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

TL;DR

This work identifies and exploits a previously unexplored side channel in trapped-ion quantum processors that arises from the radio-frequency signals used to modulate lasers for ion cooling, gate execution, and readout, thereby implementing a proof-of-principle exploitation of the novel attack vector.

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.

Figures (8)

• Figure 1: High level topology of the hardware for remote data acquisition, consisting of network devices (blue), the attacker hardware (red) and the QPU (green).
• Figure 2: Quadrupole laser switching setup of the target quantum processor gersterScalabilityQuantumProcessors, highlighting the region from which the informationally rich RF signal emissions leak.
• Figure 3: Schematic diagram of the SDRlab 122-16-based receiver system with two antennae and bandpass filters.
• Figure 4: A high energy segment is clearly visible in the RF emissions recorded, indicating that some control activity is taking place.
• Figure 5: The time differences between consecutive pulses exhibit clear patterns, which reveal the target quantum processor's delay between shots, at around 2.5 ms.