dorsal/arxiv
View SchemaDecoherence in a Josephson junction qubit
| Authors | A. J. Berkley, H. Xu, M. A. Gubrud, R. C. Ramos, J. R. Anderson, C. J. Lobb, F. C. Wellstood |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0303001 |
| URL | https://arxiv.org/abs/quant-ph/0303001 |
| DOI | 10.1103/PhysRevB.68.060502 |
Abstract
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 microwave spectroscopy to enhance the escape rate to the voltage state. The widths of the resonances give a measurement of the coherence time of the two states involved in the transitions. We observe a decoherence time shorter than that expected from dissipation alone in resonantly isolated 20 um x 5 um Al/AlOx/Al junctions at 60 mK. The data is well fit by a model including dephasing effects of both low-frequency current noise and the escape rate to the continuum voltage states. We discuss implications for quantum computation using current-biased Josephson junction qubits, including the minimum number of levels needed in the well to obtain an acceptable error limit per gate.
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"abstract": "The zero-voltage state of a Josephson junction biased with constant current\nconsists of a set of metastable quantum energy levels. We probe the spacings of\nthese levels by using microwave spectroscopy to enhance the escape rate to the\nvoltage state. The widths of the resonances give a measurement of the coherence\ntime of the two states involved in the transitions. We observe a decoherence\ntime shorter than that expected from dissipation alone in resonantly isolated\n20 um x 5 um Al/AlOx/Al junctions at 60 mK. The data is well fit by a model\nincluding dephasing effects of both low-frequency current noise and the escape\nrate to the continuum voltage states. We discuss implications for quantum\ncomputation using current-biased Josephson junction qubits, including the\nminimum number of levels needed in the well to obtain an acceptable error limit\nper gate.",
"arxiv_id": "quant-ph/0303001",
"authors": [
"A. J. Berkley",
"H. Xu",
"M. A. Gubrud",
"R. C. Ramos",
"J. R. Anderson",
"C. J. Lobb",
"F. C. Wellstood"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevB.68.060502",
"title": "Decoherence in a Josephson junction qubit",
"url": "https://arxiv.org/abs/quant-ph/0303001"
},
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