Engineering nonlinear collective optical dynamics In nano-arrays of quantum emitters

Helmut Ritsch

An array of closely spaced dipole-dipole coupled quantum emitters exhibits collective energy shifts as well as super-and sub-radiance with characteristic tailorable spatial radiation patterns.We identify a sub-wavelength sized ring of exactly 9 identical dipoles with an identical absorbing atom at the center as the most efficient configuration to deposit incoming photon energy to the center.

Simon Panyella Pedersen, Georg M. Bruun, Thomas Pohl

Subwavelength arrays of quantum emitters offer an efficient free-space approach to coherent light-matter interfacing, using ultracold atoms or two-dimensional solid-state quantum materials. The combination of collectively suppressed photon losses and emerging optical nonlinearities due to strong photon coupling to mesoscopic numbers of emitters holds promise for generating nonclassical light and engineering effective interactions between freely propagating photons. While most studies have thus far relied on numerical simulations, we describe here a diagrammatic Green's function approach that permits analytical investigations of nonlinear processes. We illustrate the method by deriving a simple expression for the scattering matrix that describes photon-photon interactions in an extended two-dimensional array of quantum emitters and reproduces the results of numerical simulations of coherently driven arrays. The approach yields intuitive insights into the nonlinear response of the system and offers a promising framework for the systematic development of a theory for interacting photons and many-body effects on collective radiance in two-dimensional arrays of quantum emitters. Published by the American Physical Society 2024

Ana Asenjo-Garcı́a

Igor Viktorovich Ryzhov, R. F. Malikov, A. V. Malyshev +1 more

We study theoretically the optical response of a monolayer comprizing regularly spaced quantum emitters with a doublet in the ground state (the so-called $Λ$-emitters). The emitters' self-action through the retarded dipole-dipole interaction provides a positive feedback, interplay of which with the intrinsic nonlinearity of an isolated emitter, leads to an exotic optical dynamics of the system and prominent effects, such as multistability, self-oscillations, and quasi-chaotic behavior. %The bifurcation diagram approach is used to classify different scenarios of the system's behavior. In a certain spectral domain, the monolayer operates as a bistable mirror. The optical response of the monolayer manifests high sensitivity to the doublet splitting and relaxation within the doublet, suggesting the latter to be the key parameters to tailor the monolayer optical response. These properties make such a system very promising for nanophotonic applications. We discuss the relevance of the predicted nonlinear effects for nano-sized all-optical devices.

Susanne F. Yelin