From Single Atoms to Engineered “Super-Atoms”: Interfacing Photons and Atoms in Free Space

Figure 13

(a) Principle of the Rydberg blockade between two atoms separated by a distance . Two states and are coupled with Rabi frequency . When the two atoms are in state they interact strongly which leads to symmetrical energy shifts . When this shift becomes larger than , the laser is out of resonance with the transition coupling the singly and doubly excited states, and only one atom at a time can be transferred to the Rydberg state. (b) When the atoms are in the blockade regime, the state , described in the text is only coupled to the ground state with a strength while the state is not coupled by the laser to the states and . The atoms are therefore described by an effective two-level system. The figure is from [134].

(a)

(b)