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. 2022 Jul 27;607(7920):687–691. doi: 10.1038/s41586-022-04891-y

Fig. 3. Schematics of the entanglement generation and atomic-state read-out schemes.

Fig. 3

a, An entangled atom–photon state is generated by the spontaneous emission of a photon subsequent to excitation of the atom. Decay from the state 52P3/2|F=0,mF=0 results in an entangled atom–photon state ΨAP=1/2(xH+xV)41, where |x1/2(|z+|z) (respectively |xi/2(|z|z)) and |H and |V denote parallel and orthogonal linear polarizations with respect to the optical table, respectively, with |V1/2(|L+|R) and |Hi/2(|L|R). b, The atomic qubit state is read out by a state-dependent ionization scheme. First, a certain superposition of the qubit state is excited to the 52P1/2 level depending on a respective polarization of the so-called read-out laser light (λ = 795 nm). The excited atom is ionized by a bright second laser applied simultaneously at λ = 473 nm. If the atom decays to the state 52S1/2|F=2 before it is ionized, it is excited to the state 52P3/2|F=3 with the third excitation laser at λ = 780 nm, which is ionized as well.