Demonstration of JMRAM arrays*

Superconducting circuits are under development as a solution to the demand for ultralow power computers. Logic technologies based in superconducting materials, such as Reciprocal Quantum Logic (RQL) require the development of a superconducting memory in order to build complex computers. Josephson Magnetic Random Access Memory (JMRAM) is a non-volatile memory utilizing the 0-π phase characteristics of pseudo-spin valve magnetic barrier Josephson junctions as a phase element within more traditional superconductor-insulator-superconductor (SIS) SQUIDs, which are used to read the phase state. Here, we present a demonstration of JMRAM from a single unit cell to 2x2 and 8x8 arrays. All arrays are built based on Ni/Cu/NiFe pseudo-spin valve junctions with 50-100 Oe switching field and high critical current of 0.5 mA. All array elements were functional with 100% switching between 0 and 1 state using external magnetic fields. This foundational demonstration serves as the basis for a more complete assessment of the progress of this technology toward practical implementation.