Resolved-sideband cooling of a single <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Be</mml:mi><mml:none/><mml:mo>+</mml:mo><mml:mprescripts/><mml:none/><mml:mn>9</mml:mn></mml:mmultiscripts></mml:math> ion in a

Manipulating the motion of individual trapped ions at the single quantum level has become standard practice in radio-frequency ion traps, enabling sweeping advances in quantum information processing and precision metrology. The key step for motional-state engineering is ground-state cooling. Full motional control also bears great potential to explore another regime of sensitivities for fundamental physics tests in Penning traps. Here we demonstrate the key enabling step by implementing resolved-sideband cooling on the axial mode of a single <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mmultiscripts><a:mi>Be</a:mi><a:none/><a:mo>+</a:mo><a:mprescripts/><a:none/><a:mn>9</a:mn></a:mmultiscripts></a:math> ion in a 5 Tesla cryogenic Penning trap. The system has been developed for the implementation of high-precision antimatter experiments to test the fundamental symmetries of the standard model with the highest accuracy in the baryonic sector. We measure an axial phonon number of <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:msub><b:mover accent="true"><b:mi>n</b:mi><b:mo>¯</b:mo></b:mover><b:mi>z</b:mi></b:msub><b:mo>=</b:mo><b:mn>0.10</b:mn><b:mrow><b:mo>(</b:mo><b:mn>4</b:mn><b:mo>)</b:mo></b:mrow></b:mrow></b:math> after cooling and demonstrate that the axial heating rate in our system is compatible with the implementation of quantum logic spectroscopy of (anti-)protons. Published by the American Physical Society 2024