Exceptional points treatment of cavity spectroscopies

The infrared response of a system of two vibrational modes in a cavity is calculated by an effective non-Hermitian Hamiltonian derived by employing the nonequilibrium Green's function (NEGF) formalism. Degeneracies of the Hamiltonian (exceptional points, EPs) widely employed in theoretical analysis of optical cavity spectroscopies are used in an approximate treatment and compared with the full NEGF. Qualitative limitations of the EP treatment are explained by examining the approximations employed in the calculation.

Automated summary

The infrared response of a two-mode vibrational system in a cavity is calculated using an effective non-Hermitian Hamiltonian derived from the nonequilibrium Green's function (NEGF) formalism. The degeneracies of the Hamiltonian (exceptional points, EPs) commonly used in the theoretical analysis of optical cavity spectroscopies are approximated and compared with the full NEGF. The qualitative limitations of the EP treatment are explained by examining the approximations used in the calculation.