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Can a person see a single photon?

We need your help to find out!

Previous research has suggested that single-photon vision may be possible, but the question has never been directly tested. This study aims to characterize the lower limit of human vision using a true source of single photons developed in our quantum information lab.

Demonstrating single-photon vision is a first step towards investigating quantum effects directly through the visual system. Such research could shed some light on how strange quantum rules produce the familiar world around us. Future projects will include looking for a visual difference between photons in a quantum superposition and photons in a statistical mixture of states. The observer in such an experiment would be the equivalent of a Schrodinger cat (vial of poison not included!)

Participants in this study will complete at least one research session at the UIUC psychology department, lasting 2-2.5 hours. The participant will sit in a dark room, with his or her head stabilized in a chin rest. For each trial, a small number of photons will be presented, and the participant will respond to indicate which direction he or she thinks the photon(s) came from. A researcher will communicate with the participant via an intercom during the experiment. The experiment lasts about 1.5 hours, including dark adaptation time. To allow for initial setup and time for instructions and questions, participants should budget 2-2.5 hours total.

For this study to succeed, participants must give each trial their full attention. Motivated participants will experience a unique physics experiment and will help to make future research on visualizing quantum superpositions possible. If you are interested in participating in this first-of-its-kind study, please complete the interest questionnaire below.

Participants who wear contacts may wear them during the experiment. Participants who normally wear glasses should be able to focus on text 25 cm away without glasses. This corresponds to near-sightedness no more severe than approximately -3.0 dioptres. If you do not meet this criteria, you may still be able to participate, but please let us know about your vision in the form below. Far-sighted participants will likely not be eligible.

Participants must have no history of scotophobia or vulnerability to darkness-related conditions.

Participants must be able to understand spoken instructions in English, including instructions given via an intercom during the experiment.