[22p-A306-1~7] 11.5 Junction and circuit fabrication process, digital applications

▲ [22p-A306-4] Un-shunted SFQ Circuits Based on SFIS Ferromagnetic π Junctions

〇(PC)Feng Li¹, Lei Yuan¹, Yuto Takeshita¹, Masayuki Higashi¹, Masamitsu Tanaka¹, Akira Fujimaki¹ (1.Nagoya Univ.)

Keywords:SFQ, pi junction

In the previous work, we developed a HFQ circuits fabrication process based on SFIS Josephson junctions. Our SFIS junction has an intrinsic π phase shift, and the McCumber parameter b_c is around 1. In this work, we tried to only use un-shunted SFIS π junctions to fabricate simple SFQ circuits, in which SFQ JTL are connected to DC/SFQ and SFQ/DC converters. The minimum critical current I_c of π junction in an actual JTL is about 40 μA (~ 80% of the design value). The output voltage of SFQ/DC is about 10 μV since the characteristic voltage of π junction is about 30 μV. The error rate can be decreased, and bias margin can be increased with increasing of I_c of π junctions. The correct output waveform indicated the possibility of integration of SFQ and HFQ within the same fabrication process in the future.