Evidential Quantum Vertical Federated Learning

TL;DR

This paper introduces Evidential Quantum Vertical Federated Learning (eviQVFL), a novel quantum framework for VFL that enhances privacy and accuracy using a hybrid quantum-classical approach and evidence theory.

Contribution

The paper proposes a new quantum VFL framework employing a hybrid architecture, quantum teleportation, and evidential fusion, addressing privacy and accuracy challenges in VFL.

Findings

eviQVFL outperforms classical and quantum baselines in accuracy

Achieves less approximation error with limited quantum resources

Maintains training stability and stronger feature privacy

Abstract

Quantum federated learning (QFL) has recently emerged as a promising paradigm for privacy-preserving collaborative learning, yet most existing studies focus on horizontal federated learning and ignore the vertical federated learning (VFL), where parties hold complementary features of aligned samples. In this work, we propose Evidential Quantum Vertical Federated Learning (eviQVFL), a VFL-tailored QFL framework that employs a hybrid classical-quantum architecture for party-side feature processing, mapping local features into a quantum state. To preserve privacy and avoid information loss, party-side output states are directly transmitted to the server via quantum teleportation, and the server fuses the received quantum states with a non-parametric evidential fusion circuit grounded in evidence theory, followed by measurement-based inference. Extensive simulations on image classification and other real-world datasets demonstrate that eviQVFL consistently achieves higher classification accuracy than other classical and quantum baselines under comparable parameter budgets. Both empirical observations and theoretical analysis indicate that eviQVFL achieve less approximation error with limited quantum resources, while maintaining training stability and offering stronger feature privacy.