The realization of efficient and controlled interactions between photons and atomic media, or other quantum emitters, is a central goal within quantum optics. Photon loss — re-scattering of a photon into unwanted directions — represents a fundamental limitation to this aim. In typical atomic ensemble models, the atoms are assumed to emit independently and in an uncorrelated fashion. This paradigm however, is expected to break down for dense and ordered atomic arrays, where interference between emitted photons from different atoms becomes relevant, and can give rise to exciting phenomena such as the well known "super-" and "sub-radiance", with a strong modification of the atomic collective photon emission.

In this talk, we will provide a comprehensive treatment of this problem, and show through several examples that it is possible to take advantage of cooperative light-scattering in dense atomic ensembles. This includes a dramatic suppression of the error in single photon storage and retrieval [1, 2], the enhancement of excitation transport between two ring-shaped nano-structures [3], or an enhanced single-photon absorption by one of these rings when a single absorptive emitter is placed at its center [4].

[1] A. Asenjo-Garcia, M. Moreno-Cardoner, A. Albrecht, H. J. Kimble, and D. E. Chang, Phys. Rev. X 7, 031024 (2017).

[2] M. T. Manzoni, M. Moreno-Cardoner, A. Asenjo-Garcia, J. V. Porto, A. V. Gorshkov, and D. E. Chang, New Journal of Physics 20, 083048 (2018).

[3] M. Moreno-Cardoner, D. Plankensteiner, L. Ostermann, D. E. Chang, and H. Ritsch, Phys. Rev. A 100, 023806 (2019).

[4] M. Moreno-Cardoner, D. Holzinger, and H. Ritsch, arXiv:2010.09771 (2020).