Plate Nº 15 · recorded November 11, 2026
PhysicsReported finding
Delft Team Flips One Atom's Nuclear Spin and Stumps Itself
A Delft team flipped the nuclear spin of a single atom with radio waves. The observation holds up; the mechanism behind it does not, and lead researcher Sander Otte says it should not have happened.
By James Calloway4 min read759 words
In brief
- Published 24 October 2026 in Nature Communications; DOI 10.1038/s41467-026-78801-5
- Nuclear spin frequencies run 100 to 1,000 times lower than electron spin frequencies
- Two radio signals applied simultaneously — one tuned to the electron, one to the nucleus
- Method: double magnetic resonance adapted to a single atom via a modified scanning tunneling microscope
- Lead author Hester G. Vennema; lead researcher Sander Otte; both at Delft University of Technology
A Delft University of Technology team has flipped the magnetic spin of a single atomic nucleus using radio waves — a result its own lead researcher says should not have been possible. The work appeared in Nature Communications on 24 October 2026 and describes nuclear magnetic resonance carried out on one atom with a local probe.
Lead author Hester G. Vennema and her colleagues — Cristina Mier, Evert W. Stolte, Leonard Edens, Jinwon Lee and lead researcher Sander Otte — used a modified scanning tunneling microscope, an instrument that steers electrical signals at individual atoms, to address the nucleus and the electron around it separately.
Earlier work with these microscopes concentrated on electron spin, which is stronger and easier to detect. Nuclear spin is a different animal: far weaker, and better shielded from everything around it. Otte puts the contrast this way: "By far the strongest magnetism comes from the electrons. But in some atoms, the nucleus also carries a spin. That spin is much weaker, but it is also much better shielded from the outside world."
That shielding is exactly why nuclear spins interest people building quantum computers. It is also, the team expected, the reason their experiment would fail.
How did they catch a nucleus responding?
The researchers applied two signals at the same time: one tuned to the electron's magnetic resonance, another tuned to the nucleus's. Until now, nuclear spin could only be watched indirectly, through the hyperfine interaction — a quantum coupling between the magnetic properties of an electron and its nucleus.
When the two signals ran simultaneously and their effects were read out separately, the nucleus flipped even though it was largely disentangled from the electron spin. Otte said: "According to our simple understanding, this should not really happen. The nuclear spin should not be sensitive at all to the electrical signals from a scanning tunneling microscope."
How do you tune a spin like a guitar string?
The control came from adapting double magnetic resonance, a well-established technique, to work on a single atom. In quantum mechanics, spin can only move between specific allowed states, and each change requires a signal at a matching frequency.
Vennema compares the process to a guitar: "Each possible spin rotation is like a string with its own note. You have to play precisely the right note to make a particular string vibrate. The 'notes' of a nuclear spin are a hundred to a thousand times lower than those of an electron spin."
In practice, the frequencies for the nucleus sit one hundred to one thousand times below those for the electron, so each address had to land on the right transition rather than near it.
What does this change for quantum storage?
Potentially a great deal, eventually; practically, nothing yet. Nuclear spins stay comparatively protected from external disturbances that scramble delicate quantum states, so controlling an individual one could support new ways to store and read quantum information. But the researchers themselves describe practical applications as a future possibility. No working device exists here, and the paper reports no error rates, no read-out performance, nothing beyond a single atom under laboratory conditions.
So what is actually unexplained?
The mechanism. The team can document the nucleus responding, and can tune the signals to make it respond, but they cannot yet say what physical process permits the nuclear spin to answer when its coupling to the electron spin is insufficient to account for the observed behavior. That question, they say, needs further investigation.
"Back to the drawing board, then," Otte said. "That is really how science works. There is always something new left to figure out."
A skeptic's reading: the experiment establishes the observation, not the explanation. The framing of "this should not happen" is genuine — the team's own model predicted no response — but a failed prediction does not by itself identify new physics. It can equally mean the model was oversimplified, or that an unrecognized coupling channel did the work. The paper does not settle which, and nothing in it yet settles the practical question either.
The paper in brief
- Title: "Nuclear magnetic resonance on a single atom with a local probe"
- Authors: Hester G. Vennema, Cristina Mier, Evert W. Stolte, Leonard Edens, Jinwon Lee, Sander Otte
- Journal: Nature Communications, 24 October 2026
- DOI: 10.1038/s41467-026-78801-5
- Method: a modified scanning tunneling microscope, two simultaneous radio signals, double magnetic resonance adapted to a single atom
- Result: nuclear spin flipped despite weak coupling to the electron spin; the physical mechanism behind the response remains unidentified
via google.com (Original)
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Staff writer covering regulation, policy and their impact on general science news at SciBeat.
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