"Below Threshold Quantum Error Correction", Alexandre Bourassa, Senior Research Scientist, Google AI

"Below Threshold Quantum Error Correction", Alexandre Bourassa, Google Quantum, AI

Abstract: Quantum error correction (QEC) is critical for achieving useful quantum computers, since it allows us to combine many noisy physical qubits into one high-quality logical qubit with exponentially decreasing logical error rate. In this talk, we will discuss Google’s latest error correction results where we achieved below threshold surface code performance with logical qubits at distances=(3, 5, 7) and error suppression factor of 2.14 [1]. We also report the ability to decode QEC experiments in real-time for up to 1 million rounds, and we show a 10,000x reduction in the rare correlated errors by measuring the repetition code in the very low error regime. Additionally, we will discuss our recent color code results [2] and QEC experiments beyond memory. Ultimately, our results show device performance that, if scaled, could realize the operational requirements of large-scale fault-tolerant quantum algorithms. [1] Google Quantum AI and Collaborators. Quantum error correction below the surface code threshold. Nature 638, 920–926 (2025) [2] N. Lacroix*, A. Bourassa* et al. Scaling and logic in the color code on a superconducting quantum processor, arXiv:2412.14256 (Dec 2024)

Bio: Alexandre Bourassa is a Senior Research Scientist at Google Quantum AI working on building a scalable quantum computer based on superconducting qubits. Alex’s current role focuses on implementing quantum error correction experiments on hardware. Before joining Google, he also worked with other quantum systems including optomechanics, NV centers in diamonds, and defect centers in semiconductor material.