# How To Make Quantum Algorithms Cheaper | Craig Gidney on Magic-State Factories, Resource Estimates

Page: https://stenobird.com/podcast/632nm-6933948/how-to-make-quantum-algorithms-cheaper-craig-gidney-on-magic-state-factories-resource-estimates
Text version: https://stenobird.com/podcast/632nm-6933948/how-to-make-quantum-algorithms-cheaper-craig-gidney-on-magic-state-factories-resource-estimates.md
Podcast: [632nm](https://stenobird.com/podcast/632nm-6933948)
Published: 2026-03-27T15:00:00+00:00
Episode link: https://share.transistor.fm/s/e45f1906
Audio file: https://media.transistor.fm/e45f1906/7d970070.mp3
Processing state: not_requested
JSON: https://stenobird.com/v1/public/podcasts/632nm-6933948/episodes/how-to-make-quantum-algorithms-cheaper-craig-gidney-on-magic-state-factories-resource-estimates
Duration seconds: 7427

## Resource

How do you actually make quantum algorithms work on real hardware? Build your own quantum circuits in Crumble: https://algassert.com/crumble In this episode, we speak with Craig Gidney of Google Quantum AI, whose work focuses on the practical realities of building fault-tolerant quantum computers. Gidney explains how seemingly small implementation choices, like how you perform arithmetic, can dominate the cost of entire quantum algorithms. We explore why factoring small numbers like 15 in Shor's algorithm can be misleadingly easy, and why scaling to larger numbers requires dramatically more resources due to operations like modular multiplication. He breaks down how quantum circuits are often dominated by classical reversible logic, and why optimizing these routines is critical for making quantum computing viable. The conversation covers quantum error correction, including why T gates are especially expensive, how magic state factories works, and how different hardware architectures change what “cost” even means. Gidney also explains how resource estimates for breaking cryptography have dropped by orders of magnitude and what drove those improvements. We also dive into the tools he built, including Stim, Quirk, and Crumble, which help researchers simulate noise, visualize circuits, and track how errors propagate through complex systems. Gidney shares his unconventional path into the field, the role of intuition and tooling in discovery, and how software engineering shapes modern quantum research. Whether you’re interested in quantum computing, error correction, cryptography, or the engineering challenges behind scalable quantum systems, this episode offers a clear and grounded look at what it really takes to turn quantum algorithms into reality. Follow us for more techn…

## Actions

- request_transcript: `POST https://stenobird.com/v1/public/podcasts/632nm-6933948/episodes/how-to-make-quantum-algorithms-cheaper-craig-gidney-on-magic-state-factories-resource-estimates/transcription-requests` — Idempotently request low-priority transcript generation for this episode.
- read_markdown: `GET https://stenobird.com/podcast/632nm-6933948/how-to-make-quantum-algorithms-cheaper-craig-gidney-on-magic-state-factories-resource-estimates.md` — Read the agent-friendly Markdown representation of this episode resource.

A page view does not enqueue transcription. Agents should invoke `request_transcript` explicitly when they need this episode processed.

## Transcript

Full transcripts are not published on public pages unless there is a clear rights basis.