Superconducting optical system to scale up ‘brain-Inspired’ computing

NIST-developed networks have tiny light sources at each neuron to broadcast to connections.

Scientists have long looked to the brain as an inspiration for designing computing systems. Some researchers have recently gone even further by making computer hardware with a brainlike structure. These “neuromorphic chips” have already shown great promise, but they have used conventional digital electronics, limiting their complexity and speed.

Now, a team at the U.S. National Institute of Standards and Technology (NIST) has demonstrated a solution to these communication challenges that may someday allow artificial neural systems to operate 100,000 times faster than the human brain.

As described in a new Nature Electronics paper, NIST researchers have achieved for the first time a circuit that behaves much like a biological synapse yet uses just single photons to transmit and receive signals. Such a feat is possible using superconducting single-photon detectors.

The computation in the NIST circuit occurs where a single-photon detector meets a superconducting circuit element called a Josephson junction, essentially a sandwich of superconducting materials separated by a thin insulating film.

If the current through the sandwich exceeds a certain threshold value, the Josephson junction begins to produce small voltage pulses called fluxons. Upon detecting a photon, the single-photon detector pushes the Josephson junction over this threshold and fluxons are accumulated as current in a superconducting loop. Researchers can tune the amount of current added to the loop per photon by applying a bias to one of the junctions, known as the synaptic weight.