A central goal in quantum information processing is the development of scalable quantum processors and quantum networks. Towards this end, solid-state “artificial atoms” such as colour centres in diamond are especially promising because they combine efficient optical interfaces, minutes of spin coherence, and potentially very-large-scale fabrication. Indeed, in the past 20 years of quantum engineering, it has been the ultimate vision to manufacture such artificial qubit systems at volumes comparable to integrated electronics. Although there has been remarkable progress in this very active area of research, fabrication and materials complications have thus far yielded just 2-3 emitters per photonic system[1–5]. In 2020, CUA researchers introduced a process for the large-scale manufacturing and integration of coherent artificial atoms with photonic circuits. As a proof of principle, they demonstrated a 128-channel defect-free array of waveguide-coupled diamond quantum emitters in an aluminium nitride photonics platform – the largest integrated artificial atom-photonics chip by nearly two orders of magnitude.
Figure: Left: illustration of a “diamond quantum microchiplet” integrated into a photonic integrated circuit. Right: Completed circuit component with 8 diamond channels from inside a circuit of 128 diamond memory channels.
Already, the integration of quantum emitters with integrated photonics at this scale brings solid-state spin technologies to the forefront of scalable quantum information processing hardware, given that another CUA breakthrough earlier in 2020 demonstrated the utility of memory-enhanced quantum communication.