Variational Quantum Circuits

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Overview

Variational quantum circuits use adjustable gate parameters to prepare quantum states or make predictions, with a classical optimizer typically updating those parameters from measured outcomes. Common approaches include hardware-efficient and problem-inspired ansätze, data re-uploading, quantum kernels, and hybrid models for tasks such as classification, forecasting, and molecular simulation. Work studies how circuit depth, entanglement, initialization, gradient methods, and measurement choices affect expressivity and trainability, especially under barren plateaus and hardware noise. Compact circuits have shown promise on selected benchmarks, but broad practical advantage remains unsettled: results depend on task and hardware, and careful comparisons with tuned, capacity-matched classical models are essential.

Latest papers

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114 papers14 papers in the last four weeks, up 27% on the four weeks before. 0.1% of all new papers.

  1. Hidden selection rules and amplitude ceilings in quantum Fourier models

    Oct 31, 2026Pavel Sulimov, Claude LehmannQuantum Circuit ExpressibilityVariational Quantum Circuits

    Zurich University of Applied Sciences (ZHAW), Zurich, Switzerland

  2. Fully quantum training of parametric circuits with Quantum Hamiltonian Descent

    Oct 23, 2026Marco Burato, Leonardo BanchiQuantum Circuit OptimizationVariational Quantum Algorithms

    Department of Physics and Astronomy, University of Florence, via G. Sansone 1, I-50019 Sesto Fiorentino (FI), Italy · INFN Sezione di Firenze, via G. Sansone 1, I-50019, Sesto Fiorentino (FI), Italy

  3. Quantum-Classical Link Prediction on Dark Web Hyperlink Graphs

    Oct 23, 2026Vojtěch Novák, Radovan Rečka, Ondřej Knebl +2Link PredictionHybrid Quantum-Classical ML

    Department of Computer Science, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, Ostrava, Czech Republic. · IT4Innovations National Supercomputing Center, VSB-Technical University of Ostrava, Ostrava, 708 00, Czech Republic. · Department of Informatics and Statistics, Marine Research Institute, Klaipeda University, Klaipeda, Lithuania.

  4. Task-aligned spectral inductive biases in parameterized quantum circuits

    Oct 16, 2026Felix Frohnert, Adrián Pérez-Salinas, Sebastian Lange +3Quantum Machine LearningSpectral Bias

    ⟨aQaL⟩Applied Quantum Algorithms, Universiteit Leiden, Leiden, The Netherlands · Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, Germany · Institute for Theoretical Physics, ETH Zürich, Switzerland +2

  5. Same Spectrum, Harder First-Order Training: Phase-Locking in Single- versus Multi-Qubit Re-Uploading Circuits

    Oct 15, 2026Michael Poppel, David Bucher, Maximilian Zorn +5Quantum Circuit TrainabilityQuantum Machine Learning

    Department of Computer Science, LMU Munich, Germany · Aqarios GmbH, Munich, Germany

  6. A Quantum Machine Learning Approach to Content-Based Media Recommendation

    Oct 15, 2026Mina Abbaszadeh, Ouissal Moumou, Anna Pearson +4Quantum NLPRecommender Systems

    Quantinuum United Kingdom · University College London United Kingdom · Relational Intelligence United Kingdom +1

  7. Reducing the Cost of Qudit State Preparation by Learning a Sparse Structure for SNAP Gates

    Oct 15, 2026Marco Pennazio, Leonardo Ignazio Pagliochini, Riccardo Pellini +2Quantum State PreparationVariational Quantum Circuits

    Politecnico di Milano, Milano, Italy

  8. A Tutorial on Quantum Amplitude Embedding with Data Re-Uploading

    Oct 13, 2026Hyojun Ahn, Joongheon KimQuantum Circuit ExpressibilityQuantum Machine Learning

    Department of Electrical & Computer Engineering, Korea University, Seoul, Republic of Korea

  9. QBFF: Deep Quantum Bottleneck for Automatic Speaker Verification Anti-Spoofing

    Oct 12, 2026Anton Firc, Nouhaila Innan, Vojtěch Staněk +6Audio Deepfake DetectionSpeaker Verification

    eBRAIN Lab, Division of Engineering, New York University Abu Dhabi (NYUAD), Abu Dhabi, UAE · Center for Quantum and Topological Systems (CQTS), NYUAD Research Institute, NYUAD, Abu Dhabi, UAE · SDU Microelectronics, Institute of Mechanical and Electrical Engineering, University of Southern Denmark, Odense, Denmark

  10. Diversity-Aware Ensemble of Quantum-Classical Models via Combinatorial Fusion

    Oct 9, 2026Jingyan Xu, Yuanhong Wu, Samuel Yen-Chi Chen +3Ensemble LearningHybrid Quantum-Classical ML

    Laboratory of Informatics and Data Mining, Department of Computer and Information Science, Fordham University, New York, NY, USA · Wells Fargo, New York, NY, USA · Division of Computer Science, Mathematics and Science, St. John’s University, Queens, NY, USA

  11. Large-Scale Benchmarking of Quantum Neural Network Configurations for Financial Time Series Forecasting

    Oct 8, 2026Jack Waller, Xing Liang, Dimitrios Makris +1Quantum Neural NetworksQuantum Machine Learning

    School of Computer Science and Mathematics, Kingston University London, London, KT1 2EE, U.K.. · Department of Electronics and Electrical Engineering, Brunel University of London, London, UB8 3PH, U.K..

  12. Q-Capsule: A Localized Capsule-Based Quantum Neural Architecture for Barren Plateau Mitigation

    Oct 8, 2026Awal Ahmed Fime, Tasfia Zaman Samiha, Saika Zaman +4Quantum Neural NetworksQuantum Circuit Trainability

    Florida Atlantic University, Boca Raton, Florida, USA · Khulna University of Engineering & Technology, Khulna, Bangladesh · Southern Illinois University Carbondale, Carbondale, Illinois, USA

  13. Mu-DisCoCat: A Variational Pipeline for Compositional Generalization on Quantum Processors

    Oct 6, 2026Mina Abbaszadeh, Matilda Karabina Moore, Raem Haq +2Quantum Machine LearningVariational Quantum Circuits

    Department of Computer Science University College London London, United Kingdom · Institute for Logic, Language and Computation University of Amsterdam Amsterdam, Netherlands

  14. What Does It Cost to Simulate a Quantum Sentence Classifier? An Energy and Compute Perspective on Near-Term QNLP

    Oct 5, 2026Kishlay Kashyap, Sandipan GangulyQuantum NLPQuantum Machine Learning

    Heritage Institute of Technology

  15. Variational Quantum Attention for Molecular Graph Learning

    Oct 3, 2026Yu-Cheng Lin, Yu-Chao Hsu, Tai-Yue Li +2Graph Attention NetworksQuantum Machine Learning

    Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300092, Taiwan. · Department of Internal Medicine, School of Medicine College of Medicine, Taipei Medical University, Taipei, Taiwan · School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea +2

  16. Evolving Hybrid Quantum-Classical Architectures for Image Classification

    Oct 2, 2026Devroop Kar, Daniel Krutz, Travis DesellHybrid Quantum-Classical MLQuantum Architecture Search

    Rochester Institute of Technology Rochester, NY 14623, USA

  17. Evaluating Hybrid Quantum-Classical Models for Reduced-Order Brain Deformation Dynamics

    Sep 30, 2026Tao Liu, Ge He, Dongyu Liang +1Time Series ForecastingProper Orthogonal Decomposition

    Lawrence Technological University · North Carolina State University

  18. Comparative Study of Quantum and Classical Machine Learning Models in Binary Classification

    Sep 20, 2026Anand Kumar Mishra, Ramanuj AwasthiQuantum Machine LearningQuantum Kernel Methods

    School of Engineering & Technology (UIET), CSJM University, Kanpur, Uttar Pradesh, India

  19. From IceCube to IT-Sphere: A Hybrid Quantum-Classical GNN for Banking IT Root Cause Analysis

    Sep 19, 2026Antonio Greco, Riccardo Paoletti, Roberto Cappuccio +1Root Cause AnalysisHybrid Quantum-Classical ML

    Department of Physical Sciences, Earth and Environment (DSFTA), University of Siena, Siena, Italy · Istituto Nazionale di Fisica Nucleare (INFN), Pisa, Italy · IBM Consulting—Promontory, IBM Industry Diamond, Banking & Financial Markets, Milan, Italy

  20. Quantum Graph Convolutional Networks: Implementation and Trainability Analysis

    Sep 17, 2026Paul San Sebastian Sein, Theodor Iosif, Tilen G. Limbäck-Stokin +2Graph-Based Semi-Supervised LearningVariational Quantum Circuits

    Ikerlan Technology Research Centre, Basque Research and Technology Alliance (BRTA), Arrasate-Mondragon, Spain · University of the Basque Country/Euskal Herriko Unibertsitatea-EHU · Quantum Learning Labs, Department of Computer Science, University College London, London, United Kingdom +4

  21. Learning to Program Adaptive Non-Local Observables for Machine Learning

    Sep 16, 2026Yu-Ting Lee, Samuel Yen-Chi Chen, Huan-Hsin TsengVariational Quantum CircuitsQuantum Neural Networks

    Graduate Institute of Communication Engineering, National Taiwan University, Taipei, Taiwan · Wells Fargo, New York, NY, USA · Brookhaven National Laboratory, AI & ML Department, Upton, NY, USA

  22. Variational Quantum Transformer Architecture for Synthetic Language Generation

    Sep 16, 2026Julian Hager, Michael Kölle, Gerhard Stenzel +3Quantum NLPQuantum Machine Learning

    Institute of Informatics, LMU Munich, Oettingenstraße 67, 80538 Munich, Germany

  23. Hybrid Variational Quantum Circuits for Multivariate Regression and High-Dimensional Data Reconstruction

    Sep 15, 2026Koffi Ognandon Ayena, Frédéric Holweck, Serge Iovleff +1Quantum Feature MapsImage Reconstruction

    ICB · UR4662 · BP 1515 Lomé-Togo

  24. Parameter-Efficient Quantum NLP for Paraphrase Detection: Performance, Robustness, and Entanglement

    Sep 13, 2026Farha Nausheen, Khandakar Ahmed, Farina RiazQuantum NLPQuantum Machine Learning

    ISILC, Victoria University, Melbourne, VIC, Australia · CSIRO, Australian International Institute of Higher Education, Sydney, NSW, Australia

  25. Certification cost of quantum models: measurement correlation, not parameter count

    Sep 13, 2026Pavel Sulimov, Claude LehmannFisher InformationVariational Quantum Circuits

    Zurich University of Applied Sciences (ZHAW), Winterthur, Switzerland · University of Zurich, Zurich, Switzerland

  26. Hierarchical Fourier Approximation for Variational Quantum Distribution Learning

    Sep 5, 2026Taha Hoseinpour Asli, Sajjad Hashemian, Ebrahim Ardeshir-LarijaniQuantum Circuit Born MachinesQuantum Machine Learning

    Sharif University of Technology · University of Tehran · Iran University of Science and Technology

  27. A Unified Physics-Aware Quantum Machine Learning Framework across Power GaN HEMTs and Logic Nanowire FETs: Predicting Unseen Process Splits and Held-Out Geometry Combinations with Lower Error and Tighter Split-to-Split Variability

    Sep 4, 2026Rushat Rai, Yun-Yuan Wang, Autsada Kakaen +10Quantum Machine LearningOOD Generalization

    National Yang Ming Chiao Tung University, Taiwan · NVIDIA AI Technology Center, Taiwan · Chiang Mai University, Thailand +2

  28. Hybrid Variational Quantum-Classical Framework with Adaptive Weighting and Efficiency Assessment

    Aug 30, 2026Dilli Hang RaiHybrid Quantum-Classical MLQuantum Neural Networks

    Institute of Science and Technology Tribhuvan University, Kritipur, Nepal

  29. Quantum-Inspired Hybrid Neural Networks for Neural Decoding: A Controlled Ablation Study of Learnable Quantum Sidecar Integration

    Aug 23, 2026Diana Legziel Levy, Menachem Finkelstein, Peter Chin +2Hybrid Quantum-Classical MLQuantum Neural Networks

    Reichman University, Herzliya, Israel · Dartmouth College, USA · The Edmond and Lily Safra Center for Brain Sciences at The Hebrew University of Jerusalem, Israel

  30. VQC-ZTI: Variational Quantum Control for Zero Trust Protection of the Tactile Internet

    Aug 19, 2026Mubassir Serneabat Sudipto, Shakil Ahmed, Ashfaq KhokharCybersecurityZero-Trust Security

    Iowa State University · Electrical and Computer Engineering, Iowa State University, Ames, Iowa, USA · Grand Valley State University +3