Observation of a Relativistic, Bistable Hysteresis in the Cyclotron Motion of a Single Electron

A bistable hysteresis in the cyclotron motion of a single electron has been observed which is so pronounced that it provides the best signal-to-noise ratio ever observed with a single elementary particle in a trap. The effect is due entirely to the relativistic mass increase despite very low kinetic energies between 0.016 and 10 eV. During these experiments, a single electron was trapped continuously for more than 10 months in a Penning trap.