Single flux quantum circuitry for quantized flux bias control

Abstract

A system comprises a superconducting quantizing inductor and superconducting control circuitry, which is coupled to the superconducting quantizing inductor to form a superconducting loop, and which is configured to selectively inject a quantized amount of positive or negative current into the superconducting loop to generate a quantized circulating current in the superconducting loop. The quantized circulating current comprises a time-varying or static circulating current. The superconducting control circuitry comprises first and second current generator circuits which comprise a first and second plurality of Josephson junctions, respectively, which are configured to inject quantized amounts of positive current and negative current into the superconducting loop in response to single flux quantum pulses. The first and second current generator circuits comprise respective first and second current distribution networks that are configured to distribute circulating current in the superconducting loop to the respective Josephson junctions without causing switching of the Josephson junctions.