Delft University of Technology researchers have achieved a frist-of-its-kind observation: the real-time fluctuation of an atom’s magnetic nucleus. Published today in Nature Communications, the breakthrough utilized a scanning tunneling microscope to indirectly measure the nuclear spin via its interaction with surrounding electrons. This advancement marks a significant step toward greater control of atomic properties with potential implications for advancements in quantum computing and materials science,building on prior work focused on electron spin measurement.
Dutch researchers have, for the first time, directly observed the magnetic nucleus of an atom fluctuating in real-time. This breakthrough, published in the journal Nature Communications, represents a significant advancement in the field of atomic-level quantum sensing and could pave the way for more precise control of atomic properties.
The team, from Delft University of Technology, extracted information about the nuclear spin from the atom’s electrons using a scanning tunneling microscope (STM). They observed the nuclear spin remaining stable for several seconds – a relatively long duration that suggests potential for improved control over the magnetic nucleus.
A scanning tunneling microscope utilizes an incredibly sharp, atomic-scale tip to sense individual atoms on a surface and create high-resolution images. Crucially, the STM can detect the electrons surrounding an atom’s nucleus. Both electrons and the nucleus, depending on the type of atom, can behave like tiny magnets.
Both electrons and nuclei possess a property called spin, which is the quantum mechanical equivalent of magnetism. Researchers were previously able to measure the movement of a single electron’s spin using an STM. Now, the team led by Professor Sander Otte aimed to determine if the microscope could also be used to read the nuclear spin in real time.
Reading the Nuclear Spin
Because the STM isn’t directly sensitive to the nucleus, the researchers had to use the electron to indirectly read the nuclear spin. “The general idea was clear several years ago – to take advantage of the strong interaction between the electron spin and the nuclear spin,” explained Professor Otte. “But these early measurements were too slow to follow the nuclear spin’s movement over time.”
Lead researchers Everett Stolte and Jin Won Lee conducted rapid measurements on an atom known to carry nuclear spin. To their surprise, they observed the signal switching between two distinct levels in real-time, directly on the computer screen. “We were able to show that this switching reflects the nuclear spin flipping from one quantum state to another, and back again,” said Stolte.
The researchers found that the nuclear spin takes approximately five seconds to change, a much longer period than many other quantum systems observable with an STM. For example, the lifetime of an electron spin in the same atom is only about 100 nanoseconds.
Single-Shot Readout
The team successfully measured the state of the nuclear spin faster than it changed, without disturbing the spin itself – a feat known as single-shot readout. This achievement opens up new experimental possibilities for precise control of the nuclear spin. In the long term, advances in reading and controlling nuclear spins on surfaces could have applications in quantum simulation and atomic-level quantum sensing.
“The first step in any new experimental field is the ability to measure it, and that’s what we’ve achieved for nuclear spins at the atomic level,” Stolte stated. This research offers a fundamental step toward harnessing the power of the nucleus for advanced technologies, potentially impacting fields like materials science and quantum computing.
