Strong field vacuum birefringence in plane wave pulses

By combining an adiabatic approach based on a ‘locally monochromatic’ approximation with a local Hilbert transform, it is demonstrated how vacuum birefringence in the strong field regime can be calculated using a rate approach suitable for Monte Carlo simulation codes. Results for the flipping of the photon’s polarisation (helicity) are benchmarked with evaluation of exact expressions in a circularly (linearly) polarised plane wave of finite extent. For the circularly polarised case, the Heisenberg–Euler approach predicts a null result; an approximation similar to the ‘locally constant’ form is presented, which recovers the correct low-energy scaling. Example probabilities are given for typical experimental parameters.