2020/09/30 by Dripto M. Debroy, Kenneth R. Brown · 21 citations
Computer Science · Mathematics · Physics and Astronomy · #Algebra over a field #Algorithm #Computer engineering #Computer hardware #Computer science #Error detection and correction #Flag (linear algebra) #Gate count #Mathematics #Overhead (engineering) #Physics #Quantum #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum computer #Quantum mechanics #Qubit #Unitary state #quant-ph
paper · pdf · doi:10.1103/physreva.102.052409
published in Physical Review A 102(5) (American Physical Society) · 7 pages, 7 figures
openalex publication_date 2020/11/10 · arxiv created 2021/01/25 · arxiv updated 2021/01/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Flag verification techniques are useful in quantum error correction for detecting critical faults. Here we present an application of flag-verification techniques for improving postselected performance of near-term algorithms. We extend the definition of what constitutes a flag by creating error-detection gadgets based on known transformations of unitary operators. In the case of Clifford or near-Clifford circuits, these unitary operators can be chosen to be controlled Pauli gates, leading to gadgets which require only a small number of additional Clifford gates. We show that such flags can improve circuit fidelities by up to a factor of 2 after postselection, and demonstrate their effectiveness over error models featuring single-qubit depolarizing noise, crosstalk, and two-qubit coherent overrotation.