Physicists Successfully Control the Magnetic Nucleus of a Single Atom Using Radio Waves

Researchers at the Delft University of Technology have successfully manipulated the magnetic core of a single atom using targeted radio waves. The breakthrough, achieved using a scanning tunneling microscope, demonstrates direct control over an atomic nucleus—a feat previously considered impossible by quantum physicists.[2][3]

The experiment targeted a single titanium-47 isotope, sending simultaneous but distinct radio frequencies to both its orbiting electron and its nucleus. By isolating the nuclear response, the team proved that the highly shielded core can be driven independently of the electron's magnetic field.[5][6]

The findings were published on October 24, 2026, in the journal Nature Communications. The observation challenges established models of atomic interaction and opens a new pathway for developing highly stable quantum memory systems.[4][6]

The Shielded Core

In transition metals like iron and titanium, every individual atom acts as a microscopic magnet. This magnetism is primarily generated by the electrons orbiting the core, which possess a fundamental quantum property known as spin.[2][4]

However, in certain isotopes, the nucleus itself also carries a spin. This nuclear magnetism is significantly weaker than the electron's, but it is heavily shielded from external electromagnetic noise and environmental interference.[2][4]

Because of this intense isolation, physicists long assumed that the nuclear spin was immune to direct manipulation by external electrical signals. The nucleus was considered a locked vault, inaccessible to the standard tools used to probe atomic structures.[4][5]

Previous experiments could only influence the nucleus indirectly by first altering the electron. This relied on a slight natural entanglement between the two, known as the hyperfine interaction, which acts as a narrow bridge between the outer shell and the core.[4][5]

Bypassing the Hyperfine Route

To test the limits of this shielding, the Delft team, led by physicist Sander Otte and lead author Hester Vennema, modified a scanning tunneling microscope. This instrument uses an atomically sharp tip to direct electrical currents with extreme precision at individual atoms resting on a surface.[2][4]

The researchers employed a technique called electron-nuclear double resonance. They fired two distinct radio wave signals at the titanium-47 atom simultaneously, tuning one frequency to the electron and the other to the nucleus.[3][6]

"You can compare it to the strings of a guitar," Vennema explained in a university release. "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."[3][4]

The resonant frequencies required to flip a nuclear spin are a hundred to a thousand times lower than those needed for an electron. By playing both "notes" at once, the team could observe the nucleus's behavior while the electron was independently occupied.[3][4]

To their surprise, the targeted radio waves successfully flipped the nuclear spin even when it was largely disentangled from the electron. The nucleus responded directly to the local electrical probe, bypassing the expected hyperfine interaction entirely.[1][4]

Experimental Precision

The experimental setup required extreme precision. The scanning tunneling microscope operates in an ultra-high vacuum at temperatures near absolute zero, ensuring that the titanium atom remains perfectly still during the measurement.[1][6]

The team positioned the microscope's tip just fractions of a nanometer above the titanium atom. From this vantage point, the tip acts as an incredibly localized antenna, broadcasting the radio frequencies directly into the atom's core.[1][4]

Titanium-47 was chosen specifically for its complex nuclear structure. Unlike simpler isotopes, its spin of 5/2 means it has six distinct magnetic energy levels. The quadrupole interaction within the nucleus shifts these levels slightly, creating unique resonant frequencies for each transition.[1][6]

By sweeping the radio frequency, the researchers mapped out these distinct transitions, confirming that they were indeed manipulating the nucleus and not just detecting background noise. The resulting spectrum matched their theoretical eigenenergy calculations perfectly.[1][6]

A Quantum Storage Vault

Modern quantum processors rely on qubits made from superconducting circuits or trapped ions, which require massive cooling infrastructure and remain highly sensitive to errors. A single stray magnetic field can destroy the quantum state, a problem known as decoherence.[1][3]

Researchers have long viewed individual atoms as the ultimate limit for miniaturizing quantum hardware. If data could be reliably written to and read from a single atomic nucleus, it would enable quantum computers with unprecedented density and stability.[3][6]

However, the very property that makes the nucleus stable—its isolation—has historically made it useless for rapid computation. If you cannot easily write information to the nucleus, it cannot function as a practical qubit.[2][5]

The Delft breakthrough bridges this gap. By demonstrating that radio waves can directly drive the nuclear spin, the researchers have shown that the nucleus can be both highly stable and actively controlled.[4][6]

Unexplained Physics

Despite the experimental success, the underlying theoretical mechanism remains a mystery. Standard quantum models do not explain how the electrical signals from the scanning tunneling microscope bypass the electron to couple directly with the nucleus.[1][4]

"According to our simple understanding, this should not really happen," Otte stated following the publication. "The nuclear spin should not be sensitive at all to the electrical signals from a scanning tunneling microscope."[2][3]

The observation forces theoretical physicists to re-evaluate how local probes interact with the innermost magnetic degrees of freedom. The standard picture of atomic resonance cannot account for the direct coupling observed in the Delft laboratory.[1][4]

The research team is now working to identify the exact physical mechanism driving the unexpected resonance. They suspect that the electric field gradient from the microscope tip might be interacting with the nucleus's quadrupole moment, but this remains unproven.[1][6]

"Back to the drawing board, then," Otte conceded. "That is really how science works. There is always something new left to figure out."[3][4]