Light-induced topological phase transition via nonlinear phononics in superconductor CsV₃Sb₅

The recent observations of exotic quantum phenomena in AV₃Sb₅ (A = K, Rb, Cs) kagome superconductors have attracted significant attention in materials physics. Here, we propose an innovative two-frequencies laser model for ultrafast control of transient structural distortions. Using first-principles density functional theory in conjunction with the perturbative regime of nonlinear phononics, we investigate the nonharmonic potential energy, the crystal lattice dynamics and the topological properties of CsV₃Sb₅. We find that driving two infrared-active phonons of different frequencies promotes the desired Raman phonon vibrations, in which the displacement of Sb atoms is closely related to superconductivity. We demonstrate that the dimensional crossover and the topological nontrivial to trivial state transition of superconductor CsV₃Sb₅ can be triggered by ultrafast optical control. This work can be applied to other layered quantum materials and provide guidance for experiments related to photoinduced topology and superconductivity.