First Observation of Matter-Wave Diffraction in Positronium

Tue, 28 Apr 2026 21:51:00 +0200

Researchers from Tokyo University of Science have achieved a significant milestone in quantum physics by observing wave-like interference in a beam of positronium for the first time. Positronium, an exotic and short-lived atom consisting of an electron and its antimatter counterpart, the positron, orbiting a common center of mass, demonstrated clear diffraction patterns when passed through a thin sheet of graphene. The team, led by Professor Yasuyuki Nagashima along with Associate Professor Yugo Nagata and Dr. Riki Mikami, created a high-quality, coherent positronium beam with energies up to 3.3 keV using negatively charged positronium ions and a precisely timed laser pulse to detach an extra electron. This neutral beam was directed at a graphene sheet whose atomic spacing matched the de Broglie wavelength of the positronium atoms, resulting in observable first-order diffraction peaks. The experiment confirms that positronium behaves as a single unified quantum object rather than two i