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# Experimental characterization of fault-tolerant circuits in small-scale quantum processors

Cane, Rosie, Chandra, Daryus, Ng, Soon Xin and Hanzo, Lajos (2021) Experimental characterization of fault-tolerant circuits in small-scale quantum processors. IEEE Access, 9, 162996-163011.

Record type: Article

## Abstract

Experiments conducted on open-access cloud-based IBM Quantum devices are presented for characterizing their fault tolerance using $[4,2,2]$-encoded gate sequences. Up to 100 logical gates are activated in the "IBMQ Bogota" and "IBMQ Santiago" devices and we found that a [4,2,2] code's logical gate set may be deemed fault-tolerant for gate sequences larger than 10 gates. However, certain circuits did not satisfy the fault tolerance criterion. In some cases the encoded-gate sequences show a high error rate that is lower bounded at approximately 0.1, whereby the error inherent in these circuits cannot be mitigated by classical post-selection. A comparison of the experimental results to a simple error model reveal that the dominant gate errors cannot be readily represented by the popular Pauli error model. Finally, it is most accurate to assess the fault tolerance criterion when the circuits tested are restricted to those that give rise to an output state with a low dimension.

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Experimental Characterization of Fault-Tolerant Circuits in Small-Scale Quantum Processors - Accepted Manuscript
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Experimental_Characterization_of_Fault-Tolerant_Circuits_in_Small-Scale_Quantum_Processors - Version of Record

Accepted/In Press date: 5 December 2021
Published date: 6 December 2021
Keywords: Quantum error correction codes, encoded gates, fault tolerant circuit, ibm quantum, quantum circuits, quantum gates

## Identifiers

Local EPrints ID: 453228
URI: http://eprints.soton.ac.uk/id/eprint/453228
ISSN: 2169-3536
PURE UUID: e3c337ab-95bb-4e56-8bb9-f5648227e24e
ORCID for Daryus Chandra: orcid.org/0000-0003-2406-7229
ORCID for Soon Xin Ng: orcid.org/0000-0002-0930-7194
ORCID for Lajos Hanzo: orcid.org/0000-0002-2636-5214

## Catalogue record

Date deposited: 11 Jan 2022 17:40

## Contributors

Author: Rosie Cane
Author: Daryus Chandra
Author: Soon Xin Ng
Author: Lajos Hanzo