Circuits demonstrating flags for multiple cases. In (a.) we show a general flag gadget for a general n-qubit unitary U. In (b.) we show that for a Clifford subcircuit (here shown surrounded by T-gates) this can be simplified to Pauli flags. In (c.) we show how Pauli flags can be used for a circuit with non-Clifford elements. Lastly in (d.) we show how multiple flags can be used to verify a single circuit.
We simulate four quantum error correcting codes under error models inspired by realistic noise sources in near-term ion trap quantum computers: T2 dephasing, gate overrotation, and crosstalk. We use this data to find preferred codes for given error parameters along with logical error biases and a pseudothreshold which compares the physical and logical gate failure rates for a CNOT gate. Using these results we conclude that Bacon–Shor-13 is the most promising near term candidate as long as the impact of crosstalk can be mitigated through other means. doi: 10.1088/2058-9565/ab7e80
Debroy, Dripto M; Li, Muyuan; Huang, Shilin; Brown, Kenneth R.
