Gate-based spin readout in planar Si-MOS quantum dots using an off-chip microwave resonator.

Planar Si-MOS technology provides a promising platform to build scalable two-dimensional arrays with nearest neighbor connectivity needed to implement, efficiently, the surface code [1]. Reflectometry techniques can perform spin read-out through the gate and are therefore a promising approach to read out dense two-dimensional qubit arrays without compromising the qubit connectivity. However, in planar technologies, efforts to achieve high-fidelity gate-based read-out have been hindered by multiple factors, such as lower gate lever arms and parasitic two-dimensional electron gases in accumulation mode devices. In this work, we interface the quantum device fabricated on a 300mm wafer with a newly developed high-impedance off-chip resonator at 1.32 GHz. With our approach, we demonstrate dispersive detection of an inter-dot charge transition with a state-of-the-art signal-to-noise ratio of 1 in 100 us in planar Si-MOS [2] and perform singlet-triplet spin readout via Pauli spin blockade.

[1] Li et al. 2018, “A crossbar network for silicon quantum dot qubits”, Science Advances.

[2] West et al. 2019, “Gate-based single-shot readout of spins in silicon”, Nature Nanotechnology.