It is not known if humans can consciously see a single photon, the quantum of light – next to fundamental interest, knowledge of this would expand our understanding of visual signal processing in the brain with the smallest possible excitations. We recently have discovered1 that a novel quantum optical technique, quantum detector tomography, is ideally suited to answer this question. In this technique, faint classical light pulses of different intensity are sent to the eye, and computer analysis of a few thousand trials enables reconstruction of the N-photon responsivities. Firstly, our proposed experiment is much simpler than using true quantum light sources, making larger scale experiments with more humans possible - true “citizen science”. This has many advantages, e.g. it enables screening the human population in various dimensions resulting in important information for several stakeholders. Secondly, in contrast to all previously performed or proposed experiments, we can also determine the visual responsivity to photon number states with N photons – exciting from a photo-physical point of view. Finally, our involvement of cognitive neuroscientists from the start on makes this a truly interdisciplinary effort.
