Decoherence in Josephson qubits from dielectric loss

Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the tunnel junction can lead to short coherence times. We show that a variety of microwave and qubit measure...

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Bibliographic Details
Published inPhysical review letters Vol. 95; no. 21; p. 210503
Main Authors Martinis, John M, Cooper, K B, McDermott, R, Steffen, Matthias, Ansmann, Markus, Osborn, K D, Cicak, K, Oh, Seongshik, Pappas, D P, Simmonds, R W, Yu, Clare C
Format Journal Article
LanguageEnglish
Published United States 18.11.2005
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Summary:Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the tunnel junction can lead to short coherence times. We show that a variety of microwave and qubit measurements are well modeled by loss from resonant absorption of two-level defects. Our results demonstrate that this loss can be significantly reduced by using better dielectrics and fabricating junctions of small area . With a redesigned phase qubit employing low-loss dielectrics, the energy relaxation rate has been improved by a factor of 20, opening up the possibility of multiqubit gates and algorithms.
ISSN:0031-9007
DOI:10.1103/physrevlett.95.210503