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Title: Optimization of a solid-state electron spin qubit using Gate Set Tomography

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, whereas 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.
 [1] ;  [2] ;  [3] ;  [3] ; ;  [3] ;  [4] ;  [5] ;  [4] ;  [4]
  1. Univ. of New South Wales, Sydney, NSW (Australia); QuTech & Kavli Institute of Nanoscience, CJ Delft (The Netherlands)
  2. Univ. of New South Wales, Sydney, NSW (Australia); FOM Institute AMOLF, Amsterdam (The Netherlands)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  4. Univ. of New South Wales, Sydney, NSW (Australia)
  5. Univ. of New South Wales, Sydney, NSW (Australia); Simon Fraser Univ., Burnaby, BC (Canada)
Publication Date:
Report Number(s):
Journal ID: ISSN 1367-2630; 640506
Grant/Contract Number:
Published Article
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 18; Journal Issue: 10; Journal ID: ISSN 1367-2630
IOP Publishing
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
97 MATHEMATICS AND COMPUTING; quantum computing; silicon; tomography
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1325155; OSTI ID: 1328808