Towards Sympathetic Cooling of Single (Anti-)Protons

TL;DR

This paper develops methods for manipulating and detecting the motional and spin states of single protons or antiprotons, including sympathetic laser cooling and quantum logic spectroscopy, to improve precision measurements at CERN.

Contribution

It introduces techniques for sympathetic cooling and quantum logic spectroscopy of single (anti-)protons using a co-trapped Be+ ion in a Penning trap, advancing state control for fundamental physics tests.

Findings

Demonstrated controlled interaction of two Be+ ions in a double-well potential.

Achieved sympathetic cooling of one ion by another in a Penning trap.

Outlined implementation for antiproton g-factor measurement experiments.

Abstract

We present methods to manipulate and detect the motional state and the spin state of a single antiproton or proton which are currently under development within the BASE (Baryon Antibaryon Symmetry Experiment) collaboration. These methods include sympathetic laser cooling of a single (anti-)proton using a co-trapped atomic ion as well as quantum logic spectroscopy with the two particles and could be implemented within the collaboration for state preparation and state readout in the antiproton $g$-factor measurement experiment at CERN. In our project, these techniques shall be applied using a single $^9\text{Be}^+$ ion as the atomic ion in a Penning trap system at a magnetic field of 5 T. As an intermediate step, a controlled interaction of two beryllium ions in a double-well potential as well as sympathetic cooling of one ion by the other shall be demonstrated.