  Research on laser-plasma interaction in the quantum-electrodynamic (QED)
regime has been greatly advanced by particle-in-cell & Monte-Carlo simulations
(PIC-MC). While these simulations are widely used, we find that noticeable
numerical error arises due to inappropriate implementation of the quantum
process accounting for hard photon emission and pair production in the PIC-MC
codes. The error stems from the low resolution of the QED table used to sample
photon energy, which is generated in the logarithmic scale and cannot resolve
high energy photons. We propose a new sampling method via Sigmoid function that
handles both the low energy and high energy end of the photon emission
spectrum. It guarantees the accuracy of PIC-MC algorithms for hard photon
radiation and other related processes in the strong-field QED regime.
