Decoherence in Josephson Qubits from Dielectric Loss

Published

November 16, 2005

Author(s)

John M. Martinis, Ken B. Cooper, Robert Mcdermott, Matthias Steffen, Markus Ansmann, Kevin Osborn, Katarina Cicak, Seongshik Oh, David P. Pappas, Raymond Simmonds, Clare Yu

Abstract

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 < 10 'm^2. 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 multi-qubit gates and algorithms.

Citation

Science

Volume

95

Pub Type

Journals

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Local Download

Keywords

Josephson junctions, quantum computing, superconductors

Citation

Martinis, J. , Cooper, K. , Mcdermott, R. , Steffen, M. , Ansmann, M. , Osborn, K. , Cicak, K. , Oh, S. , Pappas, D. , Simmonds, R. and Yu, C. (2005), Decoherence in Josephson Qubits from Dielectric Loss, Science, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=32029 (Accessed October 13, 2025)