Circuit-centric quantum classifiers, Maria Schuld, Alex Bocharov, Krysta Svore, and Nathan Wiebe, 2020Physical Review A, Vol. 101 (American Physical Society)DOI: 10.1103/PhysRevA.101.032308 - A foundational paper presenting parameterized quantum circuits as classifiers, often used in hybrid architectures.
Supervised learning with quantum-enhanced feature spaces, Vojtěch Havlíček, Antonio D. Córcoles, Kristan Temme, Aram W. Harrow, Abhinav Kandala, Jerry M. Chow, and Jay M. Gambetta, 2019Nature, Vol. 567DOI: 10.1038/s41586-019-0980-2 - Introduces the concept of quantum feature maps for supervised learning, relevant to the encoding and feature extraction aspects of hybrid models.
Barren plateaus in quantum neural networks, Jarrod R. McClean, Sergio Boixo, Vadim N. Smelyanskiy, Ryan Babbush, and Hartmut Neven, 2018Nature Communications, Vol. 9 (Springer Nature)DOI: 10.1038/s41467-018-05305-2 - A seminal paper identifying the barren plateau problem, a significant challenge for training deep parameterized quantum circuits in quantum machine learning.