Entangled photons amplified 100-fold
Nicolas Sangouard, a theoretical physicist at the University of Basel, together with two quantum physicists from Delft, Netherlands, and Innsbruck, Austria, has now shown in the scientific journal Optica how it may be possible to detect entangled photons directly. The basic idea of the experiment is that an entangled photon is generated and then amplified using a special technique, without destroying the quantum physical entanglement.
In the process, about 100 entangled photons are present, which, according to current knowledge, is the precise number needed to create the impression of light in humans. But although hundreds of photons reach the retina, there are also significant losses: only about seven actually reach one of the 120 million light-detecting rods of the retina. These photons then generate the nerve impulse that triggers the perception of light in the brain.
Two entangled states
In the experiment proposed by the three quantum physicists, entanglement is created by a single photon directed at a semi-transparent mirror. Sangouard explains what happens next: “The single photon is not transmitted or reflected by the mirror; instead — quantum physics is strange — the photon is simultaneously transmitted and reflected. Behind the mirror, the photon exists in a ‘transmitted’ and ‘reflected’ state, whereby these two states are entangled with another.”