Optimizing RF readout for silicon spin qubits in an access array

Efficient and scalable qubit readout is a critical requirement for realizing quantum computing. Radio-frequency (RF) readout emerges as a promising candidate due to its high speed and multiplexing capabilities. In this study, we employ a two-dimensional access array to significantly reduce the number of control lines needed per qubit for readout. We demonstrate frequency-domain multiplexing (FDM) and simultaneous readout at two distinct frequencies in a semiconductor quantum device. Optimizations in circuit design, device proximity, power levels, and RF readout frequency enhanced the signal-to-noise ratio by an order of magnitude. Despite these advancements, challenges such as bandwidth overlap persist, which can impact the scalability of FDM. Our findings highlight both the potential and the limitations of RF readout in scalable quantum computing systems.