Measuring and Suppressing Quantum State Leakage in a Superconducting Qubit

Zijun Chen, Julian Kelly, Chris Quintana, R. Barends, B. Campbell, Yu Chen, B. Chiaro, A. Dunsworth, A. G. Fowler, E. Lucero, E. Jeffrey, A. Megrant, J. Mutus, M. Neeley, C. Neill, P. J. J. O’Malley, P. Roushan, D. Sank, A. Vainsencher, J. Wenner, T. C. White, A. N. Korotkov, and John M. Martinis
Phys. Rev. Lett. 116, 020501 – Published 13 January 2016
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Abstract

Leakage errors occur when a quantum system leaves the two-level qubit subspace. Reducing these errors is critically important for quantum error correction to be viable. To quantify leakage errors, we use randomized benchmarking in conjunction with measurement of the leakage population. We characterize single qubit gates in a superconducting qubit, and by refining our use of derivative reduction by adiabatic gate pulse shaping along with detuning of the pulses, we obtain gate errors consistently below 103 and leakage rates at the 105 level. With the control optimized, we find that a significant portion of the remaining leakage is due to incoherent heating of the qubit.

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  • Received 22 September 2015

DOI:https://doi.org/10.1103/PhysRevLett.116.020501

© 2016 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Zijun Chen1, Julian Kelly2, Chris Quintana1, R. Barends2, B. Campbell1, Yu Chen2, B. Chiaro1, A. Dunsworth1, A. G. Fowler2, E. Lucero2, E. Jeffrey2, A. Megrant1,3, J. Mutus2, M. Neeley2, C. Neill1, P. J. J. O’Malley1, P. Roushan2, D. Sank2, A. Vainsencher1, J. Wenner1, T. C. White1, A. N. Korotkov4, and John M. Martinis1,2,*

  • 1Department of Physics, University of California, Santa Barbara, California 93106-9530, USA
  • 2Google Inc., Santa Barbara, California 93117, USA
  • 3Department of Materials, University of California, Santa Barbara, California 93106, USA
  • 4Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA

  • *jmartinis@google.com

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Issue

Vol. 116, Iss. 2 — 15 January 2016

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