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Macroscopic quantum dynamics of pi-junctions with ferromagnetic insulators

Shiro Kawabata·Satoshi Kashiwaya·Yasuhiro Asano·Yukio Tanaka·Alexander A. Golubov
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Abstract

We theoretically investigate the macroscopic quantum dynamics of a pi junction with a superconductor (S) and a multiferroic material or a ferromagnetic insulator (FI). By deriving the effective action from a microscopic Hamiltonian, a pi-junction qubit (a S-FI-S superconducting quantum interference device ring) is proposed. In this qubit, a quantum two-level system is spontaneously generated and the effect of the quasiparticle dissipation is found to be very weak. These features make it possible to realize a quiet qubit with high coherency. We also investigate macroscopic quantum tunneling (MQT) in current-biased S-FI-S pi junctions and show that the influence of the quasiparticle dissipation on MQT is negligibly small.

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Shiro Kawabata, Satoshi Kashiwaya, Yasuhiro Asano, Yukio Tanaka, Alexander A. Golubov. 2006-11-09. Macroscopic quantum dynamics of pi-junctions with ferromagnetic insulators. https://doi.org/10.1103/physrevb.74.180502

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