The first antimatter quantum waves
First demonstration of quantum interference of antimatter. The work has appeared in a paper on Science Advances by a collaboration that includes the Positron Laboratory of the Politecnico di Milano L-NESS in Como, Italy (R. Ferragut), the Milan unit of the Istituto Nazionale di Fisica Nucleare (INFN, M. Giammarchi), the Università degli Studi di Milano in Italy (S. Sala) and the Albert Einstein Center for Fundamental Physics and Laboratory for High Energy Physics of the University of Bern, Switzerland (C. Pistillo).
This is the first version made with antimatter of the single particle interference experiment proposed by A. Einstein and R. Feynman and realized in 1976 by Merli, Missiroli and Pozzi, and in 1989 by Tonomura et al. In this experiment (according to Physics World “the most beautiful experiment in Physics”) the specifically quantum effect of single particle interference was demonstrated, which – according to Feynman – is the central “mystery” of Quantum Theory. The researchers of the Como-Milan-Bern group have for the first time demonstrated the same effect by using an antiparticle: the positron (anti-electron), postulated in 1928 by P.A.M. Dirac and discovered in 1932. Single anti-particle interferometry has been possible because of three crucial features: a single-particle positron beam, an interferometer working in Talbot-Lau mode and a nuclear emulsion detector.
This work has constituted the PhD Thesis of Simone Sala at the Università degli Studi di Milano and is a part of the QUPLAS (QUantum interferometry with Positrons and LASers. Spokesperson M. Giammarchi, INFN Milano) project for the study of positronium interference and gravitation. Future applications of this interferometric technique include the measurement of the gravitational acceleration of neutral antimatter systems exploiting the inertial sensing capabilities of Talbot-Lau interference.