A collaboration between IBM Research Zurich, the University of Manchester, Oxford University, ETH Zurich, EPFL and the University of Regensburg has created a molecule that had never been synthesised, observed or even formally predicted: C13Cl2, a carbon ring bearing two chlorine atoms whose electrons adopt a half-Mobius topology. The molecule was assembled atom by atom at IBM from a custom precursor synthesised at Oxford, with individual atoms removed by calibrated voltage pulses under ultra-high vacuum at temperatures near absolute zero.
Scanning tunnelling and atomic force microscopy confirmed the structure, but proving the exotic electronic topology required computational muscle beyond classical reach. A quantum-centric supercomputing workflow on an IBM quantum computer simulated 32 electrons, beyond the roughly 16 to 18 that classical methods can treat exactly, revealing helical molecular orbitals that twist 90 degrees per circuit of the ring, the fingerprint of the half-Mobius state.
Published in Science, the work shows the electronic structure can be reversibly switched between twisted and untwisted states, evidence that electronic topology, a property normally dictated by nature, can be deliberately engineered. For molecular electronics and quantum materials research, the result opens a path to designing molecules whose function derives from topology rather than composition alone.