Quantum Electrodynamic Corrections to Cyclotron States in a Penning Trap
We analyze the leading and higher-order quantum electrodynamic corrections to the energy levels for a single electron bound in a Penning trap, including the Bethe logarithm correction due to virtual excitations of the reference quantum cyclotron state. The effective coupling parameter alpha_c in the Penning trap is identified as the square root of the ratio of the cyclotron frequency, converted to an energy via multiplication by the Planck constant, to the electron rest mass energy. We find a large, state-independent, logarithmic one-loop self-energy correction of order alpha alpha_c^4 m c^2 ln(alpha_c^(-2)), where m is the electron rest mass and c is the speed of light. Furthermore, we find a state-independent "trapped" Bethe logarithm. We also obtain a state-dependent higher-order logarithmic self-energy correction of order alpha alpha_c^6 m c^2 ln(alpha_c^(-2)). In the high-energy part of the bound-state self energy, we need to consider terms with up to six magnetic interaction vertices inside the virtual photon loop.