2006/08/31 by Shiro Kawabata, Satoshi Kashiwaya, Yasuhiro Asano +3
Materials Science · Physics and Astronomy · #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat.mes-hall #cond-mat.supr-con #quant-ph
paper · pdf · doi:10.1103/physrevb.74.180502
published as Phys. Rev. B 74 (2006) 180502(R) · 4 pages, 2 figures
openalex publication_date 2006/11/08 · arxiv created 2006/11/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We theoretically investigate the macroscopic quantum dynamics of a \ensuremathπ junction with a superconductor (S) and a multiferroic material or a ferromagnetic insulator (FI). By deriving the effective action from a microscopic Hamiltonian, a \ensuremathπ-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 \ensuremathπ junctions and show that the influence of the quasiparticle dissipation on MQT is negligibly small.