Figure 4
The second and third gate (QD2 and QD3) in Fig. 2. The sequential interactions between three photons, A, C, and D (B, C, and D), and an electron spin 2 (3) in QD2 (QD3) are operated by the reflection operator \({\hat{\text{R}}}_{1}^{{{\text{Id}}}} \left( \omega \right)\) in Eq. 6, with a frequency of \(\omega - \omega_{c} = \kappa /2\). The prepared excess electron spin state in QD2 [QD3] is in the state \(\left| { +_{{\text{e}}} } \right\rangle_{2}\) (\(\left| { +_{{\text{e}}} } \right\rangle_{3}\)). This electron spin 1 (2) is then measured after the interactions, in accordance with the second [third] time table for switches, S1, S2, S3, and S4 (S5, S6, S7, and S8), in sequence.
