Decoherence in a superconducting flux qubit with a pi-junction

[摘要] We consider the use of a pi junction for flux qubits to realize degenerate quantum levels without external magnetic field. On the basis of the Caldeira-Leggett model, we derive an effective spin-Boson model and study decoherence of this type of qubits. We estimate the dephasing time by using parameters from recent experiments of superconductor-insulator-ferromagnet-superconductor junctions and show that high critical current and large subgap resistance are required for the pi junction to realize a long coherent time.

[发布日期] 2007-11-01

[关键词] PAIRING SYMMETRY;DYNAMICS