Dynamic Pulse Switching for Protection of Quantum Computation on Untrusted Clouds

Quantum computing resources are now becoming easily accessible from various cloud providers. Although still in the Noisy Intermediate Scale Quantum regime, quantum computers hold promise to be able to execute novel algorithms and create invaluable data. However, just as with any other type of computing resource, they may be vulnerable to security attacks and should have defenses built into their design. This paper explores a particular threat of untrusted cloud providers, and how to protect user's quantum programs and data from the untrusted cloud provider. By leveraging trusted hardware in the quantum computer, a new obfuscation-based protection is developed based on switching of control pulses between different drive and control channels of the quantum computer. This work demonstrates that simple hardware modifications can enable dynamic, run-time pulse switching, which makes it extremely difficult for the cloud provider to decode what actual circuit is executed on the quantum computer. This work presents a basic architecture that employs pulse switching, and an extended architecture that includes use of dummy qubits for increased protection. The overhead of the proposed changes, as well as attack complexity for different types of user circuits and obfuscation levels is evaluated in this work.