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Variational quantum circuits (VQCs) hold promise for quantum machine learning but face challenges in expressivity, trainability, and noise resilience. We propose VQC-MLPNet, a hybrid architecture where a VQC generates the first-layer…

Quantum Physics · Physics 2025-11-06 Jun Qi , Chao-Han Yang , Pin-Yu Chen , Min-Hsiu Hsieh

We view disentanglement learning as discovering an underlying structure that equivariantly reflects the factorized variations shown in data. Traditionally, such a structure is fixed to be a vector space with data variations represented by…

Machine Learning · Computer Science 2021-06-08 Xinqi Zhu , Chang Xu , Dacheng Tao

In this work, we introduce a quantum-control-inspired method for the characterization of variational quantum circuits using the rank of the dynamical Lie algebra associated with the hermitian generator(s) of the individual layers.…

Quantum Physics · Physics 2022-09-30 Abhinav Anand , Sumner Alperin-Lea , Alexandre Choquette , Alán Aspuru-Guzik

One of the main challenges in the Variational Quantum Eigensolver (VQE) framework is construction of the unitary transformation. The dimensionality of the space for unitary rotations of $N$ qubits is $4^N-1$, which makes the choice of a…

Quantum Physics · Physics 2021-12-21 Artur F. Izmaylov , Manuel Díaz-Tinoco , Robert A. Lang

The Quantum Approximate Optimization Algorithm (QAOA) is a leading candidate for achieving quantum advantage in combinatorial optimization on Near-Term Intermediate-Scale Quantum (NISQ) devices. However, random initialization of the…

Quantum Physics · Physics 2025-12-30 Matthaus Zering , Jolyon Joyce , Tal Gurfinkel , Jingbo Wang

In this paper, we develop a Lie group theoretic approach for parametric representation of unitary matrices. This leads to develop a quantum neural network framework for quantum circuit approximation of multi-qubit unitary gates. Layers of…

Quantum Physics · Physics 2025-03-26 Rohit Sarma Sarkar , Bibhas Adhikari

Barren plateaus, which means the training gradients become extremely small, pose a major challenge in optimizing parameterized quantum circuits, often making the learning process impractically slow or stall. This work shows why using neural…

Quantum Physics · Physics 2025-12-03 Zhehao Yi , Rahul Bhadani

The Variational Quantum Eigensolver (VQE) is a promising candidate for quantum applications on near-term Noisy Intermediate-Scale Quantum (NISQ) computers. Despite a lot of empirical studies and recent progress in theoretical understanding…

Quantum Physics · Physics 2022-05-26 Xuchen You , Shouvanik Chakrabarti , Xiaodi Wu

Variational Quantum Algorithms (VQAs) are a class of hybrid quantum-classical algorithms that leverage on classical optimization tools to find the optimal parameters for a parameterized quantum circuit. One relevant application of VQAs is…

Quantum Physics · Physics 2026-01-26 Mirko Legnini , Julian Berberich

Variational quantum algorithms (VQAs) and their applications in the field of quantum machine learning through parametrized quantum circuits (PQCs) are thought to be one major way of leveraging noisy intermediate-scale quantum computing…

Quantum Physics · Physics 2025-05-22 Dirk Heimann , Hans Hohenfeld , Gunnar Schönhoff , Elie Mounzer , Frank Kirchner

Variational quantum compiling (VQC) algorithms aim to approximate deep quantum circuits with shallow parameterized ansatzes, making them more suitable for NISQ hardware. In this article a variant of VQC named the recursive variational…

Quantum Physics · Physics 2025-03-12 Stian Bilek , Kristian Wold

Near-term quantum machine learning must balance expressivity, optimization, and hardware constraints. We study quantum re-uploading units (QRUs) as compact circuits and compare them, at matched parameter count, to a standard mono-encoded…

Quantum Physics · Physics 2026-02-03 Léa Cassé , Bernhard Pfahringer , Albert Bifet , Frédéric Magniette

Quantum neural networks (QNNs) and parameterized quantum circuits (PQCs) are key building blocks for near-term quantum machine learning. However, their scalability is constrained by excessive parameters, barren plateaus, and hardware…

Quantum Physics · Physics 2025-12-11 Haijian Shao , Bowen Yang , Wei Liu , Xing Deng , Yingtao Jiang

Variational quantum algorithms (VQAs) hold great potentials for near-term applications and are promising to achieve quantum advantage on practical tasks. However, VQAs suffer from severe barren plateau problem as well as have a large…

Quantum Physics · Physics 2023-09-27 Shuo Liu , Shi-Xin Zhang , Shao-Kai Jian , Hong Yao

Quantum unitaries of the form $\Sigma_{c}\ket{c}\bra{c}\otimes U_{c}$ are ubiquitous in quantum algorithms. This class encompasses not only standard uniformly controlled gates (UCGs) but also a wide range of circuits with uniformly…

Quantum Physics · Physics 2025-12-11 Chengzhuo Xu , Xiao Chen , Xi Li , Zhihao Liu , Zhigang Li

Variational Quantum Algorithms (VQAs) are becoming the primary computational primitive for next-generation quantum computers, particularly those embedded as resource-constrained accelerators in the emerging Quantum Internet of Things…

Quantum Physics · Physics 2025-12-05 Ratun Rahman , Dinh C. Nguyen

Variational quantum algorithm (VQA), which is comprised of a classical optimizer and a parameterized quantum circuit, emerges as one of the most promising approaches for harvesting the power of quantum computers in the noisy intermediate…

Quantum Physics · Physics 2021-12-01 Samuel Stein , Yufei Ding , Nathan Wiebe , Bo Peng , Karol Kowalski , Nathan Baker , James Ang , Ang Li

Gradient estimation is a central challenge in training parameterized quantum circuits (PQCs) for hybrid quantum-classical optimization and learning problems. This difficulty arises from several factors, including the exponential…

Quantum Physics · Physics 2026-05-25 Mohsen Heidari , Masih Mozakka , Wojciech Szpankowski

In this work, a scalable algorithm for the approximate quantum state preparation problem is proposed, facing a challenge of fundamental importance in many topic areas of quantum computing. The algorithm uses a variational quantum circuit…

Quantum Physics · Physics 2025-03-19 Giacomo Belli , Marco Mordacci , Michele Amoretti

Quantum machine learning -- and specifically Variational Quantum Algorithms (VQAs) -- offers a powerful, flexible paradigm for programming near-term quantum computers, with applications in chemistry, metrology, materials science, data…

Quantum Physics · Physics 2024-03-15 M. Bilkis , M. Cerezo , Guillaume Verdon , Patrick J. Coles , Lukasz Cincio