An international team of scientists from IBM, the University of Manchester, Oxford University, ETH Zurich, EPFL, and the University of Regensburg has created and characterised a molecule unlike any previously known, one whose electrons travel through its structure in a corkscrew-like pattern that fundamentally alters its chemical behaviour.
Published in Science, the work represents the first experimental observation of a half-Möbius electronic topology in a single molecule. The molecule, with the formula C₁₃Cl₂, was assembled atom-by-atom at IBM from a custom precursor. To the scientists’ knowledge, a molecule with such topology had never before been synthesised, observed, or even formally predicted.
Quantum Computing Validates the Discovery
Understanding the molecule’s behaviour at the electronic structure level required high-fidelity quantum computing simulation. Using an IBM quantum computer, the team found helical molecular orbitals for electron attachment, a fingerprint of the half-Möbius topology. The quantum simulations helped reveal the origin of the topology switching, an effect called the helical pseudo-Jahn-Teller effect.
Rather than compressing or approximating the exponential structure of the Hilbert space, quantum algorithms represent it directly in physical qubits. This capability is something classical computers cannot replicate at the molecular scale, making the quantum simulation essential to the discovery.
Two Fronts of Scientific Advance
Alessandro Curioni, IBM Fellow and Vice President for Europe and Africa at IBM Research Zurich, said: “First, we designed a molecule we thought could be created, then we built it, and then we validated it and its exotic properties with a quantum computer. This is a leap towards the dream laid out by renowned physicist Richard Feynman decades ago.”
The discovery advances science on two fronts. For chemistry, it demonstrates that electronic topology can be deliberately engineered, not merely found in nature. For quantum computing, it is a concrete demonstration of quantum simulation producing scientific insight that would otherwise have remained out of reach.
Researchers resolved the enantiomeric geometries using Atomic Force Microscopy (AFM) and mapped the helical orbital densities via Scanning Tunneling Microscopy (STM), confirming the quantum simulation predictions with experimental observation.
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