Backdoor Threats in Variational Quantum Circuits: Taxonomy, Attacks, and Defenses

Variational quantum algorithms, a cornerstone of noisy intermediate-scale quantum computing, harbor a significant security risk due to their dependence on pre-designed variational quantum circuits. These circuits can be compromised by backdoor attacks, which embed hidden malicious behaviors that remain inactive until triggered by specific inputs. Researchers have identified a taxonomy of such threats and outlined potential attacks and defenses¹. The vulnerability stems from the use of pre-trained circuits, which can be manipulated to include backdoors without being detected. As quantum computing continues to advance, the potential for these backdoor attacks to compromise the security of quantum systems grows. The development of secure variational quantum circuits is crucial to mitigate these risks. So what matters to practitioners is that securing quantum systems against backdoor threats is essential to ensure the integrity of quantum computing and its applications.