Physics World

Seeing single photons

Rebecca M. Holmes

Published Dec 1, 2016• 4 citations

Abstract

The decades-old question of whether humans can see individual photons is on the brink of being answered thanks to advances in quantum optics. A positive result would let us use human observers as “detectors” to explore quantum effects such as entanglement, as Rebecca Holmes explains

DOI: 10.1088/2058-7058/29/12/47

Related papers

Human eye sees single photons

NatureJul 26, 20161 citation

Correspondence: Still no evidence for single photon detection by humans

Rebecca M. Holmes, Ranxiao Frances Wang, Paul G. Kwiat

The rod photoreceptors in the retina are known to be sensitive to single photons, but it has long been debated whether these single-photon signals propagate through the rest of the visual system and lead to perception. Recently, single-photon sources developed in the field of quantum optics have enabled direct tests of single-photon vision that were not possible with classical light sources. Using a heralded source based on spontaneous parametric downconversion to generate single photons which were sent to an observer at either an early or late time, Tinsley and Molodtsov et al. (2016) had observers judge when the photon was seen. Based on the above-chance accuracy in both a subset of high-confidence trials and in all post-selected trials, they claimed to show that humans can see single photons. However, we argue that this work suffers from three major issues: self-contradicting results, inappropriate statistical analyses, and a critical lack of statistical power. As a result, we cannot conclude that humans can see single photons based on the data of this study. We present a careful examination of the statistical analyses and the internal consistency of the data, which indicated that none of the key evidence holds.

arXiv:1707.09341Jul 28, 20171 citation

First for single photons

The ability of physicists to control single quantum particles, such as individual atoms and photons, has improved greatly in recent years and has allowed many “thought experiments” to be actually performed in the laboratory Experimental techniques have now advanced to the stage where it is possible to repeatedly observe a single photon in a cavity without destroying it (G Nogues et al. l999 Nature 400 239).

Physics WorldAug 1, 19990 citations

Testing the limits of human vision with quantum states of light: past, present, and future experiments

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.

arXiv:1806.08430Advanced Photon Counting TechniquesMay 14, 20184 citations

Yksittäisfotonilähteen käyttö yksittäisfotonivasteiden mittaamiseen verkkokalvon sauvasoluissa

Jussi Tiihonen

Our eyes are able to encode information from broad daylight down to only a handful of photons, but could we perceive a single photon? For decades the intrinsic Poisson variation of classical light sources has prevented definitive answers to this question. However, recent advances in quantum optics and non-classical light sources have reignited new interest in the question. Studies relying on sub-Poisson light sources have postulated that it is possible to produce sub-Poisson biological response distributions along the visual pathway, and even claimed that humans can perceive single photons. However, unambiguous experimental evidence for the prerequisite of sub-Poisson response statistics in the visual sciences has not been provided, that is, to which extent biological response statistics can differ between Poisson and sub-Poisson stimulation when taking retinal single-photon signal losses into account. In this thesis, we use a state-of-the-art sub-Poisson light source combined with the suction pipette technique to stimulate retinal rods in an axial geometry and measure their single-photon signal losses. We resolve the constraints set by the loss of single-photon signals to biological signal statistics from rods to human psychophysics. We show that due to the loss of single-photon signals it is impossible to distinguish the response distributions originating from Poisson or sub-Poisson light sources in the retina and at the level of perception on a biologically relevant timescale. Our results require fundamental re-evaluation of the previous results relying on sub-Poisson light stimulation in vision.

Dec 16, 20190 citations

Simultaneous, Full Characterization of a Single-Photon State

Tim O. Thomay, Sergey V. Polyakov, Olivier Gazzano +5 more

Advances in quantum optics and quantum information technologies increasingly require a way to fully understand the state of single indistinguishable photons. While previous approaches have needed two or more measurements, a new experiment demonstrates a way to characterize single-photon states with just one measurement.

Physical Review XNov 15, 201720 citations