Eight-Qubit Operation of a 300 mm SiMOS Foundry-Fabricated Device

TL;DR

This paper demonstrates the successful tuning, control, and measurement of an eight-qubit silicon spin qubit array fabricated using a 300 mm CMOS-compatible process, marking a significant step towards scalable quantum computing.

Contribution

It presents the first scalable eight-qubit silicon spin qubit array fabricated in a standard foundry process, with high coherence times and high-fidelity readout capabilities.

Findings

All eight qubits are successfully tuned and characterized.

Coherence times up to 41 μs (dephasing) and 1.31 ms (Hahn echo) achieved.

High-fidelity, simultaneous readout of the entire array demonstrated.

Abstract

Silicon spin qubits are a promising candidate for quantum computing, thanks to their high coherence, high controllability and manufacturability. However, the most scalable complementary metal-oxide-semiconductor (CMOS) based implementations have so far been limited to a few qubits. Here, to take a step towards large scale systems, we tune and coherently control an eight-dot linear array of silicon spin qubits fabricated in 300 mm CMOS-compatible foundry process, establishing operational scalability beyond the two-qubit regime. All eight qubits are successfully tuned and characterized as four double dot pairs, exhibiting Ramsey dephasing times $T_2^*$ up to 41(2) $\mu$s and Hahn-echo coherence times $T_2^{\mathrm{Hahn}}$ up to 1.31(4) ms. Readout of the central four qubits is achieved via a cascaded charge-sensing protocol, enabling simultaneous high-fidelity measurements of the entire multi-qubit array. Additionally, we demonstrate a two-qubit gate operation between adjacent qubits with low phase noise. We demonstrate here that we can scale silicon spin qubit arrays to medium-sized arrays of 8 qubits while maintaining coherence of the system.