Tensor network simulation of polaron-polaritons in organic microcavities

Abstract

In the regime of strong coupling between molecular excitons and confined optical modes, the intra-molecular degrees of freedom are profoundly affected, leading to a reduced vibrational dressing of polaritons compared to bare electronically excited states. However, existing models only describe a single vibrational mode in each molecule, while actual molecules possess a large number of vibrational degrees of freedom and additionally interact with a continuous bath of phononic modes in the host medium in typical experiments. In this work, we investigate a small ensemble of molecules with an arbitrary number of vibrational degrees of freedom under strong coupling to a microcavity mode. We demonstrate that reduced vibrational dressing is still present in this case, and show that the influence of the phononic environment on most electronic and photonic observables in the lowest excited state can be predicted from just two collective parameters of the vibrational modes. Besides, we explore vibrational features that can be addressed exclusively by our extended model and could be experimentally tested. Our findings indicate that vibronic coupling is more efficiently suppressed for environments characterised by low-frequency (sub-Ohmic) modes.

A molecular movie of ultrafast singlet fission

“…The compelling match between simulation and experiment allowed us further to infer the crucial coupling modes of the system and record the underlying molecular movie for the singlet fission reaction in a complex molecular system of over 100 atoms. While we have focused exclusively on intramolecular singlet fission in this report, both the experimental and theoretical techniques can be equally well applied to a wide range of ultrafast photochemical processes, from charge transfer 1 and photoisomerisation 8 to polaritonic chemistry 76,77 . Together, these methods set up a powerful tool for describing and understanding reaction dynamics beyond the Born-Oppenheimer approximation, providing detailed insight into the reaction mechanism at conical intersections or avoided crossings in complex materials of practical interest.…”

Cumulant expansion for the treatment of light–matter interactions in arbitrary material structures

“…When this approximation is not applicable, more advanced numerical approaches such as tensor network calculations 47,48 or hierarchical equations of motion 49 can be employed, possibly after a chain transformation of the associated Hamiltonian 50 . Such approaches have been used to study static properties and dynamics in organic polaritons 51,52 . However, these are numerically demanding approaches that require significant computational resources.…”

Simulating Quantum Vibronic Dynamics at Finite Temperatures With Many Body Wave Functions at 0 K

“…Such trees tensor networks have recently been interfaced with ab initio methods to explore ultra-fast photophysics of real molecules and their pump-probe spectra (Schnedermann et al, 2019 ), but such efforts have so far been limited to zero temperature. Finally, the cooperative, antagonistic or sequential actions of different types of environments, i.e., light and vibrations (Wertnik et al, 2018 ), or even the creation of new excitations, such as polaritons (Memmi et al, 2017 ; Del Pino et al, 2018 ; Herrera and Owrutsky, 2020 ), could play a key role in sophisticated new materials for energy transduction, catalysis or regulation (feedback) of reactions, and T-TDEPODA-based tensor networks are currently being used to explore these developing areas.…”