Tuning Y-Ba-Cu-O Focused Helium Ion beam Josephson Junctions for use as THz Mixers

We present Josephson junctions fabricated from high transition temperature superconductor YBa2Cu3O7 coupled to spiral THz antennas. The fabrication process involves creating a Josephson junction at the center of a superconducting bridge embedded into a THz spiral antenna using irradiation from a focused helium ion beam. For low doses of helium irradiation, the junctions have metallic barriers and ...