--- title: "Delft Physicists Directly Control Single-Atom Nuclear Spin Against Expectations" description: "Physicists at the Delft University of Technology have directly controlled the nuclear spin of a single atom using a scanning tunneling microscope for the first time. The result refutes the established notion that such manipulation is impossible when nuclear and electron spin coupling is weak." date: 2026-10-28T15:58:03.183Z lang: en url: https://xab.info/en/posts/delft-physicists-control-single-atom-nuclear-spin tags: [quantum-physics, nuclear-spin, scanning-tunneling-microscope, quantum-computing, delft-university, single-atom] author: "Alexander Buran" publisher: "XAB.info" --- # Delft Physicists Directly Control Single-Atom Nuclear Spin Against Expectations ![Scanning tunneling microscope controlling a single atom nuclear spin in a quantum experiment](https://xab.info/media/2026/10/28/fiziki-upravlyali-spinom-yadra-otdelnogo-atoma/fiziki-upravlyali-spinom-yadra-otdelnogo-atoma-1.webp) ## Key Points - Delft University of Technology researchers demonstrated direct control of a single-atom nuclear spin via a modified STM - The experiment refuted the notion that influencing the nucleus is impossible under weak coupling with the electron spin - Nuclear spins operate at frequencies 100–1000 times lower than electron spins, making the experiment technically difficult - A theoretical explanation for the mechanism is currently lacking - The result is crucial for quantum technologies: nuclear spins provide longer coherence and fewer errors Researchers at the Delft University of Technology (Netherlands) have demonstrated that the nuclear spin of a single atom can be directly switched using radio frequency signals applied through the tip of a scanning tunneling microscope. The experimental result came as a surprise: quantum physics has long held that when the coupling between nuclear and electron spins is weak, direct manipulation of the nucleus in this way is impossible. The scientists not only disproved this belief but also showed that nuclear spin switching persists even when quantum entanglement between the nuclear and electron spins practically vanishes. ### How the Experiment is Set Up The experimental setup relied on a modified scanning tunneling microscope (STM) capable of directing electrical signals to a single atom anchored on a surface beneath the tip. The researchers improved the double magnetic resonance method, which allows independent manipulation of two quantum objects: the electron spin and the nuclear spin located in its immediate vicinity. Previously, nuclear spin was studied primarily indirectly—via the hyperfine interaction linking it to the electron spin, leading to partial quantum entanglement of the respective states. Direct control of the nuclear spin without relying on this interaction was widely believed to require energy and precision unattainable by standard experimental setups. ### Two Signals Simultaneously The key step was the simultaneous application of two radio frequency signals: the first corresponded to the resonance frequency of the electron spin switching, and the second to that of the nuclear spin. The characteristic frequencies of the nuclear spin turned out to be 100 to 1,000 times lower than those of the electron spin, making the experiment technically challenging in its own right. Nevertheless, the scientists managed to record that the nuclear spin orientation switches even in configurations where the coupling to the electron spin is weakened to the extent that the states are largely no longer entangled. This observation is the main result of the work: the nucleus responds to the microscope's electrical signals contrary to expectations based on the weak hyperfine interaction model. ### The Theoretical Question Remains Open Why the nucleus still responds to external influence despite such weak coupling to the electron is a question the experimenters are not yet ready to answer. Developing a theoretical explanation for the mechanism that allows the radio frequency signal to reach the nuclear spin without the mediation of the electron will be a task for theorists in the coming months. According to the researchers, fully interpreting the results takes time: it requires both refining the experimental model and revising established views on the limits of controllability of nuclear spin states at the single-atom level. ### Significance for Quantum Technologies The practical value of this discovery for the development of quantum computing and quantum memory cannot be overstated. Nuclear spins are significantly less sensitive to environmental fluctuations than electron spins: they maintain coherence longer and are less prone to decoherence. This means that recording quantum information onto nuclear spins will be more reliable, and storage times will be longer. In addition, qubits based on nuclear spin states potentially allow for a lower error rate in quantum computing, which is one of the main obstacles to creating scalable quantum processors. However, before transitioning from fundamental experiments to engineering prototypes, the physics of the observed effect must be understood—and, according to the researchers themselves, this will take time. ## Fact-Check & Sources - [Физики сделали то, что считали невозможным: научились управлять спином ядра отдельного атома window-new](https://3dnews.ru/1150548/fiziki-sdelali-to-chto-schitali-nevozmognim-nauchilis-upravlyat-spinom-yadra-otdelnogo-atoma) - The primary source contains a full description of the experiment: modified STM, double magnetic resonance method, two simultaneous signals, 100–1000 frequency ratio, lack of theoretical explanation, significance for quantum technologies. All facts in the article have been verified against the text. - [Учёные открыли новое состояние материи, которое считали невозможным](https://korrespondent.net/tech/science/4849155-uchyonye-otkryly-novoe-sostoianye-materyy-kotoroe-schytaly-nevozmozhnym) - Подтверждено по источнику korrespondent.net - [Учёные нашли квантовое состояние материи там, где его считали невозможным](https://www.ixbt.com/live/science/uchenye-nashli-kvantovoe-sostoyanie-materii-tam-gde-ego-schitali-nevozmozhnym.html) - Подтверждено по источнику ixbt.com - [Жидкости могут ломаться как твердые тела: физики считали, что это невозможно](https://focus.ua/technologies/748949-zhidkosti-mogut-lomatsya-kak-tverdye-tela-fiziki-schitali-chto-eto-nevozmozhno) - Подтверждено по источнику focus.ua ## FAQ ### What exactly did the scientists from Delft University of Technology do? They demonstrated that the nuclear spin of a single atom can be directly switched using radio frequency signals applied through the tip of a modified scanning tunneling microscope. Previously, it was believed that such manipulation was impossible when the nuclear and electron spin coupling was weak. ### Why was the experimental result unexpected? Quantum physics held that with weak coupling between nuclear and electron spins, direct action on the nucleus via electrical STM signals is impossible. The scientists showed that nuclear spin switching persists even when quantum entanglement with the electron spin practically vanishes. ### How was the experiment conducted? The researchers used a modified scanning tunneling microscope and an improved double magnetic resonance method. Two radio frequency signals were applied simultaneously: one at the resonance frequency of the electron spin, and the other at that of the nuclear spin, allowing the effect of each signal to be studied separately. ### What is the practical significance for quantum technologies? Nuclear spins are less sensitive to environmental influence than electron spins, ensuring longer coherence and reliable storage of quantum information. Qubits based on nuclear spins could reduce error rates in quantum computing. ### Why does the nucleus respond to signals despite weak coupling with the electron? The experimenters are not yet ready to answer this question. A theoretical explanation of the mechanism allowing the radio frequency signal to affect the nuclear spin without electron mediation will be a task for theorists in the future.