Press Release  Max-Planck-Institut für Kernphysik Heidelberg

Priv. Doz. Dr. Sven Sturm has been awarded one of the prestigious ERC Advanced Grants in the latest round of calls for proposals by the European Research Council. His LSym project, which will be supported with about 2.5 million Euros, aims to understand the mystery of antimatter. This is already the third successful ERC Advanced Grant application at the MPIK.

Why does our universe consist almost exclusively of matter and not antimatter? In fact, our current theories of physics state that almost identical amounts of matter and antimatter should have been created in the Big Bang. However, this seems incompatible with the observation that our universe today contains almost no antimatter anymore.

The solution to this great mystery seems to be closely related to the fundamental properties of matter and antimatter. Our Standard Model, i.e., the summary of our present knowledge of fundamental interactions, involves a deep symmetry of matter and antimatter, the so-called CPT (charge-parity-time) symmetry. Specifically, this implies that the fundamental properties of matter and antimatter, such as mass, charge, and magnetic moments, must be identical (up to the sign). It is precisely this anti-matter symmetry that Dr. Sven Sturm wants to put to the test with his novel experiment “LSym (Lepton Symmetry Experiment)”, because if it were to be violated even very slightly, this would have a very decisive impact on our understanding of physics.

To this end, the researcher and his team will, for the first time, simultaneously store a single electron and its antimatter equivalent, the positron, in a novel Penning trap and measure them with an accuracy of 14 digits – orders of magnitude more precise than was previously possible. In the strong magnetic field of this trap, the spins of both particles spin (“precess”) very rapidly around the trap’s magnetic field axis, much like microscopic gyroscopes. If for example the positron was slightly lighter than the positron, this could be detected in the experiment as a tiny difference in the rotation speed. However, to achieve the targeted accuracy, the particles must be extremely cold, namely in the quantum mechanical ground state of motion. They then form a so-called Coulomb crystal. “Developing the new technologies needed to do this will be one of the first challenges for the project, but I am confident that we will succeed,” Sturm explains. Conditions at the Max Planck Institut für Kernphysik (MPIK) in Heidelberg are ideal for us, since we can rely on years of experience with high-precision experiments in ion traps, as well as have access to excellent on-site mechanical and electrical workshops. In addition, we work closely with the theory department of the institute to accurately predict quantum electrodynamic contributions needed for a measurement,” he adds.

If successful, LSym will provide the world’s most sensitive test of matter-antimatter symmetry for leptons, helping to solve the mystery of matter/antimatter asymmetry in our universe.

Priv. Doz. Dr. Sven Sturm is a group leader in the Blaum division at the Max Planck Institut für Kernphysik. He studied physics at the University of Heidelberg before receiving his PhD with honors from Johannes Gutenberg University Mainz in 2012. Since then, he has been working as a scientist at MPIK and is responsible for several groundbreaking results in the determination of, for example, electron or proton mass.


PD Dr. Sven Sturm
MPI für Kernphysik
Tel.: +49 6221 516-447