[jIyajbe]

I read the paper; much of the electronics details got past me on the first read, but I think that the part most relevant to your question is their statement that it needs to be determined if the LED is a deterministic or a probabilistic single-photon light source.

[anfractuosity]

Yeah, that's a good point, I've just been looking at - https://en.wikipedia.org/wiki/Single-photon_source#Character... which talks a little about what deterministic means with respect to a single photon source.

It sounds like if it's probabilistic it could also generate multiple photons.