Y.V Kislinskii, G.A. Ovsyannikov, K.Y. Constantinyan, A.V. Shadrin, I.V. Borisenko, F.V. Komissinskiy, N.V. Klenov, V.K. Kornev
We present results of an analysis of hybrid s/d-junctions based on d-wave metal oxide and the s-wave superconductors for applications in quantum computing as quiet qubits. Parameters of multilayer Josephson s/d heterostructures are discussed for their transition temperature T* from thermal fluctuations to the macroscopic quantum tunneling process when a double-well potential could be experimentally realized in the dc superconducting quantum interferometer device. Experimental samples made from epitaxial thin films of YBa2Cu3O7 (d-wave superconductor), antiferromagnetic interlayer Ca1xSrxCuO2 and Au/Nb bilayer s-wave superconductor were deposited on NdGaO3 substrates. The I-V characteristics of hybrid Josephson junctions and the frequency selective detector response functions have been registered in mm wave frequency band in order to evaluate the amplitude and the sign of the 2-nd harmonic of superconducting current-phase relation. The estimated values of T* extrapolated from experimental results of dc measurements obtained at temperature T=4.2 K are discussed taking into account results of theoretical analysis.