Atomic clock transitions in silicon-based spin qubits

TL;DR

This paper demonstrates the existence of clock transitions in silicon-based spin qubits, significantly enhancing their coherence times and robustness against environmental noise, which is crucial for quantum technology applications.

Contribution

It introduces the observation of clock transitions in solid-state electron spins, specifically in bismuth donors in silicon, leading to improved coherence and noise resilience.

Findings

Clock transitions observed in silicon-based electron spins.

Coherence times exceeding seconds achieved.

Reduced sensitivity to magnetic and electric field noise.

Abstract

A major challenge in using spins in the solid state for quantum technologies is protecting them from sources of decoherence. This can be addressed, to varying degrees, by improving material purity or isotopic composition for example, or active error correction methods such as dynamic decoupling, or even combinations of the two. However, a powerful method applied to trapped ions in the context of frequency standards and atomic clocks, is the use of particular spin transitions which are inherently robust to external perturbations. Here we show that such `clock transitions' (CTs) can be observed for electron spins in the solid state, in particular using bismuth donors in silicon. This leads to dramatic enhancements in the electron spin coherence time, exceeding seconds. We find that electron spin qubits based on CTs become less sensitive to the local magnetic environment, including the presence of 29Si nuclear spins as found in natural silicon. We expect the use of such CTs will be of additional importance for donor spins in future devices, mitigating the effects of magnetic or electric field noise arising from nearby interfaces.