Auxiliary Field Quantum Monte Carlo for Electron-Photon Correlation

Abstract: Hybrid light-matter polaritonic states have shown great promise for altering already known and enabling novel chemical reactions and controlling photophysical phenomena. This field has recently become one of the most prominent and active areas of research that connects the communities of chemistry and quantum optics. The ab initio modeling of such polaritonic phenomena has led to updating commonly used electronic structure methods, such as Hartree-Fock, density functional, and coupled cluster theories, to explicitly include Bosonic degrees of freedom. In this work, we explore the quantum electrodynamic auxiliary field quantum Monte Carlo (QED-AFQMC) method to accurately capture the polaritonic ground state of representative quantum chemical benchmark systems to explore electron-photon correlations. We analyze these correlations across multiple examples and benchmark the QED-AFQMC results against other ab initio quantum electrodynamics methods, including QED-coupled cluster and QED-full configuration interaction, demonstrating the method's accuracy and its potential for scalable simulations of strongly coupled light-matter systems.