A scheme for two-photon lasing with two coupled flux qubits in circuit quantum electrodynamics*
Huang Wena),b), Zou Xu-Boa),b)†, Guo Guang-Cana),b)
       
The steady-state populations of the qubits states vary as the two-photon resonance detuning δ for κ = 0.08 g , γ = 0.05 g , J = 3.8 (2 π  GHz) and pumping rate (a) p = 0.2 g , (b) p = 0.5 g , (c) p = 0.8 g , (d) p = 1.2 g . The curves correspond to the populations of state |↑↑〉 (green dashed lines), |+〉 (red dot–dashed lines), and |↓↓〉 (blue solid lines) respectively.