Building control systems for the long-lived logical qubit challenge

To build a fault-tolerant quantum computer, we first have to master the challenge of building long-lived logical qubits. The quantum computing control system is a crucial part of this endeavor. It not only controls the quantum system but also provides the decoder - the key classical element correcting errors at the quantum level. In this talk, we focus on the critical aspects in building control systems for quantum error correction: a scalable system architecture, hardware-software codesign, and reliability.

We exemplify these insights with our quantum computing control system designed to run 100-qubit scale quantum error correction experiments. At the heart of the system is a synchronization and feedback hub, which orchestrates up to 448 microwave and flux control channels. We discuss implementations of fast tune-up experiments, long characterization experiments, and real-time decoders, which can be run on a high-performance engine within our synchronization hub. Such features, together with the scalable system architecture, make our control system ideally suited for quantum error correction research aimed at developing logical qubits with algorithmically relevant error rates.