Readout of small-scale semiconductor spin-qubit arrays

The engineering of readout methods becomes crucial as single qubits are scaled up in linear and two-dimensional arrays to form NISQ processors. In particular, fast, high-fidelity and simultaneous measurements across these small arrays are essential. I will present our work on readout techniques and scaling efforts, in particular involving RF-reflectometry, in small two-dimensional arrays of quantum dots in GaAs and silicon. In these systems we utilize techniques such as crosstalk mitigation, multi-qubit DC and pulse calibration, sensor compensation, virtual gates, and adaptive searching in high-dimensional spaces. First, I will discuss simultaneous, single-shot, and interlaced measurements for singlet-triplet spin qubits, performed via four independent sensors spaced across a GaAs chip. I will also show single-shot reflectometry measurements via compact gate-based dispersive sensing, carried out in a two-dimensional CMOS silicon array. These methods, combined with pulsed-gate techniques, enable deterministic single-electron shuttling within the array, and may be beneficial for many other quantum-dot devices or spin- and charge-based hybrid systems.

*In collaboration with Fabio Ansaloni, Federico Fedele, Heorhii Bohuslavskyi, Saeed Fallahi, Geoffrey C. Gardner, Michael J. Manfra, Louis Hutin, Maud Vinet, Yann-Michel Niquet, Silvano De Franceschi, and Ferdinand Kuemmeth.