Time-division multiplexed superconducting qubit control using ultra-low-power, base-temperature cryo-CMOS multiplexer*

Large-scale superconducting quantum computing systems entail high-fidelity control and readout of large numbers of qubits at millikelvin temperatures. State-of-the-art control architectures use dedicated control lines for each qubit, thereby resulting in a massive input-output bottleneck. The hardware cost and wiring complexity for large-scale systems can be significantly reduced by functionally multiplexing the qubit control lines at the base temperature stage of a dilution refrigerator. In this talk, we demonstrate the feasibility to perform functional time-division multiplexing of qubit control signals using a custom-designed, ultra-low power (<1 µW), fast switching (~2 ns) cryo-CMOS multiplexer operating at the base temperature stage of a dilution refrigerator, with port-to-port signal crosstalk suppressed by greater than 30 dB. We employ this capability to demonstrate novel two-qubit operations using a single qubit control line in a tunable-coupler based two-qubit device. Finally, we discuss the limitations and the scalability of the multiplexer for large-scale systems. Our results pave the way for a viable path to address the wiring bottleneck for large-scale quantum processor control and quantum error correction protocols.