The effect of permanent dipole moment on the polar molecule cavity quantum electrodynamics

TL;DR

This paper develops a dressed-state perturbation theory beyond the rotating wave approximation to analyze how permanent dipole moments influence the energy spectrum and wave functions in polar molecule cavity QED, revealing significant shifts and dressed state couplings.

Contribution

It introduces an explicit analytical method to incorporate permanent dipole moments and counter-rotating terms in polar molecule cavity QED beyond RWA, enhancing understanding of energy shifts and dressed states.

Findings

PDM causes more dressed states to couple and larger energy shifts.

The energy shift is proportional to the square of the normalized PDM difference.

Giant dipole molecules exhibit a greater Bloch-Siegert shift.

Abstract

A dressed-state perturbation theory beyond the rotating waveapproxi-mation (RWA) is presented to investigate the interaction between a two level electronic transition of the polar molecules and a quantized cavity field. Analytical expressions can be explicitly derived for both the ground- and excited-state-energy spectrums and wave functions of the system, where the contribution of permanent dipole moments (PDM) and the counter-rotating wave term (CRT) can be shown separately. The validity of these explicit results is discussed by comparing with the direct numerical simulation. Comparing to CRT coupling, PDM results in the coupling of more dressed states and the energy shift proportional to the square of the normalized permanent dipole difference, and a greater Bloch-Siegert shift could be produced in giant dipole molecule cavity QED. In addition, our method could also be extended to the solution of two-level atom Rabi model Hamiltonian beyond the RWA.