Effects of disorder on polaritonic and dark states in a cavity using the disordered Tavis-Cummings model

Gera, T and Sebastian, KL (2022) Effects of disorder on polaritonic and dark states in a cavity using the disordered Tavis-Cummings model. In: Journal of Chemical Physics, 156 (19).

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Abstract

We consider molecules confined to a microcavity of dimensions such that an excitation of the molecule is nearly resonant with a cavity mode. The molecular excitation energies are assumed to be Gaussianly distributed with mean ϵa and variance σ. We find an asymptotically exact solution for large number density N. Conditions for the existence of the polaritonic states and expressions for their energies are obtained. Polaritonic states are found to be quite stable against disorder. Our results are verified by comparison with simulations. When ϵa is equal to energy of the cavity state ϵc, the Rabi splitting is found to increase by 2σ2N|Ṽ|, where Ṽ is the coupling of a molecular excitation to the cavity state. An analytic expression is found for the disorder-induced width of the polaritonic peak. Results for various densities of states and the absorption spectrum are presented. The dark states turn "gray"in the presence of disorder with their contribution to the absorption increasing with σ. Lifetimes of the cavity and molecular states are found to be important, and for sufficiently large Rabi splitting, the width of the polaritonic peaks is dominated by them. We also give analytical results for the case where the molecular levels follow a uniform distribution. We conclude that the study of the width of the polaritonic peaks as a function of the Rabi splitting can give information on the distribution of molecular energy levels. Finally, the effects of (a) orientational disorder and (b) spatial variation on the cavity field are presented.

Item Type:	Journal Article
Publication:	Journal of Chemical Physics
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright for this article belongs to the American Institute of Physics Inc.
Keywords:	Absorption spectroscopy; Excited states, Cavity mode; Condition; Dark state; Energy; Exact solution; Molecular excitations; Number density; Polaritonics; Rabi splitting; Tavis-Cummings models, Molecules, absorption spectroscopy; article; excitation; simulation
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	24 Jun 2022 10:18
Last Modified:	24 Jun 2022 10:18
URI:	https://eprints.iisc.ac.in/id/eprint/73634

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