Josephson network as a~model for high-temperature superconductor and beyond: Macroscopic quantum coherence probed by microwave absorption

Abstract

Since the seminal experiment by Stankowski et al. [Phys. Rev. B 36, 7126 (1987)] on YBa${}_2$Cu${}_3$O${}_{7-x}$, Magnetically-Modulated Microwave Absorption (MMMA) has become an important technique for detecting the superconducting transition in inhomogeneous ceramic compounds. The rise of microwave absorption below $T_c$ is accompanied by several low-field anomalies, usually attributed to the weak links between superconducting grains showing the Josephson effect, or to the dynamics of Abrikosov-Josephson vortices. In this article, we briefly review selected theoretical models rationalizing MMMA spectra for high-temperature superconductors, focusing on the $3$-dimensional array of Josephson junctions with random parameters including the resistivity, capacity and inductance of each junction, showing characteristic absorption anomalies observed in the experiment. The implications for recently studied microwave absorption in Josephson junction qubits are also discussed.

RevTeX, 10 pages, 6 figures. Submitted to the special issue of Acta Phys. Pol. A, in commemoration of the 40th anniversary of the discovery of high-temperature superconductivity