Federated learning has emerged as a viable distributed solution to train machine learning models without the actual need to share data with the central aggregator. However, standard neural network-based federated learning models have been shown to be susceptible to data leakage from the gradients shared with the server. In this work, we introduce federated learning with variational quantum circuit model built using expressive encoding maps coupled with overparameterized ans\"atze. We show that expressive maps lead to inherent privacy against gradient inversion attacks, while overparameterization ensures model trainability. Our privacy framework centers on the complexity of solving the system of high-degree multivariate Chebyshev polynomials generated by the gradients of quantum circuit. We present compelling arguments highlighting the inherent difficulty in solving these equations, both in exact and approximate scenarios. Additionally, we delve into machine learning-based attack strategies and establish a direct connection between overparameterization in the original federated learning model and underparameterization in the attack model. Furthermore, we provide numerical scaling arguments showcasing that underparameterization of the expressive map in the attack model leads to the loss landscape being swamped with exponentially many spurious local minima points, thus making it extremely hard to realize a successful attack. This provides a strong claim, for the first time, that the nature of quantum machine learning models inherently helps prevent data leakage in federated learning.

使用具有表达性编码映射和超参数化参量的变分量子电路模型引入了联邦学习，显示了表达性映射对抗梯度反演攻击具有内在隐私保护能力，而超参数化则确保了模型的可训练性。同时，通过数值扩展论证了攻击模型中表达性映射的欠参数化导致丢失地形被大量虚假局部极小点淹没，使得攻击难以成功，从而强有力地宣称量子机器学习模型的本质性质有助于防止联邦学习中的数据泄露。

表达丰富的变分量子电路在联邦学习中提供固有的隐私保护