Computing with many encoded logical qubits beyond break-even
Abstract
High-rate quantum error correcting (QEC) codes encode many logical qubits in a given number of physical qubits, making them promising candidates for quantum computation. Implementing high-rate codes at a scale that both frustrates classical computing and improves performance by encoding requires both high fidelity gates and long-range qubit connectivity -- both of which are offered by trapped-ion quantum computers. Here, we demonstrate computations that outperform their unencoded counterparts in the high-rate iceberg quantum error detecting (QED) and two-level concatenated iceberg QEC codes, using the 98-qubit Quantinuum Helios trapped-ion quantum processor. Utilizing new gadgets for encoded operations, we realize this "beyond break-even" performance with reasonable postselection rates across a range of fault-tolerant (FT) and partially-fault-tolerant (pFT) component and application benchmarks with between and logical qubits. These benchmarks include FT state preparation and measurement, QEC cycle benchmarking, logical gate benchmarking, GHZ state preparation, and a pFT quantum simulation of the three-dimensional model of quantum magnetism. Additionally, we illustrate that postselection rates can be suppressed by increasing the code distance via concatenation. Our results represent state-of-the-art logical component and state fidelities and provide evidence that high-rate QED/QEC codes are viable on contemporary quantum computers for near-term beyond-classical-scale computation.
Cite
@article{arxiv.2602.22211,
title = {Computing with many encoded logical qubits beyond break-even},
author = {Shival Dasu and Matthew DeCross and Andrew Y. Guo and Ali Lavasani and Jan Behrends and Asmae Benhemou and Yi-Hsiang Chen and Karl Mayer and Chris N. Self and Selwyn Simsek and Basudha Srivastava and M. S. Allman and Jake Arkinstall and Justin G. Bohnet and Nathaniel Q. Burdick and J. P. Campora and Alex Chernoguzov and Samuel F. Cooper and Robert D. Delaney and Joan M. Dreiling and Brian Estey and Caroline Figgatt and Cameron Foltz and John P. Gaebler and Alex Hall and Craig A. Holliman and Ali A. Husain and Akhil Isanaka and Colin J. Kennedy and Yuga Kodama and Nikhil Kotibhaskar and Nathan K. Lysne and Ivaylo S. Madjarov and Michael Mills and Alistair R. Milne and Brian Neyenhuis and Annie J. Park and Anthony Ransford and Adam P. Reed and Steven J. Sanders and Charles H. Baldwin and David Hayes and Ben Criger and Andrew C. Potter and David Amaro},
journal= {arXiv preprint arXiv:2602.22211},
year = {2026}
}