The displacement operator $D(\alpha)$ has the property $D^{\dagger}(\alpha) \hat{a} D(\alpha) = \hat{a} + \alpha$. We obtain the Hamiltonian $\hat{H}'$ in the displaced frame from the transformation $\hat{H} \rightarrow D^{\dagger}(\alpha) \hat{H} D(\alpha) = \hat{H}'$. The evolution of the density operator is given by the von Neumann equation $$ \dot{\rho} = -i \left[ \hat{H}, \rho \right] + \kappa \left (2 \hat{a} \rho \hat{a}^{\dagger} - \hat{a}^{\dagger} \hat{a} \rho - \rho \hat{a}^{\dagger} \hat{a} \right) = \mathcal{L} \rho \tag{1} $$ with $\mathcal{L}$ the Liouvillian super operator. What is the transformation I have to apply to $\mathcal{L}$ to obtain it in the displaced frame? I would like to transform $(1)$ with a displacement transformation by $\alpha$ where $\alpha$ is obtained from mean-field equation therefore obtaining equations for the quantum fluctuations.