The objects in the quantum world were long believed to be impossible to detect with the naked eye. However, a recent study has discovered that humans are capable of sensing the flashes of light from a photon. The study was led by Alipasha Vaziri, a physicist at the Rockefeller University in New York City.
Previously, it was believed that rod cells in the eyes of frogs fired in response to single photons. However, it was unclear whether the firing of one rod cell would trigger a signal that would be carried all the way to the brain. There were also doubts as to whether humans were capable of consciously sensing such a signal if it did reach their brains.
Thanks to Vaziri’s experiments, we now know that people can detect light emitting from a single photon. In fact, the scientist himself participated in the experiment and was stunned by the results. “The most amazing thing is that it’s not like seeing light. It’s almost a feeling, at the threshold of imagination,” he said to Nature.
For the experiment, Vaziri kept three people in total darkness for about 40 minutes. They then stared into an optical system and pushed a button. Two sounds, separated by a second, would emanate. One of the sounds would be accompanied by the emission of a photon.
The volunteers then had to state the occasions on which a photon was emitted. They were also required to rate their confidence about the sighting on a scale from 1 to 3. In total, the volunteers sat through over 2,400 trials. The high volume of testing involved in the experiments provided enough statistical data to conclude that human beings can detect photons.
Some scientists are not convinced by Vaziri’s findings since only three individuals have been tested. However, they agree that his method provides a solid way to settle the debate once and for all. The only thing that needs to be done is to run the experiment with a larger group of volunteers.
The ability of humans to detect photons also raises the possibility of more accurate biometrics based on the laws of quantum mechanics. Considering that quantum cryptography essentially promises to be the ultimate form of security, Vaziri’s discovery could soon find its way into the creation of unhackable biometric recognition systems.
In fact, Michail Loulakis and his research team at the National Technical University of Athens in Greece are already working on exploiting quantum mechanics to identify people.
At a basic level, the environment will determine the number of photons that arrive at a person’s retina and the path they take. Optical losses involved in the passage of light through the pupil, lens, cornea, vitreous humor, etc. need to be considered. Physicists group these factors into a single parameter called the alpha so that they can accurately measure the probability of detection.
The way alpha changes (alpha map) will depend on the unique patterns of blood vessels, nerves, and light-sensitive cells in a person’s eye. As such, the alpha map becomes an excellent biometric signature. However, there are a few problems the team needs to solve first.
“One important question is how to accurately measure anybody’s alpha map in the first place. There is no clear answer to that. Another problem is how alpha varies over time. Everybody’s eyesight deteriorates as they get older, which suggests that an alpha map would have an expiration date of uncertain length,” according to MIT Technology Review.
Despite such challenges, interest in using photon detection to develop quantum biometrics remains pretty high.