Shuttle-Exploiting Attacks and Their Defenses in Trapped-Ion Quantum Computers

TL;DR

This paper identifies security vulnerabilities in multi-programmed trapped-ion quantum computers where shuttle operations can be exploited to significantly degrade computation fidelity, and proposes countermeasures to mitigate such attacks.

Contribution

It introduces shuttle-exploiting attack strategies in shared TI quantum systems and offers defense mechanisms to enhance security and reliability.

Findings

Shuttle-exploiting attacks can reduce fidelity by up to 63 times.

Adversarial programs can be systematically generated to maximize shuttle operations.

Countermeasures like dummy qubits and shuttle caps improve system robustness.

Abstract

Trapped-ion (TI) quantum bits are a front-runner technology for quantum computing. TI systems with multiple interconnected traps can overcome the hardware connectivity issue inherent in superconducting qubits and can solve practical problems at scale. With a sufficient number of qubits on the horizon, the multi-programming model for Quantum Computers (QC) has been proposed where multiple users share the same QC for their computing. Multi-programming is enticing for quantum cloud providers as it can maximize device utilization, throughput, and profit for clouds. Users can also benefit from the short wait queue. However, shared access to quantum computers can create new security issues. This paper presents one such vulnerability in shared TI systems that require shuttle operations for communication among traps. Repeated shuttle operations increase quantum bit energy and degrade the reliability of computations (fidelity). We show adversarial program design approaches requiring numerous shuttles. We propose a random and systematic methodology for adversary program generation. Our analysis shows shuttle-exploiting attacks can substantially degrade the fidelities of victim programs by 2X to 63X. Finally, we present several countermeasures such as adopting a hybrid initial mapping policy, padding victim programs with dummy qubits, and capping maximum shuttles.