Breakeven demonstration of quantum low-density parity-check codes

• URL: http://arxiv.org/abs/2606.06455v1
• Date: Thu, 04 Jun 2026 17:49:27 GMT
• Title: Breakeven demonstration of quantum low-density parity-check codes
• Abstract summary: We leverage the flexibility of a trapped-ion quantum computer to demonstrate nine quantum error-correcting codes.<n>With a qLDPC code encoding 4 logical qubits into 18 physical qubits, we achieve a logical error rate up to $9times$ better than a previous demonstration.<n>Our implementation exhibits breakeven performance, with some instances achieving qubit lifetimes comparable to or slightly exceeding that of our trapped-ion qubits.
• Score: 0.8910173568215413
• License: http://creativecommons.org/licenses/by/4.0/
• 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 $9\times$ 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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