Individually Addressed Logical Pauli Measurements by QLDPC Surgery on a Trapped Ion Quantum Computer
Abstract
Quantum low-density parity check (QLDPC) codes may lead to order-of-magnitude reductions in the qubit overhead required for fault-tolerant quantum computation. Achieving this improved overhead requires logical operations that selectively address individual logical qubits encoded within multi-qubit code blocks. Recently proposed architectures achieve this through QLDPC surgery, in which non-destructive Pauli measurements are performed using ancillary ''gadget'' systems transiently entangled with the code block, generalising lattice surgery. Here we implement QLDPC surgery on a [[10,2,3]] generalised bicycle code using Quantinuum's H2-2 trapped ion processor. A single-round surgery measurement using seven gadget qubits measures the X̅1 operator with a 0.72 [0.32, 1.41]% (95% credible interval) error rate and agrees with subsequent transversal measurement with 1.03 [0.60, 1.65]% error. Decoding across three rounds of syndrome extraction suppresses the gadget measurement error, reducing the error rate to below 0.26%. The syndrome after surgery confirms return to the code space and the unaddressed ''spectator'' qubit is preserved with error 0.21 [0.04, 0.67]% during the three-round measurement. We further demonstrate composition of conjugate basis gadgets by sequentially measuring X̅1 then Z̅2, reusing the gadget qubits, and obtain a 1.12 [0.60, 1.94]% error in the Z̅2 measurement. These results constitute a hardware validation of the generalised surgery primitive underlying Pauli-based computing for QLDPC architectures.
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BibTeX
@misc{luthra2026individually,
title = {{Individually Addressed Logical Pauli Measurements by QLDPC Surgery on a Trapped Ion Quantum Computer}},
author = {Surabhi Luthra and Alex Owens},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.39067},
eprint = {2610.39067},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.39067},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Individually Addressed Logical Pauli Measurements by QLDPC Surgery on a Trapped Ion Quantum Computer
AU - Surabhi Luthra
AU - Alex Owens
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.39067
UR - https://arxiv.org/abs/2610.39067
AB - Quantum low-density parity check (QLDPC) codes may lead to order-of-magnitude reductions in the qubit overhead required for fault-tolerant quantum computation. Achieving this improved overhead requires logical operations that selectively address individual logical qubits encoded within multi-qubit code blocks. Recently proposed architectures achieve this through QLDPC surgery, in which non-destructive Pauli measurements are performed using ancillary ''gadget'' systems transiently entangled with the code block, generalising lattice surgery. Here we implement QLDPC surgery on a [[10,2,3]] generalised bicycle code using Quantinuum's H2-2 trapped ion processor. A single-round surgery measurement using seven gadget qubits measures the X̅_1 operator with a 0.72 [0.32, 1.41]% (95% credible interval) error rate and agrees with subsequent transversal measurement with 1.03 [0.60, 1.65]% error. Decoding across three rounds of syndrome extraction suppresses the gadget measurement error, reducing the error rate to below 0.26%. The syndrome after surgery confirms return to the code space and the unaddressed ''spectator'' qubit is preserved with error 0.21 [0.04, 0.67]% during the three-round measurement. We further demonstrate composition of conjugate basis gadgets by sequentially measuring X̅_1 then Z̅_2, reusing the gadget qubits, and obtain a 1.12 [0.60, 1.94]% error in the Z̅_2 measurement. These results constitute a hardware validation of the generalised surgery primitive underlying Pauli-based computing for QLDPC architectures.
ER -