Empa researchers have experimentally recreated a basic theoretical mannequin from quantum physics, initially proposed by Nobel Prize winner Werner Heisenberg. The experiment was primarily based on “quantum Lego,” composed of tiny carbon molecules often known as nanographenes. This artificial bottom-up method allows versatile experimental research of quantum applied sciences, probably advancing the sphere sooner or later.
In 2024, Empa researchers and their collaborators efficiently realized a one-dimensional alternating Heisenberg mannequin utilizing an artificial materials. This theoretical quantum-physical mannequin, which has been in use for practically a century, describes a linear chain of spins—a type of quantum magnetism. The researchers, led by Roman Fasel, Head of Empa’s nanotech@surfaces lab, recreated this mannequin within the lab.
The alternating mannequin includes a sample of sturdy and weak couplings between spins, whereas the brand new mannequin has equally coupled spins. Regardless of this minor distinction, the properties of the fashions are considerably distinct. The homogeneous chain has no vitality distinction between the bottom and excited states, and the spins are extremely entangled with long-range correlations.
In distinction, the alternating chain varieties an vitality hole, with spins tending to kind sturdy pairwise connections, and correlations quickly reducing exponentially.
The researchers validated these theoretical predictions utilizing nanographene spin chains. Nanographenes, small items of the two-dimensional carbon materials graphene, have been used to create each fashions. By adjusting the form of those items, the researchers can modify their (quantum) bodily traits, aiming to develop a fabric platform for the experimental research of assorted quantum fashions and results, just like “quantum Lego.”
Transferring Quantum Applied sciences a (Tiny) Step Nearer to Sensible Functions
The 2 Heisenberg experiments display this methodology. For the alternating spin chain mannequin, the researchers used hourglass-shaped nanographene molecules known as Clar’s goblets, which consist of 11 carbon rings. For the homogeneous Heisenberg chain, they used Olympicene, a nanographene with 5 rings, named for its resemblance to the Olympic rings.
We’ve got now demonstrated for the second time that theoretical fashions of quantum physics might be realized with nanographenes, making their predictions experimentally testable.
Roman Fasel, Head, nanotech@surfaces Lab, Empa
The scientists plan to develop and research ferrimagnetic spin chains utilizing nanographenes. In these chains, the magnetic moments don’t totally cancel out however align antiparallel. Two-dimensional spin lattices are additionally of serious curiosity, as they exhibit a broader vary of phases than spin chains, equivalent to quantum spin liquids, unique vital phenomena, and topological states. That is significantly related for each primary analysis and sensible functions.
Reproducing quantum fashions from textbooks serves a sensible function past educational curiosity. It’s anticipated to result in developments in communication, processing energy, measuring applied sciences, and extra areas of expertise.
Nonetheless, analysis into sensible functions is difficult as a result of fragility of quantum states and the problem in understanding their results. Researchers at Empa goal to higher perceive these quantum results and allow the event of sensible quantum applied sciences utilizing their nanographene-based “quantum Lego.”
Journal Reference:
Zhao, C., et al. (2025) Spin excitations in nanographene-based antiferromagnetic spin-1/2 Heisenberg chains. Nature Supplies.doi.org/10.1038/s41563-025-02166-1
