DE2848579

In a film cryotron used e.g. for switching logic, in which two superconducting electrodes (4, 5) coupled by a univariately distributed Josephson junction (6) are associated with an insulated ground plane (2) and connected to supply lines (9, 10), the ground plane is provided with two holes (11, 12) opposite one of the electrodes (4), at least one superconducting control line (8) extending above the electrode (4). The holes (11, 12) are arranged so as to form the first screened portion (14) under the electrode (4), shaped as a strip extending along and adjacent to the Josephson junction (6), as well as a second screened portion (15) interposed between the holes (11, 12) and connecting the supply line (9) to the middle of the first screened portion (14), and a third screened portion consisting of two halves (18 and 19) which connect the ends of the first screened portion (14) to points (16, 17) of intersection of a control line (8) and the electrode (4). The width (w1) of the second screened portion (15) and of the third screened portion (18, 19) at the points of their connection to the first portion (14) is not in excess of the width (h) of the first screened portion (14).