Numerical and experimental evaluation of mutual inductances between two superconducting striplines coupled through a superconducting intermediate layer

We evaluated mutual inductances between two superconducting striplines coupled through a superconducting intermediate layer in Nb Josephson IC. In order to measure the mutual inductances we designed eight test circuits based on a superconducting quantum interference device (SQUID), which included intermediate layers of two different thicknesses and four different widths. The inductance extraction program FastHenry with superconductor support was used for numerical calculation. The experimental results agreed with the calculated results, both of which confirmed that a thicker and wider intermediate layer reduced the mutual coupling more efficiently.