  Using the infinite-volume photon propagator, we developed a method which
allows us to calculate electromagnetic corrections to stable hadron masses with
only exponentially suppressed finite-volume effects. The key idea is that the
infinite volume hadronic current-current correlation function with large time
separation between the two currents can be reconstructed by its value at modest
time separation, which can be evaluated in finite volume with only
exponentially suppressed errors. This approach can be extended to other
possible applications such as QED corrections to (semi-)leptonic decays and
some rare decays.
