Superconducting optoelectronic hardware could be used to create large-scale and computationally powerful artificial spiking neural networks. The approach combines integrated photonic components that offer few-photon, light-speed communication with superconducting circuits that offer fast, energy-efficient computation. However, the monolithic integration of photonic and superconducting devices is needed to scale this technology. Here we report superconducting optoelectronic synapses that are created by monolithically integrating superconducting nanowire single-photon detectors with Josephson junctions. The circuits perform analogue weighting and the temporal leaky integration of single-photon presynaptic signals. Synaptic weighting is implemented in the electronic domain allowing binary, single-photon communication to be maintained. Records of recent synaptic activity are locally stored as current in superconducting loops, and dendritic and neuronal nonlinearities are implemented with a second stage of Josephson circuitry. This hardware offers synaptic time constants spanning four orders of magnitude (hundreds of nanoseconds to milliseconds). The synapses are responsive to presynaptic spike rates exceeding 10 MHz and consume approximately 33 aJ of dynamic power per synapse event before accounting for cooling. This demonstration also introduces new avenues for realizing large-scale single-photon detector arrays.
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The data that support the findings of this study are publicly available via Figshare at https://doi.org/10.6084/m9.figshare.21277845.
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We appreciate the recommendations on the read-out SQUID design from B. Mates, M. Durkin and J. Aumentado. We appreciate insights on the experimental characterization from M. Castellanos-Beltran and D. Rampini. This work was made possible by the institutional support from the National Institute of Standards and Technology (award no. 70NANB18H006; B.A.P.) and the effort to advance hardware for artificial intelligence and by the DARPA Invisible Headlights Program (HR0011149863 and HR0011151332; S.K. and J.M.S.).
The authors declare no competing interests.
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Khan, S., Primavera, B.A., Chiles, J. et al. Superconducting optoelectronic single-photon synapses. Nat Electron 5, 650–659 (2022). https://doi.org/10.1038/s41928-022-00840-9
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