Single-Proton Self-Excited Oscillator

A new apparatus and experiment adapts the techniques from the recent electron g-2 measurement to a single proton suspended within a Penning trap. The smaller proton charge/mass presents significant experimental challenges, but if we can overcome the substantially weaker signal/noise, the payoffs are considerable. Our primary goal is a direct observation of the single-proton spin-flip transition, which would open the way to a novel measurement of the proton magnetic moment, and allow a comparison of the proton and antiproton g-factors at precision likely to be a million times higher than achieved to date. As an initial milestone, we have achieved the first single-proton self-excited oscillator. This technique allows for a large-amplitude oscillation despite the inherent anharmonicity of our Penning trap, and promises stability approaching the level required for spin-flip detection.