Researchers demonstrate single-positron trap with motion and spin readout

Northwestern University researchers have demonstrated a way to trap a single positron, cool its circling motion to its lowest energy state, and read its motion and spin without disturbing either, Phys.org reported. The work appeared in Physical Review Letters. The team split an electron-positron pair inside a trap that uses electric and magnetic fields, leaving the positron confined. Microwaves moved it between distinct energy levels, while tiny shifts in its bobbing motion revealed its state. A captured positron can remain stored for several months. The demonstration could support more precise comparisons with the electron's magnetic properties. It does not itself establish the projected improvement in measurement accuracy.