Josephson Currents in Superconducting Tunneling: The Effect of Microwaves and Other Observations

Tunneling crossings of low resistance (5 to 20 OMEGA with a crossing area of 1.5 x 10/sup -4/ cm/sup -2/) were fabricated. Each of these exhibited zero-voltage currents predicted by Josephson and attributed, in effect, to the tunneling of Cooper pairs. New effects are summarized from experiments on the Al/ Al2/sub 2//sub 3//Sn samples. (R.E.U.)