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IBM Scientists Unveil First-Ever 'Half-Mobius' Molecule

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5 days 16 hours ago
BrianFagioli shares a report from NERDS.xyz: An international team of scientists has done something chemistry has never seen before. IBM, working alongside researchers from the University of Manchester, Oxford University, ETH Zurich, EPFL, and the University of Regensburg, has created and characterized a molecule whose electrons travel through its structure in a corkscrew-like pattern, fundamentally altering its chemical behavior. The findings were published today in Science. The molecule, known as C13Cl2, is the first experimental observation of what scientists call a half-Mobius electronic topology in a single molecule. To the researchers' knowledge, nothing like it has ever been synthesized, observed, or even formally predicted. And proving why it behaves the way it does required something equally extraordinary -- a quantum computer. The whole thing started at IBM, where the molecule was assembled atom by atom from a custom precursor synthesized at Oxford. Working under ultra-high vacuum at near-absolute-zero temperatures, researchers used precisely calibrated voltage pulses to remove individual atoms one at a time. The result is an electronic structure that undergoes a 90-degree twist with each circuit through the molecule, requiring four complete loops to return to its starting phase. That is a topological property that has no counterpart anywhere in chemistry's existing record. What makes it even more interesting to folks who follow materials science is that this topology can be switched. The molecule can move reversibly between clockwise-twisted, counterclockwise-twisted, and untwisted states. That means electronic topology is not just a curiosity to be stumbled upon in nature -- it can be deliberately engineered. That is a big deal. The quantum computing angle here is not just a supporting role. Electrons within C13Cl2 interact in deeply entangled ways, each influencing the others simultaneously. Modeling that requires tracking every possible configuration of those interactions at once -- something that causes computational demands to grow exponentially and can quickly overwhelm classical machines. A decade ago, researchers could exactly model 16 electrons classically. Today that number has crept to 18. Using IBM's quantum computer, the team was able to explore 32 electrons. Quantum computers can represent these systems directly rather than approximate them, because they operate according to the same quantum mechanical laws that govern electrons in molecules. In this case, that capability helped reveal helical molecular orbitals for electron attachment -- a fingerprint of the half-Mobius topology -- and exposed the mechanism behind the unusual structure: a helical pseudo-Jahn-Teller effect.

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