Multiplexed single photons from deterministically positioned nanowire quantum dots

Abstract

Solid-state quantum emitters are excellent sources of on-demand indistinguishable or entangled photons and can host long-lived spin memories, crucial resources for photonic quantum-information applications. However, their scalability remains an outstanding challenge. Here, we present a scalable technique to multiplex streams of photons from multiple independent quantum dots, on chip, into a fiber network for use "off chip." Multiplexing is achieved by incorporating a multicore fiber into a confocal microscope and spatially matching the multiple foci, seven in this case, to quantum dots in an array of deterministically positioned nanowires. As a proof-of-principle demonstration, we perform parallel spectroscopy on the nanowire array to identify two nearly identical quantum dots at different positions, which are subsequently tuned into resonance with an external magnetic field. Multiplexing of background-free single photons from these two quantum dots is then achieved. Our approach, applicable to all types of quantum emitters, can readily be integrated into scalable photonic based quantum technologies.