Human Eyes Detect Single Photons

Under tightly controlled conditions, a dark-adapted human eye can detect a single photon, although the experience does not resemble seeing an ordinary object. In 2016, Jonathan Tinsley and his colleagues conducted 30,767 trials with three men in their twenties using a quantum optical device. The participants detected individual photons at a rate slightly above 50 percent, a small but statistically significant improvement over chance. Researchers described the sensation as a fleeting feeling of having seen something, similar to a faint star appearing for one moment and disappearing the next.

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