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 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.
Martinis
John M
JM
Department of Physics, University of California, Santa Barbara, California 93106, USA.
Cooper
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McDermott
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Steffen
Matthias
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Ansmann
Markus
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Osborn
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Cicak
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Oh
Seongshik
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Pappas
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Simmonds
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Yu
Clare C
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