The physics arXiv blog is reporting that scientists from the University of Geneva are claiming that eyes could one day be used in quantum entanglement experiments as detectors. A good example of quantum entanglement is Einstein-Podolsky-Rosen paradox (check out “Simple version” and “Measurements on an entangled state” sections in Wikipedia).
From physics arXiv:
“Quantum experiments with human eyes as detectors appear possible, based on a realistic model of the eye as a photon detector,” they say.
One problem is that human eyes cannot se single photons-a handful are needed to trigger a nerve impulse to the brain.
That might have scuppered the possibility of a Bell-type experiment were it not for some interesting work from Francesco De Martini and buddies at the University of Rome, pointing out how the quantum properties of a single particle can be transferred to an ensemble of particles.
That allows a single entangled photon, which a human eye cannot see, to be amplified into a number of entangled photons that can be seen. The eye can then be treated like any other detector.
From the abstract:
We show theoretically that the multi-photon states obtained by cloning single-photon qubits via stimulated emission can be distinguished with the naked human eye with high efficiency and fidelity. Focusing on the “micro-macro” situation realized in a recent experiment [F. De Martini, F. Sciarrino, and C. Vitelli, Phys. Rev. Lett. 100, 253601 (2008)], where one photon from an original entangled pair is detected directly, whereas the other one is greatly amplified, we show that performing a Bell experiment with human-eye detectors for the amplified photon appears realistic, even when losses are taken into account. The great robustness of these results under photon loss leads to an apparent paradox, which we resolve by noting that the Bell violation proves the existence of entanglement before the amplification process. However, we also prove that there is genuine micro-macro entanglement even for high loss.
More from physics arXiv blog…
Abstract: Quantum experiments with human eyes as detectors based on cloning via stimulated emission
(hat tip: Slashdot)