Pure dephasing induced single-photon parametric down-conversion in an ultrastrong coupled plasmon-exciton system

TL;DR

This paper demonstrates that pure dephasing in an ultrastrongly coupled plasmon-exciton system enables single-photon parametric down-conversion, with pure dephasing supporting photon pair generation as the main relaxation pathway.

Contribution

It reveals a novel mechanism where pure dephasing facilitates photon pair generation in hybrid quantum systems, expanding understanding of dissipation pathways.

Findings

Pure dephasing breaks symmetry and enables forbidden optical transitions.

Fast pure dephasing supports photon pair generation.

Pure dephasing acts as the dominant energy relaxation pathway.

Abstract

In coupled quantum systems pure dephasing mechanisms acting on one constituent of the hybrid system break symmetry and enable optical transitions which are forbidden in the non-coupled system, i.e., the pure dephasing bath opens a cascaded dissipation pathway. Here we show that this mechanism enables single-photon induced parametric down-conversion in an ultrastrongly coupled plasmon-exciton system. Fast pure dephasing of the exciton is shown to support photon pair generation as the dominant energy relaxation pathway.