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

Area of Science:

• Quantum Computing
• Semiconductor Physics
• Materials Science

Background:

• Linear arrays of semiconductor spin qubits have surpassed 10 qubits, but scaling to 2D is necessary for fault-tolerant quantum computing.
• Fabrication challenges arise from increased gate electrode density in 2D arrays, complicating qubit control and entanglement.
• Interstitial exchange gates are required for two-qubit operations in dense 2D qubit structures.

Purpose of the Study:

• To present a novel 2D array of silicon metal-oxide-semiconductor (MOS) quantum dots.
• To demonstrate tunable interdot coupling between all neighboring quantum dots in the 2D array.
• To provide a foundational benchmark for advancing MOS spin qubit technology into the 2D regime.

Main Methods:

• Fabrication of a 2D array of silicon MOS quantum dots.
• Characterization of the device at 4.2 K.
• Measurement of interdot coupling tunability and control over double- and triple-dot configurations.

Main Results:

• The 2D MOS quantum dot array exhibits exceptional tunability.
• The device successfully forms and isolates both double- and triple-dot configurations.
• Achieved tunnel coupling control spanning up to 30 decades per volt.

Conclusions:

• The developed 2D quantum dot array addresses key fabrication and control challenges for scaling quantum processors.
• The demonstrated tunable interdot coupling is critical for implementing two-qubit gates in dense 2D qubit architectures.
• These findings offer vital technical feedback and establish a benchmark for future 2D MOS spin qubit development.