Fault-tolerant magic state preparation with flag qubits

Christopher Chamberland; Andrew W. Cross

doi:10.22331/q-2019-05-20-143

Fault-tolerant magic state preparation with flag qubits

Christopher Chamberland^1,2 and Andrew W. Cross¹

¹IBM T. J. Watson Research Center, Yorktown Heights, NY, 10598, United States
²Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada

Published:	2019-05-20, volume 3, page 143
Eprint:	arXiv:1811.00566v2
Doi:	https://doi.org/10.22331/q-2019-05-20-143
Citation:	Quantum 3, 143 (2019).

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Abstract

Magic state distillation is one of the leading candidates for implementing universal fault-tolerant logical gates. However, the distillation circuits themselves are not fault-tolerant, so there is additional cost to first implement encoded Clifford gates with negligible error. In this paper we present a scheme to fault-tolerantly and directly prepare magic states using flag qubits. One of these schemes requires only three ancilla qubits, even with noisy Clifford gates. We compare the physical qubit and gate cost of our scheme to the magic state distillation protocol of Meier, Eastin, and Knill (MEK), which is efficient and uses a small stabilizer circuit. For low enough noise rates, we show that in some regimes the overhead can be improved by several orders of magnitude compared to the MEK scheme which uses Clifford operations encoded in the codes considered in this work.

► BibTeX data

@article{Chamberland2019faulttolerantmagic,
  doi = {10.22331/q-2019-05-20-143},
  url = {https://doi.org/10.22331/q-2019-05-20-143},
  title = {Fault-tolerant magic state preparation with flag qubits},
  author = {Chamberland, Christopher and Cross, Andrew W.},
  journal = {{Quantum}},
  issn = {2521-327X},
  publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},
  volume = {3},
  pages = {143},
  month = may,
  year = {2019}
}

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