Diffraction is one of those textbook proofs that particles can act like waves. Electrons do it, neutrons do it, even whole helium atoms and molecules do it. What had never been shown, until now, was whether positronium – the short-lived pairing of an electron and its antimatter counterpart, the positron – does the same thing.
According to a paper published in Nature Communications, researchers sent a high-quality, energy-tunable positronium beam through a sheet of graphene and watched what came out the other side. Using time-of-flight selection paired with spatially resolved detection, they picked out a clear first-order diffraction peak, and its position matched exactly what matter-wave physics predicts for positronium. Not a rough approximation: a precise match.
That single peak matters more than it sounds. It gives, in the researchers’ own framing, direct and definitive evidence of quantum interference in positronium beams. Maybe the more striking part is what it rules out: the data confirm positronium behaves as a single quantum entity, not as two separate particles quietly interfering with each other. A small antimatter system, acting exactly the way de Broglie’s century-old wave theory said it should.
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