Evaluation of Fluxon Synapse Device Based on Superconducting Loops for Energy Efficient Neuromorphic Computing

Ashwani Kumar ^1* Uday Goteti ² Ertugrul Cubukcu ³ Robert C. Dynes ² Duygu Kuzum ^1*

• ¹ Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, United States
• ² Department of Physics, University of California, San Diego, La Jolla, United States
• ³ Deparment of Chemical and NanoEngineering, University of California, San Diego, La Jolla, United States

With Moore's law nearing its end due to the physical scaling limitations of CMOS technology, alternative computing approaches have gained considerable attention as ways to improve computing performance. Here, we evaluate performance prospects of a new approach based on disordered superconducting loops with Josephson-junctions for energy efficient neuromorphic computing. Synaptic weights can be stored as internal trapped fluxon states of three superconducting loops connected with multiple Josephson-junctions (JJ) and modulated by input signals applied in the form of discrete fluxons (quantized flux) in a controlled manner. The stable trapped fluxon state directs the incoming flux through different pathways with the flow statistics representing different synaptic weights. We explore implementation on matrix-vector-multiplication (MVM) operations using arrays of these fluxon synapse devices. We investigate the energy efficiency of online-learning and offline classification of MNIST dataset. Our results suggest the fluxon synapse array can provide ~100 reduction in energy consumption compared to other state-of-the-art synaptic devices. This work presents a proof-of-concept that will pave the way for development of high-speed and highly energy efficient neuromorphic computing systems based on superconducting materials.