Efficient State Preparation for Quantum Machine Learning

TL;DR

This paper introduces a matrix product state-based method for efficient, low-depth quantum state encoding in quantum machine learning, enhancing robustness against adversarial attacks and demonstrated on real quantum hardware.

Contribution

It presents a novel matrix product state approach for state encoding in QML that maintains accuracy and improves adversarial robustness, with experimental validation.

Findings

Low-depth encoding does not reduce classification accuracy.

The method increases robustness against classical adversarial attacks.

Successful demonstration on superconducting quantum hardware.

Abstract

One of the key considerations in the development of Quantum Machine Learning (QML) protocols is the encoding of classical data onto a quantum device. In this chapter we introduce the Matrix Product State representation of quantum systems and show how it may be used to construct circuits which encode a desired state. Putting this in the context of QML we show how this process may be modified to give a low depth approximate encoding and crucially that this encoding does not hinder classification accuracy and is indeed exhibits an increased robustness against classical adversarial attacks. This is illustrated by demonstrations of adversarially robust variational quantum classifiers for the MNIST and FMNIST dataset, as well as a small-scale experimental demonstration on a superconducting quantum device.