Banishing quasiparticles from Josephson-junction qubits: why and how to do it

摘要: Current-biased Josephson junctions are prime candidates for the realization of quantum bits; however, a present limitation is their coherence time. In this paper it shown qualitatively that quasiparticles create decoherence. We can decrease number in by two methods - reducing creation rate with current shunts and increasing depletion normal-metal traps. Experimental data demonstrate both required to significantly reduce increase system's coherence. conclude these effective design Josephson-junction qubits must consider role quasiparticles.