Scaling of silicon spin qubits under correlated noise

TL;DR

This paper investigates the spatial correlations of noise in silicon spin qubits, identifying sources and assessing their impact on quantum error correction, crucial for scalable fault-tolerant quantum computing.

Contribution

It provides quantitative analysis of noise correlations in silicon spin qubits and evaluates their effects on quantum error correction feasibility.

Findings

Magnetic field drifts cause global, perfectly correlated noise that can threaten QEC.

Charge noise correlations are moderate, short-range, and manageable for fault-tolerant operation.

Results establish benchmarks for correlated noise and its impact on scalable silicon qubit arrays.

Abstract

The path to fault-tolerant quantum computing hinges on hardware that scales while remaining compatible with quantum error correction (QEC). Silicon spin qubits are a leading hardware candidate because they combine industrial fabrication compatibility with a nanoscale footprint that could accommodate millions of qubits on a chip. However, their suitability for QEC remains uncertain since spatially correlated noise naturally emerges from the resulting close proximity of qubits. These correlations increase the likelihood of simultaneous errors and erode the redundancy that QEC depends on. Here we quantify the spatial extent of noise correlations in a five-qubit silicon array and assess their impact on QEC. We identify two distinct sources of correlated noise: global magnetic field drifts that generate perfectly correlated fluctuations, and charge noise from two-level fluctuators that produces short-range correlations decaying within neighboring qubits. While magnetic drifts represent a critical correlated noise source that can compromise QEC, they can be mitigated. In contrast, the measured charge noise correlations are moderate, electrically tunable, and compatible with fault-tolerant operation with minimal qubit overhead. Our results establish quantitative benchmarks for correlated noise and clarify how such correlations impact the viability of quantum error correction in scalable qubit arrays.