Quantum entanglement dynamics based on composite quantum collision model
Li Xiao-Ming, Chen Yong-Xu, Xia Yun-Jie †, Zhang Qi, Man Zhong-Xiao ‡
       

The sketch of collision model. (a) Pairwise collisions S1–S2, S2–SA, S1–SA occur between system qubits and auxiliary qubit SA, then they are correlated. (b) Auxiliary qubit SA collides with the first environment qubit R1, the dotted lines in the graph denote the correlation among S1, S2, and SA established after their collisions (i.e., after step (a)). (c) The collision between ancilla qubits R1 and R2, the dotted lines denote the correlation among S1, S2, SA, and R1 established after step (b). (d) The ancilla qubit R1 is traced out, then repeat the process (a)–(c).