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

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.