Future heat transfer concerns in Josephson junction computers

Using the superconducting properties of Josephson junctions enable extremely high switching speeds unmatched in semiconducting electronics. Much research has been conducted in recent decades in order to produce high performance electronics based on Josephson junction logic. In addition to the high speeds attainable by this technology, also of significance is the very low heat dissipated by Josephson circuits. Josephson devices have made great strides in the last ten years with microprocessors reaching levels of integration as high as 10/sup 5/ junctions/cm/sup 2/. Dissipation in these devices is easily managed, but integrations reaching 10/sup 7/ must be considered if Josephson electronics are to compete with the complexity and functionality of semiconducting electronics. Coupling this level of integration with dissipations of 0.34 and 2.98 /spl mu/W/junction in low and high temperature cases respectively, produces large heat fluxes difficult to remove at cryogenic temperatures. While other technical difficulties currently overshadow heat transfer concerns, the future of Josephson electronics research will likely need to address them.