The prospects for Lorentz- and CPT- violating quantum electrodynamics are explored in this work. The theory of Lorentz-violating spinor electrodynamics with operators of mass dimension up to six is developed using the framework of the Standard-Model Extension (SME). Both theoretical aspects and experimental observables are investigated for particles confined in a variety of electromagnetic systems.

A novel class of SME coefficients associated with interactions involving electromagnetic fields is discussed in construction of their Lagrangian density, and possible field redefinitions are addressed to remove experimental unobservables. Perturbation theory is applied to derive Lorentz- and CPT-violating shifts in the energy levels of a particle in the presence of electromagnetic fields. Additional nonminimal Lorentz-violating effects generated by operators controlled by these novel SME coefficients are also considered.

Specific experimental observables are established for both minimal and nonminimal Lorentz and CPT violation that are relevant to existing and forthcoming experiments. Properties of the observables including sidereal variation are analyzed to identify potential signals for Lorentz and CPT violation. Existing experimental measurements and potential sensitivities are used to extract new or improved bounds on numerous coefficients for Lorentz and CPT violation.