetheless, enforcing constraints in a disciplined fashion has been largely unexplored. To address this gap,…

Quantum Physics · Physics 2024-04-30 Thinh Viet Le , Vassilis Kekatos

Many quantum algorithms have daunting resource requirements when compared to what is available today. To address this discrepancy, a quantum-classical hybrid optimization scheme known as "the quantum variational eigensolver" was developed…

Quantum Physics · Physics 2016-02-05 Jarrod R. McClean , Jonathan Romero , Ryan Babbush , Alán Aspuru-Guzik

Variational quantum algorithms (VQAs) face an inherent trade-off between expressivity and trainability: deeper circuits can represent richer states but suffer from noise accumulation and barren plateaus, while shallow circuits remain…

Quantum Physics · Physics 2025-10-31 Shaojun Wu , Shan Jin , Abolfazl Bayat , Xiaoting Wang

Variational quantum algorithms (VQAs) are expected to become a practical application of near-term noisy quantum computers. Although the effect of the noise crucially determines whether a VQA works or not, the heuristic nature of VQAs makes…

Quantum Physics · Physics 2023-05-02 Kosuke Ito , Wataru Mizukami , Keisuke Fujii

Variational quantum algorithms (VQAs) have demonstrated considerable potential in solving NP-hard combinatorial problems in the contemporary near intermediate-scale quantum (NISQ) era. The quantum approximate optimisation algorithm (QAOA)…

Quantum Physics · Physics 2024-05-09 Boy Choy , David J. Wales

The computational capabilities of near-term quantum computers are limited by the noisy execution of gate operations and a limited number of physical qubits. Hybrid variational algorithms are well-suited to near-term quantum devices because…

Quantum Physics · Physics 2024-10-09 Teague Tomesh , Nicholas Allen , Daniel Dilley , Zain Saleem

We propose using variational quantum algorithms (VQAs) to simulate established quantum algorithms under realistic noise conditions, aiming to surpass the fidelity of theoretical circuits in noisy environments. Focusing on the Quantum…

This work tackles the problem of finding a good ansatz initialization for Variational Quantum Algorithms (VQAs), by proposing CAFQA, a Clifford Ansatz For Quantum Accuracy. The CAFQA ansatz is a hardware-efficient circuit built with only…

Hybrid quantum-classical optimization techniques, which incorporate the pre-optimization of Variational Quantum Algorithms (VQAs) using Tensor Networks (TNs), have been shown to allow for the reduction of quantum computational resources. In…

Quantum Physics · Physics 2025-07-16 Andrés N. Cáliz , Jordi Riu , Josep Bosch , Pau Torrente , Jose Miralles , Arnau Riera

Quantum computers show potential for achieving computational advantage over classical computers, with many candidate applications in combinatorial optimisation. We present an application level benchmarking framework for near-term quantum…

Variational Quantum Algorithms (VQAs) are expected to be promising algorithms with quantum advantages that can be run at quantum computers in the close future. In this work, we review simple rules in basic quantum circuits, and propose a…

Quantum Physics · Physics 2023-12-12 Jaehoon Hahm , Hayeon Kim , Young June Park

The state-of-the-art machine learning approaches are based on classical von Neumann computing architectures and have been widely used in many industrial and academic domains. With the recent development of quantum computing, researchers and…

Machine Learning · Computer Science 2020-07-21 Samuel Yen-Chi Chen , Chao-Han Huck Yang , Jun Qi , Pin-Yu Chen , Xiaoli Ma , Hsi-Sheng Goan