QubitHammer Attacks: Qubit Flipping Attacks in Multi-tenant Superconducting Quantum Computers

Quantum computing is rapidly evolving its capabilities, with a corresponding surge in its deployment within cloud-based environments. Various quantum computers are accessible today via pay-as-you-go cloud computing models, offering unprecedented convenience. Due to its rapidly growing demand, quantum computers are shifting from a single-tenant to a multi-tenant model to enhance resource utilization. However, this widespread accessibility to shared multi-tenant systems also introduces potential security vulnerabilities. In this work, we present for the first time a set of novel attacks, named together as the QubitHammer attacks, which target state-of-the-art superconducting quantum computers. We show that in a multi-tenant cloud-based quantum system, an adversary with the basic capability to deploy custom pulses, similar to any standard user today, can utilize the QubitHammer attacks to significantly degrade the fidelity of victim circuits located on the same quantum computer. Upon extensive evaluation, the QubitHammer attacks achieve a very high variational distance of up to 0.938 from the expected outcome, thus demonstrating their potential to degrade victim computation. Our findings exhibit the effectiveness of these attacks across various superconducting quantum computers from a leading vendor, suggesting that QubitHammer represents a new class of security attacks. Further, the attacks are demonstrated to bypass all existing defenses proposed so far for ensuring the reliability in multi-tenant superconducting quantum computers.