Miniaturization of Josephson Junctions for Digital Superconducting Circuits

In this work, we briefly overview various options for Josephson junctions, which should be scalable down to nanometer range utilization in nanoscale digital superconducting technology. Such junctions possess high values of critical current, ${I}_{c}$, and normal state resistance, ${R}_{N}$. Another requirement is the reproducibility junction parameters across a wafer fabrication process. We argue that superconductor-normal metal-superconductor ($SN$-$N$-$NS$) ``variable thickness bridge'' geometry promising choice meet these requirements. Theoretical analysis $SN$-$N$-$NS$ performed case where distance between $S$ electrodes comparable coherence length $N$ material. The restriction on geometrical providing existence superconductivity derived current flowing through an order ${I}_{c}$. heating, as well available mechanisms heat removal, analyzed. obtained results show with (submillivolt) value ${I}_{c}{R}_{N}$ product can fabricated from broadly utilized combination materials like Nb/Cu using well-established technological processes. area scaled semiconductor transistors frame 40-nm