Besides 1 V series arrays consisting of 8,192 junctions, we successfully fabricate 10 V series arrays consisting of about 70,000 SNS or SINIS junctions. The SNS or SINIS junctions consist of a multilayer of Superconductor / Normal metal / Superconductor or Superconductor / Insulator / Normal metal / Insulator / Superconductor, respectively, which we fabricate in the clean room center of PTB using thin film technology. The current-voltage characteristic of a 10 V series array consisting of 69,632 Josephson junctions clearly shows constant-voltage steps at the 10 V level under microwave irradiation at a frequency of 70 GHz.

Current-voltage characteristic and photo of a 10 V series array consisting of 69,632 Josephson junctions divided into segments following a binary sequence.