A 2 × 2 Quantum Dot Array in Silicon with Fully Tunable Pairwise Interdot Coupling

This is the authors' abstract. We don't add key points for this paper.

Recent advances in semiconductor spin qubits have enabled linear arrays with more than 10 qubits. Scaling to two-dimensional (2D) arrays is essential for fault-tolerant implementations but introduces significant fabrication challenges due to the increased density of the gate electrodes. Moreover, implementing two-qubit entanglement control requires the addition of interstitial exchange gates between quantum dots in this dense gate structure. In this work, we present a 2D array of silicon metal-oxide-semiconductor (MOS) quantum dots with tunable interdot coupling between all neighboring dots. Characterized at 4.2 K, the device exhibits exceptional tunability, supports the formation and isolation of both double- and triple-dot configurations, and achieves tunnel coupling control spanning up to 30 decades per volt. These results provide critical technical feedback and a foundational benchmark for advancing MOS spin qubit technology into the 2D regime.