It seems like we have good mathematical representation for light sources that emit many photons and for light sinks that receive many photons. However, how would we model a light source that emits a single photon? Would it even be necessary to model single photons since the effect would be negligible?

It seems like we have good mathematical representation for light sources that emit many photons and for light sinks that receive many photons. However, how would we model a light source that emits a single photon? Would it even be necessary to model single photons since the effect would be negligible?