Abstract
In most theoretical descriptions of collective strong coupling of organic molecules to a cavity mode, the molecules are modeled as simple two-level systems. This picture fails to describe the rich structure provided by their internal rovibrational (nuclear) degrees of freedom. We investigate a first-principles model that fully takes into account both electronic and nuclear degrees of freedom, allowing an exploration of the phenomenon of strong coupling from an entirely new perspective. First, we demonstrate the limitations of applicability of the Born-Oppenheimer approximation in strongly coupled molecule-cavity structures. For the case of two molecules, we also show how dark states, which within the two-level picture are effectively decoupled from the cavity, are indeed affected by the formation of collective strong coupling. Finally, we discuss ground-state modifications in the ultra-strong coupling regime and show that some molecular observables are affected by the collective coupling strength, while others only depend on the single-molecule coupling constant.
Highlights
Strong coupling in quantum electrodynamics is a wellknown phenomenon that occurs when the coherent energy exchange between a light mode and quantum emitters is faster than the decay and decoherence of either constituent [1,2]
We focus on two model molecules, which approximately reproduce the absorption spectra of rhodamine 6G (R6G) and anthracene molecules that are commonly used in experimental realizations of strong coupling [12,15,17]
We present a simple model that offers a new perspective on strong coupling with organic molecules
Summary
Strong coupling in quantum electrodynamics is a wellknown phenomenon that occurs when the coherent energy exchange between a light mode and quantum emitters is faster than the decay and decoherence of either constituent [1,2]. We introduce a simple first-principles model that fully describes nuclear, electronic, and photonic degrees of freedom, but can be solved without approximations This allows us to provide a simple picture for understanding the induced modification of molecular structure. IV, we focus on the so-called ultrastrongcoupling regime, where the Rabi frequency reaches a significant fraction of the electronic transition energy, as achieved in experiments In this regime, not just excitedstate, and ground-state properties are modified—for example, the ground state acquires a photonic contribution [24,35]. We use atomic units unless stated otherwise (4πε0 1⁄4 ħ 1⁄4 me 1⁄4 e 1⁄4 1, with electron mass me and elementary charge e)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
