Second-order coherence properties of ultrafast polariton dynamics in plasmonic lattices

Abstract:The first-order coherence properties of strongly coupled systems supporting polariton lasing and Bose-Einstein condensation (BEC) have been thoroughly studied and show consistent results. In contrast, second-order coherence properties have been found to vary for different systems, and the second-order coherence function can deviate from the value of one, typical for atomic BEC, revealing super-Poissonian fluctuations even above the BEC/polariton lasing threshold. This calls for a deeper understanding of the emission statistics and dynamics in light-based condensates, especially in the non-equilibrium regime. Here we demonstrate a coherent state of polariton emission from a plasmonic lattice measured as the second-order coherence function value separately for $\mathrm{\Gamma}$- and non-$\mathrm{\Gamma}$-point radiation (ground state and high-energy tail). We observe a high degree of coherence with the value $g^{(2)}(\tau=0)-1<10^{-4}$. We also demonstrate the ultrafast ($>$1 THz) nature of the dynamics. The process can be interpreted as a BEC with ultrafast, sub-50-fs thermalization, but we also suggest an alternative explanation as superradiance in a system where the emitters have vibrational degrees of freedom.

Quantum Gases (cond-mat.quant-gas); Optics (physics.optics); Quantum Physics (quant-ph)

arXiv:2609.37142 [cond-mat.quant-gas]

(or arXiv:2609.37142v1 [cond-mat.quant-gas] for this version)

https://doi.org/10.48550/arXiv.2609.37142 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.

Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.

Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs.