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Title: Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography

Abstract

Quantum information processors promise fast algorithms for problems inaccessible to classical computers. But since qubits are noisy and error-prone, they will depend on fault-tolerant quantum error correction (FTQEC) to compute reliably. Quantum error correction can protect against general noise if—and only if—the error in each physical qubit operation is smaller than a certain threshold. The threshold for general errors is quantified by their diamond norm. Until now, qubits have been assessed primarily by randomized benchmarking, which reports a different error rate that is not sensitive to all errors, and cannot be compared directly to diamond norm thresholds. Finally, we use gate set tomography to completely characterize operations on a trapped-Yb +-ion qubit and demonstrate with greater than 95% confidence that they satisfy a rigorous threshold for FTQEC (diamond norm ≤6.7 × 10 -4).

Authors:
 [1];  [1];  [2];  [1];  [3];  [2];  [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Computing Research
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Maryland and National Institute of Standards and Technology, College Park, MD (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program; Intelligence Advanced Research Projects Activity (IARPA) (United States)
OSTI Identifier:
1323885
Report Number(s):
SAND-2016-4951J
Journal ID: ISSN 2041-1723; 640732
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING; atomic and molecular interactions with photons; quantum information; qubits

Citation Formats

Blume-Kohout, Robin, Gamble, John King, Nielsen, Erik, Rudinger, Kenneth, Mizrahi, Jonathan, Fortier, Kevin, and Maunz, Peter. Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography. United States: N. p., 2017. Web. doi:10.1038/ncomms14485.
Blume-Kohout, Robin, Gamble, John King, Nielsen, Erik, Rudinger, Kenneth, Mizrahi, Jonathan, Fortier, Kevin, & Maunz, Peter. Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography. United States. doi:10.1038/ncomms14485.
Blume-Kohout, Robin, Gamble, John King, Nielsen, Erik, Rudinger, Kenneth, Mizrahi, Jonathan, Fortier, Kevin, and Maunz, Peter. Wed . "Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography". United States. doi:10.1038/ncomms14485. https://www.osti.gov/servlets/purl/1323885.
@article{osti_1323885,
title = {Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography},
author = {Blume-Kohout, Robin and Gamble, John King and Nielsen, Erik and Rudinger, Kenneth and Mizrahi, Jonathan and Fortier, Kevin and Maunz, Peter},
abstractNote = {Quantum information processors promise fast algorithms for problems inaccessible to classical computers. But since qubits are noisy and error-prone, they will depend on fault-tolerant quantum error correction (FTQEC) to compute reliably. Quantum error correction can protect against general noise if—and only if—the error in each physical qubit operation is smaller than a certain threshold. The threshold for general errors is quantified by their diamond norm. Until now, qubits have been assessed primarily by randomized benchmarking, which reports a different error rate that is not sensitive to all errors, and cannot be compared directly to diamond norm thresholds. Finally, we use gate set tomography to completely characterize operations on a trapped-Yb+-ion qubit and demonstrate with greater than 95% confidence that they satisfy a rigorous threshold for FTQEC (diamond norm ≤6.7 × 10-4).},
doi = {10.1038/ncomms14485},
journal = {Nature Communications},
number = ,
volume = 8,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}

Journal Article:
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  • Here, state of the art qubit systems are reaching the gate fidelities required for scalable quantum computation architectures. Further improvements in the fidelity of quantum gates demands characterization and benchmarking protocols that are efficient, reliable and extremely accurate. Ideally, a benchmarking protocol should also provide information on how to rectify residual errors. Gate Set Tomography (GST) is one such protocol designed to give detailed characterization of as-built qubits. We implemented GST on a high-fidelity electron-spin qubit confined by a single 31P atom in 28Si. The results reveal systematic errors that a randomized benchmarking analysis could measure but not identify, whereasmore » GST indicated the need for improved calibration of the length of the control pulses. After introducing this modification, we measured a new benchmark average gate fidelity of 99.942(8)%, an improvement on the previous value of 99.90(2)%. Furthermore, GST revealed high levels of non-Markovian noise in the system, which will need to be understood and addressed when the qubit is used within a fault-tolerant quantum computation scheme.« less
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