Scientists use radio waves to flip nuclear spin of single atom

Summary

Researchers at Delft University of Technology demonstrated that radio-frequency electrical signals from a scanning tunneling microscope can flip the nuclear spin of a single atom, even when it is largely decoupled from the electron spin. This result defies current theoretical expectations. The study, published in Nature Communications, employed a refined dual magnetic resonance technique to independently target nuclear and electron spins.

Why it matters

Nuclear spins are among the most promising candidates for long-lived quantum memory due to their resilience against environmental noise. However, directly controlling these spins has always been challenging. The discovery of an unexpected electrical control channel opens a potential new pathway for storing and reading quantum information without relying solely on hyperfine coupling. This finding also highlights a gap in our understanding of how nuclei interact with local electric fields at the single-atom scale.

Highlights

• According to lead researcher Sander Otte, the nuclear spin was flipped while largely decoupled from the electron spin; this refutes the 'simple understanding'.
• Dual magnetic resonance refined to the single-atom level allowed researchers to tune nuclear and electron spins at their characteristic frequencies (nuclear transitions are 100–1,000 times lower).
• The physical mechanism underlying the observed transition has not yet been determined; a functional quantum memory has not been demonstrated.

Critical take

The article carefully notes that the mechanism remains unexplained and that no functional quantum device has been produced. However, framing it as something that 'could ultimately support' risks presenting a single-atom proof-of-concept as a near-term breakthrough in quantum computing. The fact that the team's own model cannot explain the observation suggests the result may be an artifact of the specific STM geometry rather than a general control channel.