A 300 mm foundry silicon spin qubit unit cell exceeding 99% fidelity in all operations

TL;DR

This paper demonstrates high-fidelity silicon spin qubits fabricated in a 300 mm CMOS foundry, showing promising scalability for quantum computing with over 99% control fidelity and long coherence times.

Contribution

It provides the first evidence that high-fidelity, long-coherence silicon qubits can be reliably produced in industrial-scale CMOS fabrication processes.

Findings

Single- and two-qubit control fidelities exceed 99%.

State preparation and measurement fidelity exceeds 99.9%.

Coherence times up to 30.4 μs and 6.3 s for T2* and T1, respectively.

Abstract

Fabrication of quantum processors in advanced 300 mm wafer-scale complementary metal-oxide-semiconductor (CMOS) foundries provides a unique scaling pathway towards commercially viable quantum computing with potentially millions of qubits on a single chip. Here, we show precise qubit operation of a silicon two-qubit device made in a 300 mm semiconductor processing line. The key metrics including single- and two-qubit control fidelities exceed 99% and state preparation and measurement fidelity exceeds 99.9%, as evidenced by gate set tomography (GST). We report coherence and lifetimes up to $T_\mathrm{2}^{\mathrm{*}} = 30.4$ $\mu$s, $T_\mathrm{2}^{\mathrm{Hahn}} = 803$ $\mu$s, and $T_1 = 6.3$ s. Crucially, the dominant operational errors originate from residual nuclear spin carrying isotopes, solvable with further isotopic purification, rather than charge noise arising from the dielectric environment. Our results answer the longstanding question whether the favourable properties including high-fidelity operation and long coherence times can be preserved when transitioning from a tailored academic to an industrial semiconductor fabrication technology.