  The ultralight dark photon is one of intriguing dark matter candidates. The
interaction between the visible photon and dark photon is introduced by the
gauge kinetic mixing between the field strength tensors of the Abelian gauge
groups in the Standard Model and dark sector. The relativistic electrodynamics
was generalized to quantum electromagnetodynamics (QEMD) in the presence of
both electric and magnetic charges. The photon is described by two
four-potentials corresponding to two $U(1)$ gauge groups and satisfying
non-trivial commutation relations. In this work, we construct the low-energy
dark photon-photon interactions in the framework of QEMD and obtain new dark
photon-photon kinetic mixings. The consequent field equations and the new
Maxwell's equations are derived in this framework. We also investigate the
detection strategies of dark photon as light dark matter as well as the generic
kinetic mixings at haloscope experiments.
