Entanglement is a concept at the heart of a physical theory, called quantum theory. It is a property of two or more systems that are described as a whole only. Entanglement has been used to teleport information between particles located kilometers apart, to generate random numbers and is envisioned as a key resource for secure communication. Despite these successes, opinions still diverge on whether entanglement can survive at any scale. On the one hand, there is nothing in quantum theory preventing entanglement to apply at any scale. On the other hand, we do not observe quantum effects in our daily experience. Recent results have shown that one of the main problem comes from the measurement: entanglement would apply at macroscopic scales but it takes measurements with an extreme precision to be revealed in macroscopic systems. This naturally raises the question on whether the human eye -- with its many imperfections -- can see entanglement. The objective of this project is to lay the theoretical groundwork that is needed to answer this question experimentally.

The methodology is made with three steps. The starting point is to establish a practical expression of the quantum observable modeling the human eye. The second step consists in studying various optical amplification methods to bring quantum light up to the domain where it can be seen by human eyes. The third step is to develop detection schemes to reveal the quantum nature of light beams with naked eye detectors. All experimental imperfections will be taken into account to provide detailed recipes allowing one to test experimentally our capability to see entanglement.

In the short term, our results should allow us to gain insight into the role of the eye in our classical perception of physical reality. In the medium and long term, we anticipate applications in ophthalmology for example for quantum-enabled sensing of vision deceases.