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Decoherence in Josephson Qubits from Junction Resonances

Published

Author(s)

Raymond W. Simmonds, Kristine Lang, Dustin A. Hite, David P. Pappas, John M. Martinis

Abstract

We present experimental data that demonstrates a large reduction in the coherence of a Josephson phase qubit from spurious microwave resonances. These resonances are believed to arise from resonant fluctuators in the tunnel junction that couple to the junction critical current. We present a model that connects the subgap current-voltage characteristics with the magnitude of the rsonances, as well as the magnitude and density of 1/f critical-current fluctuations. This mechanism is argued to be a dominant source of decoherence in all present Josephson qubits. Improvements in the coherence of Josephson qubits will require materials research directed at reducing critical current fluctuations in tunnel junctions.
Citation
Physical Review Letters
Volume
93
Issue
7

Keywords

1/f noise, decoherence, Josephson tunnel juntions, superconducting qubit
Created August 13, 2004, Updated February 19, 2017