Exact solution of the two-mode quantum Rabi model

Qiong-Tao Xie

Figure 1. Energy spectrum of the two-mode QRM as a function of g/ω with ω = 1 and Δ/ω = 1. The square denotes the exact energy ${E}_{2,1}^{\mathrm{II}}$. The triangles denote the exact energies ${E}_{3,\kappa }^{\mathrm{II}}$ with $\kappa =1/2,1,3/2$. The circles denote the exact energies ${E}_{1,1}^{\mathrm{II}}$. The dots denote the exact energies ${E}_{1,\kappa }^{{\rm{I}}}$ with $\kappa =1/2,1$.