Decoherence in a Josephson-junction qubit

被引：46

作者：

Berkley, AJ ^{[1
]}

Xu, H ^{[1
]}

Gubrud, MA ^{[1
]}

Ramos, RC ^{[1
]}

Anderson, JR ^{[1
]}

Lobb, CJ ^{[1
]}

Wellstood, FC ^{[1
]}

机构：

[1] Univ Maryland, Dept Phys, Ctr Superconduct Res, College Pk, MD 20742 USA

来源：

PHYSICAL REVIEW B | 2003年 / 68卷 / 06期

关键词：

D O I：

10.1103/PhysRevB.68.060502

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The zero-voltage state of a Josephson junction biased with constant current consists of a set of metastable quantum energy levels. We probe the spacings of these levels by using microwaves to induce transitions and thereby enhance the escape rate to the voltage state. The widths of the resonances give a measurement of the spectroscopic coherence time of the two metastable states involved in the transitions. We observe a decoherence time shorter than that expected from dissipation alone in resonantly isolated 20x5 mum(2) area Al/AlOx/Al junctions at 60 mK. The data are well fit by a model that includes the dephasing effects of both low-frequency current noise and the escape rate to the voltage state. We discuss implications for quantum computation using current-biased Josephson-junction qubits, including limits on the minimum number of levels needed in the well.

引用

页数：4

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