Coogee '26 Talks - Alex Cowtan (Xanadu)

Coogee '26 Talks - Alex Cowtan (Xanadu)

by Alex Cowtan

Formal & Physical Sciences Computing & Cybersecurity UYComputer scienceUYXNatural computing
🎙 Alex Cowtan 👥 137 📅 February 18, 2026 ⏱ 59 min 👁 166 📄 original study 🧭 2026-08-16
Available in: English (current) Français

Keywords

quantum LDPC codessurgeryfault tolerancemapping conesspace-time volume

Summary

Alex Cowtan presents a talk on reducing the spacetime overhead of quantum LDPC code surgery by eliminating idling time between rounds. He introduces a formalism using mapping cones on 4-term fault complexes to capture the spacetime volume of sequential surgery operations. He proves conditions under which idling is unnecessary and only O(1) rounds are sufficient, based on properties of ancilla systems and local-testability of the code. The talk covers the basics of lattice surgery, mapping cones, and fault complexes, and discusses the importance of meta-checks for fast surgery. He emphasizes the need to consider space-time codes and fault complexes to reason about the full volume. The talk is technical and aimed at researchers in quantum error correction.

117 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk provides valuable insights into reducing the time overhead of quantum LDPC surgery, a critical issue for practical quantum computing. The argumentation is rigorous, building on established concepts like mapping cones and fault complexes. The speaker clearly explains the formalism and the conditions for eliminating idling, supported by proofs and references to prior work. The talk is well-structured and the technical depth is appropriate for an expert audience.

Scientific Rigor, Source Quality, Title Accuracy

The talk is based on a paper co-authored with Sunny Dom and Ted Yoder, and references work by the Iceberg team on fast surgery. The speaker also mentions prior work by others in the field. The title is generic and does not reflect the specific content, but the description provides a clear summary. The talk appears scientifically rigorous, with a clear methodology and results.

148 words

Title / Content Match

The title 'Coogee '26 Talks - Alex Cowtan (Xanadu)' is generic and does not reflect the specific topic of the talk, which is about performing quantum code surgery without idling. The description provides more detail.

Quality & Reliability

8/10

The talk presents original research on quantum LDPC code surgery, with a clear formalism and proofs. The speaker is a researcher at Xanadu, a quantum computing company. The content is technical and appears rigorous, but the video is a conference talk and not peer-reviewed.

Key Moments

Markers derived by PSI from the transcript: the creator did not define chapters.

Cited Sources

  • Paper on surgery with LDPC codes (October 2025) — The talk is based on the appendix of this paper, joint work with Sunny Dom and Ted Yoder.
  • Iceberg team's fast surgery paper — Mentioned as a recent work on fast surgery with meta-checks.

Concurring Sources

Contribution & Novelties

The talk presents a novel formalism for analyzing the spacetime volume of quantum LDPC surgery using mapping cones and fault complexes. It provides conditions under which idling between surgery rounds can be eliminated, reducing time overhead. This is an original contribution to the field of fault-tolerant quantum computing.

Pour aller plus loin :

78 words

Radar Profile

The radar profile shows high scores in technical level and information quantity, indicating a dense, expert-level talk. The lower score in information quality relative to quantity suggests that while the talk is rich in content, some parts may be less accessible or well-explained.

Reliability 8/10

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