Practical Microwave Direct Digital Synthesis for Superconducting Qubit Control*

To conduct experiments with higher numbers of superconducting qubits, the availability of scalable control hardware is essential. To address this, we have incorporated custom superconducting qubit control logic into off-the-shelf hardware employing direct RF synthesis at 5 GHz for low-noise and low-latency pulse generation up to 7.5 GHz. Our approach eliminates the need for upconversion (which requires precise calibration to prevent leakage) and highly stable microwave sources (which can be expensive). The wide bandwidth enables efficient experiment configurations, such as control and readout using a single channel. We characterize the performance of the hardware using a five-transmon IBM device and demonstrate no additional decoherence or gate error for one- and two-qubit gates compared to traditional configurations, establishing a foundation for scalable quantum control beyond intermediate-scale systems.