Unidirectional and collective emission of integrated quantum emitters

Madhura Ghosh Dastidar, Aprameyan Desikan, Gniewomir Sarbicki +1 more

Xiaoyu Yao, Fuli Li

We study the collective decay dynamics of two or three quantum emitters coupled to a one-dimensional chiral waveguide. We find that both the asymmetry of emission intensity and the propagation phases play crucial roles in determining radiation behavior. Under suitable parameters, we show that the multiple emitters exhibit tunable radiance in the two-emitter case, such as one emitter exhibits superradiance while the other exhibits subradiance. Furthermore in the three-emitter case, the emitter can experience successive changes of radiation states. Our results highlight how chiral and anisotropic waveguide properties can be used to engineer controllable quantum light-matter interactions, with potential applications implemented in unidirectional quantum devices, and help explore more complex multibody radiation effects in waveguide quantum electrodynamics platforms.

Uri Israeli, Shahar Levi, Sagi Ben-Avi +4 more

Quantum metasurfaces comprised of subwavelength atomic arrays emerged as a promising platform for enhanced atom-photon interaction. However, realizing such a system with solid-state emitters has been considered impractical due to strong inhomogeneous broadening, which was expected to suppress the photon-mediated interactions that underpin collective emission. Here we report the observation of collective emission from subwavelength arrays of silicon-vacancy centres in diamond -- solid-state emitters whose inhomogeneous broadening exceeds the natural linewidth by two orders of magnitude -- demonstrating that collective effects such as resonance shifts, modified decay rates and directional coherent emission survive this disorder. A crucial enabling element is the implantation of a high density of silicon ions at each array site. This creates so-called superatoms, local ensembles that probabilistically achieve frequency matching across the array and enhance the collective response. We support our observations with a theoretical analysis explaining the mechanisms that preserve the collective effects even in the presence of inhomogeneity. These observations have direct implications for the realization of subwavelength arrays in any solid-state system, paving the way for quantum-emitter metasurfaces that are naturally integrated into nanophotonic environments.

Mete Atatüre

Oliver Dudgeon

Carlos Barahona-Pascual, Hong Jiang, Alan C. Santos +1 more

Abstract This work introduces a theoretical framework to model the collective dynamics of quantum emitters in highly non-Markovian environments, interacting through the exchange of photons with significant retardations. The formalism consists on a set of coupled delay differential equations for the emitter’s raising/lowering operators σ i ± , supplemented by input–output relations that describe the field mediating the interactions. These equations capture the dynamics of both linear (bosonic) and nonlinear (two-level) emitter arrays. It is exact in some limits—e.g. bosonic emitters or generic systems with up to one collective excitation—and can be integrated to provide accurate results for larger numbers of photons. These equations support a study of collective spontaneous emission of emitter arrays in open waveguide-QED environments. This study uncovers an effect we term cascaded super- and sub-radiance, characterized by light-cone-limited propagation and increasingly correlated photon emission across distant emitters. The collective nature of this dynamics for two-level systems is evident both in the enhancement of collective emission rates, as well as in a superradiant burst with a faster than linear growth. While these effects should be observable in existing circuit QED devices or slight generalizations thereof, the formalism put forward in this work can be extended to model other systems such as network of quantum emitters or the generation of correlated photon states.