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Title: High-Fidelity Single-Shot Readout for a Spin Qubit via an Enhanced Latching Mechanism

The readout of semiconductor spin qubits based on spin blockade is fast but suffers from a small charge signal. Previous work suggested large benefits from additional charge mapping processes; however, uncertainties remain about the underlying mechanisms and achievable fidelity. In this work, we study the single-shot fidelity and limiting mechanisms for two variations of an enhanced latching readout. We achieve average single-shot readout fidelities greater than 99.3% and 99.86% for the conventional and enhanced readout, respectively, the latter being the highest to date for spin blockade. The signal amplitude is enhanced to a full one-electron signal while preserving the readout speed. Furthermore, layout constraints are relaxed because the charge sensor signal is no longer dependent on being aligned with the conventional (2,0)–(1,1) charge dipole. Silicon donor-quantum-dot qubits are used for this study, for which the dipole insensitivity substantially relaxes donor placement requirements. One of the readout variations also benefits from a parametric lifetime enhancement by replacing the spin-relaxation process with a charge-metastable one. This provides opportunities to further increase the fidelity. The relaxation mechanisms in the different regimes are investigated. This work demonstrates a readout that is fast, has a one-electron signal, and results in higher fidelity. As a result,more » it further predicts that going beyond 99.9% fidelity in a few microseconds of measurement time is within reach.« less
 [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [3] ;  [3] ;  [3] ;  [4] ;  [5] ;  [3]
  1. Univ. de Sherbrooke, Sherbrooke, QC (Canada); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. McGill Univ., Montreal, QC (Canada)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  4. McGill Univ., Montreal, QC (Canada); Canadian Institute for Advanced Research, Toronto, ON (Canada); Univ. of Copenhagen, Copenhagen (Denmark)
  5. Univ. de Sherbrooke, Sherbrooke, QC (Canada); Canadian Institute for Advanced Research, Toronto, ON (Canada)
Publication Date:
Report Number(s):
SAND-2018-5964J; SAND-2017-2523J
Journal ID: ISSN 2160-3308; PRXHAE; 664051
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Physical Review. X
Additional Journal Information:
Journal Volume: 8; Journal Issue: 2; Journal ID: ISSN 2160-3308
American Physical Society
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1465797