Exceptional solutions in two-mode quantum Rabi models

Understand

We study two models describing the interaction of a two-level system with two quantum field modes.

• The first one is equivalent to a dissipative two-state system with just two boson fields in the absence of tunneling.
• The second describes two orthogonal fields interacting with the corresponding orthogonal dipoles of a two-level system.
• We show that both models present a partial two-mode $SU(2)$ symmetry and that they can be solved in the exceptional case of resonant fields.