“If an atom sends out a photon, the photon can go any direction. Our idea is that to get stronger interactions between single photons and single atoms, we want to reverse whatever the atom does. So here the illumination comes from all directions,” explains Steiner.
First, they focused the red laser through a strongly-focusing lens positioned in front of the atom. At the back, the laser again passed through a strongly-focusing lens to reach the atom. With the light coming at it from both sides, the atom scattered around 2 in every 5 photons – double what was seen with just one lens. The atom not only changed the photons’ direction, but also their spacing. This is evidence of an interaction between the atoms and photons that is ‘nonlinear’.
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