Propagation of photons in homogeneous magnetic fields: Index of refraction

Abstract

The index of refraction associated with the vacuum polarization induced by homogeneous magnetic fields is calculated for two cases: (i) high-energy photons traversing fields weak compared with the critical field, ${H}_{\mathrm{cr}}=\frac{{m}^{2}{c}^{3}}{e\ensuremath{\hbar}}\ensuremath{\cong}4.41\ifmmode\times\else\texttimes\fi{}{10}^{13}$ G; and (ii) low-energy photons in fields of arbitrary intensity. Some implications for the physical optics of intense magnetic fields are briefly discussed.