Integrating cryogenic digital multiplexing with superconducting qubits

Superconducting quantum computers require control lines that deliver high-fidelity rf signals for performing single qubit gates. The number of control lines scales linearly with the number of qubits, such that a utility-scale system will likely require millions of coaxial lines, posing significant engineering challenges. An alternative approach is to integrate digital control electronics within the package [1], such that digital multiplexing can be leveraged to reduce line-count. We have developed control circuits utilizing Single-Flux-Quantum (SFQ) logic that integrate digital multiplexing, allowing for a single clock line to address several qubits. We report on results from these circuits on a multi-qubit device and discuss ongoing improvements and technical challenges.

 

[1] Bernhardt, et al. "Quantum Computer Controlled by Superconducting Digital Electronics at Millikelvin Temperature", doi:10.48550/arXiv.2503.09879.