Characterization of errors in a CNOT between surface code patches

Fuente: arXiv
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Autori principali: Domokos, Bálint, Márton, Áron, Asbóth, János K.
Natura: Preprint
Pubblicazione: 2024
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author Domokos, Bálint
Márton, Áron
Asbóth, János K.
author_facet Domokos, Bálint
Márton, Áron
Asbóth, János K.
contents As current experiments already realize small quantum circuits on error corrected qubits, it is important to fully understand the effect of physical errors on the logical error channels of these fault-tolerant circuits. Here, we investigate a lattice-surgery-based CNOT operation between two surface code patches under phenomenological error models. (i) For two-qubit logical Pauli measurements -- the elementary building block of the CNOT -- we optimize the number of stabilizer measurement rounds, usually taken equal to $d$, the size (code distance) of each patch. We find that the optimal number can be greater or smaller than $d$, depending on the rate of physical and readout errors, and the separation between the code patches. (ii) We fully characterize the two-qubit logical error channel of the lattice-surgery-based CNOT. We find a symmetry of the CNOT protocol, that results in a symmetry of the logical error channel. We also find that correlations between X and Z errors on the logical level are suppressed under minimum weight decoding.
format Preprint
id arxiv_https___arxiv_org_abs_2405_05337
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Characterization of errors in a CNOT between surface code patches
Domokos, Bálint
Márton, Áron
Asbóth, János K.
Quantum Physics
As current experiments already realize small quantum circuits on error corrected qubits, it is important to fully understand the effect of physical errors on the logical error channels of these fault-tolerant circuits. Here, we investigate a lattice-surgery-based CNOT operation between two surface code patches under phenomenological error models. (i) For two-qubit logical Pauli measurements -- the elementary building block of the CNOT -- we optimize the number of stabilizer measurement rounds, usually taken equal to $d$, the size (code distance) of each patch. We find that the optimal number can be greater or smaller than $d$, depending on the rate of physical and readout errors, and the separation between the code patches. (ii) We fully characterize the two-qubit logical error channel of the lattice-surgery-based CNOT. We find a symmetry of the CNOT protocol, that results in a symmetry of the logical error channel. We also find that correlations between X and Z errors on the logical level are suppressed under minimum weight decoding.
title Characterization of errors in a CNOT between surface code patches
topic Quantum Physics
url https://arxiv.org/abs/2405.05337