  Tremendous progress has been realized in quantum optics for engineering and
detecting the quantum properties of light. Today, photon pairs are routinely
created in entangled states. Entanglement is revealed using single-photon
detectors in which a single photon triggers an avalanche current. The resulting
signal is then processed and stored in a computer. Here, we propose an approach
to get rid of all the electronic devices between the photons and the
experimentalist i.e. to use the experimentalist's eye to detect entanglement.
We show in particular, that the micro entanglement that is produced by sending
a single photon into a beam-splitter can be detected with the eye using the
magnifying glass of a displacement in phase space. The feasibility study
convincingly demonstrates the possibility to realize the first experiment where
entanglement is observed with the eye.
