Curator's Take
This article shows that a global accumulation gate combined with single‑layer depletion gates can deliver RF single‑shot readout and coherent control of Ge/SiGe hole spin qubits while dramatically simplifying the fabrication process. By matching coherence times and exchange tunability reported for more complex overlapping‑gate devices, it proves that performance need not be sacrificed for manufacturability—a key step toward wider adoption of spin‑based processors. The reduced lithography overhead lowers the barrier for academic groups to build few‑qubit prototypes, potentially speeding up experimental progress toward larger, error‑corrected arrays.
— Mark Eatherly
Summary
Hole spin qubits in undoped Ge/SiGe quantum well structures have advanced rapidly in performance and scalability. However, stringent multi-layer patterning and overlay requirements of conventional overlapping-gate devices create a bottleneck for academic proof-of-concept experiments involving few-qubit devices. Here we present fabrication and measurements of Ge/SiGe spin qubit devices with a global accumulation gate and single-layer depletion fine gates, which substantially reduce fabrication complexity. With careful design of the gate-2DHG capacitance, we demonstrate RF-based single-shot spin readout and coherent control of two single-spin qubits. We also characterize the spin coherence times and exchange tunability, which are similar to those reported in recent overlapping-gate Ge/SiGe spin qubit devices. By simplifying fabrication without sacrificing performance, our approach offers a more accessible device design for spin-based quantum technology research.