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Theory of Macroscopic Quantum Tunneling in High-T_c c-Axis Josephson Junctions by Yokoyama, Takehito; Kawabata, Shiro; Kato, Takeo; Tanaka, Yukio is a scholarly article available to read on EtoBox.

What is Theory of Macroscopic Quantum Tunneling in High-T_c c-Axis Josephson Junctions about?

We study macroscopic quantum tunneling (MQT) in c-axis twist Josephson junctions made of high-T_c superconductors in order to clarify the influence of the anisotropic order parameter symmetry (OPS) on MQT. The dependence of the MQT rate on the twist angle $\gamma$ about the c-axis is calculated by using the functional integral and the bounce method. Due to the d-wave OPS, the $\gamma$ dependence of standard deviation of the switching current distribution and the crossover temperature from thermal activation to MQT are found to be given by $\cos2\gamma$ and $\sqrt{\cos2\gamma}$, respectively. We also show that a dissipative effect resulting from the nodal quasiparticle excitation on MQT is negligibly small, which is consistent with recent MQT experiments using Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8 + \delta}$ intrinsic junctions. These results indicate that MQT in c-axis twist junctions becomes a useful experimental tool for testing the OPS of high-T_c materials at low temperature, and suggest high potential of such junctions for qubit applications.

Author

Yokoyama, Takehito; Kawabata, Shiro; Kato, Takeo; Tanaka, Yukio

Published

2007

Language

EN