A sub-flux quantum generator includes an N-turn ring having a plurality of connected
turns about a common aperture. The width of each respective turn in the N-turn
ring exceeds the London penetration depth of a superconducting material used to
make the respective turn. The generator includes a switching device configured
to introduce a reversible localized break in the superconductivity of at least
one turn in the N-turn ring. The generator includes a magnetism device configured
to generate a magnetic field within the aperture of the N-turn ring. A method for
biasing a superconducting structure that encompasses all or a portion of an N-turn
ring. While a supercurrent is flowing through the N-turn ring, a quantized magnetic
flux is introduced into the aperture of the N-turn ring using a reversible localized
break in a turn in the ring. The quantized magnetic flux is trapped in the ring
by removal of the localized break. The trapped flux biases the superconducting structure.
