The eye as a detector of light: quantum fluctuations in vision.

Malvin Carl Teich, Paul R. Prucnal, Giovanni Vannucci +2 more

Jonito Aerts Arguëlles

Harish Parthasarathy

Rebecca M. Holmes, Michelle Victora, Ranxiao Frances Wang +1 more

The human eye contains millions of rod photoreceptor cells, and each one is a single-photon detector. Whether people can actually see a single photon|which requires the rod signal to propagate through the rest of the noisy visual system and be perceived in the brain|has been the subject of research for nearly 100 years. Early experiments hinted that people could see just a few photons, but classical light sources are poor tools for answering these questions. Single-photon sources have opened up a new area of vision research, providing the best evidence yet that humans can indeed see single photons, and could even be used to test quantum effects through the visual system. We discuss our program to study the lower limits of human vision with a heralded single-photon source based on spontaneous parametric downconversion, and present two proposed experiments to explore quantum effects through the visual system: testing the perception of superposition states, and using a human observer as a detector in a Bell test.

Ellen Hisdal

The information content in a thermal photon beam and in a single-mode maser beam is computed, taking account of the limited quantum efficiency of the detector, and extending the results to polychromatic radiation in the thermal case. Formulas for fluctuations of the measured quantity in a polychromatic thermal beam are found, both for a photoelectric and for a thermal type of detector. Numerical examples of the information content are given for three common thermal light sources, using the eye as detector. For all three sources the information is found to be of the order of 104–105 bits/sec for a sample of 1 cm2 at 1 m distance from the the eye.

M. H. Pirenne