Self-Excitation and Feedback Cooling of an Isolated Proton

TL;DR

This paper demonstrates the first self-excited oscillator and feedback cooling of a single proton in a Penning trap, enabling high-precision measurements of proton properties and potential improvements in fundamental symmetry tests.

Contribution

It introduces the first implementation of a proton self-excited oscillator and feedback cooling, achieving high-precision frequency resolution in a Penning trap.

Findings

Resolved SEO frequency with high precision for proton spin flip detection

Achieved sideband cooling to a 14 mK theoretical limit

Observed frequency shifts larger than those from a spin flip

Abstract

The first one-proton self-excited oscillator (SEO) and one-proton feedback cooling are demonstrated. In a Penning trap with a large magnetic gradient, the SEO frequency is resolved to the high precision needed to detect a one-proton spin flip. This is after undamped magnetron motion is sideband-cooled to a 14 mK theoretical limit, and despite random frequency shifts (larger than those from a spin flip) that take place every time sideband cooling is applied in the gradient. The observations open a possible path towards a million-fold improved comparison of the antiproton and proton magnetic moments.