SUPERCONDUCTIVE DEVICES

摘要

1485655 Superconductive devices INTERNATIONAL BUSINESS MACHINES CORP 24 Nov 1975 [31 Dec 1974] 48154/75 Heading H3X In a superconducting storage loop comprising at least one superconductor connected to two Josephson tunnelling junctions, the inductance of the loop is enhanced by forming at least a portion of the superconductor of such reduced thickness as to be less than the superconducting penetration depth. One such loop is shown in Fig. 2, and comprises lead or lead alloy superconductors 202, 203 forming Josephson junctions with tunnel barrier oxides 204, 205 and a niobium superconductor 201 thinner than the superconducting penetration depth. Insulation 206 such as silicon oxide is provided between superconductors 201 and 203. Optionally superconductor 203 may be reduced in thickness to less than the penetration depth where shown by a broken line. An external electrode is connected to conductor 201, Fig. 3 (not shown). A similar arrangement is shown in Fig. 4 and comprises superconductors 401, 402, 403, tunnel barrier oxides 405, and insulating layers 404, 406, 408, electrodes 403, 407 and three overlying mutually isolated control lines being also provided. As previously and in other embodiments a broken line 410 shows the extent by which superconductor 403 may be reduced to provide an additional inductance enhancement region thinner than the penetration depth. Figs. 6 and 7 show arrangements in which a loop is formed by two superconductors 201, 203 and two tunnelling barrier oxides 204, 205. In Fig. 6 the superconductor 201 is wholly of the required thinness, whereas in Fig. 7 the superconductor has a restricted region 700 only of less than the penetration depth. In a modification of Fig. 7, the restricted region 700 is formed by an anodized region 800 of conductor 201, Fig. 8. A superconductive - normal - metal - superconductor (S-N-S) structure is shown in Fig. 9 which comprises superconductors 201, 203, a layer of copper or other normal metal 900, and a thin layer of a superconducting metal 901 of thickness less than the penetration depth. Constructional details and a mathematical analysis are given.