Quantum Dynamics Simulations of the 2D Spectroscopy for Exciton Polaritons

We develop an accurate and numerically efficient non-adiabatic path-integral approach to simulate the non- linear spectroscopy of exciton-polariton systems. This approach is based on the partial linearized density matrix (PLDM) approach to model the exciton dynamics with an explicit propagation of the phonon bath environment, combined with a stochastic Lindblad dynamics approach to model the cavity loss dynamics. Through simulating both linear and polariton 2-dimensional electronic spectra (2DES), we systematically investigate how light-matter coupling strength and cavity loss rate influence the optical response signal. Our results confirm the polaron decoupling effect, which is the reduced exciton-phonon coupling among polariton states due to the strong light-matter interactions. We further demonstrate that the polariton coherence time can be significantly prolonged compared to the electronic coherence outside the cavity.