Researchers at Delft University of Technology have achieved a world first: observing an atomic nucleus flip its spin in real time. Using a scanning tunneling microscope (STM), the team measured the nuclear state indirectly through the atom’s electrons, revealing an unexpected stability lasting several seconds.
The findings, published in Nature Communications, mark an important step toward controlling quantum states at the atomic scale, opening new horizons for applications in quantum simulation and sensing.
A microscope that “feels” atoms
The STM, equipped with an atomically sharp needle, can detect and image single atoms by sensing the electrons around them. Both electrons and atomic nuclei behave like tiny magnets, each carrying a property called “spin.” While STM techniques enabled the measurement of electron spins a decade ago, probing nuclear spins in real time remained elusive.
Capturing nuclear motion
To overcome this challenge, the Delft team exploited the hyperfine interaction—the coupling between nuclear and electron spins. By performing rapid measurements, PhD researchers Evert Stolte and Jinwon Lee observed the nuclear spin switching between two distinct quantum states directly on their screens. Remarkably, the flips occurred roughly every five seconds, far longer than the fleeting lifetimes of electron spins, which typically last only nanoseconds.
Towards single-shot quantum readout
Crucially, the team demonstrated “single-shot readout”: measuring the nuclear spin state faster than it flips and largely without disturbing it. This capability paves the way for more advanced experiments in controlling nuclear spins at the atomic scale.
“Our work shows the very first step: being able to measure nuclear spins directly at the surface,” explains Stolte. “From here, we can explore their use in quantum simulation and ultra-sensitive quantum sensing.”
With this achievement, Delft researchers have opened a new frontier in quantum physics—bringing the inner workings of the atomic nucleus into view in real time.
