Side-channel Attacks Targeting Classical-Quantum Interface in Quantum Computers

With the growing interest in emerging and upcoming quantum computers, it is important to consider possible hardware security vulnerabilities and countermeasures. This work proposes side-channel attacks targeting classical-quantum interface circuits in superconducting quantum computers. Particularly, a single flux quantum (SFQ) technology-based classical controller, which is a promising candidate for large-scale in-fridge qubit control and readout circuitry, is considered. We have uncovered a substantial side-channel leakage from superconducting interface circuits through the power supply variations. An attacker, who has access to room temperature electronics where the power is generated, can successfully decode certain information about various components within quantum computers.