Radio-Frequency Side-Channel Analysis of a Trapped-Ion Quantum Computer

TL;DR

This paper uncovers a new side channel in trapped-ion quantum computers caused by RF signal leakage from acousto-optical modulators, demonstrating how it can be exploited to extract gate information and proposing mitigation strategies.

Contribution

It identifies and demonstrates a previously unrecognized RF leakage side channel in trapped-ion quantum processors, with practical attack and mitigation methods.

Findings

RF leakage can be detected with off-the-shelf components

Gate pulse characteristics can be extracted from RF leakage data

Mitigation strategies can reduce information leakage

Abstract

Analogously to classical computers, quantum processors exhibit side channels that may give attackers access to potentially proprietary algorithms. We identify and exploit a previously unexplored side channel in trapped-ion quantum processors that arises from the radio-frequency (RF) signals used to modulate lasers for ion cooling, gate execution, and readout. In these quantum processors, acousto-optical modulators (AOMs) imprint phase and frequency modulations onto laser fields interacting with the ions to implement individual and collective unitaries. The AOMs are driven by strong RF signals, a fraction of which leaks out of the device. We discuss general strategies to exploit this side channel and demonstrate how to detect RF leakage from a state-of-the-art qudit-based quantum processor using off-the-shelf components. From this data, we extract pulse characteristics of single-ion and entangling gates, thereby implementing a proof-of-principle exploitation of the novel attack vector. Finally, we outline ways to mitigate the information leakage through the presented side channel.