Single flux-quantum memory cells

Detailed investigations have been carried out on two-junction interferometers. These devices have potential as memory elements. Information is stored as single-flux quanta (SFQ cells) in overlapping vortex modes and is destructively read out by switching from a vortex to the voltage state. The devices are fabricated with a lead alloy and the junction oxide is formed by rf oxidation. Most investigations have been done on devices with an area of about 1000 μm², but storage and reading have also been demonstrated in our smallest interferometers having a size of about 150 μm². Computer studies of cell properties, especially of the vortex transitions, have given good agreement with experiments. It has also been found that the cell behavior is little affected by loads such as would exist in an array environment.