title: Direct detection of a single photon by humans.
abstract: Despite investigations for over 70 years, the absolute limits of human vision have remained unclear. Rod cells respond to individual photons, yet whether a single-photon incident on the eye can be perceived by a human subject has remained a fundamental open question. Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds.
authors.affiliation: Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Research Platform Quantum Phenomena &Nanoscale Biological Systems (QuNaBioS), University of Vienna, Dr Bohr-Gasse 7, 1030 Vienna, Austria.
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Tinsley
authors.affiliation: Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Research Platform Quantum Phenomena &Nanoscale Biological Systems (QuNaBioS), University of Vienna, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, 1030 Vienna, Austria.
authors.forename: Maxim I
authors.initials: MI
authors.lastname: Molodtsov
authors.affiliation: Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Research Platform Quantum Phenomena &Nanoscale Biological Systems (QuNaBioS), University of Vienna, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, 1030 Vienna, Austria.
authors.forename: Robert
authors.initials: R
authors.lastname: Prevedel
authors.affiliation: Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.
authors.forename: David
authors.identifier: 0000-0002-0084-1622
authors.initials: D
authors.lastname: Wartmann
authors.affiliation: Research Platform Quantum Phenomena &Nanoscale Biological Systems (QuNaBioS), University of Vienna, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Faculty of Physics, VCQ, University of Vienna, Boltzmanngasse 5, 1090 Vienna Austria.
authors.forename: Jofre
authors.initials: J
authors.lastname: Espigulé-Pons
authors.affiliation: Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.
authors.forename: Mattias
authors.initials: M
authors.lastname: Lauwers
authors.affiliation: Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Research Platform Quantum Phenomena &Nanoscale Biological Systems (QuNaBioS), University of Vienna, Dr Bohr-Gasse 7, 1030 Vienna, Austria.|Max F. Perutz Laboratories, University of Vienna, Dr Bohr-Gasse 9, 1030 Vienna, Austria.|Laboratory of Neurotechnology and Biophysics, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.
authors.forename: Alipasha
authors.initials: A
authors.lastname: Vaziri
mesh_terms: D006801:Humans; D008027:Light; D017785:Photons; D011336:Probability; D011789:Quantum Theory; D013997:Time Factors; D014796:Visual Perception