Breakeven demonstration of quantum low-density parity-check codes
Abstract
High-rate quantum low-density parity-check (qLDPC) codes are a leading candidate for fault-tolerant quantum computing. They feature higher encoding rates than planar alternatives such as the surface code, but their implementation often entails significant hardware hurdles like the need for long-range couplers. We leverage the flexibility of a trapped-ion quantum computer to demonstrate nine quantum error-correcting codes with starkly different qubit connectivity requirements on a single device without any hardware reconfiguration. These experiments span three families of quantum error-correcting codes: qLDPC codes, topological codes, and concatenated codes. With a qLDPC code encoding 4 logical qubits into 18 physical qubits, we achieve a logical error rate up to 9× better than a previous demonstration of a similar code on superconducting solid-state qubits. Moreover, our implementation exhibits breakeven performance, with some instances achieving qubit lifetimes comparable to or slightly exceeding that of our trapped-ion qubits. We use a novel implementation of the optical-metastable-ground (OMG) architecture for addressable mid-circuit measurement and reset, which enables us to perform these experiments without any ion transport or dedicated coolant ions, requirements that typically consume a large fraction of the runtime or ion count of trapped-ion quantum computers.
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BibTeX
@misc{tham2026breakeven,
title = {{Breakeven demonstration of quantum low-density parity-check codes}},
author = {Edwin Tham and Michael L. Goldman and Shantanu Debnath and Ashay N. Patel and Jyothi Saraladevi and Jason Nguyen and Erik Nielsen and Neal Pisenti and Kenneth Wright and John Gamble and Nicolas Delfosse},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.06455},
eprint = {2606.06455},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.06455},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Breakeven demonstration of quantum low-density parity-check codes
AU - Edwin Tham
AU - Michael L. Goldman
AU - Shantanu Debnath
AU - Ashay N. Patel
AU - Jyothi Saraladevi
AU - Jason Nguyen
AU - Erik Nielsen
AU - Neal Pisenti
AU - Kenneth Wright
AU - John Gamble
AU - Nicolas Delfosse
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2606.06455
UR - https://arxiv.org/abs/2606.06455
AB - High-rate quantum low-density parity-check (qLDPC) codes are a leading candidate for fault-tolerant quantum computing. They feature higher encoding rates than planar alternatives such as the surface code, but their implementation often entails significant hardware hurdles like the need for long-range couplers. We leverage the flexibility of a trapped-ion quantum computer to demonstrate nine quantum error-correcting codes with starkly different qubit connectivity requirements on a single device without any hardware reconfiguration. These experiments span three families of quantum error-correcting codes: qLDPC codes, topological codes, and concatenated codes. With a qLDPC code encoding 4 logical qubits into 18 physical qubits, we achieve a logical error rate up to 9× better than a previous demonstration of a similar code on superconducting solid-state qubits. Moreover, our implementation exhibits breakeven performance, with some instances achieving qubit lifetimes comparable to or slightly exceeding that of our trapped-ion qubits. We use a novel implementation of the optical-metastable-ground (OMG) architecture for addressable mid-circuit measurement and reset, which enables us to perform these experiments without any ion transport or dedicated coolant ions, requirements that typically consume a large fraction of the runtime or ion count of trapped-ion quantum computers.
ER -