  Cooperative phenomena stemming from radiation-field-mediated coupling between
individual quantum emitters are presently attracting broad interest for on-chip
photonic quantum memories and long-range entanglement. Common to these
applications is the generation of electromagnetic modes over macroscopic
distances. Much research, however, is still needed before such systems can be
deployed in the form of practical devices, starting with the investigation of
alternate physical platforms. Quantum emitters in two-dimensional (2D) systems
provide an intriguing route because these materials can be adapted to
arbitrarily shaped substrates to form hybrid systems where emitters are
near-field-coupled to suitable optical modes. Here, we report a scalable
coupling method allowing color center ensembles in a van der Waals material -
hexagonal boron nitride - to couple to a delocalized high quality plasmonic
surface lattice resonance. This type of architecture is promising for photonic
applications, especially given the ability of the hexagonal boron nitride
emitters to operate as single-photon sources at room temperature.
