Numerical approach for the evolution of spin-boson systems and its application to the Buck–Sukumar model

Xue-Ying Liu,Xue-Zao Ren,Chen Wang,Xian-Long Gao,Ke-Lin Wang

Figure 4. Top panel: difference between the jth ($j=1,2,3,\ldots $) excited-state energy and the ground-state energy (${\rm{\Delta }}E={E}_{j}-{E}_{0}$) in the RWA-void BS model with parameters ${\omega }_{f}={\omega }_{0}=1$ and ${g}_{-}={g}_{+}=2{\omega }_{f}$, calculated by the TEEE method truncated by P = 2000 (red line) and P = 3000 (blue line). Bottom panel: energy-level differences for P = 2000 (red line in bottom left) and P = 3000 (blue line in bottom right panel), respectively.