Quantum adversarial machine learning is an emerging field that studies the
vulnerability of quantum learning systems against adversarial perturbations and
develops possible defense strategies. Quantum universal adversarial
perturbations are small perturbations, which can make different input samples
into adversarial examples that may deceive a given quantum classifier. This is
a field that was rarely looked into but worthwhile investigating because
universal perturbations might simplify malicious attacks to a large extent,
causing unexpected devastation to quantum machine learning models. In this
paper, we take a step forward and explore the quantum universal perturbations
in the context of heterogeneous classification tasks. In particular, we find
that quantum classifiers that achieve almost state-of-the-art accuracy on two
different classification tasks can be both conclusively deceived by one
carefully-crafted universal perturbation. This result is explicitly
demonstrated with well-designed quantum continual learning models with elastic
weight consolidation method to avoid catastrophic forgetting, as well as
real-life heterogeneous datasets from hand-written digits and medical MRI
images. Our results provide a simple and efficient way to generate universal
perturbations on heterogeneous classification tasks and thus would provide
valuable guidance for future quantum learning technologies.

本文发现在两个不同的分类任务中，即便是能够实现几乎达到最先进水平分类精度的量子分类器也能被一个精心设计的通用扰动彻底欺骗，为实现异构分类任务生成通用扰动提供了一个简单而有效的方法，从而为未来的量子学习技术提供有价值的指导。