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Observation of the geometric spin Hall effect of light

You are standing in front of a two-storey building, talking to your friend who is overlooking you from a window at the ground floor. Then, you move a few meters to your right, parallel to the facade of the building. When you look again at your friend, from a slanted direction, he suddenly appears to be at the first floor! How is this possible? Well, this situation that looks (and, admittedly, is) impossible to realize with people, is instead feasible with light, by exploiting a property of the light that people do not possess: polarization. This strange effect is known as the geometric spin Hall effect of light (SHEL) and amounts to the apparent displacement of the bright spot of a circularly polarized beam of light (think of a laser pointer) when projected upon a tilted screen. Recently, we reported the first direct observation of this elusive phenomenon for a light beam transmitted across an oblique polarizer.

Phys. Rev. Lett. 112, 113902 (2014)

Contact: Andrea Aiello