Superconductor digital circuits for low-energy information networks

Abstract

Here, I describe a new trend in superconductor digital circuits, which are being developed for high-end devices used in low-energy information networks. Recently, high energy efficiency has even been required for SFQ(single flux quantum) circuits. Several new SFQ circuits have been proposed, and their power consumptions were reduced to about one-tenth that of the previous SFQ circuit. New cryogenic memories have also been proposed. These memories are based on superconductor-ferromagnetic material-superconductor trilayer Josephson junctions. Critical currents depend on the direction of magnetization in the ferromagnetic materials. The small size of a memory cell is the most attractive feature compared to previous SFQ-based memories.