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Junior Research Group Antimatter Spectroscopy

Welcome to the Antimatter Spectroscopy group embedded in the Laser Spectroscopy Division of Professor T.W. Hänsch, Max Planck Institute for Quantum Optics. This research group started in 2008 is led by Masaki Hori funded by the European Research Council. We carry out precise laser spectroscopy of atoms containing antiprotons, and develop new techniques to manipulate them. Since 2013 we are also attempting the first laser spectroscopy of an atom containing a pion made of two valence quarks.


According to the CPT theorem of particle physics, the “antiworld” – constructed by replacing all the matter particles in the universe with antimatter, inverting their spatial configuration, and reversing the flow of time - would be indistinguishable from our real matter world. One cornerstone of this symmetry is that atoms made of antimatter, i.e. “antiatoms”, are expected to resonate at exactly the same characteristic optical and microwave frequencies as their matter counterparts; particles and their antiparticles are assumed to have exactly the same mass, and equal and opposite electric charge and magnetic moment. Any deviation, however small, would indicate that this fundamental symmetry of nature is broken. We carry out sub-Doppler two-photon laser spectroscopy of antiprotonic helium atoms. This yields a comparison between the antiproton and proton masses and charges at a precision of 10 digits, and a measurement of the antiproton-to-electron mass ratio.


Our experiments are carried out at the Antiproton Decelerator of CERN, and the 590-MeV Ring Cyclotron of the Paul Scherrer Institute.