FRAM1HA02
GSI, Darmstadt, Germany
Precise experiments on cooled individual particles in Penning traps have opened opportunities for fundamental tests of physical theories. The determination of the magnetic moment of the electron bound in highly charged ions is a sensitive test of the theory of bound-state quantum electrodynamics in the strong-field regime. The observation of spin flips with a single trapped proton has paved the way for a comparison of the proton and antiproton magnetic moments as a test of CPT invariance. At the same time, such precision experiments make it possible to determine fundamental constants, like the electron mass, the fine-structure constant alpha, and the proton magnetic moment. The cooling methods employed in precision trap experiments comprise resistive cooling, electronic feedback cooling to sub-K temperatures, sympathetic cooling to mK temperatures by laser-cooled ions, and electron cooling.
*S. Sturm et al., Phys. Rev. Lett. 107, 023002 (2011).
**A. Wagner et al., Phys. Rev. Lett. 110, 033003 (2013).
